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Dietary intake of lead by children and adults from Germany measured by the duplicate method
International Journal of Hygiene and Environmental Health
Int. J. Hyg. Environ. Health 206, 493 ± 503 (2003) ¹ Urban & Fischer Verlag http: // www.urbanfischer.de/journals/intjhyg
Dietary intake of lead by children and adults from Germany measured by the duplicate method Michael Wilhelma , J¸rgen Wittsiepea, Petra Schreya, Christiane Feldmanna, Helga Idelb a b
Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum, Bochum, Germany Institute of Hygiene, Heinrich-Heine-University D¸sseldorf, D¸sseldorf, Germany
Received March 12, 2003 ¥ Revision received June 30, 2003 ¥ Accepted July 1, 2003
Abstract The dietary lead intake was studied among children and adults from Germany. Two different age groups of children (A: 1.8, 1.3 ± 3.0 years, B: 3.8, 1.8 ± 5.2 years) and one group of adults (D: 40.9, 24 ± 64 years) were from the highly industrialized Ruhr district and one group of children from the North Sea island Amrum (C: 3.9, 1.5 ± 5.3 years). A total of 229 duplicate food portions were collected from 49 individuals between December 1994 and May 1995. Sampling period for each participant was either 3 (groups B and D) or 7 days (groups A and C). Lead levels in duplicate samples were measured by electrothermal atomic absorption spectrometry. The lead intakes (median, range) for the different groups were as follows: Group A: 0.21 (0.05 ± 1.5) mg/(kg bw ¥ day), group B: 0.68 (0.06 ± 1.6) mg/(kg bw ¥ day), group C: 0.29 (0.04 ± 1.6) mg/(kg bw ¥ day) and group D: 0.26 (0.07 ± 0.83) mg/(kg bw ¥ day). No value exceeded the provisional tolerable weekly intake (PTWI) of 25 mg/(kg bw ¥ week) proposed by the WHO. The median and maximum of the different groups amounted to 7.2 ± 16% and 16 ± 36% of the PTWI, respectively. It is concluded that health risks due to dietary lead intake seem to be low in Germany. Key words: Lead ± dietary intake ± duplicate study ± children ± infants ± adults ± provisional tolerable weekly intake ± PTWI ± Germany
Introduction Despite successful international programs geared to lower the level of lead in the environment, human exposure to lead remains of concern to public health (WHO, 1995). This is especially true for children, since epidemiological and experimental data reveal adverse health effects from lead at lower levels of lead exposure (WHO 1995, Altmann et al. 1998, Walkowiak et al. 1998, Markowitz 2000).
Food is the major source of lead exposure in the general non-smoking population, and children are most susceptible to lead. Compared with adults they need more energy and water related to their body weight. Lead absorption occurs more readily in a child compared to an adult and the child's development is very vulnerable to lead. Estimates of health risks due to dietary lead intake are periodically
Corresponding author: Prof. Dr. Michael Wilhelm, Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum, Universit‰tsstr. 150, D-44801 Bochum, Germany. Fax: 49 234 321 4199, E-mail: [email protected]
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carried out and compared to the provisional tolerable weekly intake (PTWI) of 25 mg/(kg bw ¥ week) given by the FAO/WHO (WHO 1993). For this purpose the use of the duplicate method is especially suitable and has been successfully applied by our working group in several studies (Schrey et al. 1998, Wilhelm et al. 1995a, 1995b, 2002a, 2002b, 2003, Wittsiepe et al. 2001, 2003). In our previous study (sampling period 1988 ± 89) with children living in an industrial area of Germany (Duisburg, North Rhine-Westphalia) we calculated a weekly lead intake of 5.6 mg/(kg bw ¥ week) which corresponds to 22.4% of the PTWI (Wilhelm et al. 1995b). The maximum daily lead intake amounted to 72.1% of the PTWI when converted into daily values. In the present study, we report the results on lead dietary intake from our German duplicate studies, in which samples were collected in 1994 and 1995. The study groups comprised of children at different ages as well as one group of adults. Additionally, one group of children each from an industrial area and a remote area were included. Through this grouping, we wanted to find out if there are differences in the dietary lead intake between children and adults, between children at different ages as well as between children from a rural and an industrialized region. Finally, the results are compared with our study performed in 1988 ± 89 and with data from the literature. Results on the cadmium dietary intake of the same study groups have been reported recently (Wilhelm et al. 2002a) and results concerning the dietary intake of lead, cadmium, copper and zinc of children from the remote area have been published by Schrey et al. (2000).
Materials and methods Participants and study design Daily duplicate food portions (n 229) were collected from 49 individuals between December 1994 and May 1995. The study was undertaken in the Ruhr district as well as on the North Sea island Amrum. The Ruhr district is a highly industrialized area of North Rhine-Westphalia, Germany. The North Sea island Amrum is a remote area of Germany. Participants were children aged between 1.3 and 5.2 years and adults aged between 24 and 64 years, divided into four groups. Details referring to the groups are summarized in Table 1. A short medical check-up revealed no acute or chronic illnesses. All participants consumed a standard diet. None of the participants was on a special diet and none was vegetarian. The dietary lead intakes were measured by the duplicate method, according to the WHO-Guidelines (WHO 1985). Daily duplicate portions of all consumed food, beverages and snacks were collected in precleaned containers. The participants or their parents kept a food diary in which the kind, art of preparation and amount of the food ingested by their children was entered. As lead in tap water may be an important source of lead exposure and of contamination of food, tap water samples were also collected. Water samples were obtained from the taps from which the subjects normally draw water for cooking and drinking purposes. Sampling was carried out following overnight stagnation in the water pipe. Analytical procedure The food samples were collected by us each day, weighed, homogenized, lyophilized, and frozen at 20 8C. About 500 ± 600 mg of the lyophilisate were weighed in Teflon tubes (Microwave Laboratory Systems GmbH). After addition of 2 ml HNO3 (p. a., 65 %, Merck) and 1 ml H2O2 (p. a., 30 %, Merck) the samples were digested with a microwave system (MLS 1200 mega, Microwave Laboratory Systems GmbH). The temperature-powerprogram was: 2 min, 200 W; 1 min 0 W; 2 min, 350 W; 1 min 0 W; 2 min 450 W; 1 min 0 W; 3 min 550 W. The analysis was carried out by electrothermal atomic absorption spectrometry (Zeeman 3030 with HGA 600, Perkin-
Table 1. Summarized data on age, sex, place of residence, number of sampling days, and number of duplicate samples with respect to the four groups participating in the German duplicate study (sampling period December 1994 to May 1995). Group
Number of participants
A
7
B
14
C
14
D
14
a
Age [years] (mean, range) 1.8 1.3 ± 3.0 3.8 1.8 ± 5.2 3.9 1.5 ± 5.1 41 24 ± 64
Number of females (f) and males (m)
Place of residence
Number of sampling days
Number of duplicates
4 f; 3 m
Ruhr district
7
47a
7 f; 7 m
Ruhr district
3
42
7 f; 7 m
Amrum
7
98
7 f; 7 m
Ruhr district
3
42
2 samples were excluded from the study due to incomplete sampling.
Dietary lead intake in Germany Elmer). Analytical conditions are described in detail by Wilhelm et al. (1989). The detection limit for lead was 7.6 mg/kg dry weight. Results lower than the detection limit were estimated by substituting one-half the detection limit. The accuracy of the method was confirmed by analyzing reference materials EQC Sample No. 965 B (National Food Administration, Sweden) and HDP-reference material (Laboratory of Food Chemistry, Food Research Institute, Agricultural Center of Finland). The analyzed values were within the certified reference range. The laboratory participated successfully in an interlaboratory quality control study, organized by the National Food Administration, Sweden. In addition, our lab was reference laboratory for the establishment of certified concentrations of heavy metals in diet reference materials (Jorhem et al. 1995). All collection materials were rinsed with diluted nitric acid. Prior to sampling, the vessels for tap water sampling were prepared with 200 ml nitric acid (65%, suprapur, Merck, Darmstadt, Germany). Analysis of the water samples was performed according to German standard methods (DEV 1981). The limit of detection of lead in drinking water was 0.2 mg/l. For quality control, the standard reference material 1643d from the National Institute of Standards and Technology in Gaithersburg, Maryland (U. S. A.), was used. Lead levels lower than the detection limit were estimated by substituting one-half the detection limit. Calculation of dietary intake and statistics On the basis of the measured concentrations in the food duplicates the daily dietary intake of lead was calculated. The weekly intakes were obtained by adding the seven daily intakes from each individual. In cases where sampling periods amounted only 3 days, weekly intake was calculated as follows: sum of the 3 daily intakes 7³3. The intake rates were additionally related to the body weight of the children and to their body surface area. The body surface area was calculated by using the equation of DuBois and DuBois: body surface area [cm2] 71.84 weight [kg]0.425 height [cm]0.725 (Schmidt and Thews 1990). Differences between groups were tested for statistical significance with analysis of variance (ANOVA) and the `Mann-Whitney U-test'. The correlations were done using the Pearson Product-Moment Correlation. All data
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were analysed using the statistical software ™Statistica∫ 5.5 or 6 (StatSoft, Inc., Tulsa, OK, USA).
Results In Tables 2 to 4 the basic statistical data of the concentrations of the food duplicates as well as the calculated rates of the dietary intakes for the four groups of investigations are shown. Comparison of the dietary lead intake [mg/(kg bw ¥ day)] of the four groups is shown in Figure 1. Lead levels of the food duplicates (median) ranged between 12.0 and 45.9 mg/kgdry weight. Lead concentrations of 14 samples (31.1%) of group A, one sample of group B (2.4%) and 22 (22.5%) of group C were below the detection limit. Lead concentrations of duplicate samples of the small children from the industrialized area (group A) and of children from the North Sea island (group C) were lower compared with those of children (group B) and adults (group D) from the industrialized area (P <
Fig. 1. Comparison of the dietary lead intake [mg/(kgbw ¥ day)] of the four study groups from Germany. Boxplots: (A) small children, (B) children and (D) adults from the industrialized Ruhr district and (C) children living on the North Sea island Amrum.
Table 2. Lead concentrations [mg/kgdw] in the food duplicates.
Group A Group B Group C Groups A B C Group D
N
N0
MIN
Median
P 90
P 95
MAX
AM
SD
GM
47 42 98 187 42
14 1 22 37 0
3.8 3.8 3.8 3.8 12.5
12.0 41.0 18.7 20.1 45.9
41.2 65.2 45.3 52.4 96.2
50.0 82.7 61.1 64.8 99.5
98.7 106.3 92.0 106.3 114.6
18.7 40.5 22.4 25.6 52.3
17.9 21.9 17.6 20.3 26.9
12.6 34.2 15.9 17.8 45.6
CI of GM 9.6 28.0 13.2 15.6 38.4
16.5 41.8 19.1 20.3 54.1
AM arithmetic mean; CI 95%-confidence interval; dw dry weight; GM geometric mean; MAX maximum; MIN minimum; N number of samples; N0 number of samples below the detection limit; values given are one-half of the detection limit; P percentile; SD standard deviation.
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Table 3. Calculated weekly lead intake rates. N
MIN
Median
P 90
P 95
MAX
AM
SD
GM
CI of GM
Pb (mg/week) Group A Group B Group C Groups A B C Group D
7 14 14 35 14
9.0 19.2 10.0 9.0 54.7
16.9 69.1 31.1 48.7 166.6
59.9 141.8 85.3 98.2 283.3
59.9 150.7 86.4 141.8 611.8
59.9 150.7 86.4 150.7 611.8
25.6 80.2 40.3 53.3 185.0
18.1 36.4 24.4 36.3 136.0
21.2 71.9 34.1 41.8 155.0
11.6 53.3 23.9 32.3 110.0
38.6 97.0 48.6 53.9 218.0
Pb [mg/(kgbw ¥ week)] Group A Group B Group C Groups A B C Group D
7 14 14 35 14
0.8 1.3 0.6 0.6 0.7
1.8 4.0 2.1 3.0 2.5
4.1 8.1 4.6 6.1 4.6
4.1 8.9 5.1 8.1 7.5
4.1 8.9 5.1 8.9 7.5
2.1 4.7 2.4 3.3 2.6
1.2 2.1 1.3 2.0 1.7
1.8 4.3 2.1 2.7 2.2
1.0 3.2 1.5 2.2 1.5
3.1 5.7 2.9 3.4 3.1
Pb [mg/(m2bsa ¥ week)] Group A Group B Group C Groups A B C Group D
7 14 14 35 14
18.8 31.5 15.5 15.5 30.6
37.6 95.4 49.7 76.1 86.6
95.5 195.5 113.0 147.8 167.6
95.5 209.5 129.0 195.5 313.7
95.5 209.5 129.0 209.5 313.7
48.3 115.0 59.2 79.4 101.0
27.8 49.3 32.4 48.6 70.8
41.8 105.0 51.3 65.5 85.1
24.4 79.4 36.8 52.3 60.4
71.6 138.0 71.5 82.0 120.0
AM arithmetic mean; bsa body surface area; bw body weight; CI 95%-confidence interval; GM geometric mean; MAX maximum; MIN minimum; N number of samples; P percentile; SD standard deviation.
Table 4. Daily lead intake rates. N
MIN
Median
P 90
P 95
MAX
AM
SD
GM
Pb (mg/day) Group A Group B Group C Groups A B C Group D
47 42 98 187 42
0.6 0.9 0.6 0.6 4.5
2.7 11.7 4.6 5.0 17.8
7.3 22.2 11.3 14.2 40.2
11.2 24.7 15.2 16.9 50.5
19.6 26.0 29.4 29.4 63.2
3.8 11.5 5.8 6.6 23.5
3.8 6.3 5.1 5.8 14.4
2.5 9.5 3.9 4.3 19.5
Pb [mg/(kgbw ¥ day)] Group A Group B Group C Groups A B C Group D
47 42 98 187 42
0.05 0.06 0.04 0.04 0.07
Pb [mg/(m2bsa ¥ day)] Group A Group B Group C Groups A B C Group D
47 42 98 187 42
1.2 1.5 1.0 1.0 2.8
0.21 0.68 0.29 0.35 0.26 4.9 16.2 6.9 8.2 9.8
0.71 1.27 0.59 0.84 0.62 16.0 28.5 15.1 20.6 21.9
0.76 1.39 0.85 0.98 0.70 17.8 32.9 21.0 25.4 29.4
1.51 1.63 1.58 1.63 0.83 35.7 38.4 40.0 40.0 32.4
0.31 0.68 0.35 0.41 0.34 7.2 16.4 8.5 9.9 13.0
0.28 0.36 0.28 0.33 0.21 6.5 8.6 7.1 8.1 7.8
0.22 0.57 0.24 0.29 0.28 5.0 13.9 5.9 6.9 10.7
CI of GM 1.9 7.7 3.3 3.7 15.9 0.17 0.46 0.20 0.25 0.22 3.8 11.3 4.9 6.0 8.7
3.3 11.8 4.8 5.0 23.8 0.28 0.70 0.29 0.33 0.34 6.5 17.0 7.1 7.9 13.1
AM arithmetic mean; bsa body surface area; bw body weight; CI 95%-confidence interval; GM geometric mean; MAX maximum; MIN minimum; N number of samples; P percentile; SD standard deviation.
0.001). In the industrialized area lead levels of food duplicates of adults were higher than those of group B children (P 0.03). With respect to the daily lead intake (mg/day) the median values ranged from 2.7 to 17.8 for the four groups. Dietary lead intake was high in children from the industrialized Ruhr district (group B 11.7 mg/d) compared with the other children (2.7 ±
4.6 mg/day) (P < 0.001). Dietary lead intake (mg/d) of adults was higher than that of children (P < 0.001). Lead intake related to body weight or body surface was low for the small children (P < 0.001) compared with the other groups. The lead intake for the children from of the industrialized Ruhr district was higher (P < 0.001) compared with the other groups (Figure 1). There was no difference (P 0.43) in the
Dietary lead intake in Germany
Fig. 2. Variation of the daily lead intake [mg/(kgbw ¥ day)] within the study period for each group. Group (A) small children, (B) children and (D) adults from the industrialized Ruhr district and (C) children living on the North Sea island Amrum.
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Table 5. Consumption of fish and drinking water on the basis of the food diaries. Group
N
N1
Min
P 10
A B C
7 14 14
4 4 11
0 0 0
0 0 0
A B C
7 14 14
6 11 7
0 0 0
Median
Fish consumption (g/d) 6.4 0.0 4.2
P 90
Max
AM
SD
27.7 19.4 16.6
27.7 46.1 29.1
7.1 6.1 7.6
9.8 13.2 8.5
Drinking water consumption (g/d) 0 83.9 315.3 0 50.0 133.3 0 7.1 185.7
315.3 216.7 452.9
136.1 60.8 73.7
125.5 60.6 128.1
AM arithmetic mean; Maxmaximum; Min minimum; N number of participants; N1 number of participants with consumption in general; P percentile; SD standard deviation.
Table 6. Comparison of the dietary intake of lead by the four different groups with the FAO/WHO PTWI (Provisional tolerable weekly intake). Small children from Ruhr district
With With With With
With With With With 1)
the the the the
the the the the
Children from Ruhr district
Children from Amrum
Adults from Ruhr district
mean [%] median [%] geometric mean [%] maximum [%]
Comparison on the basis of the weekly intake PTWI [25 mg/(kgbw ¥ week)] 8.4 19 7.2 16 7.2 17 16 36
9.6 8.4 8.4 20
10 10 8.8 30
mean [%] median [%] geometric mean [%] maximum [%]
Comparison on the basis of daily intake PTDI 1) [3.57 mg/(kgbw ¥ day)] 8.7 20 5.9 19 5.9 16 42 44
9.8 8.1 6.7 44
9.5 7.3 7.8 23
PTDI provisional tolerable daily intake.
lead intake between the small children from the Ruhr district (group A) and those from the North Sea island (group C). The variation of the daily dietary lead intake within the study period for each group is shown in Figure 2. Analysis of variance showed that lead intake was not influenced by the day of sampling. Lead levels in the tap water samples from the industrialized district were low (median 0.64, range < 0.2 ± 2.8 mg/l). The higher lead levels from households in Amrum (median 4.8, range 3.2 ± 11.8 mg/l) are probably due the fact that most of the participants from Amrum obtained their drinking water from private wells. However, in comparison with the guideline value for lead in drinking water of 10 mg/l as proposed by the WHO and in future also legal in Europe (until 2003, 40 mg/l), we found no severe lead contamination of the drinking water. This is especially true, since the sampling procedure in this study (`first ± draw' sample) is not representative for the average lead level in tap water.
Testing individual correlations for each group, we found no correlation between the dietary lead intake and the age of the participants. Lead intake was not influenced by the gender of the participants. An analysis of the food diaries for the consumption of fish and drinking water is shown in Table 5 for the children groups A to C. Although children from Amrum ate more often fish there were no differences in the total consumption of fish (g/d) between the groups A to C (Kruskal-Wallis Test, P 0.28). No differences were also found with regard to the consumption of drinking water [g/d] under the same test conditions (P 0.21). Histograms of the daily lead intakes [mg/(kg bw ¥ day)] are shown in Figure 3 and compared with the PTWI converted into a daily dose 3.57 mg/(kg bw ¥ day). None of the dietary lead intake values exceeded the tolerable intake. The comparison of the dietary lead intake with the FAO/WHO PTWI is summarized in Table 6. The median values ranged from 7.2 to 16% for the different groups related to
Dietary lead intake in Germany
Fig. 3. Histograms of the daily dietary intake of lead [mg/(kgbw ¥ day)] by the four study groups from Germany in comparison to the FAO/WHO PTWI* (Provisional Tolerable Weekly Intake) of 25 mg/(kgbw ¥ week) converted into daily intake. (A) small children, (B) children and (D) adults from the industrialized Ruhr district and (C) children living on the North Sea island Amrum.
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the weekly intake and between 5.9 and 19% related to the daily intake of the PTWI. The corresponding maximum values ranged between 16 ± 36% and 23 ± 44% of the PTWI respectively. The highest percentage of PTWI was observed among the children study group of the industrialized Ruhr district (group B). The respective values of the four groups (mean, median and geometric mean) declined in the following order: children Ruhr district > adults Ruhr district > children Amrum > small children Ruhr district.
Discussion This study shows data on the dietary lead intake for children and adults living in Germany related to food samples collected between December 1994 to May 1995. A comparison with data from the literature for children is given in Table 7 and for adults in Table 8. There are only a few other studies on children's dietary lead intake. In general, these data show great variation. This may be due to differences in the study area, the year of the studies, the study type, and statistical analyses, especially with respect to handling the numbers of data below the detection limit. Most results obtained by using the total diet study (e.g. the ™market basket approach∫) show higher values for the lead intake than results obtained by using the duplicate portion technique. However, the median lead dietary intake values of all groups
measured in this study are in the range of other studies (Table 7, Table 8). Assuming that our data is representative for Germany the results show that the German population has a low to moderate dietary lead intake. To evaluate the health risks due to this, our data is compared with the FAO/WHO PTWI. In 1986, JECFA (Joint Expert Committee on Food Additives) established a PTWI of 25 mg/(kg bw ¥ week) for infants and children (WHO 1987). The PTWI was reconfirmed by JECFA in 1993 and extended to all age groups (WHO 1993). It is likely that by comparing our data to the PTWI, health risks of the German population due to dietary lead intake are low (Table 6). However, it has to be considered that some of the health effects associated with children's lead exposure occur at blood lead levels < 100 mg/l without a threshold (WHO 1995, Walkowiak et al. 1998, Canfield et al. 2003). For this reason, US EPA has decided not to develop a reference dose (RfD) for inorganic lead. Additionally, ATSDR (Agency for Toxic Substances and Disease Registry) has not derived MRLs (Minimal Risk Levels) for lead. We found that children living in the industrialized Ruhr region (mean age 1.8 ± 5.2 years; median lead intake 11.7 mg/d and 0.68 mg/(kg bw ¥ day), have a significant higher lead intake compared to small children and to adults living in the Ruhr district as well as compared to children living on the North Sea island Amrum. The higher dietary lead intake of children from the industrial area (group B) compared with those from the rural region (group C) could not be deeply explained. Daily records of the
Table 7. Data from the literature on the dietary lead intake by children published after 1995. Country
Type of study
Germany
24-h food duplicates
Germany
Year of study Age of the participants (mg/d) (years)
2.7 ± 11.7 0.21 ± 0.68
24-h food duplicates2) 1989 ± 1991
12 ± 21
United States
24-h food duplicates
1996 ± 1998
1.3 ± 3.7
5.9 (f) 9.8 (m) 7.6
United States
Total Diet
1990 / 1991
0.5 ± 0.9 2 1.5 ± 3 1±4 4±7 7 ± 10
Eastern Europe India
6-d food duplicates 24-h food duplicates
± 1988 / 1989
± 1986 ± 1994
(f) females, (m) males 1) Arithmetic mean (AM) or geometric mean (GM) or median 2) Daily rations of youth centers
6 ± 11 6 ± 10
1.82 1.87 4.95 10 (f /m) 13 (f /m) 17 (f) 18 (m) ± 16.5
References
[mg/(kgbw ¥ day)]
1.3 ± 5.2
United States 24-h food duplicates The Netherlands Total Diet
1995
Dietary lead intake1)
±
Median This study (range) Median Arnold et al. (1998) Median Melnyk et al. (2000) AM Bolger et al. (1996) AM AM Stanek et al. (1998) AM Brussaard et al. (1996) AM AM
0.21 ±
AM GM
0.20 0.14 ± ±
Gulson et al. (1997) Raghunath et al. (1999)
Dietary lead intake in Germany
501
Table 8. Data from the literature on the dietary lead intake by adults published after 1995. Country
Type of study
Year of study
Dietary lead intake1)
Age of the participants (years)
mg/d
mg/kg
0.26 0.28 (f) 0.24 (m) 0.52 ±
Germany Germany
24-h food duplicates 24-h food duplicates
1995 1996
24 ± 64 20 ± 60
17.8 19 (f /m)
Germany Germany
24-h food duplicates 24-h food-duplicates2)
1990 ± 1991 1989 ± 1991
25 ± 69 61 ± 92
East Asia and South-East Asia3) Japan
24-h food duplicates
1991 ± 1998
women
37 7.5 (f) 12.3 (m) 7 ± 32
24-h food duplicates
1991 ± 1994
France
food duplicates5)
1998 / 1999
United States
Total Diet
1990 / 1991
women 4) / 53.0 ( AM ) general population 25 ± 30 60 ± 65
The Netherlands
Total Diet
1988 / 1989
22 ± 50 50 ± 65
4)
bw
References
d Median AM
This study Seifert and Anke (2000)
Median Median
Becker et al. (1996) Arnold et al. (1998) Ikeda et al. (2000)
±
GM (range) GM
Watanabe et al. (1996)
52
±
AM
Leblanc et al. (2000)
3.28 (f) 4.17 (m) 3.05 (f) 3.46 (m) 28 (f /m) 30 (f) 29 (m)
0.06 (f /m)
AM
Bolger et al. (1996)
0.05 (f /m)
AM
± ±
AM AM
7.1
±
Brussaard et al. (1996)
(f) females, (m) males, AM arithmetic mean 1) Arithmetic mean (AM), geometric mean (GM), median 2) Daily rations of senior centers 3) Including the countries China, Japan, Korea, Philippines, Malaysia, Taiwan, and Thailand 4) Groups of study consisting of non-smoking participants 5) Duplicates of the two most frequently consumed meals identified as breakfast and lunch in mass catering establishments
consumed foods did not show any consumption of items which are typically considered to be lead contaminated or which could have been contributing because of high consumption. Lead in household drinking tap water and consumption of fish could also be excluded as a significant route of lead exposure in this group. Consumption of home grown vegetables or fruits was observed in both groups but was not related to the dietary lead intake. However, it is likely that home grown vegetables and fruits from the industrialized area are more lead contaminated than those from the remote island thus contributing to the higher lead intake. This aspect will be analyzed more detailed in our current duplicate study. In our previous study conducted on children (age 5 ± 8 years) from the Ruhr district during winter and spring 1988 ± 89, the median dietary lead intake was 0.79 mg/(kg bw ¥ day) and 22.1 mg/(m2 bsa ¥ day) (Wilhelm et al., 1995b), therefore higher than the data obtained in the present study (median 0.68 mg/ (kg bw ¥ day) and 16.2 mg/(m2 bsa ¥ day). This may reflect the general reduction of lead in the environment during the last decades. This can be mainly attributed to the reduction of lead in petrol and vehicle fuel and in industrial emissions, which has subsequently led to a reduction of lead in the air, dust
and soils. As a result of successful programs to lower the level of lead in the environment, also mean blood lead levels in the general population decreased over the past twenty years (WHO 1995, ATSDR 1999, Markowitz 2000, Becker et al. 2002, Wilhelm et al. 2002c). The general reduction of lead contamination of the environment is also reflected by lead levels in food as has been reported by authors from various countries (e. g. Bolger et al. 1996, Brussaard et al. 1996, Pirkle et al. 1998, Ysart et al. 2000). This decline of lead levels in food and the rather low contaminations of food is underlined by the German Food Monitoring scheme which is conducted by the Bundesinstitut f¸r gesundheitlichen Verbraucherschutz und Veterin‰rmedizin (BgVV) (BgVV 1995 ± 1999). During 1995 ± 1999 (annually 20 ± 22 food items were tested), maximal permissible or guide levels for lead were only exceeded in samples of a few food items such as paprika-powder and meat of wild boar (BgVV 1995 ± 1999). Clearly declining tendencies of the lead contamination can in particular be observed for those kinds of food which were typically considered to be frequently lead contaminated. For example, different monitoring schemes performed in Germany during the period 1983 ± 1989 showed that the maximal permissible or guide levels for lead were frequently
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exceeded in samples of salad greens, kale, parsley and other herbs as well as in samples of offal from pork, cattle and calf (M¸ller and Weigert 1990). Other potential sources of dietary lead such as lead solder in food cans or beverage cans, tin-coated lead foil capsules on wine-bottles and lead-glazed ceramic ware have been significantly reduced in many countries (Bolger et al. 1996, WHO 1995). Despite the general decrease of the dietary lead intake, it should be kept in mind that there may be still groups at risk with respect to oral lead exposure. These include high level consumers, young infants and children aged 2 ± 4 years who may additionally be exposed to lead by swallowing contaminated airborne dust or soil. To minimize environmental exposure to lead, maximum levels for major contributors to the dietary exposure have been set recently by the European Commission (EC 2001).
Conclusion In conclusion, with regard to the PTWI of 25 mg/ (kgbw ¥ week), a low to moderate dietary intake of lead with amounts (median values for four different groups) between 1.8 and 4.0 mg/(kgbw ¥ week) was found, which corresponds to 7 ± 16% of the PTWI. Therefore, health risks due to the dietary intake of lead seem to be low for children and adults in Germany. This is also true for children and adults living in industrialized areas. Acknowledgements. The authors wish to thank Ursula Budde, Petra Mackrodt and Evelyn Wins for assistance in recruiting volunteers as well as for sampling of duplicate portions, and Annett Hilbig for the analysis of the food diaries.
References Altmann, L., Sveinsson, K., Kramer, U., WeishoffHouben, M., Turfeld, M., Winneke, G. and Wiegand, H.: Visual functions in 6-year-old children in relation to lead and mercury levels. Neurotoxicol Teratol, 20, 9 ± 17 (1998). Arnold, R., Kibler, R. and Brunner, B.: Die aliment‰re Aufnahme von ausgew‰hlten Schadstoffen und Nitrat ± Ergebnisse einer Duplikatstudie in bayerischen Jugend- und Seniorenheimen. Z Ern‰hrungswiss, 37, 328 ± 335 (1998). ATSDR (Agency for Toxic Substances and Disease Registry), U.S. Department of Health and Human Services, Public Health Service: Toxicological profile for lead. http://www.atsdr.cdc.gov/toxprofiles/ tp13.html (1999).
Becker, K., Nˆllke, P., Hermann-Kunz, E., Krause, C., Schenker, D. and Schulz, C.: Umwelt-Survey 1990/ 1991, Band III: Zufuhr von Spurenelementen und Schadstoffen mit der Nahrung (Duplikate und Diet History) in den alten Bundesl‰ndern. WaBoLu-Hefte, edited by Umweltbundesamt ± Institut f¸r Wasser-, Boden- und Lufthygiene, Berlin (1996). Becker, K., Kaus, S., Krause, C., Lepom, P., Schulz, C., Seiwert, M. and Seifert, B.: German Environmental Survey 1998 (GerES III): environmental pollutants in blood of the German population. Int J Hyg Environ Health 205, 297 ± 308 (2002). BgVV (Bundesinstitut f¸r gesundheitlichen Verbraucherschutz und Veterin‰rmedizin, Berlin). http:// www.bgvv.de (1995, 1996, 1997, 1998, 1999). Bolger, P. M., Yess, N. J., Gunderson, E. L., Troxell, T. C. and Carrington, C. D.: Identification and reduction of sources of dietary lead in the United States. Food Addit Contam, 13, 53 ± 60 (1996). Brussaard, J. H., Van Dokkum, W., Van der Paauw, C. G., De Vos, R. H., De Kort, W. L. and Lowik, M. R.: Dietary intake of food contaminants in The Netherlands (Dutch Nutrition Surveillance System). Food Addit Contam, 13, 561 ± 573 (1996). Canfield, R. L., Henderson, C. R., Cory-Slechta, D. A., Cox, C., Jusko, T. A. and Lanphear, B. P.: Intellectual impairment in children with blood lead concentrations below 10 mg per deciliter. N Engl J Med, 348, 1517 ± 1526 (2003). DEV (Deutsches Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung), DIN 38402, WileyVCH Berlin, Beuth, Berlin (1981). EC (European Communities), Commission Regulation No 466/2001 of 8 March 2001: setting maximum levels for certain contaminants in foodstuffs. European Communities, L 77, 1 ± 13 (2001). Gulson, B. L., Mahaffey, K. R., Jameson, C. W., Vidal, M., Law, A. J., Mizon, K. J., Smith, A. J. and Korsch, M. J.: Dietary lead intakes for mother/child pairs and relevance to pharmacokinetic models. Environ Health Perspect, 105, 1334 ± 1342 (1997). Ikeda, M., Zhang, Z. W., Shimbo, S., Watanabe, T., Nakatsuka, H., Moon, C. S., Matsuda-Inoguchi, N. and Higashikawa, K.: Urban population exposure to lead and cadmium in east and south-east Asia. Sci Total Environ, 249, 373 ± 384 (2000). Jorhem, L., Slorach, S., Engman, J., Schˆder, T. and Johansson, M.: The establishment of certified concentrations of thirteen elements in six simulated diet reference materials. National Food Administration Rapport 4/1995, Uppsala, Sweden (1995). Leblanc, J. C., Malmauret, L., Gue¬rin, T., Bordet, F., Boursier, B. and Verger, P.: Estimation of the dietary intake of pesticide residues, lead, cadmium, arsenic and radionuclides in France. Food Addit Contam, 17, 925 ± 932 (2000). Markowitz, M.: Lead poisoning: a disease for the next millennium. Curr Probl Pediatr, 30, 62 ± 70 (2000). Melnyk, L. J., Berry, M. R., Sheldon, L. S., Freeman, N. C. G., Pellizzari, E. D. and Kinman, R. N.: Dietary
Dietary lead intake in Germany exposure of children in lead-laden environments. J Exp Anal Environ Epidemiol, 10, 723 ± 731 (2000). M¸ller, J. and Weigert, P.: Bleigehalte in und auf Lebensmitteln. ZEBS-Hefte, edited by Bundesgesundheitsamt ± Zentrale Erfassungs- und Bewertungsstelle f¸r Umweltchemikalien (Berlin) (1990). Pirkle, J. L., Kaufmann, R. B., Brody, D., Hickman, T., Gunter, E. W. and Paschal, D. C.: Exposure of the U. S. population to lead. 1991 ± 1994. Environ. Health Perspect, 106, 745 ± 750 (1998). Raghunath, R., Tripathi, R. M., Kumar, A. V., Sathe, A. P., Khandekar, R. N. and Nambi, K. S. V.: Assessment of Pb, Cd, Cu and Zn exposures of 6- to 10year-old children in Mumbai. Environ Res, A 80, 215 ± 221 (1999). Schmidt, R. F. and Thews, G. (editors): Physiologie des Menschen. 24th edition, Springer-Verlag, Berlin (1990). Schrey, P., Wittsiepe, J., Mackrodt, P. and Selenka, F.: Human fecal PCDD/F-excretion exceeds the dietary intake. Chemosphere, 37, 1825 ± 1831 (1998). Schrey, P., Wittsiepe, J., Budde, U., Heinzow, B., Idel, H., Wilhelm, M.: Dietary intake of lead, cadmium, copper and zine by children from the North Sea island Amrum. Int J Hyg Environ Health, 203 : 1 ± 9 (2000). Seifert, M. and Anke, M.: Alimentary lead intake of adults in Thuringia/Germany determined with the duplicate portion technique. Chemosphere, 41, 1037 ± 1043 (2000). Stanek, K., Manton, W., Angle, C., Eskridge, K., Kuehneman, A. and Hanson, C.: Lead consumption of 18- to 36-month-old children as determined from duplicate diet collections: Nutrient intakes, blood lead levels, and effects on growth. J Am Diet Assoc, 98, 155 ± 158 (1998). Walkowiak, J., Altmann, L., Kr‰mer, U., Sveinsson, K., Turfeld, M., Weishoff-Houben, M. and Winneke, G.: Cognitive and sensorimotor functions in 6-year-old children in relation to lead and mercury levels: Adjustment for intelligence and contrast sensitivitiy in computerized testing. Neurotoxicol Teratol, 20, 511 ± 521 (1998). Watanabe, T., Nakatsuka, H., Shimbo, S., Iwami, O., Imai, Y., Moon, C. S., Zhang, Z. W., Iguchi, H. and Ikeda, M.: Reduced cadmium and lead burden in Japan in the past 10 years. Int Arch Occup Environ Health, 68, 305 ± 314 (1996). WHO (World Health Organization): GEMS: Global Environmental Monitoring System, Guidelines for the study of dietary intakes of chemical contaminants. WHO Offset Publ, No. 87 (1985). WHO (World Health Organization): Joint FAO/WHO Expert Committee on Food Additives, Toxicological evaluation of certain food additives and contaminants, pp. 223 ± 255. WHO Food Additives Series, No. 21, Cambridge, Cambridge University Press (1987).
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WHO (World Health Organization): Evaluation of certain food additives and contaminants: forty-first report of the Joint FAO/WHO Expert Committee on Food Additives. World Health Organ Tech Rep Ser, No. 837, Geneva (1993). WHO (World Health Organization): Inorganic lead. Environmental Health Criteria 165. WHO, Geneva (1995). Wilhelm, M., Ohnesorge, F. K., Lombeck, I. and Hafner, D.: Uptake of aluminium, cadmium, copper, lead and zinc by human scalp hair and elution of the adsorbed metals. J Anal Toxicol, 13, 17 ± 21 (1989). Wilhelm, M., Lombeck, I., Kouros, B., Wuthe, J. and Ohnesorge, F. K.: Duplicate study on the dietary intake of some metals/metalloids by German children. Part I: Arsenic and mercury. Zentralbl Hyg, 197, 345 ± 356 (in German) (1995a). Wilhelm, M., Lombeck, I., Kouros, B., Wuthe, J. and Ohnesorge, F. K.: Duplicate study on the dietary intake of some metals/metalloids by German children. Part II: Aluminium, cadmium and lead. Zentralbl Hyg, 197, 357 ± 369 (in German) (1995b). Wilhelm, M., Wittsiepe, J., Schrey, P., Budde, U. and Idel, H.: Dietary intake of cadmium by children and adults from Germany using duplicate portion sampling. Sci Total Environ, 285, 11 ± 19 (2002a). Wilhelm, M., Schrey, P., Wittsiepe, J., and Heinzow, B.: Dietary intake of persistent organic pollutants (POPs) by German children using duplicate portion sampling. Int J Hyg Environ Health, 204, 359 ± 362 (2002b). Wilhelm, M., Pesch, A., Rostek, U., Begerow, J., Schmitz, N., Idel, H., Ranft, U.: Concentrations of lead in blood, hair and saliva of German children living in three different areas of traffic density. Sci Total Environ, 297 (1 ± 3), 109 ± 118 (2002c). Wilhelm, M., Wittsiepe, J., Schrey, P. Lajoie-Junge, L. Busch, V.: Dietary intake of arsenic, mercury and selenium by children from a German North Sea island using duplicate portion sampling. J Trace Elem Med Biol, 17 (2), 123 ± 132 (2003) Wittsiepe, J., Schrey, P. and Wilhelm, M.: Dietary intake of PCDD/F by small children with different food consumption measured by the duplicate method. Chemosphere, 43, 881 ± 887 (2001). Wittsiepe, J.; Schrey, P., Wilhelm, M., Begerow, J., Dunemann, L.: Dietary intake of platinum and gold by children from Germany using duplicate portion sampling. J Trace Elem Med Biol, 17 (2), 117 ± 122 (2003). Ysart, G., Miller, P., Croasdale, M., Crews, H., Robb, P., Baxter, M., de L'Argy, C. and Harrison, N., 1997 UK Total Diet Study ± dietary exposures to aluminium, arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, tin and zinc. Food Addit Contam, 17, 775 ± 786 (2000).
Int. J. Hyg. Environ. Health 206, 493 ± 503 (2003) ¹ Urban & Fischer Verlag http: // www.urbanfischer.de/journals/intjhyg
Dietary intake of lead by children and adults from Germany measured by the duplicate method Michael Wilhelma , J¸rgen Wittsiepea, Petra Schreya, Christiane Feldmanna, Helga Idelb a b
Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum, Bochum, Germany Institute of Hygiene, Heinrich-Heine-University D¸sseldorf, D¸sseldorf, Germany
Received March 12, 2003 ¥ Revision received June 30, 2003 ¥ Accepted July 1, 2003
Abstract The dietary lead intake was studied among children and adults from Germany. Two different age groups of children (A: 1.8, 1.3 ± 3.0 years, B: 3.8, 1.8 ± 5.2 years) and one group of adults (D: 40.9, 24 ± 64 years) were from the highly industrialized Ruhr district and one group of children from the North Sea island Amrum (C: 3.9, 1.5 ± 5.3 years). A total of 229 duplicate food portions were collected from 49 individuals between December 1994 and May 1995. Sampling period for each participant was either 3 (groups B and D) or 7 days (groups A and C). Lead levels in duplicate samples were measured by electrothermal atomic absorption spectrometry. The lead intakes (median, range) for the different groups were as follows: Group A: 0.21 (0.05 ± 1.5) mg/(kg bw ¥ day), group B: 0.68 (0.06 ± 1.6) mg/(kg bw ¥ day), group C: 0.29 (0.04 ± 1.6) mg/(kg bw ¥ day) and group D: 0.26 (0.07 ± 0.83) mg/(kg bw ¥ day). No value exceeded the provisional tolerable weekly intake (PTWI) of 25 mg/(kg bw ¥ week) proposed by the WHO. The median and maximum of the different groups amounted to 7.2 ± 16% and 16 ± 36% of the PTWI, respectively. It is concluded that health risks due to dietary lead intake seem to be low in Germany. Key words: Lead ± dietary intake ± duplicate study ± children ± infants ± adults ± provisional tolerable weekly intake ± PTWI ± Germany
Introduction Despite successful international programs geared to lower the level of lead in the environment, human exposure to lead remains of concern to public health (WHO, 1995). This is especially true for children, since epidemiological and experimental data reveal adverse health effects from lead at lower levels of lead exposure (WHO 1995, Altmann et al. 1998, Walkowiak et al. 1998, Markowitz 2000).
Food is the major source of lead exposure in the general non-smoking population, and children are most susceptible to lead. Compared with adults they need more energy and water related to their body weight. Lead absorption occurs more readily in a child compared to an adult and the child's development is very vulnerable to lead. Estimates of health risks due to dietary lead intake are periodically
Corresponding author: Prof. Dr. Michael Wilhelm, Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum, Universit‰tsstr. 150, D-44801 Bochum, Germany. Fax: 49 234 321 4199, E-mail: [email protected]
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carried out and compared to the provisional tolerable weekly intake (PTWI) of 25 mg/(kg bw ¥ week) given by the FAO/WHO (WHO 1993). For this purpose the use of the duplicate method is especially suitable and has been successfully applied by our working group in several studies (Schrey et al. 1998, Wilhelm et al. 1995a, 1995b, 2002a, 2002b, 2003, Wittsiepe et al. 2001, 2003). In our previous study (sampling period 1988 ± 89) with children living in an industrial area of Germany (Duisburg, North Rhine-Westphalia) we calculated a weekly lead intake of 5.6 mg/(kg bw ¥ week) which corresponds to 22.4% of the PTWI (Wilhelm et al. 1995b). The maximum daily lead intake amounted to 72.1% of the PTWI when converted into daily values. In the present study, we report the results on lead dietary intake from our German duplicate studies, in which samples were collected in 1994 and 1995. The study groups comprised of children at different ages as well as one group of adults. Additionally, one group of children each from an industrial area and a remote area were included. Through this grouping, we wanted to find out if there are differences in the dietary lead intake between children and adults, between children at different ages as well as between children from a rural and an industrialized region. Finally, the results are compared with our study performed in 1988 ± 89 and with data from the literature. Results on the cadmium dietary intake of the same study groups have been reported recently (Wilhelm et al. 2002a) and results concerning the dietary intake of lead, cadmium, copper and zinc of children from the remote area have been published by Schrey et al. (2000).
Materials and methods Participants and study design Daily duplicate food portions (n 229) were collected from 49 individuals between December 1994 and May 1995. The study was undertaken in the Ruhr district as well as on the North Sea island Amrum. The Ruhr district is a highly industrialized area of North Rhine-Westphalia, Germany. The North Sea island Amrum is a remote area of Germany. Participants were children aged between 1.3 and 5.2 years and adults aged between 24 and 64 years, divided into four groups. Details referring to the groups are summarized in Table 1. A short medical check-up revealed no acute or chronic illnesses. All participants consumed a standard diet. None of the participants was on a special diet and none was vegetarian. The dietary lead intakes were measured by the duplicate method, according to the WHO-Guidelines (WHO 1985). Daily duplicate portions of all consumed food, beverages and snacks were collected in precleaned containers. The participants or their parents kept a food diary in which the kind, art of preparation and amount of the food ingested by their children was entered. As lead in tap water may be an important source of lead exposure and of contamination of food, tap water samples were also collected. Water samples were obtained from the taps from which the subjects normally draw water for cooking and drinking purposes. Sampling was carried out following overnight stagnation in the water pipe. Analytical procedure The food samples were collected by us each day, weighed, homogenized, lyophilized, and frozen at 20 8C. About 500 ± 600 mg of the lyophilisate were weighed in Teflon tubes (Microwave Laboratory Systems GmbH). After addition of 2 ml HNO3 (p. a., 65 %, Merck) and 1 ml H2O2 (p. a., 30 %, Merck) the samples were digested with a microwave system (MLS 1200 mega, Microwave Laboratory Systems GmbH). The temperature-powerprogram was: 2 min, 200 W; 1 min 0 W; 2 min, 350 W; 1 min 0 W; 2 min 450 W; 1 min 0 W; 3 min 550 W. The analysis was carried out by electrothermal atomic absorption spectrometry (Zeeman 3030 with HGA 600, Perkin-
Table 1. Summarized data on age, sex, place of residence, number of sampling days, and number of duplicate samples with respect to the four groups participating in the German duplicate study (sampling period December 1994 to May 1995). Group
Number of participants
A
7
B
14
C
14
D
14
a
Age [years] (mean, range) 1.8 1.3 ± 3.0 3.8 1.8 ± 5.2 3.9 1.5 ± 5.1 41 24 ± 64
Number of females (f) and males (m)
Place of residence
Number of sampling days
Number of duplicates
4 f; 3 m
Ruhr district
7
47a
7 f; 7 m
Ruhr district
3
42
7 f; 7 m
Amrum
7
98
7 f; 7 m
Ruhr district
3
42
2 samples were excluded from the study due to incomplete sampling.
Dietary lead intake in Germany Elmer). Analytical conditions are described in detail by Wilhelm et al. (1989). The detection limit for lead was 7.6 mg/kg dry weight. Results lower than the detection limit were estimated by substituting one-half the detection limit. The accuracy of the method was confirmed by analyzing reference materials EQC Sample No. 965 B (National Food Administration, Sweden) and HDP-reference material (Laboratory of Food Chemistry, Food Research Institute, Agricultural Center of Finland). The analyzed values were within the certified reference range. The laboratory participated successfully in an interlaboratory quality control study, organized by the National Food Administration, Sweden. In addition, our lab was reference laboratory for the establishment of certified concentrations of heavy metals in diet reference materials (Jorhem et al. 1995). All collection materials were rinsed with diluted nitric acid. Prior to sampling, the vessels for tap water sampling were prepared with 200 ml nitric acid (65%, suprapur, Merck, Darmstadt, Germany). Analysis of the water samples was performed according to German standard methods (DEV 1981). The limit of detection of lead in drinking water was 0.2 mg/l. For quality control, the standard reference material 1643d from the National Institute of Standards and Technology in Gaithersburg, Maryland (U. S. A.), was used. Lead levels lower than the detection limit were estimated by substituting one-half the detection limit. Calculation of dietary intake and statistics On the basis of the measured concentrations in the food duplicates the daily dietary intake of lead was calculated. The weekly intakes were obtained by adding the seven daily intakes from each individual. In cases where sampling periods amounted only 3 days, weekly intake was calculated as follows: sum of the 3 daily intakes 7³3. The intake rates were additionally related to the body weight of the children and to their body surface area. The body surface area was calculated by using the equation of DuBois and DuBois: body surface area [cm2] 71.84 weight [kg]0.425 height [cm]0.725 (Schmidt and Thews 1990). Differences between groups were tested for statistical significance with analysis of variance (ANOVA) and the `Mann-Whitney U-test'. The correlations were done using the Pearson Product-Moment Correlation. All data
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were analysed using the statistical software ™Statistica∫ 5.5 or 6 (StatSoft, Inc., Tulsa, OK, USA).
Results In Tables 2 to 4 the basic statistical data of the concentrations of the food duplicates as well as the calculated rates of the dietary intakes for the four groups of investigations are shown. Comparison of the dietary lead intake [mg/(kg bw ¥ day)] of the four groups is shown in Figure 1. Lead levels of the food duplicates (median) ranged between 12.0 and 45.9 mg/kgdry weight. Lead concentrations of 14 samples (31.1%) of group A, one sample of group B (2.4%) and 22 (22.5%) of group C were below the detection limit. Lead concentrations of duplicate samples of the small children from the industrialized area (group A) and of children from the North Sea island (group C) were lower compared with those of children (group B) and adults (group D) from the industrialized area (P <
Fig. 1. Comparison of the dietary lead intake [mg/(kgbw ¥ day)] of the four study groups from Germany. Boxplots: (A) small children, (B) children and (D) adults from the industrialized Ruhr district and (C) children living on the North Sea island Amrum.
Table 2. Lead concentrations [mg/kgdw] in the food duplicates.
Group A Group B Group C Groups A B C Group D
N
N0
MIN
Median
P 90
P 95
MAX
AM
SD
GM
47 42 98 187 42
14 1 22 37 0
3.8 3.8 3.8 3.8 12.5
12.0 41.0 18.7 20.1 45.9
41.2 65.2 45.3 52.4 96.2
50.0 82.7 61.1 64.8 99.5
98.7 106.3 92.0 106.3 114.6
18.7 40.5 22.4 25.6 52.3
17.9 21.9 17.6 20.3 26.9
12.6 34.2 15.9 17.8 45.6
CI of GM 9.6 28.0 13.2 15.6 38.4
16.5 41.8 19.1 20.3 54.1
AM arithmetic mean; CI 95%-confidence interval; dw dry weight; GM geometric mean; MAX maximum; MIN minimum; N number of samples; N0 number of samples below the detection limit; values given are one-half of the detection limit; P percentile; SD standard deviation.
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Table 3. Calculated weekly lead intake rates. N
MIN
Median
P 90
P 95
MAX
AM
SD
GM
CI of GM
Pb (mg/week) Group A Group B Group C Groups A B C Group D
7 14 14 35 14
9.0 19.2 10.0 9.0 54.7
16.9 69.1 31.1 48.7 166.6
59.9 141.8 85.3 98.2 283.3
59.9 150.7 86.4 141.8 611.8
59.9 150.7 86.4 150.7 611.8
25.6 80.2 40.3 53.3 185.0
18.1 36.4 24.4 36.3 136.0
21.2 71.9 34.1 41.8 155.0
11.6 53.3 23.9 32.3 110.0
38.6 97.0 48.6 53.9 218.0
Pb [mg/(kgbw ¥ week)] Group A Group B Group C Groups A B C Group D
7 14 14 35 14
0.8 1.3 0.6 0.6 0.7
1.8 4.0 2.1 3.0 2.5
4.1 8.1 4.6 6.1 4.6
4.1 8.9 5.1 8.1 7.5
4.1 8.9 5.1 8.9 7.5
2.1 4.7 2.4 3.3 2.6
1.2 2.1 1.3 2.0 1.7
1.8 4.3 2.1 2.7 2.2
1.0 3.2 1.5 2.2 1.5
3.1 5.7 2.9 3.4 3.1
Pb [mg/(m2bsa ¥ week)] Group A Group B Group C Groups A B C Group D
7 14 14 35 14
18.8 31.5 15.5 15.5 30.6
37.6 95.4 49.7 76.1 86.6
95.5 195.5 113.0 147.8 167.6
95.5 209.5 129.0 195.5 313.7
95.5 209.5 129.0 209.5 313.7
48.3 115.0 59.2 79.4 101.0
27.8 49.3 32.4 48.6 70.8
41.8 105.0 51.3 65.5 85.1
24.4 79.4 36.8 52.3 60.4
71.6 138.0 71.5 82.0 120.0
AM arithmetic mean; bsa body surface area; bw body weight; CI 95%-confidence interval; GM geometric mean; MAX maximum; MIN minimum; N number of samples; P percentile; SD standard deviation.
Table 4. Daily lead intake rates. N
MIN
Median
P 90
P 95
MAX
AM
SD
GM
Pb (mg/day) Group A Group B Group C Groups A B C Group D
47 42 98 187 42
0.6 0.9 0.6 0.6 4.5
2.7 11.7 4.6 5.0 17.8
7.3 22.2 11.3 14.2 40.2
11.2 24.7 15.2 16.9 50.5
19.6 26.0 29.4 29.4 63.2
3.8 11.5 5.8 6.6 23.5
3.8 6.3 5.1 5.8 14.4
2.5 9.5 3.9 4.3 19.5
Pb [mg/(kgbw ¥ day)] Group A Group B Group C Groups A B C Group D
47 42 98 187 42
0.05 0.06 0.04 0.04 0.07
Pb [mg/(m2bsa ¥ day)] Group A Group B Group C Groups A B C Group D
47 42 98 187 42
1.2 1.5 1.0 1.0 2.8
0.21 0.68 0.29 0.35 0.26 4.9 16.2 6.9 8.2 9.8
0.71 1.27 0.59 0.84 0.62 16.0 28.5 15.1 20.6 21.9
0.76 1.39 0.85 0.98 0.70 17.8 32.9 21.0 25.4 29.4
1.51 1.63 1.58 1.63 0.83 35.7 38.4 40.0 40.0 32.4
0.31 0.68 0.35 0.41 0.34 7.2 16.4 8.5 9.9 13.0
0.28 0.36 0.28 0.33 0.21 6.5 8.6 7.1 8.1 7.8
0.22 0.57 0.24 0.29 0.28 5.0 13.9 5.9 6.9 10.7
CI of GM 1.9 7.7 3.3 3.7 15.9 0.17 0.46 0.20 0.25 0.22 3.8 11.3 4.9 6.0 8.7
3.3 11.8 4.8 5.0 23.8 0.28 0.70 0.29 0.33 0.34 6.5 17.0 7.1 7.9 13.1
AM arithmetic mean; bsa body surface area; bw body weight; CI 95%-confidence interval; GM geometric mean; MAX maximum; MIN minimum; N number of samples; P percentile; SD standard deviation.
0.001). In the industrialized area lead levels of food duplicates of adults were higher than those of group B children (P 0.03). With respect to the daily lead intake (mg/day) the median values ranged from 2.7 to 17.8 for the four groups. Dietary lead intake was high in children from the industrialized Ruhr district (group B 11.7 mg/d) compared with the other children (2.7 ±
4.6 mg/day) (P < 0.001). Dietary lead intake (mg/d) of adults was higher than that of children (P < 0.001). Lead intake related to body weight or body surface was low for the small children (P < 0.001) compared with the other groups. The lead intake for the children from of the industrialized Ruhr district was higher (P < 0.001) compared with the other groups (Figure 1). There was no difference (P 0.43) in the
Dietary lead intake in Germany
Fig. 2. Variation of the daily lead intake [mg/(kgbw ¥ day)] within the study period for each group. Group (A) small children, (B) children and (D) adults from the industrialized Ruhr district and (C) children living on the North Sea island Amrum.
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Table 5. Consumption of fish and drinking water on the basis of the food diaries. Group
N
N1
Min
P 10
A B C
7 14 14
4 4 11
0 0 0
0 0 0
A B C
7 14 14
6 11 7
0 0 0
Median
Fish consumption (g/d) 6.4 0.0 4.2
P 90
Max
AM
SD
27.7 19.4 16.6
27.7 46.1 29.1
7.1 6.1 7.6
9.8 13.2 8.5
Drinking water consumption (g/d) 0 83.9 315.3 0 50.0 133.3 0 7.1 185.7
315.3 216.7 452.9
136.1 60.8 73.7
125.5 60.6 128.1
AM arithmetic mean; Maxmaximum; Min minimum; N number of participants; N1 number of participants with consumption in general; P percentile; SD standard deviation.
Table 6. Comparison of the dietary intake of lead by the four different groups with the FAO/WHO PTWI (Provisional tolerable weekly intake). Small children from Ruhr district
With With With With
With With With With 1)
the the the the
the the the the
Children from Ruhr district
Children from Amrum
Adults from Ruhr district
mean [%] median [%] geometric mean [%] maximum [%]
Comparison on the basis of the weekly intake PTWI [25 mg/(kgbw ¥ week)] 8.4 19 7.2 16 7.2 17 16 36
9.6 8.4 8.4 20
10 10 8.8 30
mean [%] median [%] geometric mean [%] maximum [%]
Comparison on the basis of daily intake PTDI 1) [3.57 mg/(kgbw ¥ day)] 8.7 20 5.9 19 5.9 16 42 44
9.8 8.1 6.7 44
9.5 7.3 7.8 23
PTDI provisional tolerable daily intake.
lead intake between the small children from the Ruhr district (group A) and those from the North Sea island (group C). The variation of the daily dietary lead intake within the study period for each group is shown in Figure 2. Analysis of variance showed that lead intake was not influenced by the day of sampling. Lead levels in the tap water samples from the industrialized district were low (median 0.64, range < 0.2 ± 2.8 mg/l). The higher lead levels from households in Amrum (median 4.8, range 3.2 ± 11.8 mg/l) are probably due the fact that most of the participants from Amrum obtained their drinking water from private wells. However, in comparison with the guideline value for lead in drinking water of 10 mg/l as proposed by the WHO and in future also legal in Europe (until 2003, 40 mg/l), we found no severe lead contamination of the drinking water. This is especially true, since the sampling procedure in this study (`first ± draw' sample) is not representative for the average lead level in tap water.
Testing individual correlations for each group, we found no correlation between the dietary lead intake and the age of the participants. Lead intake was not influenced by the gender of the participants. An analysis of the food diaries for the consumption of fish and drinking water is shown in Table 5 for the children groups A to C. Although children from Amrum ate more often fish there were no differences in the total consumption of fish (g/d) between the groups A to C (Kruskal-Wallis Test, P 0.28). No differences were also found with regard to the consumption of drinking water [g/d] under the same test conditions (P 0.21). Histograms of the daily lead intakes [mg/(kg bw ¥ day)] are shown in Figure 3 and compared with the PTWI converted into a daily dose 3.57 mg/(kg bw ¥ day). None of the dietary lead intake values exceeded the tolerable intake. The comparison of the dietary lead intake with the FAO/WHO PTWI is summarized in Table 6. The median values ranged from 7.2 to 16% for the different groups related to
Dietary lead intake in Germany
Fig. 3. Histograms of the daily dietary intake of lead [mg/(kgbw ¥ day)] by the four study groups from Germany in comparison to the FAO/WHO PTWI* (Provisional Tolerable Weekly Intake) of 25 mg/(kgbw ¥ week) converted into daily intake. (A) small children, (B) children and (D) adults from the industrialized Ruhr district and (C) children living on the North Sea island Amrum.
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the weekly intake and between 5.9 and 19% related to the daily intake of the PTWI. The corresponding maximum values ranged between 16 ± 36% and 23 ± 44% of the PTWI respectively. The highest percentage of PTWI was observed among the children study group of the industrialized Ruhr district (group B). The respective values of the four groups (mean, median and geometric mean) declined in the following order: children Ruhr district > adults Ruhr district > children Amrum > small children Ruhr district.
Discussion This study shows data on the dietary lead intake for children and adults living in Germany related to food samples collected between December 1994 to May 1995. A comparison with data from the literature for children is given in Table 7 and for adults in Table 8. There are only a few other studies on children's dietary lead intake. In general, these data show great variation. This may be due to differences in the study area, the year of the studies, the study type, and statistical analyses, especially with respect to handling the numbers of data below the detection limit. Most results obtained by using the total diet study (e.g. the ™market basket approach∫) show higher values for the lead intake than results obtained by using the duplicate portion technique. However, the median lead dietary intake values of all groups
measured in this study are in the range of other studies (Table 7, Table 8). Assuming that our data is representative for Germany the results show that the German population has a low to moderate dietary lead intake. To evaluate the health risks due to this, our data is compared with the FAO/WHO PTWI. In 1986, JECFA (Joint Expert Committee on Food Additives) established a PTWI of 25 mg/(kg bw ¥ week) for infants and children (WHO 1987). The PTWI was reconfirmed by JECFA in 1993 and extended to all age groups (WHO 1993). It is likely that by comparing our data to the PTWI, health risks of the German population due to dietary lead intake are low (Table 6). However, it has to be considered that some of the health effects associated with children's lead exposure occur at blood lead levels < 100 mg/l without a threshold (WHO 1995, Walkowiak et al. 1998, Canfield et al. 2003). For this reason, US EPA has decided not to develop a reference dose (RfD) for inorganic lead. Additionally, ATSDR (Agency for Toxic Substances and Disease Registry) has not derived MRLs (Minimal Risk Levels) for lead. We found that children living in the industrialized Ruhr region (mean age 1.8 ± 5.2 years; median lead intake 11.7 mg/d and 0.68 mg/(kg bw ¥ day), have a significant higher lead intake compared to small children and to adults living in the Ruhr district as well as compared to children living on the North Sea island Amrum. The higher dietary lead intake of children from the industrial area (group B) compared with those from the rural region (group C) could not be deeply explained. Daily records of the
Table 7. Data from the literature on the dietary lead intake by children published after 1995. Country
Type of study
Germany
24-h food duplicates
Germany
Year of study Age of the participants (mg/d) (years)
2.7 ± 11.7 0.21 ± 0.68
24-h food duplicates2) 1989 ± 1991
12 ± 21
United States
24-h food duplicates
1996 ± 1998
1.3 ± 3.7
5.9 (f) 9.8 (m) 7.6
United States
Total Diet
1990 / 1991
0.5 ± 0.9 2 1.5 ± 3 1±4 4±7 7 ± 10
Eastern Europe India
6-d food duplicates 24-h food duplicates
± 1988 / 1989
± 1986 ± 1994
(f) females, (m) males 1) Arithmetic mean (AM) or geometric mean (GM) or median 2) Daily rations of youth centers
6 ± 11 6 ± 10
1.82 1.87 4.95 10 (f /m) 13 (f /m) 17 (f) 18 (m) ± 16.5
References
[mg/(kgbw ¥ day)]
1.3 ± 5.2
United States 24-h food duplicates The Netherlands Total Diet
1995
Dietary lead intake1)
±
Median This study (range) Median Arnold et al. (1998) Median Melnyk et al. (2000) AM Bolger et al. (1996) AM AM Stanek et al. (1998) AM Brussaard et al. (1996) AM AM
0.21 ±
AM GM
0.20 0.14 ± ±
Gulson et al. (1997) Raghunath et al. (1999)
Dietary lead intake in Germany
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Table 8. Data from the literature on the dietary lead intake by adults published after 1995. Country
Type of study
Year of study
Dietary lead intake1)
Age of the participants (years)
mg/d
mg/kg
0.26 0.28 (f) 0.24 (m) 0.52 ±
Germany Germany
24-h food duplicates 24-h food duplicates
1995 1996
24 ± 64 20 ± 60
17.8 19 (f /m)
Germany Germany
24-h food duplicates 24-h food-duplicates2)
1990 ± 1991 1989 ± 1991
25 ± 69 61 ± 92
East Asia and South-East Asia3) Japan
24-h food duplicates
1991 ± 1998
women
37 7.5 (f) 12.3 (m) 7 ± 32
24-h food duplicates
1991 ± 1994
France
food duplicates5)
1998 / 1999
United States
Total Diet
1990 / 1991
women 4) / 53.0 ( AM ) general population 25 ± 30 60 ± 65
The Netherlands
Total Diet
1988 / 1989
22 ± 50 50 ± 65
4)
bw
References
d Median AM
This study Seifert and Anke (2000)
Median Median
Becker et al. (1996) Arnold et al. (1998) Ikeda et al. (2000)
±
GM (range) GM
Watanabe et al. (1996)
52
±
AM
Leblanc et al. (2000)
3.28 (f) 4.17 (m) 3.05 (f) 3.46 (m) 28 (f /m) 30 (f) 29 (m)
0.06 (f /m)
AM
Bolger et al. (1996)
0.05 (f /m)
AM
± ±
AM AM
7.1
±
Brussaard et al. (1996)
(f) females, (m) males, AM arithmetic mean 1) Arithmetic mean (AM), geometric mean (GM), median 2) Daily rations of senior centers 3) Including the countries China, Japan, Korea, Philippines, Malaysia, Taiwan, and Thailand 4) Groups of study consisting of non-smoking participants 5) Duplicates of the two most frequently consumed meals identified as breakfast and lunch in mass catering establishments
consumed foods did not show any consumption of items which are typically considered to be lead contaminated or which could have been contributing because of high consumption. Lead in household drinking tap water and consumption of fish could also be excluded as a significant route of lead exposure in this group. Consumption of home grown vegetables or fruits was observed in both groups but was not related to the dietary lead intake. However, it is likely that home grown vegetables and fruits from the industrialized area are more lead contaminated than those from the remote island thus contributing to the higher lead intake. This aspect will be analyzed more detailed in our current duplicate study. In our previous study conducted on children (age 5 ± 8 years) from the Ruhr district during winter and spring 1988 ± 89, the median dietary lead intake was 0.79 mg/(kg bw ¥ day) and 22.1 mg/(m2 bsa ¥ day) (Wilhelm et al., 1995b), therefore higher than the data obtained in the present study (median 0.68 mg/ (kg bw ¥ day) and 16.2 mg/(m2 bsa ¥ day). This may reflect the general reduction of lead in the environment during the last decades. This can be mainly attributed to the reduction of lead in petrol and vehicle fuel and in industrial emissions, which has subsequently led to a reduction of lead in the air, dust
and soils. As a result of successful programs to lower the level of lead in the environment, also mean blood lead levels in the general population decreased over the past twenty years (WHO 1995, ATSDR 1999, Markowitz 2000, Becker et al. 2002, Wilhelm et al. 2002c). The general reduction of lead contamination of the environment is also reflected by lead levels in food as has been reported by authors from various countries (e. g. Bolger et al. 1996, Brussaard et al. 1996, Pirkle et al. 1998, Ysart et al. 2000). This decline of lead levels in food and the rather low contaminations of food is underlined by the German Food Monitoring scheme which is conducted by the Bundesinstitut f¸r gesundheitlichen Verbraucherschutz und Veterin‰rmedizin (BgVV) (BgVV 1995 ± 1999). During 1995 ± 1999 (annually 20 ± 22 food items were tested), maximal permissible or guide levels for lead were only exceeded in samples of a few food items such as paprika-powder and meat of wild boar (BgVV 1995 ± 1999). Clearly declining tendencies of the lead contamination can in particular be observed for those kinds of food which were typically considered to be frequently lead contaminated. For example, different monitoring schemes performed in Germany during the period 1983 ± 1989 showed that the maximal permissible or guide levels for lead were frequently
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exceeded in samples of salad greens, kale, parsley and other herbs as well as in samples of offal from pork, cattle and calf (M¸ller and Weigert 1990). Other potential sources of dietary lead such as lead solder in food cans or beverage cans, tin-coated lead foil capsules on wine-bottles and lead-glazed ceramic ware have been significantly reduced in many countries (Bolger et al. 1996, WHO 1995). Despite the general decrease of the dietary lead intake, it should be kept in mind that there may be still groups at risk with respect to oral lead exposure. These include high level consumers, young infants and children aged 2 ± 4 years who may additionally be exposed to lead by swallowing contaminated airborne dust or soil. To minimize environmental exposure to lead, maximum levels for major contributors to the dietary exposure have been set recently by the European Commission (EC 2001).
Conclusion In conclusion, with regard to the PTWI of 25 mg/ (kgbw ¥ week), a low to moderate dietary intake of lead with amounts (median values for four different groups) between 1.8 and 4.0 mg/(kgbw ¥ week) was found, which corresponds to 7 ± 16% of the PTWI. Therefore, health risks due to the dietary intake of lead seem to be low for children and adults in Germany. This is also true for children and adults living in industrialized areas. Acknowledgements. The authors wish to thank Ursula Budde, Petra Mackrodt and Evelyn Wins for assistance in recruiting volunteers as well as for sampling of duplicate portions, and Annett Hilbig for the analysis of the food diaries.
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Becker, K., Nˆllke, P., Hermann-Kunz, E., Krause, C., Schenker, D. and Schulz, C.: Umwelt-Survey 1990/ 1991, Band III: Zufuhr von Spurenelementen und Schadstoffen mit der Nahrung (Duplikate und Diet History) in den alten Bundesl‰ndern. WaBoLu-Hefte, edited by Umweltbundesamt ± Institut f¸r Wasser-, Boden- und Lufthygiene, Berlin (1996). Becker, K., Kaus, S., Krause, C., Lepom, P., Schulz, C., Seiwert, M. and Seifert, B.: German Environmental Survey 1998 (GerES III): environmental pollutants in blood of the German population. Int J Hyg Environ Health 205, 297 ± 308 (2002). BgVV (Bundesinstitut f¸r gesundheitlichen Verbraucherschutz und Veterin‰rmedizin, Berlin). http:// www.bgvv.de (1995, 1996, 1997, 1998, 1999). Bolger, P. M., Yess, N. J., Gunderson, E. L., Troxell, T. C. and Carrington, C. D.: Identification and reduction of sources of dietary lead in the United States. Food Addit Contam, 13, 53 ± 60 (1996). Brussaard, J. H., Van Dokkum, W., Van der Paauw, C. G., De Vos, R. H., De Kort, W. L. and Lowik, M. R.: Dietary intake of food contaminants in The Netherlands (Dutch Nutrition Surveillance System). Food Addit Contam, 13, 561 ± 573 (1996). Canfield, R. L., Henderson, C. R., Cory-Slechta, D. A., Cox, C., Jusko, T. A. and Lanphear, B. P.: Intellectual impairment in children with blood lead concentrations below 10 mg per deciliter. N Engl J Med, 348, 1517 ± 1526 (2003). DEV (Deutsches Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung), DIN 38402, WileyVCH Berlin, Beuth, Berlin (1981). EC (European Communities), Commission Regulation No 466/2001 of 8 March 2001: setting maximum levels for certain contaminants in foodstuffs. European Communities, L 77, 1 ± 13 (2001). Gulson, B. L., Mahaffey, K. R., Jameson, C. W., Vidal, M., Law, A. J., Mizon, K. J., Smith, A. J. and Korsch, M. J.: Dietary lead intakes for mother/child pairs and relevance to pharmacokinetic models. Environ Health Perspect, 105, 1334 ± 1342 (1997). Ikeda, M., Zhang, Z. W., Shimbo, S., Watanabe, T., Nakatsuka, H., Moon, C. S., Matsuda-Inoguchi, N. and Higashikawa, K.: Urban population exposure to lead and cadmium in east and south-east Asia. Sci Total Environ, 249, 373 ± 384 (2000). Jorhem, L., Slorach, S., Engman, J., Schˆder, T. and Johansson, M.: The establishment of certified concentrations of thirteen elements in six simulated diet reference materials. National Food Administration Rapport 4/1995, Uppsala, Sweden (1995). Leblanc, J. C., Malmauret, L., Gue¬rin, T., Bordet, F., Boursier, B. and Verger, P.: Estimation of the dietary intake of pesticide residues, lead, cadmium, arsenic and radionuclides in France. Food Addit Contam, 17, 925 ± 932 (2000). Markowitz, M.: Lead poisoning: a disease for the next millennium. Curr Probl Pediatr, 30, 62 ± 70 (2000). Melnyk, L. J., Berry, M. R., Sheldon, L. S., Freeman, N. C. G., Pellizzari, E. D. and Kinman, R. N.: Dietary
Dietary lead intake in Germany exposure of children in lead-laden environments. J Exp Anal Environ Epidemiol, 10, 723 ± 731 (2000). M¸ller, J. and Weigert, P.: Bleigehalte in und auf Lebensmitteln. ZEBS-Hefte, edited by Bundesgesundheitsamt ± Zentrale Erfassungs- und Bewertungsstelle f¸r Umweltchemikalien (Berlin) (1990). Pirkle, J. L., Kaufmann, R. B., Brody, D., Hickman, T., Gunter, E. W. and Paschal, D. C.: Exposure of the U. S. population to lead. 1991 ± 1994. Environ. Health Perspect, 106, 745 ± 750 (1998). Raghunath, R., Tripathi, R. M., Kumar, A. V., Sathe, A. P., Khandekar, R. N. and Nambi, K. S. V.: Assessment of Pb, Cd, Cu and Zn exposures of 6- to 10year-old children in Mumbai. Environ Res, A 80, 215 ± 221 (1999). Schmidt, R. F. and Thews, G. (editors): Physiologie des Menschen. 24th edition, Springer-Verlag, Berlin (1990). Schrey, P., Wittsiepe, J., Mackrodt, P. and Selenka, F.: Human fecal PCDD/F-excretion exceeds the dietary intake. Chemosphere, 37, 1825 ± 1831 (1998). Schrey, P., Wittsiepe, J., Budde, U., Heinzow, B., Idel, H., Wilhelm, M.: Dietary intake of lead, cadmium, copper and zine by children from the North Sea island Amrum. Int J Hyg Environ Health, 203 : 1 ± 9 (2000). Seifert, M. and Anke, M.: Alimentary lead intake of adults in Thuringia/Germany determined with the duplicate portion technique. Chemosphere, 41, 1037 ± 1043 (2000). Stanek, K., Manton, W., Angle, C., Eskridge, K., Kuehneman, A. and Hanson, C.: Lead consumption of 18- to 36-month-old children as determined from duplicate diet collections: Nutrient intakes, blood lead levels, and effects on growth. J Am Diet Assoc, 98, 155 ± 158 (1998). Walkowiak, J., Altmann, L., Kr‰mer, U., Sveinsson, K., Turfeld, M., Weishoff-Houben, M. and Winneke, G.: Cognitive and sensorimotor functions in 6-year-old children in relation to lead and mercury levels: Adjustment for intelligence and contrast sensitivitiy in computerized testing. Neurotoxicol Teratol, 20, 511 ± 521 (1998). Watanabe, T., Nakatsuka, H., Shimbo, S., Iwami, O., Imai, Y., Moon, C. S., Zhang, Z. W., Iguchi, H. and Ikeda, M.: Reduced cadmium and lead burden in Japan in the past 10 years. Int Arch Occup Environ Health, 68, 305 ± 314 (1996). WHO (World Health Organization): GEMS: Global Environmental Monitoring System, Guidelines for the study of dietary intakes of chemical contaminants. WHO Offset Publ, No. 87 (1985). WHO (World Health Organization): Joint FAO/WHO Expert Committee on Food Additives, Toxicological evaluation of certain food additives and contaminants, pp. 223 ± 255. WHO Food Additives Series, No. 21, Cambridge, Cambridge University Press (1987).
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WHO (World Health Organization): Evaluation of certain food additives and contaminants: forty-first report of the Joint FAO/WHO Expert Committee on Food Additives. World Health Organ Tech Rep Ser, No. 837, Geneva (1993). WHO (World Health Organization): Inorganic lead. Environmental Health Criteria 165. WHO, Geneva (1995). Wilhelm, M., Ohnesorge, F. K., Lombeck, I. and Hafner, D.: Uptake of aluminium, cadmium, copper, lead and zinc by human scalp hair and elution of the adsorbed metals. J Anal Toxicol, 13, 17 ± 21 (1989). Wilhelm, M., Lombeck, I., Kouros, B., Wuthe, J. and Ohnesorge, F. K.: Duplicate study on the dietary intake of some metals/metalloids by German children. Part I: Arsenic and mercury. Zentralbl Hyg, 197, 345 ± 356 (in German) (1995a). Wilhelm, M., Lombeck, I., Kouros, B., Wuthe, J. and Ohnesorge, F. K.: Duplicate study on the dietary intake of some metals/metalloids by German children. Part II: Aluminium, cadmium and lead. Zentralbl Hyg, 197, 357 ± 369 (in German) (1995b). Wilhelm, M., Wittsiepe, J., Schrey, P., Budde, U. and Idel, H.: Dietary intake of cadmium by children and adults from Germany using duplicate portion sampling. Sci Total Environ, 285, 11 ± 19 (2002a). Wilhelm, M., Schrey, P., Wittsiepe, J., and Heinzow, B.: Dietary intake of persistent organic pollutants (POPs) by German children using duplicate portion sampling. Int J Hyg Environ Health, 204, 359 ± 362 (2002b). Wilhelm, M., Pesch, A., Rostek, U., Begerow, J., Schmitz, N., Idel, H., Ranft, U.: Concentrations of lead in blood, hair and saliva of German children living in three different areas of traffic density. Sci Total Environ, 297 (1 ± 3), 109 ± 118 (2002c). Wilhelm, M., Wittsiepe, J., Schrey, P. Lajoie-Junge, L. Busch, V.: Dietary intake of arsenic, mercury and selenium by children from a German North Sea island using duplicate portion sampling. J Trace Elem Med Biol, 17 (2), 123 ± 132 (2003) Wittsiepe, J., Schrey, P. and Wilhelm, M.: Dietary intake of PCDD/F by small children with different food consumption measured by the duplicate method. Chemosphere, 43, 881 ± 887 (2001). Wittsiepe, J.; Schrey, P., Wilhelm, M., Begerow, J., Dunemann, L.: Dietary intake of platinum and gold by children from Germany using duplicate portion sampling. J Trace Elem Med Biol, 17 (2), 117 ± 122 (2003). Ysart, G., Miller, P., Croasdale, M., Crews, H., Robb, P., Baxter, M., de L'Argy, C. and Harrison, N., 1997 UK Total Diet Study ± dietary exposures to aluminium, arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, tin and zinc. Food Addit Contam, 17, 775 ± 786 (2000).