Kidney and liver levels of some major, minor and trace elements in two Ontario communities

The Science of the Total Environment, 42 (1985) 223--235 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

223

KIDNEY AND LIVER LEVELS OF SOME MAJOR, MINOR AND TRACE ELEMENTS IN TWO ONTARIO COMMUNITIES

K.S. SUBRAMANIAN, J.C. MERANGER and R.T. BURNETT

Environmental Health Directorate, Health and Welfare Canada, Tunney's Pasture, Ottawa, Ontario K I A OL2 (Canada) (Received September 9th, 1984; accepted September 25th, 1984)

ABSTRACT The contents of Ag, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Se, St, Th, Ti and Zn in 143 autopsied liver and kidney specimens from two Ontario communities (Kingston and Ottawa) were determined using the techniques of inductively-coupled plasma--atomic emission spectrometry, and electrothermal atomization--atomic absorption spectrometry coupled with hydride evolution (As, Se), reduction--aeration (Hg), or solvent extraction (Pb). The majority of samples came from individuals older than 50 y. In general, the data for the various elements were independent of age or sex but showed some dependence on" location for elements such as Cu, Fe, K, Mg, Mn, Na, P, Se and Zn. Despite these differences the elemental values of the liver and kidney samples from both the communities were within the normal range.

INTRODUCTION

The elemental composition of b o d y fluids and tissues is indicative of the nutritional and pathological status of man. Although s o m e data exist for cadmium [1, 2], and lead [3] in some Canadian human tissue samples, similar information is lacking for many of the major, minor and trace elements. This is surprising, especially in view of the synergistic and antagonistic effects among metals in nutrition and toxicology. As a result it would be useful to measure the concentration of several elements in a tissue sample simultaneously. In a previous publication [4] we showed that this can be done using the simultaneous multielement technique of inductively coupled plasma--atomic emission spectrometry (ICP--AES). In this paper we present ICP--AES data on 20 elements in some autopsy samples of human liver, kidney cortex and kidney medulla from the t w o Ontario communities of Kingston and Ottawa. Also reported are results on: arsenic and selenium using hydride generation--electrothermal atomization-atomic absorption spectrometry; lead using solvent extraction--flame atomic absorption spectrometry; and mercury by cold vapour--atomic absorption spectrometry in the same samples. 0048-9697/85/$03.30

© 1985 Elsevier Science Publishers B.V.

224 EXPERIMENTAL METHODS

Apparatus The ICP--AES (Model QA-137, Applied Research Laboratories, Sunnyvale, CA) instrumental facilities and operating parameters are the same as described in a previous publication [4]. The hydride evolution--electrothermal atomization--atomic absorption spectrophotometer used for the measurement of arsenic and selenium has also been described elsewhere [5], and is schematically represented in Fig. 1. A Varian Techtron, Model AA-5, atomic absorption spectrometer equipped with a 10-cm single slot burner, and a Cathodeon lead hollowcathode lamp operated at 8 mA and at a resonance wavelength of 283.6 nm (SBP = 1.0 nm) was used for the determination of Pb. A Spectro Products (Spectrogram Corporation, North Haven, CT), Model Hg-2, mercury monitor equipped with a Varian mercury hollow cathode lamp, a Varian iron hollow cathode lamp for background correction and a strip chart recorder set at a scale of 10 mV and a chart speed of 1 cm/min was used for the measurement of Hg. Argon 27 TURNCOIL Waste~"~ l t~GAS LIQUID SEPARATOR

1

_[~'] HCI 3.9 ml/min. (As, 2M, Se, 6M) -I I Air 3.9 ml/min. 1% NaBH42ml/min. ~1 I Air 1 ml/min~,l I Sample 3.9 mt/min. , U H C I 1.2 ml/min.(As, 2M, Se, 6M)I I

15 TURNCOIL

I

PROPORTIONATING PUMP AsH3/SeH4 II--_-m Light . ~

--

Waste-*--]

RECORDER I

AA SPECTROMETER

SAMPLER

Fig. 1. Arsenic and selenium manifold (taken from ref. 5).

Reagents The reagents and solutions used for the ICP--AES and the hydride evolution studies have been described in previous publications [4, 5]. High-purity water was obtained b y passing tap water through a cellulose adsorbent, t w o mixed bed ion-exchange columns and subsequent distillation in a Coming AG-11 distillation unit. A 1-1 solution of 1% ammonium pyrrolidinedithiocarbamate (APDC) was prepared in high-purity water and was made lead-free by repeated extraction with methyl isobutyl ketone, MIBK [6]. The aqueous phase containing the APDC was stored in a precleaned 1-1 Nalgene polyethylene bottle. A pH 4.75 sodium acetate buffer solution was prepared and cleared of Pb using a

225

dithizone--carbon tetrachloride extraction procedure as described in the Environment Canada Analytical Methods Manual [ 7 ]. A saturated solution ( ~ 60 g/l) of potassium permanganate, a 20% (w/v) solution of hydroxylamine sulphate, and a 20% (w/v) solution of stannous chloride were prepared according to the procedures of Bishop et al. [8]. For the ICP--AES work single-element stock solutions containing 10 000 or 1000 mg/1 (as the metal) were prepared from specpure metals or metallic salts (Johnson-Matthey Ltd., Toronto, Ont.) using conventional procedures [9]. Two single-element and three multi-element working standards were freshly prepared daffy by serial dilution of the stock solution with either 1% HNO3 or 10% HC1 as described elsewhere [4]. A 1000 mg/1 solution each of As(III) and Se(IV) was prepared as outlined in a previous paper [5]. A 1000mg/1 solution of Hg(II) was prepared by dissolving 1.358g of mercuric chloride in a 1-1 solution of 1 0 m l concentrated nitric acid in high-purity water. A certified atomic absorption standard containing 1000 mg/1Pb(II) was obtained from Fisher Scientific. In all the above cases fresh working standards of lower concentrations were prepared daily by successive dilution of the stock solutions. All other reagents and solutions used were of the highest purity available. All the labware used was cleaned with a sequential tap water--nitric acid-high-purity water rinse as described elsewhere [ 10 ].

Samples The kidney (cortex and medulla) and liver samples were obtained from unembalmed cadavers at the Kingston General Hospital (43 males and 34 females ranging in age from 7 to 88 years) and the Ottawa Civic Hospital (43 males and 23 females ranging in age from 16 to 91 years). Based on the presence of recognised histopathological changes, all the samples were judged to have been taken from normal subjects. The autopsies were performed as described elsewhere [4]. The samples were shipped to the laboratory frozen in individual polyethylene freezer bags and were kept at - - 1 9 ° C until analyzed. Prior to analysis the frozen samples were thawed and excess blood was removed with a c o t t o n ball. Because the entire sample was used for analysis no homogenization was performed. The NBS bovine liver (SRM 1577), and oyster tissue (SRM 1566) were used as the certified standard reference materials.

Analytical procedure The procedure for the ICP--AES analysis of tissues was the same as that described in a previous paper [4 ]. Briefly, an accurately weighed (0.9--1.3 g) sample was digested to incipient dryness with 8 m l of conc. HNOs and 2 ml of conc. HC104. The resulting residue was dissolved in 1 ml of conc. HC1 and made up to 10 ml with 0 . 5 M HC1. The solution was then peristaltically p u m p e d and the aerosols produced by the nebulizer were transported

226 into the plasma torch where t h e y were vaporized, atomized and excited. The resulting emission signals of individual elements were processed through a programmable calculator and corrected for spectral overlap and stray light effects. The elemental concentration data in mgfl was obtained by reference to linear working curves and were subsequently relisted in mg/kg of wet tissue. Arsenic and selenium were determined using a slight modification of the hydride evolution--electrothermal atomic absorption spectrometric m e t h o d described in a previous publication [5]. The sample was digested as above. The digestate was cooled to room temperature, and after addition of I ml of 6 M HC1 heated to ~ 95°C for 5 m i n to ensure quantitative reduction of Se(VI) to Se(IV); the solution was then made up to 1 0 m l with 0.5MHC1. About 3--4 ml of this solution was transferred into the 5-ml polypropylene cups placed in the autosampler. The manifold tubes were inserted into the reagent solutions (HC1 and sodium borohydride) as shown in Fig. 1. The proportionating pump and the autosampler were switched on. The AsH3 or Sell4 vapour was carried by the argon stream into the silica tube furnace where it was atomized. The atomic absorption peaks of the blanks, calibration standards, reference standards and samples were recorded. The concentrations of arsenic or selenium in the test solution was obtained by reference to linear working graphs. The lead measurement procedure was basically the same as that described in the Environment Canada Analytical Methods Manual [7] except for the use of smaller volumes of sample and reagent solutions in the present work. A 4-ml aliquot of the digestate (prepared for the ICP--AES analysis) contained in a 16-mm Pyrex glass tube was neutralized with 0.3 ml of 50% NaOH solution, followed by addition of 0.5 ml 1% APDC, 0 . 5 m l acetate buffer and 2.0 ml MIBK. The Pb--APDC chelate was extracted into MIBK by shaking the test tube in a vortex mixer for 60 s. The MIBK phase was aspirated into an air--acetylene flame. The Pb content of the sample was obtained by comparison to linear working curves from aqueous Pb standards acidified to match the acid concentration of the sample digestate, followed by APDC--MIBK extraction in the same way as the samples. The mercury content of the tissue samples was monitored according to the procedure of Bishop et al. [8]. The samples were weighed out accurately into 18-mm Pyrex glass tubes and were digested with 2 ml of conc. HNO3 (Baker Ultrex), and 2 ml of conc. H2SO4 (Baker Ultrex) on an aluminium heating block at 260°C until a clear, colourless solution was obtained (~ 2 h). The solution was made up to 1 0 m l with high-purity water. Sufficient KMnO4 was added to maintain a purple colour ( 4 2 ml). The solution was allowed to stand for 30 min, whereupon 1 ml of 20% hydroxylamine sulphate, ten drops of n-octanol and 3 ml of 20% stannous chloride were added. The Pyrex glass tube was immediately attached to the mercury m o n i t o r and the sample was aerated. The absorbance was read off the chart paper at the plateau region. Prior to the next run the system was flushed by aerating the Pyrex glass tube containing high-purity water until the original

227

baseline on the recorder was reached. The concentration of mercury in the sample was determined by reference to linear working curves. The NBS standard reference materials, bovine liver and oyster tissue, were taken through the same procedure as above for the ICP--AES, hydride, Pb and Hg determinations.

Statistical methods The analysis of covariance [11] was used to examine the effect of location (Kingston vs. Ottawa), while adjusting for age and sex, on the concentration values for the various elements in liver, cortex and medulla samples. The relationship between age and concentration was examined using the Pearson correlation coefficient [11], and any sex-effect was evaluated by a two-sample t-test [11]. Details on residence, occupational history, smoking habits, alcohol consumption and cause of death were not known for the majority of subjects. As a result the effects of these variables on the concentration values could not be statistically tested.

RESULTS AND DISCUSSION

Analytical parameters Table 1 gives the detection limit, sensitivity and wavelength for each of the elements determined in the tissue samples. The detection limits are given in mg/1 and correspond to 3 SD of baseline noise. The ICP--AES detection limits were obtained under the same operating conditions for the various elements. The detection limit in mg/kg of wet tissue can be obtained by multiplying the solution detection limit (mg/1) given in Table 1 using the factor v/w where v is the total volume of the digestate and w is the sample weight. The detection limit value for each element was sufficien£1y low to permit its determination in the tissue samples of even normal individuals. The sensitivity for each element determined by ICP--AES is given as the average slope of the calibration curve for each element in units of (mg/1)/mV. The sensitivity for the elements determined by atomic absorption spectrometry, namely Pb, Hg, As and Se, is given in (mg/1)/0.0044 absorbance units. Note from Table 1 that the analytical techniques used for the various elements were sensitive down to the tLg/1 level. The ICP--AES wavelengths given in Table 1 were chosen to provide a reasonable compromise between o p t i m u m analyte sensitivity and minimum spectral interference from the major elements (Ca, Mg, K, Na, P) present in the tissue samples analyzed. The wavelengths for As, Se, Pb and Hg were the resonance lines of these elements. The ICP--AES linear dynamic range was 0--1000 mg/l for all the elements listed in Table 1, except for Ca and Mg, with linear ranges only up to 100 and 20 mg/1, respectively. It is this wide dynamic range of the ICP--AES that permits the simultaneous determination of several major, minor and trace elements using a single wet digestion procedure, a single set of operating

228 TABLE 1 ANALYTICAL PARAMETERS Element

Wavelength (nm)

Detection limit a (mg/1)

Sensitivity b

Ag Ba Be Ca Cd Co Cr Cu Fe K Mg Mn Mo Na Ni P Sr Th Ti Zn As Se Pb Hg

328.07 455.40 313.04 315.89 226.50 345.35 283.56 324.75 259.94 766.49 279.55 257.61 379.83 588.995 231.60 214.91 421.55 401.91 337.28 202.55 193.70 196.00 217.00 253.70

2.00 0.01 0.001 0.07 0.002 0.05 0.008 0.008 0.20 1.0 0.04 0.01 0.30 2.0 0.01 0.60 0.005 0.06 0.01 0.02 0.001 0.001 0.01 0.0002

0.002 0.0006 0.0001 0.007 0.0005 0.01 0.002 0.0008 0.02 0.1 0.02 0.0003 0.02 0.001 0.004 0.1 0.002 0.002 0.009 0.004 0.001 0.001 0.04 0.001

aConcentration of the element in mg/1 which will produce a net line intensity equal to 3 SD of blank with a minimum of 10 successive measurements. To convert the detection limit in mg/kg of wet tissue multiply the above values by 10. bThe sensitivity for ICP--AES elements (Ag to Zn) is given in units of (mg/1)/mV; for As, Se, Pb and Hg it is given in (rag/l)/0.0044 absorbance. c o n d i t i o n s and a single set o f calibration curves. The linear ranges in m g / m l f o r As, Hg, Pb and Se were 0 - - 0 . 0 6 , 0 - - 0 . 0 2 , 0--1 a n d 0 - - 0 . 0 7 , respectively. T h e reliability o f t h e various analytical p r o c e d u r e s used in this w o r k was ascertained b y a n a l y z i n g t h e NBS o y s t e r tissue a n d bovine liver. As can be seen f r o m Table 2, t h e observed values were in g o o d a g r e e m e n t with t h e certified values attesting t o t h e validity o f t h e analytical m e t h o d s used in t h e e l e m e n t a l d e t e r m i n a t i o n . In t h e case o f I C P - - A E S m e a s u r e m e n t s a p p r o p r i a t e c o r r e c t i o n s were e f f e c t e d f o r interferences f r o m Ca, Mg and Fe as described in a previous p u b l i c a t i o n [ 4 ] ; n o significant interferences were observed f r o m o t h e r elements p r e s e n t in high c o n c e n t r a t i o n s , such as K, Na, P and Zn.

Application to samples Table 3 gives t h e m e d i a n a n d e x t r e m e values f o r five m a j o r elements (Ca, Mg, Na, K, P), t h r e e m i n o r e l e m e n t s (Cu, Fe, Zn), a n d five trace e l e m e n t s

229

TABLE 2 R E L I A B I L I T Y O F THE I N S T R U M E N T A L M E T H O D S U S E D F O R THE L I V E R A N D K I D N E Y A N A L Y S E S : NBS B O V I N E L I V E R A N D O Y S T E R T I S S U E A = b o v i n e liver (SRM 1577); B = o y s t e r tissue (SRM 1566)

Observed value -+ SD (mg/kg) a

Certified value (mg/kg)

A

B

A

B

Ag Ba

< 2.00 0.10 + 0.04

1.01 -+ 0.09 3.09 -+ 0.18

0.1 --

--

Be

< 0.01

< 0.01

--

--

Ca

121 + 9 0.30 + 0.05 <0.5 0.38 + 0.20 183 + 8 271 + 11 9, 333 + 431 640 + 43 9.8 + 0.5

1,450 -+ 69 3.3 + 0.1 < 0.5 0.70 + 0.1 62.2 -+ 1.4 1 9 2 . 8 + 12 9,730 -+ 286 1,260 + 39 17.0 + 0.5 <3 4,933 + 128 1.1 + 0.1 7,148 + 196 8.9 + 0.3 < 0.2 5.8 + 0.7 837 + 23 11.4 -+ 1.4 2.1 + 0.1 0.5 -+ 0.1 0.052 + 0.007

123 0.27 (0.2) b -193 270 9,700 605 10.3 3 2,430 -(11,000) b 0.14 --130 0.06 1.1 0.3 0.016

1,500 3.5 -0.7 63 195 9,690 1,280 17.5 -5,100 1.0 (8,100) b 10.4 (0.1) b -852 13.4 2.1 0.5 0.057

Element

Cd Co Cr Cu Fe K Mg Mn Mo Na Ni P Sr Th Ti Zn As Se Pb Hg

6+1

2,241 + 114 0.33 + 0.16 11,371 -+ 768 0.11 + 0.03 < 0.10 < 0.01 128 -+ 12 0.050 -+ 0.004 0.94 -+ 0.05 0.3 + 0.1 0.016 -+ 0.002

0.89

aStandard deviation: calculated f r o m 25 d e t e r m i n a t i o n s , each consisting o f t h r e e 1 0 s integrations. bprovisional value only.

elements (Cd, Hg, Mn, Pb and Se) in some liver, cortex and medulla samples from Kingston and Ottawa. Table 3 represents the pooled data for males and females in the various age groups since the statistical tests [11] showed no significant changes in the concentration values of the above elements either with age or with sex. The lack of correlation with age in this study might be because 86% of the Kingston males and 85% of the Kingston females were ~ 50 years old. Similarly, in the Ottawa group 71% of the males and 74% of the females were ~ 50 years old. It is generally known that both Cd and Zn levels in the kidney cortex reach a plateau in the 40--50 year age group and thereafter show very little change [12, 13]. The data in Table 3 are presented separately for Ottawa and Kingston because statistical analysis of covariance [11 ] revealed significant differences in response for some of the elements depending on location. Thus, in the

66(74) a (40--181) b

2258(74) (1020-3250)

164(72) (92--228)

1405(77) (775--2660)

2530(76) (1570-3600)

5.4(68) (1.6--11.9)

272 (66) (71--929)

1.30(71) (0.4--3.2)

0.38 (73) (0.22--0.90)

67 (68) (25--183)

K

Mg

Na

P

Cu

Fe

Mn

Se

Zn

LK

56(62) (20-138)

0.58 (65) (0.20-1.02)

1.20(65) (0.1--2.6)

231 (62) (51--997)

4.9(66) (1.0--12.8)

2470(65) (1670-3410)

1255(64) (589--2430)

134(64) (79--213)

2010(63) (815--2960)

60(62) (33--119)

LO

Concentration (mg/kg wet wt)

Ca

Element

45 (71 ) (16--145)

0.83 (75) (0.20-2.43)

0.69(74) (0.3--1.4)

83(73) (36--165)

2.4(74) (1.0--5.1)

1740(73) (749--3665)

1823(73) (1090-3810)

132(73) (41--207)

1683(72) (787--3000)

147(71) (70--383)

CK

46 (64) (18--160)

0.90 (65) (0.62--2.30)

0.85(65) (0.5--1.7)

75 (64) (35--213)

2.4(64) (1.6--4.9)

1740(65) (1220-2570)

1900(65) (1350-2740)

127(65) (94--163)

1758(64) (1270-2890)

135(63) (63--428)

CO

35 (75) (14--156)

0.36 (69) (0.15--1.30)

0.60(75) (0.3--1.1)

78 (74) (65--190)

2.3(76) (1.0--15.9)

1620(75) (980-3220)

1885(74) (1480--3610)

132(72) (80--223)

1865(74) (1210-3540)

166(71) (71---427)

MK

30 (61) (11--142)

0.78 (63) (0.06--2.85)

0.70(60) (0.2--4.4)

73(61) (41--301)

1.9(63) (0.8--5.2)

1505(61) (1070--2630)

1955(59) (940--2990)

117(63) (42--179)

1690(63) (759--3080)

145(63) (63--408)

MO

TABLE 3 ELEMENTAL COMPOSITION OF SOME KINGSTON AND OTTAWA LIVER AND KIDNEY SAMPLES LK = Liver, Kingston; LO ----Liver, Ottawa; CK ----Cortex, Kingston; CO -- Cortex, Ottawa; MK = Medulla, Kingston; MO ----Medulla, Ottawa.

O

0.4 (64) (~< 0.1--1.7 )

~<0.1 (76) (~< 0.1--0.8)

(0.01--1.18)

0.17(72)

31.0(75) (5.1--109.0)

~< 0.1 (66) (~< 0.1--0.9)

(0.01--1.92)

0.28(65)

30.1 (64) (4.8--96.0)

~< 0.1 (76) (~< 0.1--1.3)

(0.01--1.26)

0.16(71)

16.7 (71) (1.0--71.5)

~< 0.1 (66) (~< 0.1---0.8)

(0.01--1.34)

0.22(62)

15.1 (62) (2.2--97.5)

aThe number outside the bracket gives the median value and the number within the bracket refers to the number of samples from which the median value was derived. bExtreme values (i.e. minimum and maximum values).

0.4 (71) (~< 0.1--1.6)

(0.01--0.37)

Pb

0.05(62)

0.05(72)

(0.01--0.34)

Hg

1.5(63) (0.1--9.1)

1.8(72) (0.1--9.0)

Cd

t'~

232

case of liver samples the Kingston responses were higher for Mg, Na and Fe (p ~ 0.01) and for K and Zn (0.01 ~ p ~ 0.05) than the Ottawa responses. Similarly, in the case of cortex samples the Kingston values were higher for Mg, Mn and Fe (p ~ 0.01), whereas for the medulla samples higher responses were found for K, P, Zn and Cu (p ~ 0.01), and for Mg (0.01 ~ p ~ 0.05). However, the Ottawa response was higher than that of Kingston for Se (p ~ 0.01) in the case of the liver, cortex and medulla samples. In spite of these differences, the values given in Table 3 for Ottawa and Kingston were in general agreement with the compilations of Iyengar et al. [14] and with some recent studies [12, 15--17] for normal adults in liver, kidney cortex and kidney medulla. It is interesting to note that the median Cd values we found in the cortex were in reasonable agreement with those found in Some other Canadian [1, 2], U.S. [12] and Swedish [13] studies, but higher than British [17] and lower than Japanese [16] reports. The results in Table 3 show that the concentrations of the major elements K and Mg were somewhat higher in the liver than in the kidney b u t that the Na content of the liver was significantly lower than that of the kidney. The most striking effects, however, were those for Ca and P. The median Ca content of the liver was ~ 44% of its value in the kidney, while the median P content of the kidney was nearly 66% of the liver level. The essential elements Cu, Fe, Mn and Zn preferentially accumulated in the liver, whereas the toxic elements Cd and Hg found their way to the kidney cortex and medulla. With the exception of Cd and Zn there was no significant difference in the values for the other elements between kidney cortex and medulla. The concentration of Cd in the cortex was almost twice that in the medulla while the Zn level in the medulla was roughly 73% of that in the cortex. Table 4 shows the frequency distribution of the various elements in the liver, cortex and medulla samples for selected concentration ranges. In the case of the major elements, Ca, Na, K and P, no significant differences were seen between Kingston and Ottawa. Thus, nearly 60--80% of the liver samples analyzed contained Ca, Na, K and P in the 40--70, 700--1500, 1800--2600 and 1800--2800 mg/kg range, respectively. Also no significant differences were seen between cortex and medulla. Thus, 60--90% of the cortex and medulla samples were in the range of 100--200, 1500--2600, 1300--2000 and 1300--2200mg/kg, for Ca, Na, K and P, respectively. In the case of Mg, the effect of location was evident for the liver samples. In the 9 0 - - 1 4 0 m g / k g range, the percent distribution for Mg was 20 for Kingston and 52 for Ottawa, whereas in the 140--180 mg/kg range it was 65 for Kingston and 36 for Ottawa. However, no such significant differences were seen for the cortex and medulla samples. Thus, in the 90--160 mg/kg range the percent distribution for cortex was 72 and 92, and for medulla 82 and 89, for Kingston and Ottawa, respectively. Among the essential elements the distribution of Cu was very homogenous. Thus, 85% of the Kingston and 70% of the Ottawa liver samples fell in the 3--9 mg/kg range while 90 and 97% of the cortex and medulla samples for

1800--2800

3--9

200--600

1--3

0.2--0.5 0.6--1.0

40--90

0.1--1.0 1.1--6.0

0.01--0.1

0.1--0.4

Cu

Fe

Mn

Se

Zn

Cd

Hg

Ph

64

74

80

29 62

63

78 22

82

52

85

78

69

81

34 69

70

34 63

71

51

70

69

70

52 36

72

60

% LO

.

0.1

0.05--0.5

5--20 21--100

30--70

0.1--0.5 0.6--1.3

0.1--0.5 0.6--1.0

50---90

1--4

1300--2200

1500--2600

90--160 .

1300--2000

100--200

Range (mg/kg)

.

76

64

41 52

73

26 47

35 54

62

91

82

64

72

68

60

% CK

.

69

60

36 61

83

3 83

8 68

47

97

94

89

92

69

60

% CO

.

56

55

52 43

57

74 16

49 46

49

92

72

81

82

58

60

% MK

57

60

50 37

49

24 51

27 55

27

97

74

82

89

69

60

% MO

aThe t e r m s LK, LO, CK, CO, MK, M O have t h e s a m e c o n n o t a t i o n s as in T a b l e 3. T h e % figures r e p r e s e n t t h e % o f t h e t o t a l s a m p l e s a n a l y z e d as i n d i c a t e d in T a b l e 3.

700--1500

Na

P

20 65

69

1800--2600

90--140 141--180

K

Mg

60

40--70

Ca

% LK a

Range (mg/kg)

Element

TABLE 4 ELEMENTAL FREQUENCY DISTRIBUTION OF SOME KINGSTON AND OTTAWA LIVER AND KIDNEY SAMPLES

f~

234 Kingston and Ottawa, respectively, were in the 1--4 mg/kg range (Table 4). The other essential elements, Fe, Mn, Zn and Se, were spread out particularly in the case of the liver samples. In addition there were differences in distribution of Mn, Zn and Se between cortex and medulla samples on the one hand, and between Kingston and Ottawa, on the other. Thus, in the range 0.1--0.5mg/kgMn, the percent distribution of cortex samples was 35 for Kingston and 8 for Ottawa; for medulla it was 49 and 27 for Kingston and Ottawa, respectively. Similarly, in the 0.6--1.0 mg/kg range the percent distribution was 54 and 68 for the Kingston and Ottawa cortex samples, and 46 and 55 for the Kingston and Ottawa medulla samples, respectively. In the case of Zn the 30--70 mg/kg range was covered by 73% of Kingston, and 83% of Ottawa cortex samples, whereas for the medulla samples in the same concentration range the respective percent coverages were only 57 and 49. The Se content of the liver and kidney samples was influenced by the location. For example, in the case of the liver samples the percent distributions for Kingston and Ottawa were 78 and 34 in the 0.2--0.5 mg/kg range, and 22 and 63 in the 0.6--1.0 mg/kg range respectively. In the case of cortex the percent distribution was 47 and 83 in the 0.6--1.3 mg/kg range and in the case of medulla it was 74 and 24 in the 0.1--0.5 mg/kg range, for Kingston and Ottawa, respectively. The toxic elements Cd and Hg were also dispersed. This was particularly evident in the cortex samples for Cd. Note also the preferential accumulation of Cd in the cortex (Table 4). In the case of mercury the concentration spread was an order of magnitude before one could cover 80% of the liver, 60% of the cortex, and 60% of the medulla samples. On the contrary, the spread was much less for Pb. Thus, about 70--75% of the liver samples fell in the range ~ 0.1--0.4mg/kg. Similarly, about 70--75% of the cortex and 60% of the medulla samples contained ~ 0.1 mg/kg Pb. In all the liver and kidney samples analyzed, Ag, Ba, Be, Co, Cr, Mo, Ni, Sr, Th and Ti were found to be below the ICP--AE8 detection limit for these elements, namely 0.5, 0.08, 3.0, 0.1, 0.05, 0.6 and 0.1 mg/kg of wet tissue, respectively. These results are in general agreement with the literature data [14, 15, 17] except Th for which no literature data is available at present. In conclusion, the autopsied liver and kidney samples analyzed contain the various elements in their normal levels, with no implication of immediate health risks to the residents of Kingston and Ottawa.

ACKNOWLEDGEMENT The ICP--AES analyses of the tissue samples and the NBS bovine liver and oyster tissue were performed by Barringer Magenta Limited, Rexdale, Ontario, Canada.

235 REFERENCES I 2 3. 4 5 6 7 8

9 10 11 12 13 14 15 16 17

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