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Mercury in urine and ejaculate in husbands of barren couples
Toxicology Letters Toxicology Letters 88 (1996) 227-231
ELSEVIER
Mercury in urine and ejaculate in husbands of barren couples V. Hanf”, A. Forstmannb, J.E. Codea=, G. Schieferstein”, I. F&herd, F. Schweinsberg*b aUniversitcib-Frauenklinik. hChemisches Inrhor. Ahteilung Allgemeine ‘Ahteilung “lnstitatjiir
Arheits-und
Tuiingen.
H_vgiene und Umwelthygiene,
Dermatologie Soziulmedizin.
II,
Germany
Hygiene-lnstitut,
Universitci’ts-Huutklinik. Eberhord-Kurls-Universilrif
Eugenstr. 6. 72072 Tubingen. Germany
Ttibingen, Germany Ttihingen, Tuiingen.
Germany
Abstract Mercury concentrations in morning urine and ejaculate were detected in 80 husbands of women presenting for infertility treatment. Additionally, the number of their dental amalgam fillings was documented. A routine spermiogram was performed, from which a numerical “fertility index” was calculated. Urinary mercury concentrations were in the range of non-exposed populations, only minute Hg concentrations were determined in ejaculate, 75% of the semen sample concentrations were under the detection limit of 5 fig/l. In comparison, 7 proven fertile workers with occupational mercury exposure had elevated levels of mercury in their ejaculates (range lo-65 pg/l). No positive correlation could be established between subject mercury concentrations in urine or ejaculate and the quality of their semen, expressed as fertility index. Equally, no such correlation could be established between the fertility index and the number of ,their dental amalgam fillings. From these preliminary data no evidence can be derived for the alleged relation between the mercury burden from dental amalgam fillings and male fertility disorders. Keywords:
Mercury; Amalgam; Male fertility; Semen; Urine
1. Introduction
In recent literarture a decrease in fertility in Western populations has been suggested and environmental influences were inferred as possible causes [1,2]. Persistent environmental chemicals are at the center of public attention. Besides persistent halogenated hydrocarbons, heavy metals are of especial interest because of their accumulatory potential in the human organism. While the non-essential metals lead, cadmium and mercury are all possible reproductive toxicants, the role of mercury has been discussed *Corresponding author. Tel.: + 49 7071 298 4666; Fax: +49 7071 29 3007.
more emotionally in recent years since this metal is the only one of the above to be introduced into the human body for medical purposes in the form of dental amalgam fillings. A number of publications have focussed on the influences of mercury on male fertility [3,4]. Mercury has been shown in animal and in vitro studies to interfere with spermatogenesis at various levels [S-8]. But in general these studies used high and clearly toxic doses by routes of exposure not comparable to human exposure. It is therefore difficult to interpret the significance of these experimental data for human risk assessment. Particularly little is known about the effects of mercury on human sperm function.
0378-4274/96/%15.00 0 1996 Elsevier Ireland Ltd. All rights reserved Pi1 SO378-4274(96)03742-3
228
V. Hmf
et al. I Toxicology
In order to get a better insight into possible detrimental effects of mercury from dental amalgam fillings on male fertility we measured mercury concentrations in urine and ejaculate of husbands from barren couples and tried to correlate the findings with the number of dental amalgam fillings and parameters of their spermiograms as indicators of male fertility.
2. Materials and methods 2.1. Subjects Eighty husbands (mean age 35 years) were consecutively recruited from the infertility outpatient program of the Women’s Hospital, University of Tiibingen. These husbands are referred to below as ‘study subjects’. The couples had been referred to the infertility clinic for unwanted childlessness of various causes and durations. At the first visit to the clinic they were asked to take part in the present investigation. After giving informed consent, study subjects were asked to donate a sperm sample and were advised to collect morning urine into prepared beakers. They were given a questionnaire to answer and the status of their teeth was evaluated with respect to the number and size of amalgam fillings present. A routine differential spermiogram was performed under standardized conditions as part of the clinical work at the Andrological Laboratory of the Dermatological Clinic, University of Tiibingen. [9]. A cohort of 7 workers (mean age 45 years) at a thermometer manufacturing plant served as an exposed control group. All of these subjects had fathered children while under the exposure of mercury vapor. In this group morning urine and ejaculate samples were collected, however, no spermiogram could be prepared.
Letters 88 (1996) 227-231
2.2. Fertility index At the Andrological Laboratory of the Dermatological Clinic, University of Tiibingen, routine semen analyses were performed according to WHO recommendations [9]. For better handling of the information contained in the statistical evaluations, a numerical index was calculated in principal accordance to the method by Donat and coworkers [lO,ll]. In short, sperm density (106/ml), motility (Oh) and morphology (“A normally shaped cells) were used to calculate respective indices according to the following formulae. Index of motility Index of morphology Index of density
I mot.X/(100 - X) Imorph: X/(100 - X) I,: x/20
Fertility index
(&,,JO.67) X &mph
11:
X
This fertility index has been shown to describe with sufficient accuracy the chances of fathering a child in the future [lO,ll]. The relationship between the numerical value of the fertility index Ir and the chance of fathering a child is given in Table 1. 2.3. Analytical procedure 2.3.1. Sampling
Urine samples were collected in polyethylene beakers (100 ml) containing 1 ml of acetic acid (60%) in order to minimize adsorption on container walls. Ejaculate samples were collected in polyethylene beakers. Both were immediately frozen and stored at -20°C. 2.3.2. Sample preparation and quantitative determination of mercury
Total mercury concentrations in urine and ejaculate were quantitatively determined by cold vapor atomic absorption spectroscopy after
Table 1 Relationship between numerical value of fertility index and chance of fatherhood Chance to father a child is Fertility index I,
good 26.72
Id
sufficient >1.0<6.72
poor >o<
1
none 0
229
K Hanf et al, I Toxicology Letters 88 (1996) 227-231
amalgamation in a gold trap using a Zeiss-Spectrometer SMD 3 [1.2]. 2.3.3. Urine In urine samples mercury was analyzed twice without pretreatment using standard addition. Method detection limit was 0.2 pg/l; recovery rate was 96% (range 94%-104%). Creatinine levels in urine were determined according to Jaffe’s method. The urinary mercury concentrations were adjusted for the creatinine excretion, because of diurnal fluctuations of the mercury concentrations in urine. The accuracy was checked by analysis of a reference urine in the sample series (Lyphochek/reg/, Urine Metals Control, Bio-Rad). External quality control was secured in an interlaboratory comparison conducted by the Deutsche Gesellschaft fur Arbeitsmedizin. 2.3.4. Ejaculate For the analysis of mercury in ejaculate a reliable method was established combining acidic digestion and high pressure microwave treatment. Aliquots of 0.5 ml of ejaculate were digested in 2 ml nitric acid (65%) and 2.5 ml bidistilled water. Microwave treatment was conducted using an MLS-1200 MEGA (Biichi, Germany). The digestion program was 5 min 300 W; 5 min 600 W; 4 min 900 W; 2 min 300 W; 5 min 0 W. Due to the small sample volume, no duplicate analyses were possibla Standard addition was applied. No reference materials are available for ejaculate. Method detection limit was 5 pug/I; recovery rate was 85% (range 65%-102%).
3. Results and discussion Mercury levels in urine, creatinine adjusted urinary mercury excretion and mercury levels in ejaculate are given in Table 2. The histogram in Fig. 1 shows the frequency distribution of urinary mercury levels in the husbands of barren couples (“study subjects”). The concentrations were in the range ( < 0.2-2.4 pg/g creatinine) expected for a non-exposed population; the mean concentration was 0.7 pg/g creatinine. Mercury concentrations measured in ejaculate were in the majority of samples below the detection limit of 5 pg./l (n = 61) As expected from the literature [13,14], there was a weak statistical correlation between the urinary mercury concentrations and the number of dental amalgam fillings. However, no correlation between the mercury concentrations in ejaculate and the number of amalgam fillings could be established. Even in a subgroup of study subjects with more then ten fillings (n = 21), no such association was detected. The results from the infertility group were compared with the concentrations found in occupationally mercury-exposed workers. Here, Hg concentrations in urine and in ejaculate were about 50 times higher. Fig. 2 shows the urinary Hg concentrations from study subjects plotted against the numerical fertility index. There was no apparent association between mercury concentrations in urine and the fertility index. It should be noted that in the group with a good fertility index (2 6.72), mercury concentrations from the lowest to the highest values were found. Certainly no clear-cut
Table 2 Arithmetic mean (range) of mercury concentrations in urine (Hg U) and ejaculate (Hg E) in husbands of infertility patients (study subjects) and mercury (exposed workers
Hg U (m/V Hg U @g/g creatinine) Hg E (I@) nd, not detectable.
Study subjects (n = 80)
Mercury exposed workers (n = 7)
1.4 (<0.2-5) 0.7 ( < 0.2-2.4)
70 (15-200) 50 (10-165)
Nd (n = 61),5-lO(n = 19)
28(10-65)
V. Hanf et al. I Toxicology Letters 88 (19%) 227-231
230
25
dose-response relationship seemed to be represented. Also, no correlation between the number of dental amalgam fillings and the fertility index could be established. The analysis of mercury in ejaculate is comphcated by different factors, e.g. collection of samples, the contamination of the semen with urine and the sample preparation. Up to now, mercury concentrations were repeatedly measured in blood or urine. To the best of our knowledge, so far no data on mercury concentrations in male reproductive tissues or genital tract secretions of occupationally unexposed men are available. However, compared with the measurement of Hg in urine or blood, the determination in ejaculate yields more relevant data with respect to male fertility since they represent as good a target tissue concentration as can easily be obtained in men.
AM 0.7 pg/g crea.
20
15
IO
5
0
.3
.6
. 1.2
.9
1.5
1.8
2.1
[ HgU pg/g
2.4
creatminel
Fig. 1. Frequency distribution of creatinine adjusted urinary mercury levels in study subjects.
tt
t
0
0 (42) (38)
27 25 :
(606)
0
23 -
0
0
0
sufficient
poor none 0
.5
1
1.5 HgU pg/g
2
2.5
3
3.5
creatinine
Fig. 2. Mercury concentrations in urine versus semen parameters expressed as fertility index (AM, arithmetic mean).
V. Hanf et al. I Toxicology Letters 88 (19%) 227-231
We found very low mercury concentrations in ejaculate of study subjects, with the majority of samples under the detection limit (5 pg/l). Further, urinary Hg concentrations were in the expected range for unexposed people and correlated with the number of dental amalgam fillings. As an indicator of male fertility a fertility index [lO,ll] was calculated from the semen parameters determined. It should be kept in mind that semen analysis is subject to a considerable intraindividual variability upon repetitive testing. Schwartz et al. [15] calculated an intraindividual standard deviation for the sperm density of 39%. The incorporation of the three principal parameters-density, morphology and motility into a single index value attempts to compensate partially for the ,variability of each parameter from one ejaculate to another of the same donor. Finally, fertility is the final expression of a large number of factors in both sexes. Therefore, semen parameters can only be of limited value for the prediction of male or couple fertility [16]. Although we measured a “target concentration”, we could not correlate sperm quality parameters, expressed as the fertility index, with mercury concentrations in semen; neither could we correlate semen parameters or mercury concentrations in semen with the number of dental amalgam fillings. The data presented here are still preliminary due to lack of complete quality control of the analysis, the heterogeneity of the study population, the relatively small number of subjects and the known intraindividual variability in the sperm analysis. They do, however, represent a first data pool on semen Hg concentration in relation to sperm parameters. It appears unlikely that mercury from dental amalgam fillings enters semen in considerable amounts and could be responsible for the alleged deterioration of sperm parameters in men within the past decades.
Acknowledgements The help of Mr. H. Schmitt and Mrs. M. Ah in obtaining semen and urine samples of occupationally exposed workers is gratefully acknowledged.
231
Cl1 Skakkebaek, N., Giwercman, A. and Kretser, D. (1994) Pathogenesis and management of male infertility. Lancet 343, 1473-1479. El Vergieva, T. (1993) Adverse effects of environmental chemicals on the outcome of human pregnancy. In: M. Richardson (Ed.), Reproductive Toxicology. VCH, Weinheim, pp. 73-97. c31Berlin, M., Lee, I. and Russell, L. (1983) Effects of Metals on Male Reproduction. Plenum Press, New York, pp. 29-40. M Gerhard, I. and Runnebaum, B. (1992) Environmental pollutants and fertility disorders. Heavy metals and minerals. Geburtshilfe-Frauenheilkd. 52, 383-396. Cordier, S., Deplan, F., Mandereau, L. and Hemon, D. (1991) Paternal exposure to mercury and spontaneous abortions. Br. J. Ind. Med. 48,375-381. WI Ernst, E. and Lauritsen, J.G. (1991) Effect of organic and inorganic mercury on human sperm motility. Pharm. Tox. 69,440-444. c71Lee, I. and Dixon, R. (1975) Effects of mercury on spermatogenesis studied by velocity sedimentation cell separation and serial mating. J. Pharmacol. Exp. Ther. 194 (I), 171-181. C81Miura, K., Naganuma, A., Himeno, S. and Imura, N. (1995) Mercury toxicity. In: R.A. Goyer and M.G. Cherian (Eds.), Toxicology of Metals. Springer Verlag, Berlin, Heidelberg, pp. 163-187. c91WHO (1993) Laboratory Manual for the Examination of Human Semen and Semen-Cervical Mucus Interaction, 3rd. Edn. Cambridge University Press, Cambridge. WI Donat, H., Schwarz, 1. and Matthies, J. (1989) Untersuchungen iiber den Einflub von Kohlenwasserstoherbindungen am Arbeitsplatz. Fertilitlt 5, 167- 172. Cl11Matthies, J., Schwarz, I. and Donat, H. (1989) Einflub von Schwermetallionen auf die mlnnliche Fertilitlt. Zbl. Gyn. 111, 155-166. Cl21Schierling, P. and Schaller, K.-H. (1981) Einfache und zuverlhsige Methoden zur atomabsorptionsspektrometrischen Bestimmung von Quecksilber in Blut und Urin. Arbeitsmed. Sozialmed. Priiventivmed. 16, 57-61. [I31 Schweinsberg, F. (1994) Risk estimation of mercury intake from different sources. Toxicol. Lett. 72, 345351. Cl41Herrmann, M. and Schweinsberg, F. (1993) Biomonitoring zur Beurteilung einer Quecksilberbelastung aus Amalgamfiillungen. Zbl. Hyg. 194, 271-291. Cl51Schwartz, D., Laplanche, A., Jouannet, P. and David, G. (1979) Within-subject variability of human semen in regard to sperm count, volume, total number of spermatozoa and length of abstinence. J. Reprod. Fertil. 57, 391-395. II161Engel, S., Grafe, A. and Petzold, R. (1994) Die Eignung der konventionellen Spermiogrammparameter fiir die andrologische Fertilitltsprognose. Fertilitlt 10, IO- 15.
ELSEVIER
Mercury in urine and ejaculate in husbands of barren couples V. Hanf”, A. Forstmannb, J.E. Codea=, G. Schieferstein”, I. F&herd, F. Schweinsberg*b aUniversitcib-Frauenklinik. hChemisches Inrhor. Ahteilung Allgemeine ‘Ahteilung “lnstitatjiir
Arheits-und
Tuiingen.
H_vgiene und Umwelthygiene,
Dermatologie Soziulmedizin.
II,
Germany
Hygiene-lnstitut,
Universitci’ts-Huutklinik. Eberhord-Kurls-Universilrif
Eugenstr. 6. 72072 Tubingen. Germany
Ttibingen, Germany Ttihingen, Tuiingen.
Germany
Abstract Mercury concentrations in morning urine and ejaculate were detected in 80 husbands of women presenting for infertility treatment. Additionally, the number of their dental amalgam fillings was documented. A routine spermiogram was performed, from which a numerical “fertility index” was calculated. Urinary mercury concentrations were in the range of non-exposed populations, only minute Hg concentrations were determined in ejaculate, 75% of the semen sample concentrations were under the detection limit of 5 fig/l. In comparison, 7 proven fertile workers with occupational mercury exposure had elevated levels of mercury in their ejaculates (range lo-65 pg/l). No positive correlation could be established between subject mercury concentrations in urine or ejaculate and the quality of their semen, expressed as fertility index. Equally, no such correlation could be established between the fertility index and the number of ,their dental amalgam fillings. From these preliminary data no evidence can be derived for the alleged relation between the mercury burden from dental amalgam fillings and male fertility disorders. Keywords:
Mercury; Amalgam; Male fertility; Semen; Urine
1. Introduction
In recent literarture a decrease in fertility in Western populations has been suggested and environmental influences were inferred as possible causes [1,2]. Persistent environmental chemicals are at the center of public attention. Besides persistent halogenated hydrocarbons, heavy metals are of especial interest because of their accumulatory potential in the human organism. While the non-essential metals lead, cadmium and mercury are all possible reproductive toxicants, the role of mercury has been discussed *Corresponding author. Tel.: + 49 7071 298 4666; Fax: +49 7071 29 3007.
more emotionally in recent years since this metal is the only one of the above to be introduced into the human body for medical purposes in the form of dental amalgam fillings. A number of publications have focussed on the influences of mercury on male fertility [3,4]. Mercury has been shown in animal and in vitro studies to interfere with spermatogenesis at various levels [S-8]. But in general these studies used high and clearly toxic doses by routes of exposure not comparable to human exposure. It is therefore difficult to interpret the significance of these experimental data for human risk assessment. Particularly little is known about the effects of mercury on human sperm function.
0378-4274/96/%15.00 0 1996 Elsevier Ireland Ltd. All rights reserved Pi1 SO378-4274(96)03742-3
228
V. Hmf
et al. I Toxicology
In order to get a better insight into possible detrimental effects of mercury from dental amalgam fillings on male fertility we measured mercury concentrations in urine and ejaculate of husbands from barren couples and tried to correlate the findings with the number of dental amalgam fillings and parameters of their spermiograms as indicators of male fertility.
2. Materials and methods 2.1. Subjects Eighty husbands (mean age 35 years) were consecutively recruited from the infertility outpatient program of the Women’s Hospital, University of Tiibingen. These husbands are referred to below as ‘study subjects’. The couples had been referred to the infertility clinic for unwanted childlessness of various causes and durations. At the first visit to the clinic they were asked to take part in the present investigation. After giving informed consent, study subjects were asked to donate a sperm sample and were advised to collect morning urine into prepared beakers. They were given a questionnaire to answer and the status of their teeth was evaluated with respect to the number and size of amalgam fillings present. A routine differential spermiogram was performed under standardized conditions as part of the clinical work at the Andrological Laboratory of the Dermatological Clinic, University of Tiibingen. [9]. A cohort of 7 workers (mean age 45 years) at a thermometer manufacturing plant served as an exposed control group. All of these subjects had fathered children while under the exposure of mercury vapor. In this group morning urine and ejaculate samples were collected, however, no spermiogram could be prepared.
Letters 88 (1996) 227-231
2.2. Fertility index At the Andrological Laboratory of the Dermatological Clinic, University of Tiibingen, routine semen analyses were performed according to WHO recommendations [9]. For better handling of the information contained in the statistical evaluations, a numerical index was calculated in principal accordance to the method by Donat and coworkers [lO,ll]. In short, sperm density (106/ml), motility (Oh) and morphology (“A normally shaped cells) were used to calculate respective indices according to the following formulae. Index of motility Index of morphology Index of density
I mot.X/(100 - X) Imorph: X/(100 - X) I,: x/20
Fertility index
(&,,JO.67) X &mph
11:
X
This fertility index has been shown to describe with sufficient accuracy the chances of fathering a child in the future [lO,ll]. The relationship between the numerical value of the fertility index Ir and the chance of fathering a child is given in Table 1. 2.3. Analytical procedure 2.3.1. Sampling
Urine samples were collected in polyethylene beakers (100 ml) containing 1 ml of acetic acid (60%) in order to minimize adsorption on container walls. Ejaculate samples were collected in polyethylene beakers. Both were immediately frozen and stored at -20°C. 2.3.2. Sample preparation and quantitative determination of mercury
Total mercury concentrations in urine and ejaculate were quantitatively determined by cold vapor atomic absorption spectroscopy after
Table 1 Relationship between numerical value of fertility index and chance of fatherhood Chance to father a child is Fertility index I,
good 26.72
Id
sufficient >1.0<6.72
poor >o<
1
none 0
229
K Hanf et al, I Toxicology Letters 88 (1996) 227-231
amalgamation in a gold trap using a Zeiss-Spectrometer SMD 3 [1.2]. 2.3.3. Urine In urine samples mercury was analyzed twice without pretreatment using standard addition. Method detection limit was 0.2 pg/l; recovery rate was 96% (range 94%-104%). Creatinine levels in urine were determined according to Jaffe’s method. The urinary mercury concentrations were adjusted for the creatinine excretion, because of diurnal fluctuations of the mercury concentrations in urine. The accuracy was checked by analysis of a reference urine in the sample series (Lyphochek/reg/, Urine Metals Control, Bio-Rad). External quality control was secured in an interlaboratory comparison conducted by the Deutsche Gesellschaft fur Arbeitsmedizin. 2.3.4. Ejaculate For the analysis of mercury in ejaculate a reliable method was established combining acidic digestion and high pressure microwave treatment. Aliquots of 0.5 ml of ejaculate were digested in 2 ml nitric acid (65%) and 2.5 ml bidistilled water. Microwave treatment was conducted using an MLS-1200 MEGA (Biichi, Germany). The digestion program was 5 min 300 W; 5 min 600 W; 4 min 900 W; 2 min 300 W; 5 min 0 W. Due to the small sample volume, no duplicate analyses were possibla Standard addition was applied. No reference materials are available for ejaculate. Method detection limit was 5 pug/I; recovery rate was 85% (range 65%-102%).
3. Results and discussion Mercury levels in urine, creatinine adjusted urinary mercury excretion and mercury levels in ejaculate are given in Table 2. The histogram in Fig. 1 shows the frequency distribution of urinary mercury levels in the husbands of barren couples (“study subjects”). The concentrations were in the range ( < 0.2-2.4 pg/g creatinine) expected for a non-exposed population; the mean concentration was 0.7 pg/g creatinine. Mercury concentrations measured in ejaculate were in the majority of samples below the detection limit of 5 pg./l (n = 61) As expected from the literature [13,14], there was a weak statistical correlation between the urinary mercury concentrations and the number of dental amalgam fillings. However, no correlation between the mercury concentrations in ejaculate and the number of amalgam fillings could be established. Even in a subgroup of study subjects with more then ten fillings (n = 21), no such association was detected. The results from the infertility group were compared with the concentrations found in occupationally mercury-exposed workers. Here, Hg concentrations in urine and in ejaculate were about 50 times higher. Fig. 2 shows the urinary Hg concentrations from study subjects plotted against the numerical fertility index. There was no apparent association between mercury concentrations in urine and the fertility index. It should be noted that in the group with a good fertility index (2 6.72), mercury concentrations from the lowest to the highest values were found. Certainly no clear-cut
Table 2 Arithmetic mean (range) of mercury concentrations in urine (Hg U) and ejaculate (Hg E) in husbands of infertility patients (study subjects) and mercury (exposed workers
Hg U (m/V Hg U @g/g creatinine) Hg E (I@) nd, not detectable.
Study subjects (n = 80)
Mercury exposed workers (n = 7)
1.4 (<0.2-5) 0.7 ( < 0.2-2.4)
70 (15-200) 50 (10-165)
Nd (n = 61),5-lO(n = 19)
28(10-65)
V. Hanf et al. I Toxicology Letters 88 (19%) 227-231
230
25
dose-response relationship seemed to be represented. Also, no correlation between the number of dental amalgam fillings and the fertility index could be established. The analysis of mercury in ejaculate is comphcated by different factors, e.g. collection of samples, the contamination of the semen with urine and the sample preparation. Up to now, mercury concentrations were repeatedly measured in blood or urine. To the best of our knowledge, so far no data on mercury concentrations in male reproductive tissues or genital tract secretions of occupationally unexposed men are available. However, compared with the measurement of Hg in urine or blood, the determination in ejaculate yields more relevant data with respect to male fertility since they represent as good a target tissue concentration as can easily be obtained in men.
AM 0.7 pg/g crea.
20
15
IO
5
0
.3
.6
. 1.2
.9
1.5
1.8
2.1
[ HgU pg/g
2.4
creatminel
Fig. 1. Frequency distribution of creatinine adjusted urinary mercury levels in study subjects.
tt
t
0
0 (42) (38)
27 25 :
(606)
0
23 -
0
0
0
sufficient
poor none 0
.5
1
1.5 HgU pg/g
2
2.5
3
3.5
creatinine
Fig. 2. Mercury concentrations in urine versus semen parameters expressed as fertility index (AM, arithmetic mean).
V. Hanf et al. I Toxicology Letters 88 (19%) 227-231
We found very low mercury concentrations in ejaculate of study subjects, with the majority of samples under the detection limit (5 pg/l). Further, urinary Hg concentrations were in the expected range for unexposed people and correlated with the number of dental amalgam fillings. As an indicator of male fertility a fertility index [lO,ll] was calculated from the semen parameters determined. It should be kept in mind that semen analysis is subject to a considerable intraindividual variability upon repetitive testing. Schwartz et al. [15] calculated an intraindividual standard deviation for the sperm density of 39%. The incorporation of the three principal parameters-density, morphology and motility into a single index value attempts to compensate partially for the ,variability of each parameter from one ejaculate to another of the same donor. Finally, fertility is the final expression of a large number of factors in both sexes. Therefore, semen parameters can only be of limited value for the prediction of male or couple fertility [16]. Although we measured a “target concentration”, we could not correlate sperm quality parameters, expressed as the fertility index, with mercury concentrations in semen; neither could we correlate semen parameters or mercury concentrations in semen with the number of dental amalgam fillings. The data presented here are still preliminary due to lack of complete quality control of the analysis, the heterogeneity of the study population, the relatively small number of subjects and the known intraindividual variability in the sperm analysis. They do, however, represent a first data pool on semen Hg concentration in relation to sperm parameters. It appears unlikely that mercury from dental amalgam fillings enters semen in considerable amounts and could be responsible for the alleged deterioration of sperm parameters in men within the past decades.
Acknowledgements The help of Mr. H. Schmitt and Mrs. M. Ah in obtaining semen and urine samples of occupationally exposed workers is gratefully acknowledged.
231
Cl1 Skakkebaek, N., Giwercman, A. and Kretser, D. (1994) Pathogenesis and management of male infertility. Lancet 343, 1473-1479. El Vergieva, T. (1993) Adverse effects of environmental chemicals on the outcome of human pregnancy. In: M. Richardson (Ed.), Reproductive Toxicology. VCH, Weinheim, pp. 73-97. c31Berlin, M., Lee, I. and Russell, L. (1983) Effects of Metals on Male Reproduction. Plenum Press, New York, pp. 29-40. M Gerhard, I. and Runnebaum, B. (1992) Environmental pollutants and fertility disorders. Heavy metals and minerals. Geburtshilfe-Frauenheilkd. 52, 383-396. Cordier, S., Deplan, F., Mandereau, L. and Hemon, D. (1991) Paternal exposure to mercury and spontaneous abortions. Br. J. Ind. Med. 48,375-381. WI Ernst, E. and Lauritsen, J.G. (1991) Effect of organic and inorganic mercury on human sperm motility. Pharm. Tox. 69,440-444. c71Lee, I. and Dixon, R. (1975) Effects of mercury on spermatogenesis studied by velocity sedimentation cell separation and serial mating. J. Pharmacol. Exp. Ther. 194 (I), 171-181. C81Miura, K., Naganuma, A., Himeno, S. and Imura, N. (1995) Mercury toxicity. In: R.A. Goyer and M.G. Cherian (Eds.), Toxicology of Metals. Springer Verlag, Berlin, Heidelberg, pp. 163-187. c91WHO (1993) Laboratory Manual for the Examination of Human Semen and Semen-Cervical Mucus Interaction, 3rd. Edn. Cambridge University Press, Cambridge. WI Donat, H., Schwarz, 1. and Matthies, J. (1989) Untersuchungen iiber den Einflub von Kohlenwasserstoherbindungen am Arbeitsplatz. Fertilitlt 5, 167- 172. Cl11Matthies, J., Schwarz, I. and Donat, H. (1989) Einflub von Schwermetallionen auf die mlnnliche Fertilitlt. Zbl. Gyn. 111, 155-166. Cl21Schierling, P. and Schaller, K.-H. (1981) Einfache und zuverlhsige Methoden zur atomabsorptionsspektrometrischen Bestimmung von Quecksilber in Blut und Urin. Arbeitsmed. Sozialmed. Priiventivmed. 16, 57-61. [I31 Schweinsberg, F. (1994) Risk estimation of mercury intake from different sources. Toxicol. Lett. 72, 345351. Cl41Herrmann, M. and Schweinsberg, F. (1993) Biomonitoring zur Beurteilung einer Quecksilberbelastung aus Amalgamfiillungen. Zbl. Hyg. 194, 271-291. Cl51Schwartz, D., Laplanche, A., Jouannet, P. and David, G. (1979) Within-subject variability of human semen in regard to sperm count, volume, total number of spermatozoa and length of abstinence. J. Reprod. Fertil. 57, 391-395. II161Engel, S., Grafe, A. and Petzold, R. (1994) Die Eignung der konventionellen Spermiogrammparameter fiir die andrologische Fertilitltsprognose. Fertilitlt 10, IO- 15.