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Metals and welding: Pregnancy outcome and fertility

Metals and welding: Pregnancy outcome and fertility. Markku Sallmén Finnish Institute of Occupational Health. Simultaneous exposure to several metals. Studies around Rönnskär copper smelter

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Metals and welding: Pregnancy outcome and fertility

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  1. Metals and welding: Pregnancy outcome and fertility Markku Sallmén Finnish Institute of Occupational Health

  2. Simultaneous exposure to several metals • Studies around Rönnskär copper smelter • excess of spontaneous abortion, and stillbirths in pregnancies of wives of men exposed to lead, copper, zinc, gold, silver, cadmium, mercury, arsenic, and sulfur dioxide • carry-home exposure to the wives remains a possible alternative explanation

  3. Population-based studies • Rachootin and Olsen 1983 • case couples examined or treated for a problem of infertility at Odense University Hospital • questionnaire information on job and exposure • female exposure to lead, mercury, and cadmium were associated with infertility

  4. Environmental exposure to lead • Study in Kosovo in the vicinity of a lead smelter • current (1986) blood lead levels 0.77 µmol/l (range 0.32-1.83) among women in exposed town; 0.25 (0.12-0.51) in reference town • no excess of spontaneous abortion was observed in exposed women as compared with women in reference town

  5. Female Lead Exposure and Spontaneous Abortion B-Pb µmol/l OR 95% CI • Taskinen 1988 0.5-3.1 0.8 0.5-1.4 Measured within a year of pregnancy: >1.4 1.9 0.4-9.4 • Borja-Aburto 0.24-0.48 2.3 -- et al. 1999 0.49-0.72 5.4 -- > 0.72 12.2 --

  6. Maternal lead exposure and fecundability • Sallmén et al 1995 • study among women biologically monitored for exposure to lead blood lead FDR 95% CI <0.5 µmol/l 0.93 0.56-1.57 0.5-0.9 µmol/l 0.84 0.45-1.45 1.0-2.4 µmol/l 0.80 0.42-1.54 Eight most heavily exposed subjects: 1.4-2.4 µmol/l 0.53 0.19-1.52

  7. Maternal lead exposure and cognitive development; prospective studies Study Mean Blood Lead Effect Boston 7.37 µg/dl + Cincinnati 4.6 --->14.1 + Cleveland 5.8 ---> 6.5 - Port Pirie 14.4->21.2->17.6 + Sydney 9.1->8.1->12.5 - Yugoslavia 14.4--->24.3 (+/-)

  8. Fecundability ratios by number of amalgams prepared per week and number of poor mercury hygienic factors; Rowland et al 1994 No of amalgams No of poor hygienic factors per week 0-3 4 5-8 0 1.0 - - 1-14 1.39 1.22 1.53 (1.01-1.92) (0.81-1.83) (1.03-2.25) 15-29 1.42 1.17 1.14 (1.05-1.92) (0.79-1.75) (0.73-1.77) >30 1.32 0.81 0.63 (0.97-1.80) (0.55-1.18) (0.42-0.96)

  9. Female mercury exposure and pregnancy outcome • Human data scanty and inconsistent • suggestive findings on menstrual disorders, spontaneous abortion, stillbirth and congenital malformations • also negative findings • teratogenic and fetotoxic in animal tests • => exposure should be restricted

  10. Female and Cadmium • Lower birth weight, pregnancy complications, poor mental development suggested • Classified as a carcinogen • => reasonable to restrict the exposure of pregnant women

  11. Lead and semen quality Apostoli et al 1997: • Exposure to lead at blood lead 1.9 µmol/L (40 µg/dL) is hazardous for male reproductive function • reduced sperm count, volume, and density • changed sperm motility and morphology • a modest effect on endocrine profile is possible Viskum et al 1999: • The effect is, at least partially, reversible

  12. Male lead exposure and clinically defined infertility Sitarek et al 1998 (in Polish with English abstract), infertility as the number of couples waiting 12 months or more for their pregnancy Group N (all) % infertile Controls 473 5.0 < 1 µmol/L 42 4.5 1-1.9 µmol/L 84 8.7 > 1.9 µmol/L 95 4.0 exp. level unknown 86 11.7

  13. Studies on Birth Rates and Male Exposure to Lead • Study PbB level Effect • Selevan et al. 1984 1.2 µmol/l + • Coste et al. 1991 1.9 µmol/l - • Gennart et al. 1992 2.2 µmol/l + • Lin et al. 1996 • duration of exp. >5 years, 2.4 µmol/l + • Bonde and Kolstad 1997 1.8 µmol/l - + reduced fertility, - no effect

  14. Relative Risk (RR) of Infertility and Male Exposure to Lead; Sallmén et al 2000 Estimated PbB RR 95% C.I. µmol/L 0.5-0.9 1.27 1.08-1.51 1.0-1.4 1.35 1.12-1.63 1.5-1.9 1.37 1.08-1.72 2.0-2.4 1.50 1.08-2.02 > 2.5 1.90 1.30-2.59

  15. Fecundability Density Ratio (FDR) of Pregnancies by Father’s Exposure to Lead; Sallmén et al 2000 Estimated PbB µmol/l N FDR 95% C.I. 0.5-0.9 203 0.92 0.73 - 1.16 1.0-1.4 79 0.89 0.66 - 1.20 1.5-1.8 21 0.58 0.33 - 0.96 > 1.9 23 0.83 0.50 - 1.32 > 1.5 (combined) 44 0.70 0.47 - 1.01

  16. Male Lead Exposure and Spontaneous Abortion Study PbB µmol/l OR 95% CI Selevan 1984 1.2 - 1.9 1.5 0.8-3.0 2.0 - 2.9 1.1 0.6-1.9 > 3.0 0.9 0.3-2.3 Al-Hakkak 1986 1.8 - 4.6 3.0 p<.01 Lindbohm 1991 1.0 - 1.4 1.0 0.6-1.7 1.5 - 1.8 1.3 0.5-3.4 > 1.9 1.6 0.6-4.0 Alexander 1996 1.2 - 1.8 1.0 0.6-1.7 > 1.9 0.7 0.4-1.5

  17. Male Lead Exposure and Congenital Malformations or Perinatal Death Study PbB µmol/l OR 95% CI M: Sallmén 1992 > 1.0 2.4 0.9-6.5 P: Kristensen 1993 exposed 2.4 1.2-4.9 P/M: Alexander 1996 1.2 - 1.8 2.9 0.6-13 > 1.9 2.5 0.5-11 M=malformation study P=perinatal death study

  18. Male Mercury Exposure and Spontaneous Abortion • Alcser et al 1989 (lifetime sum of individual quarter-year mercury levels) HGU-LEQU OR 95% CI 2000-3999 µg/L 1.3 1.0-1.8 4000-9000 µg/L 1.9 1.3-2.7 • Cordier et al 1991 U-HG µg/L OR 95% CI 1-19 1.3 1.0-1.7 20-49 1.7 1.0-3.0 > 50 2.3 1.0-5.2

  19. Welding and semen quality: Danish study among 430 first-time pregnancy planners • Hjollund et al 1998 • no clear differences attributable to welding in proportions of morphologically normal sperm, sperm motility, or sex hormones • finding may not apply to high-level exposure to welding fume or heat • no differences in urine concentration of chromium, manganese, or nickel between welders and non-welding metal workers

  20. Welding and time to pregnancy: Danish study among 430 first-time pregnancy planners • Hjollund et al 1998 • no overall effect of male welding on fertility • a decreased fecundability among smoking welders associated with both current and previous exposure; not a priori hypothesis • clear improvement of the work environment in Denmark during last decades

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