These results suggest that human dietary PCB exposure might have a negative impact on the sperm chromatin integrity of adult males but additional issues, including differences in the genetic background and lifestyle habits, still need to be elucidated.

The overall results of the present study create a somewhat ambiguous pattern, but give some support to the idea that dietary POP exposure might be harmful for couple fertility.

Objectives Several reports indicate a secular decline of human sperm counts. It is still not known if these findings are artifacts related to shortcomings in the data and applied methodologies. Even less is known about possible mechanisms, but it has been proposed that potential changes may be related to disruption of the hormonal regulation of testicular development in prenatal life. The objective of this study was to examine whether sperm count was related to year of birth. Methods An analysis was made of the sperm count of 1196 men participating in 10 cross-sectional occupational sperm studies in 3 regions of Denmark from 1986 through 1995. Results The median sperm concentration was 63 million per milliliter for men born in 1937-1949 and 52 million per milliliter for men born in 1970 or later, and the median total sperm was 206 million and 117 million, respectively. The inverse relationship between sperm concentration and year of birth was statistically significant even after adjustment for duration of sexual abstinence, season of the year, and study population. However, bias because of differential participation related to age and fertility or lack of comparability across the populations cannot be ruled out. C O~C~U S~O~~S The apparent decline of sperm count with increasing year of birth is compatible with the hypothesis of a common risk factor for male reproductive health operating in prenatal life or early childhood, but the evidence is circumstantial. Age-related selection bias is an alternative and perhaps not a less likely explanation.

Serum inhibin B may be a reliable marker of male fecundity for epidemiological research and may have some advantages over sperm density. Our findings do not support the replacement of sperm density by male inhibin B when obtaining sperm data is an option.

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Objective To investigate if maternal exposure to psychosocial job strain at work (high demands and low control) measured by questionnaire early in pregnancy (median week 15) is associated with malformations in the offspring.Design Population-based cohort study.Setting The Danish National Birth Cohort.Population A cohort of 60 386 singleton children with full information on mother's occupational status, exposure to psychosocial job strain and all covariates during pregnancy.Methods Logistic regression analysis was used to calculate the odds of congenital malformations as a function of job strain with adjustment for maternal age, body mass index, parity, smoking, alcohol use, manual versus nonmanual work, maternal serious disease and gestational age at interview.Main outcome measures Circulatory malformation, musculoskeletal malformation or any malformation.Results Logistic regression analyses, both crude and adjusted, indicated no associations between working under high strain and giving birth to a child with circulatory malformation (adjusted odds ratio [OR] 1.04, 95% confidence interval [95% CI] 0.75-1.44), musculoskeletal malformation (aOR 0.88, 95% CI 0.71-1.10) or any malformation (aOR 0.99, 95% CI 0.85-1.15). Supplementary analyses including restriction to first-borns and a stratified analysis with respect to manual and nonmanual work did not change the results.Conclusions Association between exposure to high job strain during pregnancy and elevated risk of circulatory, muscle and any malformations is not supported by this study.

Joining of metals by welding confer an exposure of dust particulates containing several toxic substances. Chro mium, nickel and manganese is absorbed in the lungs and may adversely affect the renal function. We compared biological markers of glomerular filtration (Kampmann clearance) and tubular function (post-shift urine spot sample concentration of respectively albumin, immuno globulin G, transferrin, orosomucoid and β2-microglobu lin) among 102 ever-welders and 33 never-welders (mostly electricians). The welders were subdivided into groups of stainless steel welders (n=35), mild steel welders (n=46) and ex-welders (n=21). Each group was separately referenced with never-welders. The Kampmann clearance was within normal limits in all workers and not related to welding exposure. However, the urinary concentration of the majority of proteins was 1.5 to 3.0 times higher in both stainless steel and mild steel welders. The number of welding years taken as a measure of cumulative welding exposure was not related to levels of proteins in urine when adjusting for the effect of age. In addition, no alteration of urinary proteins was found among the ex- welders apart from slightly elevated albumin. This indicates that the apparent effect of welding on renal tubular function may at least partially be reversible. In conclusion, this study is in support of the hypothesis that metal welding may adversely affect renal tubular func tion, but it is questionable whether welding exposure has bearings as to occurrence of clinical significant kidney disease.

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