engleski

Effects of low-level lead exposure on semen quality in men

AIMS. The influence of lead, cadmium, copper, zinc, selenium, age, smoking habits and alcohol consumption on reproductive parameters was examined in male subjects without occupational exposure to metals. METHODS. In 123 Croatian men 19-48 years of age, including those from couples suspected of infertility and voluntary semen donors for artificial insemination, the following parameters were measured: blood lead (BPb), activity of delta-aminolevulinic acid dehydratase (ALAD), erythrocyte protoporphyrin (EP), blood cadmium (BCd), serum copper (SCu), serum zinc (SZn), serum selenium (SSe), and parameters of semen quality (including sperm concentration, motility, and morphology by using CASA technique) and of reproductive endocrine function (FSH, LH, prolactin, testosterone, and estradiol in serum). The interrelationship of biomarkers of lead (BPb, ALAD, EP) and BCd, SCu, SZn, SSe, age, smoking, and alcohol to each reproductive parameter was calculated by forward stepwise multiple regression. RESULTS. Significantly higher BPb (P<0.04) and lower ALAD (P<0.03) was found in a subgroup of 32 subjects who had considerably worse reproductive findings as compared to the remaining 91 subjects (smaller testes ; higher percentage of immature sperm cells ; lower sperm concentration and count ; lower percentage and count of motile, progressively motile, and viable sperm ; lower fraction of the lactate dehydrogenase isoenzyme LDH-C4 in seminal fluid ; and higher serum FSH). There was no significant difference between these subgroups in age, smoking, alcohol, EP, BCd, SCu, SZn, and SSe. After adjusting for possible confounding variables by multiple regression, an increase in BPb was significantly associated with decreasing percentages of subnormal (P<0.005) and normal (P<0.05) sperm, and increasing percentages of overly wide (P<0.0004) and slow (P<0.03) sperm. A decrease in ALAD was significantly associated with decreasing LDH-C4 in seminal fluid (P<0.003) and testis size (P<0.02). No significant association was found between BPb, ALAD, or EP and any of the reproduction hormones, whereas BCd was significantly associated with increasing estradiol (P<0.04) and FSH (P<0.05) in serum. CONCLUSIONS. The study results indicate that even low-level lead exposure (BPb range 25-149 microg/L in 123 subjects) can significantly reduce semen quality in men. This is relevant when selecting a reference group for male reproductive health studies in occupationally exposed subjects.

lead; cadmium; copper; zinc; selenium; age; smoking; alcohol; human male reproductive health

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