Effects of Dibromochioropropane Upon Diurnal Variations of Gonadotropins and Androgens

Abstract

The effects of exposure to dibromochloropropane (DBCP) for one to seven years on testicular physiology were evaluated in five men by measuring the circulating levels of FSH, LH, androstenedione, testosterone, and dihydrotestosterone (DHT) every 4 hours throughout a 24‐hour period, and correlating this data with semen analysis and testicular biopsy. The study showed above‐normal concentrations of plasma FSH in 29 of 30 samples and plasma LH in 25 of 30 samples. With one exception, androstenedione levels were lower than normal in all subjects. Plasma testosterone and DHT concentrations were generally within the normal range (24 of 30 and 29 of 30, respectively). The anatomic damage to the testes varied from no perceptible lesions to complete absence of germinal epithelium, with the corresponding range of results of semen analysis from normal spermatogenesis to azoospermia. The results suggest that DBCP causes profound damage of the germinal epithelium and that damage may be present before a histologic abnormality can be clearly demonstrated. The observed elevated levels of LH in the face of normal testosterone concentrations would suggest damage to the Leydig cells, with the chronic overstimulation of these cells by LH being necessary to maintain essentially normal testosterone concentration. Histologic evidence of Leydig cell hyperplasia supports this interpretation of hormonal findings.