The long-term effects of DDT exposure on semen, fertility, and sexual function of malaria vector-control workers in Limpopo Province, South Africa

Abstract

Hormonally active chemicals in the environment such as DDT have been associated with declining male reproductive health, especially semen quality. A cross-sectional study of 60 workers was performed near the Malaria Control Center (MCC) in Tzaneen, Limpopo Province, South Africa. Tests included a questionnaire (sexual function, fertility, and job history), a physical examination of the reproductive system, and semen analysis (produced via coitus interruptus or masturbation). Sperm count, density, and motility using the World Health Organization criteria and morphology using the strict Tygerberg criteria were determined. Serum o'p' and p'p' isomers of DDE, DDT, and DDD were measured. Forty-eight (81.0%) participants produced a semen sample, while all completed the questionnaires and physical examination. The mean sperm count was 93.8+/-130.3 million, and sperm density was 74.6+/-85.1 million/mL. The mean normal morphology score was 2.5+/-1.8% of subjects. Eighty-four percent of morphology scores were below either the WHO or the Tygerberg criteria, with the highest individual score being 6%. Self-perceived current problems with sexual function ranged between 10% and 20%. The most prevalent genital abnormality was abnormal testis disposition at 71%. There were few significant associations between DDT exposure measures (measured as years worked at MCC and serum DDT) and reproductive outcomes. p'p'-DDT was negatively associated with semen count (beta=-3.7+/-1.7; P=0.04; R2=0.05 adjusted for age, abstinence, physical abnormality, and fever in last 2 months). While the semen quality in the study was less than normal, no strong evidence for a DDT effect was found.