Authors:
Hauser, R., Altshul, L., Chen, Z., Ryan, L., Overstreet, J., Schiff, I., Christiani, DC.

Title:
Environmental Organochlorines and Semen Quality: Results of a Pilot Study

Source:
Environmental Health Perspectives: 110 (3); 229-233. 2002

Summary:
Numerous chemicals in the environment are suspected to possess estrogenic and anti-androgenic qualities. Several of these chemicals, some PCBs and DDT, are ubiquitous in the environment and detectable in the fatty tissue of most humans. Some researchers have proposed that these chemicals may have contributed to the alleged decline in male semen quality over the past several decades.

Hauser et al. conducted a pilot study at the Massachusetts General Hospital Andrology Laboratory to investigate whether a relationship existed between serum PCB and DDT levels and decreased sperm counts. Subjects presenting to an andrology laboratory for semen evaluation were asked to participate. Most of the men were partners in couples undergoing medical evaluation for infertility (n=29).

The authors wanted to study a population without specific occupation exposures to PCBs or DDT in order to represent levels in the general population. As well, this population was chosen for the diversity of men who visit this clinic. Blood serum samples were collected and analyzed for 65 individual PCB congeners, p,p'-DDE and hexachlorobenzene (HCB). Sperm samples were analyzed by an andrologist, for spermatozoa counts, motility, and morphology. The andrologist did not have prior knowledge of the man's exposures. Reference values for sperm concentration, motility were similar to those recommended by the World Health Organization (WHO). Men above normal in all three semen parameters were used as a comparison group and considered to have normal semen. Additionally, to gain insight into the men's medical history and lifestyle, a questionnaire was given to participants.

The average age of the men was 33 years and the distribution of confounding variables (subject's age, length of sexual abstinence before semen sample collection) was similar between the two comparison groups. Subjects with below normal sperm concentration, motility and morphology tended to have higher concentrations (both mean and median) of p,p'- DDE, and some specific PCB congeners. Due to the small sample size the authors did not pursue a statistical association. There was a wider distribution of exposure concentrations of PCBs and DDE among individuals who had below normal motility compared to those with normal semen. The suggestive trends found in this pilot study justified a further full-scale investigation that is currently underway.

There may be several other factors such as stress levels, excessive heat exposure, medication use and occupation that could have influenced the results of this study. As well, it may be difficult to generalize the results because the study population comes from a fertility clinic. Using community controls would have been less convenient but more representative of the general population. Numerous epidemiologic studies have looked at declining sperm counts in various geographical regions but few have attempted to measure external factors potentially influencing fertility. This study is important as it addresses the question of organochlorine exposure and declining semen quality. The quantified measurements will also allow researchers to compare organochlorine levels in men across different studies.