Semen Analysis by Houston Zip Code & Environmental Exposure: A Retrospective Cohort Study

Male reproductive health has deteriorated during the last few decades [1]. There are marked geographic differences in the prevalence of male reproductive disorders [2] and sperm counts [3]. The reasons for these differences are currently unknown. Recent literature suggests environmental exposures such as high levels of air pollution [4] as well as heavy metal exposure [5] can cause declining sperm quality. To detect differences in semen quality by geographic location by comparing samples from different zip codes within various Houston and close surrounding areas. To determine if proximity to industrial areas has an effect on semen quality. Retrospective review of sperm samples from two Houston infertility clinics between January 2011 and July 2013 was performed. All men who gave semen samples were included. Exclusion criteria included those who lived outside of Houston/close outlying counties and patients with parameters listed that were input errors (i.e. motility >100%). Only first sample was analyzed if a patient had multiple specimens to avoid post-treatment bias. The semen data was assessed for quality by volume, concentration, total sperm count, motility, speed, white blood cell (WBC) count, red blood cell (RBC) count, total abnormal morphology, total motile, and lateral displacement. Samples were stratified by zip code according to pre-determined areas in and around Houston. Samples were also stratified by zip codes in areas with refineries vs. commercial/residential areas. Data was compared to each other using the Mann-Whitney U test. The total number of patients reviewed was 2051. The average age, volume, concentration, total sperm count, and motility were 36.5 + 6.9, 2.83 + 1.5, 45.2 + 53.3, 113.1+145, and 40.7 +26.3, respectively. Significant association was noted between age and all sperm parameters except for lateral displacement and WBC. No association was noted between zip codes and sperm parameters. The number of patients living in the same zip code as a refinery was 296. No significant association was noted between living near a refinery and sperm parameters. No significant changes were noted between semen quality and Houston area in which the patient lived, including refineries. Although over 2000 samples were evaluated for this study, we had a small number of samples from refinery-rich areas which is a limitation of our study.