Review: Environmental endocrine disruptors of testicular function

Abstract

In the last 50 years the incidence of infertility, testicular and prostate cancers and associated maladies has increased significantly. Infertility now affects 15-20% of couples as opposed to 7-8% fifty years ago. Average sperm counts among adult men have decreased by 50% since 1938, with a decline of 2% every year from 1973. This decline in male reproductive health has been linked to an increased presence in the environment of chemical contaminants in the form of pesticides and plastics. Rapid and unplanned industrialization caused large amounts of these synthetic compounds and their by-products to be released in the environment (air, soil, water and food). Studies have shown that occupational exposure to pesticides caused neonatal deaths, congenital defects, testicular dysfunction and male infertility. Many of these chemicals found in our environment and households have oestrogenic properties ("xenoestrogens") and are toxic because they affect the endocrine system ("endocrine disruptors"). Evidence of the health hazards of endocrine disrupting chemicals continues to mount. In terms of male fertility, it now seems that these ubiquitous chemicals are a significant threat at various stages, from testicular development to sperm production to the functionality of healthy sperm. This class of chemicals appears to be threatening male fertility on several fronts. That endocrine disruptors abound in our environment is not in doubt. Clinicians and other health practitioners confronted with the challenges of managing male infertility should attempt to identify the aetiology of a possible exposure to endocrine disruptors, and initiate a plan to control and prevent exposure to others. In addition, concerted efforts should be made by both government and non-governmental agencies to institute local studies that will assess local endocrine disruptors, degree of contamination, level of exposure and proffer control and preventive measures. Emphasis should be placed on establishment of chemical screening and testing program, research into dose and vulnerable periods, institution of surveillance of disease incidence, improvement of exposure monitoring, and educating community leaders and the public in general.

Before the Study Begins: Infertility Considerations in Wistar Rat Models

“…Maintaining optimal housing conditions is crucial to minimize stress-induced infertility. Exposure to environmental factors, including pollutants and endocrine-disrupting chemicals, can compromise reproductive function in Wistar rats [12]. Investigating the impact of these factors on infertility provides essential insights into the mechanisms of fertility disruption [13,14] (Figure 1).…”

Causes and Risk Factors for Male Infertility: A Scoping Review of Published Studies

“…71 Occupational exposure to pesticides caused testicular dysfunction and male infertility. 72 Oliva et al 73 studied 225 male partners from consecutively recruited couples who presented for infertility treatment in Argentina. After adjusting potential confounders such as age, BMI, and smoking, a significant association was observed between exposure to pesticides and solvents and low sperm count.…”

Speciation, Phenotypic Variation and Plasticity: What Can Endocrine Disruptors Tell Us?

“…EDs constitute a heterogeneous group of natural and synthetic chemicals that mimic, block, or disrupt the synthesis, transport, or elimination of natural chemical messengers such as classic hormones, cytokines, and neurotransmitters [14–17]. When their active forms are released to the environment, they are absorbed by organisms through epithelial linings.…”