Many agricultural pesticides – including some previously untested and commonly found in food – disrupt male hormones, according to new tests conducted by British scientists.
The scientists strongly recommended that all pesticides in use today be screened to check if they block testosterone and other androgens, the hormones critical to a healthy reproductive system for men and boys.
“Our results indicate that systematic testing for anti-androgenic activity of currently used pesticides is urgently required,” wrote the scientists from University of London’s Centre for Toxicology, led by Professor Andreas Kortenkamp.
Thirty out of 37 widely used pesticides tested by the group blocked or mimicked male hormones. Sixteen of the 30 had no known hormonal activity until now, while there was some previous evidence for the other 14, according to the study, published online last Thursday in the scientific journal Environmental Health Perspectives.
Most of the newly discovered hormone disruptors are fungicides applied to fruit and vegetable crops, including strawberries and lettuce. Traces of the chemicals remain in foods.
“This study indicates that, not surprisingly, there are many other endocrine disruptors that we have not yet identified or know very little about,” said Emily Barrett, a University of Rochester assistant professor in obstetrics and gynecology who was not involved in the study.
“This underlines the glaring problem that many of the chemicals that are most widely used today, including pesticides, are simply not adequately tested and may have serious long-term impacts on health and development,” said Barrett, who studies how environmental chemicals affect human reproduction.
The findings come as the U.S. Environmental Protection Agency faces opposition from the pesticide industry after expanding its Endocrine Disruptor Screening Program, which requires testing of about 200 chemicals found in food and drinking water to see if they interfere with estrogen, androgens or thyroid hormones.
None of the 16 pesticides with the newly discovered hormonal activity is included in the EPA’s program, which means they are not currently screened and there are no plans to do so.
The EPA’s program has been slow to implement, largely due to a controversy over testing methods. Environmental groups criticize the EPA, which was granted the authority by Congress in 1996, for taking so long to order manufacturers to test only a small group of chemicals. But chemical industry officials say that the tests cost up to $1 million per chemical and the techniques have not been fully validated. They also stress that positive results don't necessarily mean that the pesticides are harming human reproduction.
The British researchers screened the chemicals using in-vitro assays, which use human cells to check whether the pesticides activate or inhibit hormone receptors in cells that turn genes on and off. They are a widely accepted lab techniques. Scientists, however, are uncertain what actually happens in the human body at the concentrations of chemicals that people encounter in fruits and vegetables.
Fetuses and infants may be particularly at risk when exposed in the womb or through breast milk because the hormones control masculinization of the reproductive tract.
Some research has linked pesticides to abnormal genitals in baby boys, such as cryptorchidism and hypospadias, and decreased sperm counts in men. Male fertility is thought to be declining in many countries, and testicular cancer is increasing. Some scientists have dubbed this compilation of male disorders “testicular dysgenesis syndrome,” and suggested that hormone-disrupting environmental contaminants play a role.