Widely used but just tested pesticides may contribute to infertility.
Orton, F, E Rosivatz, M Scholze and A Kortenkamp. 2011. Widely used pesticides with previously unknown endocrine activity revealed as in vitro anti-androgens. Environmental Health Perspectives http://dx.doi.org/10.1289/ehp.1002895.
Several newly tested pesticides can block male hormone receptors in ways that could affect fertility in men, report researchers who tested the chemicals' hormonal actions in human cells. They report that 23 widely used pesticides – including nine previously untested chemicals – can block the androgen hormone receptor in the cells.
The chemicals vary in use, including as fungicides on crops and food, as wood preservatives and in industrial applications. Some of them replace banned or phased-out chemicals, and many are applied together as mixtures.
The results underscore the large gaps in testing compounds for hormonal activity as well as monitoring studies that track human exposures. Only a small percentage of the tens of thousands of chemicals currently produced and used in the United States are tested for hormonal activity or other health effects.
The androgen receptor is a critical male sex hormone receptor activated by testosterone. Its actions control men's sexual development and sex-specific characteristics, such as facial hair and muscle growth.
Environmentally prevalent chemicals such as those tested in the study may contribute to male infertility – which is reported to be rising worldwide – and male genital birth defects such as hypospadias and undescended testicles – by disrupting the activity of testosterone and other male sex hormones carried out through hormone receptors. Researchers call this collection of male health problems testicular dysgenesis syndrome.
Researchers at the University of London selected from a European database 34 widely used pesticides with high exposures through diet. They tested the chemicals for anti-androgenic activity in human cells. A number of the pesticides had never been tested but were predicted – based on their chemical structure – to interact with the androgen receptor.
Researchers used human cells with fluorescent readouts to examine changes in levels of genes that are controlled by the androgen receptor. A yeast assay directly measured the effects of candidate pesticides on androgen receptor activity.
The authors found that all 14 pesticides previously reported to have antiandrogenic effects also displayed androgen blocking effects in their study. Additionally, researchers identified nine new, previously unreported pesticides that altered androgen receptor activity. Many are used to kill fungus that grows on agricultural crops.
The results show that cell-based assays can quickly and efficiently predict toxicity of widely-used chemicals.
Based on potency, use, exposure and lack of knowledge, the authors "strongly recommend" additional testing to identify hormonal effects of six of the chemicals identified as anti-androgens. Further studies to determine exposures and effects in different models and species are warranted, the authors suggest.
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