(Beyond Pesticides, March 29, 2011)
According to a French study published March 2, 2011 in the online edition of Environmental Health Perspectives, prenatal exposure to the herbicide atrazine is linked to small head circumference and fetal growth restriction. The authors say the study “raises particular concerns for countries where atrazine is still in use.” Atrazine is a widespread contaminant in drinking water and is linked to various birth defects, endocrine disruption and cancer, even at concentrations below EPA standards. Although it has been excluded from re-registration in the European Union because it is found above allowable thresholds in groundwater, it is still one of the most widely used herbicides in the U.S. and around world.
The study, “Urinary Biomarkers of Prenatal Atrazine Exposure and Adverse Birth Outcomes in the PELAGIE Birth Cohort,” used a case-cohort design nested in a prospective birth cohort conducted in the Brittany region from 2002 through 2006. It collected maternal urine samples to examine pesticide exposure biomarkers before the 19th week of gestation.
Quantifiable levels of atrazine were found in urine samples from 5.5% of 579 pregnant women, and various metabolites were identified in 20-40% of samples. The presence versus absence of quantifiable levels of atrazine or a specific atrazine metabolite was associated with fetal growth restriction and small head circumference. Head circumference was also inversely associated with the presence of the herbicide metolachlor.
Atrazine is used to control broad leaf weeds and annual grasses in crops, golf courses, and even residential lawns. It is used extensively for broad leaf weed control in corn. The herbicide does not cling to soil particles, but washes into surface water or leaches into groundwater, and then finds its way into municipal drinking water. It has been linked to a myriad of health problems in humans including disruption of hormone activity, birth defects, and cancer.
In 2007, Indiana researchers reported in the Journal of Pediatric Surgery that in their state, where rates of such birth defects are also very high, atrazine levels are significantly linked with the rate of gastroschisis and other defects. Another study, published last year in Acta Paediatrica, found similar results for the general rate of birth defects in the U.S. population; it found that atrazine upped the risk of nine birth defects in babies born to mothers who conceived between April and July, when surface water levels of the pesticide are highest. Another study also found that atrazine triggers the release of stress hormones, leading researchers to believe that this may explain how the popular weed killer produces some of its harmful reproductive effects.
As the most commonly detected pesticide in rivers, streams and wells, an estimated 76.4 million pounds of atrazine is applied in the U.S. annually. It has a tendency to persist in soils and move with water, making it a common water contaminant. Research found that intersex frogs is also common in suburban areas than agricultural areas. Another study suggests it is a possible cause of male infertility.
Atrazine is a major threat to wildlife. It harms the immune, hormone, and reproductive systems of aquatic animals. Fish and amphibians exposed to atrazine can exhibit hermaphrodism. Male frogs exposed to atrazine concentrations within federal standards can become so completely female that they can mate and lay viable eggs.
The European Union banned atrazine in 2004, after repeated testing found the herbicide in drinking water supplies, and health officials were unable to find sufficient evidence that the chemical is safe. In much of Europe the burden of proof falls on the pesticide manufacturer to prove it is safe, unlike in the U.S. where EPA has assumed the burden of proving a pesticide does not meet acceptable risk standards before taking regulatory action.