Researchers knew as far back as 1938 that various pollutants found in water caused birth defects in laboratory animals. These chemicals damaged the animals by disrupting their endocrine systems. A team headed by J. A. McLachlan in 1996 confirmed the endocrine disrupter problem by comparing laboratory studies on turtles to abnormalities seen in turtles living in polluted waters. Recent studies conducted in Asia, Europe, and the United States indicate that endocrine disrupters may be impacting human health. Higher incidences of breast cancer in certain regions are correlated with high levels of suspected endocrine disrupters in the drinking water.
Similar studies link declining sperm counts to the intake of endocrine disrupters in food and water.
Endocrine disrupters are not regularly tested for in natural bodies of water. Traces of pesticides and other organic pollutants have been detected in drinking water supplies in many communities along the Gulf Coast and southern Mississippi River. There is also evidence that suspected endocrine disrupters are entering the diet on fruits and vegetables having pesticide residues. Although the levels of endocrine disrupters in the diet are minuscule, there is much concern about their prolonged intake in foods and water. Immediate effects on human health may not be readily visible.