Thursday March 4, 2010

New Experiment Shows Gender-Bending Contaminants in Water

By Patrick B. Craine

March 4, 2010 ( – Studies continue to reveal the prevalence of hormonal contraceptives and other chemicals in water sources, and the devastating consequences of these chemicals for animal populations have been well-documented.

This week, a study has been released that has revealed the potentially dangerous effects of another common water contaminant – and, in this case, there could again be the danger of adverse effects on human fertility.

A new study has shown that one of the world’s most common herbicides – atrazine – which was diluted in water at levels comparable to that found in drinking water, turned genetically male frogs into “functional females.”

“Ten per cent of the exposed genetic males developed into functional females that copulated with unexposed males and produced viable eggs,” wrote Prof. Tyrone B. Hayes of the University of California at Berkeley and colleagues, who published their findings in the Proceedings of the National Academy of Sciences on Monday.

Atrazine is a common weed killer used by farmers throughout the world for crops such as corn, sugarcane and sorghum.

The researchers compared a control group of 40 male African clawed frogs in atrazine-free water with 40 males raised in water with an atrazine concentration of 2.5 parts per billion. This level is comparable to that allowed in drinking water by the U.S.’s Environmental Protection Agency (EPA), but is half of that allowed by Health Canada.

While 10% of the frogs affected by the chemical developed ovaries and could only produce male offspring, the other 90% showed low testosterone, low sperm counts, and were unable to reproduce.

Prof. Hayes admits his study can’t show how atrazine affects humans – frogs, who live directly in the water, are more vulnerable to the chemical’s effects. But he says the study raises questions about atrazine’s safety. “We need to reconfigure how we evaluate chemicals in the environment and the impact on environmental health and public health,” he said.

CNN reports that there are scientists concerned about the herbicide’s risk to human reproductive health. Other studies have linked atrazine with low sperm count and menstrual problems, as well as birth defects, low birth weight, and prematurity.

Atrazine was banned by the European Union in 2004 because of its contamination of the water supply. While it is still popular in the U.S., the EPA announced in October that it will launch a new scientific investigation into the chemical’s effect on humans, such as its cancer risk.

See related coverage:

Hormonal Contraceptives Pollute Drinking Water – Environmentalists Turn a Blind Eye

Study Confirms Estrogen in Water from the Pill Devastating to Fish Populations

Contraceptive Hormones Mutating Fish in St. Lawrence River

Study Links Water Pollution from Contraceptives, Chemicals with Declining Male Fertility