[Purdue University 04 April 2013] — An agricultural herbicide alters reproductive and neuroendocrine genes during embryonic development in fish, according to new research. “The exact connection to health outcomes is not defined, but we found gene alterations in our animal model when exposed to the level of atrazine that is deemed safe for drinking water,” says Jennifer Freeman, an Assistant Professor of Toxicology in the School of Health Sciences at Purdue University. “Also of concern was an increase in head length in the study’s young zebrafish when exposed to low doses of this widely used herbicide.” The researchers tested atrazine at three levels, 0.3 ppb, 3 ppb, and 30 ppb, by exposing developing zebrafish embryos. The 3 ppb level is the current safe level in drinking water, and the larger amount of atrazine tested represents what a worker may be exposed to or may be present in surface water. By using the zebrafish model the researchers were able to focus on the 72-hour embryonic development time, which mirrors human prenatal development. The researchers started by evaluating the more than 35,000 genes in the zebrafish’s genome. They found that two genes, CYP17A1 and SAMHD1, were changed in all three treatments. CYP17A1 plays a role in biosynthesis of steroid hormones and the conversion of androgens to estrogen, and SAMHD1 controls immune function. Also of concern was that 42 of the genes, including CYP17A1 and SAMHD1, were affected in the 30 ppb treatments as well as in the 3 ppb treatment. The LH gene, which produces the hormone that triggers ovulation, is another example of an affected gene at both 3 ppb and 30 ppb treatment levels. “There is a connection between the current legal level of atrazine and higher concentrations that need further study,” Freeman says. Freeman says continuing to investigate changes in genes associated with cancer is critical because there needs to be more information before determining if atrazine is a human carcinogen. ${imageDescription} Comment [Photo credit: Flickr]
