With every passing year the evidence of atrazine’s harmful environmental and human health effects grows stronger.  Now a new study, summarizing over a decade of research, has further confirmed some truly scary stuff about atrazine, the most commonly detected pesticide contaminant of ground and surface water: atrazine both “demasculinizes” and “feminizes” vertebrate male gonads. (You can read the study here.)

First, you may be wondering, what the heck is the “demasculinization” and “feminization” of male gonads?   Put plainly: atrazine shrinks testicles, reduces sperm count, and can even make males grow ovaries.  Or, as the authors put it, “demasculization” is a “decrease in male gonadal characteristics including decreases in testicular size, decreases in Sertoli cell number, decreases in sperm production, and decreases in adrogen production.”  Feminization of gonads is “the development of oocytes in the testes or complete ovarian differentiation in genetic males.”  Here are some more quick take-aways from this important new study:

  • First, this is a very robust piece of work, summarizing experimental and epidemiological data going back to 1997. The study boasts an impressive list of twenty-two authors from major research institutions in the United States, Canada, Japan, Belgium, Croatia, Argentina, Brazil, and England.  These results thus represent effects “described by independent laboratories in eight different countries on five continents.”
  • Even more impressive, these “effects on the gonads are both specific and consistent and do not occur merely across populations, species or even genera or orders, but across vertebrate classes:” that is, across fish, amphibian, reptile, and mammal species.
  • How does atrazine cause these reproductive effects?  The study concludes that atrazine exposure interferes with and reduces the production of male hormones (androgens) while increasing the effect and production of estrogen (female hormones).
  • Importantly, the study points out that while changes we can actually observe in the gonads of these animals are concerning, “functional impairments are likely of greatest importance.”  The study goes on to note that male salmon exposed to atrazine showed decreased mating behavior and milt (sperm) production; that “nearly identical reproductive impairments were observed in amphibians”; that in rodents atrazine exposure “resulted in as much as a 50% decrease in epididymal sperm number and decreased sperm motility”;
  • But wait, there’s more: in addition to the effects on gonads, the study also notes that “there are many other documented reproductive effects of atrazine in laboratory rodents: induced abortion, impaired mammary development, the induction of reproductive and hormone-dependent cancers…impaired immune function (also observed in multiple studies across vertebrate classes) and impaired neural development.”

Here’s the study’s bottom line: “Atrazine” the authors write “is prevalent and persistent in the environment” and “can have dramatic effects on ecosystems, environmental health and public health.”

While it would be easy to dismiss this as a problem largely confined to fish, frogs, and rats, atrazine’s impacts hit humans below the belt too. The authors point out that “low fertility, low sperm count, and poor semen quality were also associated with atrazine exposure…in humans living in agricultural areas.”

It’s time to ban the stuff.  You can take action here.