While a jug of milk may have a label assuring that there are “no added hormones” in it, the same may not be true for the water coming out of dairy farms. According to a study published May 15 in the journal Environmental Science & Technology, large dairy farms are “a primary source” of estrogen contamination in the environment.
Estrogen from lactating cows is excreted in their waste, which is thrown into farm wastewater pools known as “lagoons” to later be used as crop fertilizer. The study found that when exposed to air estrogens break down into a harmless byproduct; however, in low-oxygen environments like dairy farm lagoon water, the hormones persist for months or even years. When the researchers tested samples of lagoon water, levels of three primary estrogens (17 alpha-estradiol, 17 beta-estradiol and estrone) fell and then rose again. Further analysis revealed that the estradiol strains were converting to estrones and then estrones were reverting back to estradiol strains. By rapidly converting from one form to another, the hormones were stalling their biodegradation—so much so that even after 52 days at 95 degrees Fahrenheit (an ideal temperature for hormone degradation), less than 30% of the hormones in the solution had broken down.
“We call this a reverse transformation,” said University of Illinois Sustainable Technology Center senior research scientist Wei Zheng, who led the study. “It inhibits further degradation. Now we have a better idea of why [the estrogens] can persist in the environment.”
Zheng warns that these morphing, resilient estrogenic hormones will be hard to detect once they enter drinking water supplies or the food chain through dairy lagoon fertilizer crop sprays. The effects on marine life are also an issue—even minor levels of estrogen can prompt male fish to develop low sperm counts or even female eggs, undermining their ability to reproduce. “These estrogens are present at levels that can affect the (reproductive functions of) aquatic animals,” Zheng said.
In November, the European Parliament will decide on a 30 billion pound proposal to clean up contraceptive hormone water contamination responsible for freshwater fish mutations and population collapses. Alarmingly, “hormone concentrations in livestock wastes are 100 to 1,000 times higher than those emitted from plants that treat human sewage,” Zheng noted, adding that strategies to “prevent these hormones from building up in the environment” are urgently needed.
Dairy farm hormone pollution is currently unregulated, along with numerous estrogen-mimicking chemicals lurking in food and personal care products. This past March, the U.S. Food and Drug Administration denied a Natural Resources Defense Council petition to ban the hormone-disrupting chemical bisphenol-A (BPA), commonly found in food can lining and beverage packaging. And this week the U.S. Environmental Protection Agency will hold a meeting to discuss whether to federally restrict the use of the gender-bending herbicide atrazine, which has been shown to cause complete sex reversal in male frog populations. Eighty million pounds of atrazine are applied in the U.S. annually, primarily on corn, sugarcane, rice, sorghum and on golf courses and lawns.