[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/06/EW-07-26-12-Dairy-Hormones.mp3|titles=EW 07-26-12 Dairy Hormones]
When buying dairy products, such as milk and cheese, we can opt to purchase items that are labeled ‘no added hormones.’ The same can’t be said of the wastewater that originates from large-scale dairy operations.
Lactating female cows produce estrogenic hormones, which are excreted in their urine and feces. Typically, this waste is collected in lagoons, where it is later applied to crops as fertilizer.
A recent study published in the journal Environmental Science & Technology found that large dairy farms are a primary source of estrogen pollution.
Hormone concentrations in livestock wastes are 100 to 1,000 times higher than those emitted from human sewage treatment plants—so reports lead author Wei Zheng of the University of Illinois’ Sustainable Technology Center.
When exposed to air, estrogen breaks down into a harmless byproduct. But Zheng and his research team found that, in low-oxygen environments like dairy lagoons, estrogen can persist for months and even years.
Lack of oxygen prevents estrogen from breaking down. Instead, the hormone rapidly converts from one form to another—stalling its biodegradation. The result? Estrogenic hormones that are both resilient and difficult to accurately measure.
Estrogen from dairy lagoons pollutes drinking water supplies, has the potential to feminize aquatic animals, and can be taken up by crops fertilized with the waste.
We are unlikely to lose our taste for cheese and ice cream. With that in mind, new strategies are needed to prevent estrogenic hormones from building up in the environment.
Photo, taken on May 2, 2006, courtesy of Kabsik Park via Flickr.