Toxic Bodies by Nancy Langston

Author:Nancy Langston [Langston, Nancy]
Language: eng
Format: epub
ISBN: 978-0-300-16299-8
Publisher: Yale University Press
Published: 2010-07-20T16:00:00+00:00

Feedlot runoff has proven to be contaminated with hormones, as Roy Hertz predicted in the 1950s (photograph courtesy of USDA Natural Resources Conservation Service)

In 2002 sites downstream of cattle feedlots were found to have significant levels of hormonally active compounds and fish with altered sexual development. In 2004 scientists tested twenty sites downstream of feed-lots for hormones, and more than half the sites had detectable levels of estrogenic activity. Estrogenic chemicals from feedlots, both from added hormones and from the animal’s own hormones, were present at concentrations high enough to harm reproductive development in fish.26 Roy Hertz was prescient in his concern that treating livestock with synthetic hormones might be creating a steroidal cycle in the environment. We have indeed altered the sexual development of aquatic life with the hormones we have given livestock. What that means for human reproductive health is still unclear.

Hormones fed to livestock create cascading changes to hormone systems within the environment and within the consumer. The meat from animals treated with hormones may contain direct chemical residues. Indirectly, the meat of animals fed grains has a nutritional profile that is different from that of grass-fed animals, and those differences include complex hormonal transformations. Grain-fed cattle, for example, are deficient in omega-3 fatty acids, which modulate the steroids involved in metabolism and reproduction. Foods low in omega-3 fatty acids may increase a woman’s risk of developing polycystic ovary syndrome, a hormonal imbalance that affects fertility.27 Grain-fed animals also contain less of a particular fatty acid known as conjugated linoleic acid. Conjugated linoleic acid blocks estrogen signaling in human breast-cancer cells, and many epidemiological studies link consumption of linoleic acid with lower rates of breast cancer. So in addition to its direct effects on breast cancer and other hormonally related conditions, the use of steroids in livestock production may indirectly increase reproductive problems in humans. Yet none of these problems can be quantified by risk-assessment protocols, and so they are ignored when it comes time to regulate.28

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