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Composted Manures? Use With Caution

Here’s an email we received today from a SafeLawns follower that we thought was worth sharing:

Hi Paul,

I’ve been reading your blog and website, and am really pleased to see what you are doing. Thank you for your efforts!

I want to share with you a strong caution regarding the recommendations to use composted manure as an organic input. It may contain organophosphate and/or other toxic pesticides even after proper composting.

Many categories of livestock in the USA, including virtually all horses for example, are fed what is known as “pass through” or “feed through” pesticides. These products are intended to be excreted in the livestock’s manure, where they then kill fly and other parasite larvae.

Pass through pesticides have long half-lives (more than a year in laboratory testing). They do not readily break down even under the best composting circumstances. The specific pesticides used are chosen because they endure heat and sunlight for lengthy periods without breaking down.

The pass through product most commonly used by grain mills that produce animal feed until recently was tetrachlorvinphos, and it is still used industry-wide, along with other toxic feed-through pesticides.

Tetrachlorvinphos is a chlolinesterase inhibitor. In studies done for lawsuits brought by horse breeders against Farnum, suppression of chlolinesterase in test horses matched levels that the federal government’s military testing programs deem indicative of a serious chemical weapons exposure — and those results were apparent within five days of commencing a program of feeding the horses the product at the current approved levels.

That these products are fed to livestock is something that remains “under the radar” still unless you are familiar with the livestock industry. Very few organic and non-toxic garden and lawn care educators and providers are aware that this is going on.

If you’d like more information about the pass-through fly control practices, I have public details about it on a webpage that I have regarding the toxicity of the pesticides used on horses, at:

If you’d be interested in details regarding the studies and the lawsuits, please contact me personally and I can get you in touch with the researcher for the breeders that brought the lawsuits, my friend and internationally respected scientist Dr. Warren Porter. Dr. Porter carried out the research studies used in the court cases which were also used by the EPA to change the labeling on these products, and he was an expert witness in the trials.

If you are not familiar with Dr. Porter’s research on the toxicity of agricultural and lawn care pesticides, I highly recommend it. He is one of the world’s renowned environmental toxicologists, and the former chair of the Department of Zoology at the University of Wisconsin-Madison. His published peer-reviewed studies of the deleterious effects of pesticides are stellar.

Best regards,

Judy Stouffer, B.S., M.S., SFO

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

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