We get this question a lot–will pharmaceuticals end up in my compost if I use human urine or animal manure? This is really three questions:
- Does composting break down pharmaceuticals?
- Are some pharmaceuticals worse than others in terms of their ability to survive the composting process?
- If pharmaceuticals persist after composting do edible plants uptake them in sufficient quantities to effect humans?
A look at what science has to say
We really need a Root Simple research department! I was able to find a few studies that, at least partially, address these questions. If you know of more please leave a link in the comments.
A 2010 study looked at the degradation of salinomycin, used on chickens to prevent coccidiosis. The study concluded,
On the basis of the results obtained in this study, it appears that the composting technique is effective in reducing salinomycin in manure.
Another 2010 study looked at the composting of sewage sludge containing fluoroquinolones (broad spectrum antibiotics),
The concentrations of pharmaceutical residues in compost were significantly lower, if compared to the relevant concentrations in sewage sludge . . . It is concluded that before using the sewage sludge compost as a fertilizer it should be carefully tested against the content of different pharmaceuticals. The content of pharmaceuticals in the compost made from sewage sludge may easily lead to the elevated concentrations in food plants, if the compost is used as a fertilizer.
A slightly contradictory Estonian study concluded:
In the current study, uptake of ciprofloxacin, norfloxacin, ofloxacin, sulfadimethoxine and sulfamethoxazole was demonstrated in lettuce. The uptake of fluoroquinolones and sulfonamides by plants like lettuce does not seem to be a major human health risk, as the detected levels of the studied pharmaceuticals were relatively low, if compared to their soil concentrations. Further studies are needed to determine the uptake of different types of pharmaceuticals and other organic pollutants by various crop plants.
What about hormones? A paper in the Journal of Environmental Quality concludes,
composting may be an environmentally friendly technology suitable for reducing, but not eliminating, the concentrations of these endocrine disrupting hormones at concentrated animal operation facilities.
But we’ve got a lot of hormones making their way into the environment due to agriculture, according to a study done by Temple University,
Animal manures (poultry manure and cow manure) contribute to a significant load of estrogen hormones in the natural environment.
Clearly we may have some big societal problems caused by the overuse of pharmaceuticals and waste generated by industrial livestock operations. Those issues are beyond the scope of this blog.
But what about home composting? Should I pee on my compost pile if I’m on lots of pills? Maybe not. But I think there are a few common sense guidelines we can follow when working with human and animal urine or manure at home:
- Don’t use municipal compost that is made with sewage sludge, though I’m more worried about heavy metals in that compost more than I am about pharmaceuticals.
- Since I’m not on any pharmaceuticals, I’m not worried about my own urine in the compost pile.
- Joel, who commented on an earlier Root Simple post about using urine in compost, had this to say, “The main thing I’d worry about is radionuclide therapy, such as treatment with radioactive iodine vs. thyroid cancer. I guess I’d also worry a little about people who are on chelation therapy to flush toxic heavy metals from their system. If it’s not concentrated enough to harm your kidneys, though, I’m thinking it’s not enough to worry about in soil…perhaps that is me being naive.”
- If I were collecting pee soaked straw bales at a French heavy metal concert (unlikely!), I might have the resulting compost tested if I were going to use it on vegetables. But composting those bales would be better than flushing all that urine down the sewer system.
As to the bigger environmental issues, the good news is that some of the research shows that composting can help reduce pollution. And, since some of us have the space to compost at home, we can all contribute to a cleaner planet.
What do you think? Leave a comment . . .