Compost and Pharmaceuticals


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 . . .

A Straw Bale Urinal

straw bale urinal

L’Uritonnoir, a plug-in straw-bale urinal. Photograph: Faltazi

At the risk of becoming a blog entirely about urine and straw bales, Anne Hars alerted me to an article in the Guardian, “L’Uritonnoir: the straw bale urinal that makes compost from ‘liquid gold’” about French design studio Faltazi’s plug-in straw bale urinal.

The device comes as a flat polypropylene sheet, which is folded into shape and slotted together, then threaded on a looping band around the bale, its funnel wedged deep into the centre of the straw to channel the fluid to the composting core. A deluxe version is also available in stainless steel – presumably for the VIP bale urinal area.

L'uritonnoir by faltazi

According to the article, Faltazi’s straw bale urinal will debut this summer at the French heavy metal festival Hellfest.

Ladies will have to pack their funnels.

How To Manage a Compost Pile Using Temperature

compost temperature chart

I’ve always been confused about when to turn a compost pile. Some people suggest lots of turning while others don’t turn at all. I built a pile in December using a technique I learned from Will Bakx, soil scientist and operations manager of Sonoma Compost. Bakx recommends keeping the pile between 131° F (55° C) and 163°F (72°C) for a period of 15 days. The only time you turn is when the pile starts to dip below 131° F or to prevent the pile from going above 163°F.

The technique is simple–all you do is take the temperature once a day with a compost thermometer and write down the result on a calendar. The graph above is the result that I got from a pile made out of horse bedding, chicken manure from our hens, plant materials, straw and brew waste from a local brewery.

The red area on the chart is the thermophilic temperature range (135° -160° Fahrenheit). The dip you see at day 15 is the one time I turned the pile so that I could keep it in the thermophilic range. Using temperature as a clue to when to turn the pile has a number of advantages:

  • You can make sure that the pile does not get too hot. Above 160° F  you start to kill off the thermophilic bacteria that decompose your pile. To decrease temperature you turn and add more carbon material and water.
  • Washington State University recommends subjecting all of the pile to temperatures above 150° F to kill potential pathogens. I’m fairly certain that, with the turn I did at day 14, all of the pile got up to 150°F.
  • Weed seeds are killed above 130°F–another reason to watch temperature.
  • Failing to get high temperatures can be an indication of too much carbon or a lack of water. To correct, add more nitrogen and water and turn.
  • A loss of temperature could indicate that the pile is going anaerobic. The solution is to add more carbon material and turn.

Once the pile has had 15 complete days over 131° F you just let it sit. Compost is done when it is dark, smells like earth and you can’t recognize the original ingredients. It will likely be several months before it’s ready to use. I’ve found that I need to turn the pile periodically and add water after the initial thermophilic period due to our dry climate.

The mass of the pile is a factor as well–I’ve found that it needs to be a minimum of one cubic yard of material to start with. So I save and scavenge materials that I can use to build a pile all at once. The small trickle of kitchen scraps we generate each day goes into our worm bin.

Despite the geekery with using a compost thermometer, I’ve found that this method saves labor. Back breaking turning only happens when it’s necessary.

Hay Hooks–The New Hipster Accessory?

With so many city chickens I predict that hay hooks will become just as indispensable to the urban hipster as is the fixed gear bicycle. After years of hauling staw bales up the 30 steps to our house (to use as bedding for the chickens) I just broke down and bought a pair.

A vaquero at the feed store intervened with a neat tip when he saw me struggling to use my new hay hooks to load some bales into a friend’s truck. Here’s what he showed me. Note the red arrow in the photo above. Odds are with new hooks that this distance needs to be shortened a bit. My hay hooks were much easier to use after the feed store guy bent them using one of the anchor points in the truck bed.

In addition to the steps, my other reason for owning hay hooks is that I have to navigate bales down a narrow side yard. Hay hooks make the maneuver above a lot less awkward.

Now when will we see Bianchi come out with the hay hook equivalent of the Pista?