We’re starting a new series, the “Garden ABC”. I thought we’d begin with a little scary information about ways that arsenic could be getting into your garden. That may sound bizarre, but actually arsenic is dangerous at very minor levels. The amounts to which we’re exposed, from sources as diverse as coal-fired electrical plants to pressure-treated lumber to municipal water to chicken dinners, add up rapidly. Arsenic is a potent carcinogen, as well as a direct poison. The Safe Water Act would have lowered municipal water levels of arsenic from 50 parts per billion to 10 ppb, but it was struck down by the current administration.
We hope that arsenic is not entering your garden through your water supply. If you suspect that it might be, you can request the Consumer Confidence Report on your water supply. The other way that arsenic can sneak into your garden is via commercial chicken manure.
Not Just Chicken Feed
Here in the USA, commercial chicken feed contains roxarsone, an organic (in the chemistry sense) arsenic compound that suppresses bacterial infections in the chickens’ guts and makes them gain weight faster. Unfortunately studies are showing that it’s secreted in the toxic, inorganic form. As one article so aptly put it, Food for Chickens, Poison for Man. It’s banned in the EU and ought to be banned here.
The rate at which bacteria convert roxarsone to toxic arsenic has been widely underestimated until the recent publication of new evidence linking chicken litter and toxic arsenic. The chicken waste is pelletized and sold as fertilizer to commercial farmers. Chicken manure is also sold in dried or composted form at hardware and garden centers. Studies show that fields which are spread with this material are getting noticeable amounts of arsenic.
If you know folks who are giving you chicken manure, check to see if they’re mixing their own ‘scratch’ feed from grains or using a pre-mixed feed that might have roxarsone. There are numerous suppliers of certified organic chicken feed and mash if one prefers a pre-mix.