What’s the first thing you think of when you hear “lead poisoning?”
Paint from old houses, perhaps – especially old window frames and sashes? Or maybe, if you’re a waterfowl enthusiast, from buckshot or fishing tackle? Both of these are common and well-publicized ways in which lead finds its way into our environment, and both can lead to neurological damage in humans or animals.
But there’s another common source of lead poisoning in humans, one that is particularly likely to affect those of us who live out in the country – out in the clean, rural areas where nobody is thinking about lead poisoning: gardening.
Before you panic, here’s the good news: lead in the environment is not a widespread, diffuse problem like acid rain or global climate change. Very little “new” lead now finds its way into the environment compared with a generation ago, thanks to various laws like the Clean Air Act. But lead is a relatively big, somewhat inert element that can sit in the soil for decades before it causes a problem. That’s why lead in the soil remains a matter of concern for those of us who live and garden in rural areas.
Picture the following tranquil scene: a rustic old farmhouse with lots of flowers growing around it, perhaps an apple tree or two out front, a tidy garden sheltered from the wind by an old foundation wall, and a somewhat dilapidated ell being used as a garage or tractor shed. This is a classic spot– a classic New England farmstead, and classic spot for possible lead poisoning.
Back in the good old days, there were three primary ways for lead to get into the environment, and our tranquil country scene has all three: lead from gasoline, lead from paint, and lead from pesticides. (OK, there was a fourth primary source – lead from smelters – but that’s a story for another, more urban, day.)
Tetraethyl lead was added to gasoline between 1924 and 1982 to improve performance and prevent engine knock. Lead carbonate (and related lead compounds) was added to paint from the 1800s up until 1978 to make colors more durable and brilliant. Lead arsenate was a pesticide used as late as 1988 to protect orchards – especially apple trees – from insect damage. It almost goes without saying that the rural parts of New Hampshire and Vermont were no strangers to gasoline, paint, or apple trees.
The good news is that airborne lead, because it is so heavy compared with other common elements and compounds, tends to land on the ground quite close to where it was emitted: within a few dozen feet of the road or driveway, within a few feet of the foundations of houses and barns, and directly underneath apple trees. The bad news is that you can get lead poisoning not only by eating vegetables grown in contaminated soil but also by breathing in lead while working the soil, especially if that soil is heavily contaminated.
The solution to avoiding lead poisoning from these sources is as simple as not gardening next to the road, the house, or the old orchard. Roads and houses are pretty easy to spot, of course, but figuring out where old orchards or apple trees once stood can be trickier. Any roads, houses, or orchards built or planted in the lead-free days since the mid-1980s shouldn’t be a problem anyway.
But what if your prize garden spot happens to be in the foundation of the old barn, or up along the sunny side of your old farmhouse? It’s certainly worth the peace of mind to have a simple soil test done to see if you have a problem – visit the website of the Vermont or New Hampshire agricultural extension service for details.
If your site tests positively, all is not lost. If the lead level is just slightly above the dangerous level, grow only flowers, and mulch the soil to keep the lead in the ground and not on you or the flowers. If you have an especially contaminated site, you can remove the top foot or two of soil and replace it with fresh loam from a clean spot somewhere else. Provided your soil hasn’t been worked deeply in the past, the lead will still be in the top few inches of soil, right where it landed 20 or 50 or 100 years ago.
But whatever you do, don’t give up gardening! The rhubarb is already up, and the first red, juicy, sun-ripened, sun-warmed tomatoes are only 10 weeks away. Just make sure your prize-winning garden vegetables aren’t being served up with a side of lead.