Dear Umbra,
you talked a fair amount about lead pollution. Since gasoline is no
longer leaded, and since it’s container gardening that wouldn’t have
any lead paint in it, and surely nobody has lead water pipes any more,
why is lead even a concern?
Teresa
Brenham, Tex.
Dearest Teresa,
Our ecological history hangs around our necks like a lead weight.
gardening issue, and would like to offer additional information useful
to all gardeners. You are right that lead in store-bought container
gardening soil is not a considered a concern. Airborne heavy metals are
the main concern for rooftop container gardeners. These airborne
particles may or may not include residual lead dust from the days of
leaded gasoline and lead paint, as well as lead (and other heavy
metals, like arsenic and cadmium) associated with our current
industrial life. Lead is still used in, among other things, the
manufacture of batteries and some plastics — and the federal
government is still grappling with how to set airborne lead standards.
States from the early 1920s until the mid-1970s, when its phase-out
began. I always thought the lead phase-out story was one of a society
suddenly awakening to the dangers of lead. Ha. The folks who developed
the lead gas additive knew it was harmful, the government knew it made
people sick, and in a duet of commercialism and pro-business
collaboration, leaded fuel stayed on the market as a solution for
engine knock for over 50 years. The lead paint story is similar, except
that lead in paint was touted not as a solution for engine knock, but
as an additive that improves paint performance.
Though these leaded items are almost completely off the market in the United States — not completely, just
almost
completely — lead poisoning is still a major issue in this country,
especially for children. Lead paint is the largest source of lead
poisoning. Just to complete the roundup, lead water pipes do still exist,
and the solder in new pipes often contains lead. The EPA estimates that
10 to 20 percent of young children’s lead exposure is from drinking
water.
So what does all this have to do with our soil? Fortunately, the
banning of household lead paint and leaded automobile gasoline has had
a huge impact on public health, and lead poisonings are greatly
reduced. But any house paint applied before 1978 must be assumed to
contain lead. We can consume this lead as the paint flakes, turns to
dust, blows into the air, or washes down the wall in a rain. We breathe
(or eat, if we are children) the dust, and/or eventually the dust winds
up in the soil. Some soils are also contaminated by the lead gasoline
additive. We must be cautious when renovating our homes, kissing the Earth when we get home from trips, and, to a lesser extent, gardening.
if you like. If the test results indicate high lead (results will
include interpretation of the mysterious numbers), then your path is
clear: set up containers in your yard. If it’s an urban yard, with lots
of cars and trucks blowing dust and exhaust about, try to follow the
recommendations mentioned in the previous column:
Put the vegetable garden away from the street, add a fence or hedge
barrier between the garden and the cars, and carefully wash your bounty.
the ground: If you garden correctly and your plants are healthy, they
will have long roots. The roots may grow down below your containers and
into the contaminated soil — three feet or more of root depth would
not be uncommon on a vigorous root vegetable. So you will need deep
containers.
lead uptake through garden food is much less of a concern than uptake
directly through eating or inhaling flaky paint or lead-imbued soil.
Just use common sense, test your soil, and don’t let your kids eat
lead-infested dirt.
Heavily,
Umbra