Dear Umbra,
In your reply to the question about pollution and rooftop gardening, 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.
Still heavy after all these years.
I apologize for lack of clarity on the rooftop 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 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.
Leaded gasoline was prevalent in the United 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.
Container gardening is a great way to garden in the face of lead-contaminated soils. If you have ground space, test your soil, through the UMass service 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.
Another note about lead-defensive gardening on 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.
I know this all may seem like bad news, but 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
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Comments View as Flat
jennconspiracy Posted 3:29 am
05 May 2008
lead poisoning
Hey Umbra - do you have a line on any resources that describe the long term effects of lead poisoning? That is to say - what happens to people who had lead poisoning as small children? When they are "cured" - are there any long term effects as they become adults (ie, immune diseases, teeth issues, bone issues, etc)?
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estark Posted 4:58 am
05 May 2008
re: lead poisoning
Effects for kids (and young animals): http://www.kidshealth.org/parent/medical/brain/lead_poiso ...
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Beccane Posted 6:18 am
05 May 2008
lead lasts a long time
just to add to umbra's article: even if lead were 100 percent removed from all industrial processes, paint and pipes, soil on the ground would still be affected by decades-old deposits of lead. Container gardening avoids this but community gardens and other sites may still have that problem
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Beccane Posted 6:21 am
05 May 2008
long-term effects of lead
to answerjenconsipiracy: lead never leaves the body or does so very slowly. to remove lead you have to have "chelation therapy" in which you ingest other metals that bind to the lead to remove it. Very icky and often dangerous to the patient.
brain damage from lead poisoning is permanent--there is no cure. High level ingestion causes clear immeidate damage but long-term low levels have been proven to lower the intelligence and functioning of children over years. Lead also binds into your bones, taking the place of other minerals.
It's nasty stuff.
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farmerjon Posted 6:37 am
05 May 2008
Lead in Drinking Water
While some older pipes are still made of lead, and older copper pipe still has lead solder, all new pipes are constructed using lead-free solder, unless a "do-it-yourselfer" has used old leaded solder on pipes. Likewise, new fixtures are low lead (called lead free, but they still allow a little lead in brass), so very little lead is contributed from drinking water in most communities.
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karenc Posted 8:35 am
05 May 2008
lead wheel weights
It is my understanding that there is still lead in wheel weights on trucks and other large vehicles and that lead dust from these contaminates the air and soil around roadways- any information on this?
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jennconspiracy Posted 3:00 pm
05 May 2008
thanks but...
...I am already familiar with the (potential) hazards of lead poisoning and sources of lead poisoning with children.
Apologies if I was not clear - what I interests me is any kind of study or survey that describes the health of people who had lead poisoning as children -- that is to say, longitudinal studies that follow them 10-20-30 years after their lead poisoning was cleared up.
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JLAJLA Posted 11:09 pm
05 May 2008
Lead in water
The discussion about lead in garden soil, gasoline and lead pipes did not inform readers that the EPA and most states administer drinking water protection programs under the federal Safe Drinking Water Act that regulate levels of lead and copper in public water supplies. In the absence of lead pipes, there is a concern about lead in soldered copper pipe connections that can leach into drinking water if the water is slightly corrosive.
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