Gardening, Lead Contamination, and Children

The Effects of Lead

Although many of the facts of this complex issue are
obscured by controversy or ignorance, no one–not even the
most ardent defenders of America’s lead industries–would
deny that, at high levels of exposure, the element labeled
“Pb” is dangerously toxic. Victims of “clinical” lead
poisoning (which is also called plumbism) can suffer
headaches, nausea, anemia, kidney damage, blindness,
hemorrhage, convulsions, coma, and death.

Another undisputed truth is the fact that children under
six (including, since lead crosses the placenta, infants
still in utero) are far more susceptible to lead poisoning
than are adults. Youngsters have high metabolic rates, are
at delicate stages of growth, and are often physically
close to such sources of lead as old paint chips,
contaminated dirt, and auto exhaust. All told, children’s
bodies can absorb and retain around 40% of the lead that
they ingest. Adults however can eliminate all but a
small percentage of the element that gets into their
systems. Consequently, youngsters are much more likely than
adults to develop serious lead poisoning. Of course, men
and women employed in lead smelting, storage battery
manufacturing, shipbuilding, automotive body painting,
printing, deleading, pottery glazing, and other lead-related
industries or crafts may–because of the high levels
of exposure in such occupations–suffer clinical lead
poisoning as well.

But the accepted truths don’t tell the whole story of lead
intoxication. Recent evidence indicates that even Pb
intakes well below established clinical levels can
seriously harm children. Youngsters with low-level lead
exposure are sometimes afflicted with headaches and
abdominal pain or such “lesser” symptoms as
irritability, clumsiness, listlessness, and loss of
appetite.

And, sadly enough, the organ most easily affected in a
growing child is the brain. Dr. Herbert L. Needleman
carefully compared the levels of lead in children’s teeth
(the heavy metal accumulates in teeth and bone) with the
same youths’ rating by various testing systems and teacher
evaluations. (The results were reported in the March 29,
1979 issue of The New England Journal of Medicine.) He
discovered that low levels of absorbed lead can decrease a
child’s attention span, impair his or her auditory and
language-processing abilities, promote poor social
behavior, and–in a word–reduce the youngster’s
intelligence.

Worse yet, the brain damage caused in young children by
“subclinical” lead poisoning is often irreversible.

Leaded Gardens?

One of the strongest recent efforts to combat the hazards
of lead exposure began in 1977, when a few members of the
Boston Urban Gardeners (BUG)–an organization
dedicated to revitalizing communities and people’s lives by
means of vegetable growing–became worried that some
soil might contain enough lead to endanger small children.
The BUG members, along with concerned scientists and public
agency representatives, investigated the subject and
demanded that their city’s public services address the
problem. The group’s dogged efforts paid off handsomely,
too: Boston (and the state of Massachusetts as a whole) now
offers soil-lead testing, blood-lead testing, and related
health information to all of its residents.

The Boston task force raised the question of whether plants
could absorb lead that’s present in garden soil. To find
the answer, Thomas H. Spittler and William A. Feder
cultivated lettuce, beets, carrots, snap beans, and
radishes in a carefully controlled greenhouse
environment during the winter of 1977-78. They found (and
published their findings in “A Study of Soil Contamination
and Plant Lead Uptake in Boston Urban Gardens,”
Communications in Soil Science and Plant Analysis, 1979) “a
definite correlation between soil Pb content and plant
uptake.” The researchers went on to observe that the
element tended to concentrate primarily in plant leaves, to
a lesser extent in roots, and hardly at all in fruits.
(Hence, tomatoes absorb much less lead from soil than do
potatoes, which in turn take in less than does
spinach.)

More important, though, Spittler and Feder also expressed a
possibility that other researchers soon verified: If one’s
garden soil is so toxic that the plants can absorb a
measurably significant amount of lead, the earth itself is
more of a health threat to children than are the crops! As
research agronomist and heavy-metal expert Rufus L. Chaney
put it, “We think we have confirmed that plants don’t take
up enough lead to matter, as far as its getting into
people’s diets is concerned. The really big risk is soil
ingestion by children.” After all, youngsters play in dirt. They’re likely to get some on their hands and
accidentally ingest contaminated soil in the course of
normal hand-to-mouth play, or–in some
cases–even develop the habit of deliberately eating
soil (and other nonfoods … a pattern of behavior called “pica”).

Essentially, then, gardening in lead-contaminated areas
can constitute a health risk to young children (although
not, at least so far as we now know, to adults), and
this threat comes primarily from the soil itself rather
than from the plants per se. (Indeed, more lead is likely
to accumulate on the surface of crops–from settled
auto exhaust fumes and garden dirt–than will collect
inside the vegetables.)

The problem of toxic soil is not a short term one, either.
The metal does not tend to percolate down through the
ground, but instead settles in the top few inches of earth,
where it can remain for centuries.

Where Does It Come From?

And just how does one’s garden plot or yard build up a
dangerous level of lead to begin with? There are several
possible means of contamination, and their relative
importance will vary from site to site, but the most
likely source of severe lead buildup is house paint. Until
1950, you see, almost all homes were protected with paints
that contained dangerous amounts of lead. (In fact, some
home coatings used for years after that date–right up to
1971–were formulated with lesser but still
significant doses of the metal.) And even though old
buildings may have since been repainted, several times,
with less toxic coverings, the original lead-based exterior
layer can still shed the dangerous element into the soil.
Chips of the material may drop off, and rain
will–over time–wash some lead down from even
nonpeeling walls. Or, worse yet, a lead-painted building
may have been burned or demolished years ago on what’s now
a gardening site.

Lead is deposited in the soil in many other ways, as well.
In areas near heavily traveled roads, auto exhaust fumes
can contribute an appreciable amount of the toxic substance
to the earth. Emissions from factories that use lead in
their manufacturing processes can constitute a very
significant local Pb source. Even treated sludge can
contaminate–rather than fertilize–garden soil.

You may be surprised to know that, contrary to popular
myth, lead-sullied soil is not only an urban problem. Rural folks need to be concerned about it too. Any country
vegetable plot that’s next to–or receives rain runoff
from–an old painted house or barn will most likely
contain an above-average level of lead. Farm plots,
like city gardens, can be located close to frequently
traveled roadways or downwind from industrial lead-using
factories. On top of that, the ground may have received an
extra burden of lead if its owner has–at one time or
another–spread wood ashes from painted boards on his or her
garden site.

A rural growing plot may also be significantly contaminated
if the soil was formerly commercial farm acreage: For many
years, lead arsenate was a common ingredient in pesticides
(particularly in those insecticides used in orchards).

The Blood Test

As you can see, having lead-contaminated ground can
increase the amount of exposure that your children will
have to the toxic metal, but remember: Human beings absorb
lead from many sources.

Therefore, it’s important that concerned parents determine
whether or not their youngsters are ingesting and retaining
harmful amounts of lead, regardless of the environmental
source. Fortunately, there is a way to determine the amount
of the dangerous element currently entering any person’s
system: a blood test.

To get your own or your child’s blood checked for lead
content, first contact your nearest health department and
ask whether it offers this service. (If the agency does so,
the testing may well be performed free of charge.) Should
the folks there not be equipped to handle this exam, ask
them–or your family doctor–who, in your region,
does have the capability. One of those parties should be
able to find out, take your blood sample, and send it off
for testing. If, however, neither your physician nor the
health department can locate a blood-lead testing service,
write the Department of Health and Human Services, Public
Health Service, Center for Disease Control. Someone at that agency will send
you the address of the testing center nearest you.

A blood-lead test will be either a fingerstick exam (in
which blood is taken from a pricked finger) or a venous
test (in which the sample is drawn from a vein in the arm).
Both types give an erythrocyte protoporphyrin, or EP,
reading. (Protoporphyrin is a substance that accumulates in
the bloodstream’s erythrocytes–the red blood
cells–when excess body lead interferes with normal
hemoglobin production. An EP test, then, is a good
indicator of the extent to which lead is currently
affecting one’s body.) EP results are given in micrograms
of protoporphyrin per 100 deciliters of blood (mcg/100dl).
A reading below 50mcg/100dl is currently considered to be a
“normal” EP level, while counts of 50-249 mcg/100dl and
250+mcg/100dl are considered “excessive” and “dangerous”,
respectively.

The venous blood test measures the blood-lead level as well
as an EP count. A level of below 30 micrograms of lead per
100 deciliters of blood is currently considered acceptable.
(The Boston Urban Gardeners people warn that it’s best to
take that “acceptable” designation with a grain of salt,
however, since it is now suspected that blood-lead
levels as low as 10mcg/100dl may cause some damage to a
child!) Readings of 30-49mcg/100dl, 50-69mcg/100dl, and
70+mcg/100dl are officially categorized as “elevated,”
“excessive,” and “dangerous,” respectively.

Both types of blood test indicate the level of lead
currently circulating through a person’s body. The
advantage of such readings is that they offer means of
gauging change: You can quickly discern how much lead your
children are ingesting, then find out, through subsequent
tests, whether you’ve been successful in reducing that
toxic intake. The limitation of the exams–on the
other hand–is that they don’t provide figures for the
total amount of previously absorbed lead that may have
permanently accumulated in the body.

To insure that your own children are safe from low-level
lead intake, you should test youngsters aged six months to
three years–and your older offspring, if you live in
a high-risk area–once every six months. Most children
beyond three years of age require only a yearly checkup.

What to Do

If blood test results indicate that a child of yours has an
excessive or dangerous lead level, you should see a doctor
for immediate treatment of this serious poisoning problem.
If, however, the results indicate no more than a possibly
elevated blood-lead count, take measures (such as those
described below) to reduce the amount of lead the youngster
ingests, and use a series of doctor visits and follow-up
blood tests to see how successful your efforts are.
According to the Center for Disease Control in Atlanta, the
child’s blood lead should remain stabilized at a safe level
for six months before the parent can feel that he or she is
effectively dealing with the problem. (Keep in mind, too,
that a youngster’s blood-lead level will often fluctuate on
a seasonal pattern and tend to be highest during those
let’s-play-outdoors summer months.)

And, of course, whatever steps you take to reduce the lead
in your child’s environment, be aware of the possibility of
exposure to the metal in your garden’s soil, along with the
other potential sources of ingestion.

Gardening With Lead 

According to the Boston Urban Gardeners’ Julie Stone, you
can feel pretty sure that your soil has a high lead level
if it’s [1] located next to an old painted building, [2] on
the site of a former building or dump, or [3] in an area
that’s heavily contaminated by auto or lead industry
exhaust. Should any of the above conditions apply to your
garden, it’s best–for the safety of young children or any
other persons in your household who face high levels of
lead exposure in their occupations–to grow all vegetables
in containers … find another, safer gardening site …
or have the topsoil replaced with clean earth. You should
also make sure any exposed garden dirt can’t become a
health hazard by covering it with gravel or with a tough
grass such as K-31 fescue.

It’s much more difficult to “guesstimate” whether your
garden may have an elevated (rather than high) lead level.
If the plot is in an area that’s not far from an old
painted building or is subject to regular smog or some auto
exhaust, though, you will probably want to take the
following gardening precautions to protect any
lead-risk family members:

• Grow leafy green vegetables and root crops as far as
  possible from busy roads or older houses.
• Use fences or tall plantings of sunflowers, morning
  glories, or dwarf fruit trees to help cut down the amount
  of airborne lead that reaches your garden.
• Wash all produce (especially the fruit grown to provide an
  airborne lead “windbreak”) thoroughly before eating and discard the outer leaves of lettuce, cabbage, chard,
  etc.
• Peel all root crops before eating them.
• Enrich the soil with peat moss, compost, or manure. The
  organic matter will help you raise healthier, more
  nourishing plants and add uncontaminated growing
  medium to your soil.
• Mulch the garden. Aside from helping plants thrive, the
  covering will keep airborne lead off the soil. (If your
  garden site is exposed to a lot of poisonous exhaust,
  discard the mulch at the end of the growing season instead
  of composting the material or tilling it into the ground to avoid adding the accumulated lead to the garden.)
• Adjust the soil pH until it’s as close to neutral as your
  crops will tolerate. It’s been suggested that a neutral pH
  will tend to inhibit lead uptake by plants grown in soil
  with a moderately low level of lead.
• Add phosphorus to your soil. Lead will often bind
  to that mineral and form the safe substance, lead
  phosphate. (In fact, research agronomist Dr. Rufus L.
  Chaney believes that neutralizing an acidic plot without
  adding extra phosphorus might even be counter-productive, since the increased alkalinity will tend to render
  ineffective whatever amounts of the lead-binding element are
  already in the soil.)

Dirt and Dust

Besides following the foregoing gardening suggestions, a
person who’s trying to reduce local heavy metal
contamination in his or her area should also wage war
against the amount of leaded dirt and dust a child may be
exposed to while at home or at play. (Such Pb “carriers”
frequently are among the major contributors to lead
poisoning in children.)

To do so, the members of the Boston Urban Gardeners
recommend that you always wash your children’s hands before
the youngsters eat and after they’ve been playing in any
dirty area; build a sandbox so they’ll have a spot to
play that doesn’t contain contaminated soil; be sure
your tots sit at a table when eating outdoors (a couple of
boards set on crates will do fine); grow a tough grass
ground cover in dusty areas; place old rags or mats
over scruff spots such as the earth under swings and at the
bottom of slides; and get rid of any paint chips found
near buildings. It’s also important to keep the interior of
your home as dust-free as possible by thoroughly wiping
furniture and sweeping and wet mopping floors. In addition,
if any member of your family works in a lead-related
industry, that person should always shower, shampoo, and
change to clean clothes and shoes before coming home.

Diet Can Make a Difference

One of the most positive steps you can take to reduce the
amount of lead your children absorb is to make sure the
youngsters have healthful diets. Iron and calcium, in
particular, are very effective in combating lead retention
in the body. Foods high in iron include dried fruits, dark
leafy vegetables, and red meat. Dairy products,
some nuts, and most vegetables are good sources of calcium.

It may be best, though, to reduce the amount of canned
foods your child eats, since the solder used to seal the
cans may contain significant amounts of lead. Indeed,
according to Dorothy M. Settle and Clair C. Patterson’s
estimates (in “Lead in Albacore: Guide to Lead Pollution in
Americans”, Science, March 14, 1980), “Half the lead in the
American diet probably originates from lead-soldered
cans.” So it’s actually possible that a person could get
more toxic metal from a tinned tomato than from one grown
in his or her own lead-contaminated garden!

Fortunately, since Settle and Patterson made their study,
many canning companies have started to drastically reduce
the amount of lead solder in their containers, so the
possibility that leaded cans may contribute significantly
to lead accumulation may be fading. Two particular canned
foods definitely worth avoiding, though, are citric juices
that have stood, opened, in the refrigerator a few days and
tinned infant formula. (Aluminum cans may be safe, but we
don’t recommend them.)

Lead in Pipes

Older homes, and some old municipal water systems, may have
lead waterlines, and such pipes can be another source of
the toxic element (particularly in regions with soft
water). People trying to reduce their family’s lead intake
should–if their drinking water comes through lead
pipes–consume bottled water, use a water
treatment unit approved for lead removal by the EPA,
or, at the very least, run the tap for a few seconds before
drawing any liquid for drinking and cooking purposes. (You
should be able to get your water tested for lead content by
your local Public Health Service, water pollution control
agency, or even a person or organization who does
blood-lead testing.)   

Lead Paint

Without a doubt, though, the easiest way for any child to
get an extremely high dose of lead is by ingesting
lead-based paint. So, besides cleaning up paint chips
inside and around your home, you may–if the house was
at one time coated with such a paint–want to cover the
interior walls with paneling or wallpaper, or remove the
toxic coating entirely.

If you decide to get rid of the lead-based paint, be
absolutely sure you take all the proper precautions. Don’t
use a power sander (which would create dangerous dust) or
burn the old coating off (which, worse yet, would vaporize
the toxic matter). Instead, remove the paint by dry
scraping only. Use a drop cloth, wear a respirator, keep the
work area and workers clean, change clothes after working,
and eat in a separate space. In other words, follow
strict sanitary measures. In addition, make absolutely
certain that children and pregnant or nursing women stay
away from the work area. There have been numerous reported
cases of well-intentioned home remodelers who received
damaging doses of lead while de-leading their houses.

Soil Testing

One of the most positive lead-control actions any concerned
person can take is to help organize a community
soil-testing program. There are very few parts of the
country right now where an individual can easily get his or
her cropping ground tested for lead content … but that
state of affairs can be changed.

The best-known example of a successful community soil-lead
testing program is, as you’d imagine, the one in Boston. As
BUG’s Julie Stone describes it, the folks there were able
to convince the extension service and other government
agencies to set up soil- and blood-lead testing services,
partially because they rallied concerned scientists and
agency officials to their cause, but primarily as a
result of “a handful of committed individuals who learned
never to take no for an answer.”

While gathering support from a number of determined people
might well be the best way to initiate a lead-testing
movement where you live, Linda Roth of the Suffolk
County, Massachusetts Agricultural Extension
Service advises that you will also have to track down
a facility that has the type of (expensive)
spectrophotometer that can run accurate soil-lead tests.
Linda suggests that you first contact those experienced
soil testers, the folks at your county extension service,
to see whether they have the needed equipment on hand.

Other places that might be able to provide access to the
machine are state agricultural extension programs,
university science labs (you could even be fortunate enough
to find a graduate student interested in testing soils as
part of his or her research work), state health boards,
regional labs of the Environmental Protection Agency, state
pollution control agencies, and private medical or research
labs. Indeed, the Boston Urban Gardeners located one of
their first testing facilities at a private laboratory after one of the members read a newspaper article about a
researcher who was looking into lead levels in pet foods!

The Big Picture

Evidence of the hazards of lead contamination keeps
mounting steadily, but unfortunately, the amount of the
toxic element being added to our total environment is also
ever on the increase. Conscientious measures to help
protect one’s own garden soil, family, and community are
important, but individual efforts obviously aren’t enough
to remedy the situation. We all need to take action to meet
the problem at its source: that is, to reduce the amount of
the toxic metal being spewed throughout our country.

And, as a first step, you should know about some pending
government decisions that may cause serious setbacks to
much of the progress that has been made in combating
environmental lead contamination in the U.S.

[1] The Clean Air Act of 1970 is up for revision this year.
This major piece of legislation has helped regulate the
amount of airborne particulates, sulfur dioxide, carbon
monoxide, hydrocarbons, nitrogen dioxide, ozone, and
lead introduced into the environment. There are many
interests that would like to see the important restrictions
of the Clean Air Act substantially weakened.

[2] The 1978 Lead Standard. The Labor Department’s
Occupational Safety and Health Administration (headed by
Thorne Auchter) wants to replace “maximum protection of
workers” as the standard for pollution in lead industries
with a “cost-benefit analysis” of individual safety
measures. The proposed slackening of health controls could
affect 835,000 American workers in at least 120
occupations.

[3] The 1971 Lead-Based Paint Poisoning Prevention Act. Run
primarily by the Center for Disease Control, the program
established under this act has already screened 3,475,659
children and referred 227,904–that’s more than a
quarter of a million!–youngsters to pediatric care for
treatment of elevated blood-lead levels. This vital public
health aid has been extended and expanded three times since
its inception but is now slated to expire this
November.

If you’d like to help create public pressure for the
continued reduction of lead in the air and the workplace,
or for the reestablishment of our only nationally effective
lead-screening program for children, you may want to write
your elected federal representatives and voice your
concerns. (You can find out the names and addresses of
these individuals by phoning your local public library.)

Lead poisoning is the number one neurological disease of
children in this country. Yet even today, scientists admit
(as Dr. Jane S. Lin-Fu pointed out in the January/February
1979 issue of Children Today) that it’s “a uniquely
neglected public health problem.” Furthermore, lead
poisoning is especially insidious because so often it slips
by unidentified, damaging children’s health and mental
potential without anyone’s even knowing the harm has
occurred!

It’s simply not enough to try, like an ostrich, to isolate
yourself by hiding your head in the ground. After all, even
that soil may not be safe anymore!

EDITOR’S NOTE: The National Center for Appropriate
Technology has just published a booklet, compiled by the
Boston Urban Gardeners, that outlines the dangers of lead
poisoning and the steps you can take to garden more safely.

In addition, the Center for Disease Control (Department of
Health and Human Services, Public Health Service, Center
for Disease Control offers two free handouts on lead: a reprint of Dr. Lin-Fu’s
“What Price Shall We Pay for Lead Poisoning in Children?”
(which contains a history of the problem) and Preventing
Lead Poisoning in Young Children (a technical booklet for
physicians and health service personnel covering cause,
identification, and treatment of plumbism).

MOTHER would like to thank the Boston Urban Gardeners
(particularly Charlotte Kahn and Julie Stone), Rufus L. Cha
ney, Linda Roth, the Center for Disease Control, NCAT’s
Nancy Goodman, and especially Ben Barber–who alerted
us to the seriousness of the lead poisoning issue–for
their kind help in gathering much of the information for
this article.