In a sobering study published in
the journal Environmental Health, researchers at UC Davis and UCLA
measured food-borne toxin exposure in children and adults by pinpointing foods
with high levels of toxic compounds and determining how much of these foods
were consumed.
The
researchers found that family members in the study, and preschool children in
particular, are at high risk for exposure to arsenic, dieldrin, DDE (a DDT
metabolite), dioxins and acrylamide. These compounds have been linked to
cancer, developmental disabilities, birth defects and other conditions.
However, the study also points to dietary modifications that could mitigate
risk.
"Contaminants get into our
food in a variety of ways," said study principal investigator Irva
Hertz-Picciotto, professor and chief of the Division of Environmental and Occupational
Health at UC Davis. "They can be chemicals that have nothing to do with
the food or byproducts from processing. We wanted to understand the dietary
pathway pesticides, metals and other toxins take to get into the body."
Researchers assessed risk by
comparing toxin consumption to established benchmarks for cancer risk and
non-cancer health risks. All 364 children in the study (207 preschool children
between two and seven and 157 school-age children between five and seven)
exceeded cancer benchmarks for arsenic, dieldrin, DDE and dioxins. In addition, more than 95
percent ofpreschool children exceeded
non-cancer risk levels for acrylamide, a cooking byproduct often found in processed foods like
potato and tortilla chips. Pesticide exposure was
particularly high in tomatoes, peaches, apples, peppers, grapes, lettuce,
broccoli, strawberries, spinach, dairy, pears, green beans and celery.
"We focused on children
because early exposure can have long-term effects on disease outcomes,"
said Rainbow Vogt, lead author of the study. "Currently, the U.S. Environmental
Protection Agency only measures risk based on exposures of individual
contaminants. We wanted to understand the cumulative risk from dietary
contaminants. The results of this study demonstrate a need to prevent exposure
to multiple toxins in young children to lower their cancer risk."
The researchers used data from the
2007 Study of Use of Products and Exposure-Related Behavior (SUPERB), which
surveyed households in California with children between two and five to
determine how their diets, and other factors, contribute to toxic exposure.
Specifically, SUPERB homed in on 44 foods known to have high concentrations
of toxic compounds:
metals, arsenic, lead and mercury; pesticides chlorpyrifos, permethrin and
endosulfan; persistent organic pollutants dioxin, DDT, dieldrin and chlordane;
and the food processing byproductacrylamide.
Toxin levels in specific foods were determined through the Total Diet Study and
other databases.
Perhaps most disturbing,
preschool-age children had higher exposure to more than half the toxic
compounds being measured. Even relatively low exposures can greatly increase
the risk of cancer or neurological impairment.
"We need to be especially
careful about children, because they tend to be more vulnerable to many of
these chemicals and their effects on the developing brain," says
Hertz-Picciotto.
Though these results are cause
for concern, the study also outlines strategies to lower family exposure. For
example, organic produce has lower pesticide levels. In addition, toxin types
vary in different foods. Certain pesticides may be found in lettuce and
broccoli, while others affect peaches and apples.
"Varying our diet and
our children's diet could help
reduce exposure," said Hertz-Picciotto. "Because different foods are
treated differently at the source, dietary variation can help protect us from
accumulating too much of any one toxin."
Families also can reduce their
consumption of animal meat and fats, which may contain high levels of DDE and
other persistent organic pollutants, and switch to organic milk. While mercury
is most often found in fish, accumulation varies greatly by species. Smaller
fish, lower on the food chain, generally have lower mercury levels. In
addition, acrilomides are relatively easy to remove from the diet.
"Acrilomides come from chips
and other processed grains, said co-author Deborah Bennett, associate professor
of Environmental and Occupational Health at UC Davis. "Even if we set
aside the potential toxins in these foods, we probably shouldn't be eating
large amounts of them anyway. However, we should be eating fruits, vegetables
and fish, which are generally healthy foods. We just need to be more careful in
how we approach them."
The study also highlights a
number of policy issues, such as how we grow our food and the approval process
for potentially toxic compounds. Though the pesticide DDT was banned 40 years
ago, the study showed significant risk of DDE exposure.
"Given the significant
exposure to legacy pollutants, society should be concerned about the
persistence of compounds we are currently introducing into the
environment," said Bennett. "If we later discover a chemical has
significant health risks, it will be decades before it's completely removed
from the ecosystem."
While the study has profound
implications for dietary habits, more work needs to be done to quantify risk.
Specifically, researchers need to determine how these food-borne toxins
interact collectively in the body.
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