Living near a toxic waste site can be a
recipe for poor health. And scientists know that the problem is widespread in
developing countries where there are few cleanup programs. A pair of new
studies adds a level of much-needed detail about exactly how widespread and
harmful the problem can be.
led by the Icahn School of Medicine at Mount Sinai in New York City looked at
373 sites across India, the Philippines and Indonesia, and calculated how much
damage elevated levels of lead, chromium and other chemicals imparted to human
health. That work, published online in Environmental Health Perspectives on May 4, found that living near toxic
sites leads to health impacts comparable to all the combined malaria issues
in those three countries, or as much as the total negative impacts of air
The researchers used â€śdisability
life-adjusted years,â€ť or DALYs, as a way to quantify the extent to which
environmental toxins led to early death or illness. One DALY equals a year of
healthy life lost.
â€śWe estimate that more than eight million
persons in these countries suffered disease, disability or death resulting from
exposures to industrial contaminants in 2010, resulting in 828,722 DALYs,â€ť the
authors wrote. That means among the approximately 8.6 million people living
near those sites, an estimated 828,722 years of healthy life were lost. Almost
two thirds of the individuals living near those sites were either women of
childbearing age or children.
authors did not have direct blood-level data or biomarker information to make
their calculations. Instead, they relied on environmental data for the areas
surrounding the sites. For lead exposure, for example, they used lead levels in
drinking water or
soil, and a U.S. Environmental Protection Agency model that translates the data
into projected blood lead levels. They also used World Health Organization
spreadsheets â€śthat would tell us how many people would develop cardiovascular
disease or mild mental retardation from those levels,â€ť sayslead author Kevin
Chatham-Stephens, a pediatrician at The Mount Sinai Hospital who focuses on
environmental health. More than 99 percent of the negative health impacts from
toxic exposures were from lead or chromium, although the authors also looked at
cadmium and pesticides such as DDT.
findings still involve some unknowns and assumptions, the authors acknowledge.
For example, the analysis does not take into account the synergistic or
antagonistic impact of being exposed to multiple chemicals simultaneously. The
authors also looked at only one major chemical contaminant per site and usually
considered just onecancer and
one non-cancer impact at each location, meaning their estimates may not be
all-inclusive. The sites, such as former tanneries and lead battery recycling
areas, were chosen from a database of toxic spots identified by the Blacksmith
Institute, an international nonprofit based in New York City. Because census
data is often not robust in low- and middle-income countries, the researchers
also relied on analysis from investigators employed by Blacksmith to estimate population
numbers with satellite imagery, government interviews and visual confirmation.
Chatham-Stephens also led the second
study, which was presented May 6 at the annual Pediatric Academic Societies
meeting in Washington, D.C. He and fellow researchers analyzed what lead
exposure from the soil and water at toxic sites in 31 low- and middle-income
countries could mean for the long-term health of infants and toddlers living in
the surrounding communities.
population estimates and calculations about lead uptake into the blood, the
team estimates that in 2010 almost 800,000 children younger than four were
exposed to lead at 200 hazardous sites. At the majority of locations, which
include battery recycling plants and
communities where miners live and inadvertently bring home toxins on their
clothing or bodies, lead levels were estimated to be high enough that they
would cause elevated blood-lead levels beyond those considered safe by the U.S.
Centers for Disease Control (CDC). In comparison, recent CDC estimates suggest
that almost 500,000 children between the ages of one and five living in the
U.S. have elevated lead levels that would prompt action.
The authors estimate that the dangerous
levels of lead in these low- and middle-income countries cause a loss of five
to eight IQ points across the population as well as more than 51,000 DALYs.
They estimate that the exposure in these settings causes mild mental
retardation in roughly six out of every 1,000 people. Those numbers sound
reasonable based on the scale of the work, says Bruce Lanphear, professor of
children's environmental health at Simon Fraser University in Vancouver, who is
not involved with the study.
Clearly, the impact of this kind of toxic
exposure is worrisome, Chatham-Stephens says. â€śIf you lose one IQ point, itâ€™s
important to think about how much that reduces lifetime learning, and to think
about its economic impact. With this data we can start to think about the
economic losses at these sites and how much it costs to clean them upâ€”and then
how much you will save by cleaning up these sites and not having these
exposures.â€ť Most of these places have no waste cleanup programs, the authors
Although the scientific community is
generally aware of the issues, â€śno one has tried to document these exposures in
terms of what happens, and this first step is a reasonable approach,â€ť says Kyle
Steenland, an environmental health professor at Emory Universityâ€™s Rollins
School of Public Health who studies occupational lead exposure. He cautioned
that because the studies rely so heavily on estimates, the data must be
considered as just a first attempt to quantify the issue. â€śThere is a large
amount of uncertainty at each step here.â€ť