Which causes more harm in developing countries: toxic waste or malaria?
Recent research suggests that exposure to toxic pollutants from contaminated sites may be equally or more harmful to human health than certain infectious diseases like malaria, or other environmental problems like outdoor air pollution.
The study, published this week in the journal Environmental Health Perspectives, measured levels of of eight different pollutants at sites in India, Indonesia and the Philippines. It then estimated the impact these chemicals had upon the health of the 8.6 million people who live near these 373 sites.
The study estimated that these pollutants caused a total of 828,722 lost years of healthy life, which surpassed the calculated impact of malaria in these countries, says study author Dr. Kevin Chatham-Stephens, a fellow in pediatric environmental health at Mount Sinai School of Medicine in New York. As with similar public health studies, this was measured in disability-adjusted life years (DALYs), or the number of healthy years of life lost due to ill health, disability or early death.
Lead was the most harmful chemical, leading to the largest amount of lost healthy years. That's not too surprising since the chemical is known to impair brain development and can cause retardation, resulting in entire lifetimes of lost healthy years, he added.
Hexavalent chromium was linked to the second most damage. The chemical is a known carcinogen and is associated with high rates of lung cancer, Chatham-Stephens says.
These two chemicals accounted for more than 99 percent of the lost healthy years. But the study also looked at the impact of cadmium, mercury, asbestos and three pesticides (DDT, aldrin and lindane).
About two-thirds of the exposed people in the study were children and women of childbearing age.
Due to the intricacies and cost of measuring eight pollutants at every site, the study focused on the predominant toxic chemical at each location, Chatham-Stephens says. The researchers then used the U.S. Environmental Protection Agency's data to estimate the exposure and health effects to citizens nearby. (This was one limitation of the study, he says.)
The primary pollutant at each sites varied depending upon its former use. Lead was the major pollutant at sites where batteries were disposed, for example, while chromium was examined at current and former tanneries.
This was the first comprehensive research into the health effects of toxic waste sites in low- and middle-income countries, according to the study. Although there are some small-scale efforts underway to clean up sites in India, a lack of funds and manpower has hampered efforts to fix the problem, Chatham-Stephens said.
Toxic waste is less of a problem in the United States, where the EPA has a comprehensive list of contaminated sites, called Superfund sites. Billions have been spent to clean up these areas.
"We were surprised by fact that the disability-adjusted life years from toxic wastes may be on par with some of these better known public health issues like malaria and outdoor air pollution," Chatham-Stephens says. He added that he hopes the research will help governments and organizations decide and prioritize what sites to clean up in the future. "This is an area of growing research and concern," he says.
He and his collaborators at Mount Sinai will soon begin working on a study examining the economic impact of these sites and possible remediation. "It can cost a lot of money to clean up—how does this compare to the health benefits you get?"
It's not hard to imagine that when you're talking about hundreds of thousands of lost healthy years, the cleanup would be worth the price.