ead stays with you. A single exposure can get in your bones and linger indefinitely. If you inhale fumes of combusted lead gasoline, for example, or ingest lead contaminated food and water, the toxic metal can lodge in your skeleton for decades. Repeated doses can result in high bone lead levels, which may ultimately trigger adverse health effects ranging from hypertension to birth defects. Particularly at risk are citizens of developing countries where lead pollution controls are often lax. Case in point is India, a nation of over one billion people, where leaded gasoline is commonplace and a host of poorly regulated industries routinely expose employees and neighboring communities to lead contamination.

Enter Howard Hu, associate professor of occupational medicine in the Department of Environmental Health, who has spent 15 years studying lead's impact on human health. Awarded a Fulbright grant and faculty sabbatical to spend the past year in India investigating the health effects of lead and other toxins, Hu seized the opportunity to launch a number of groundbreaking studies. His research could play a critical role in India's ongoing public debate on what measures it should take to control lead exposures in the environment and workplace.

In collaboration with Dr. Kalpana Balakrishnan of the Sri Ramachandra Medical College and Research Institute in Chennai (formerly Madras), Hu focused primarily on the impact of lead exposure on the mental development of children, who are the most vulnerable to lead's neurotoxic effects. "Our research has two broad aims," he says. "First, to assess to what extent the genetic and nutritional profile of the Indian population will modify the toxic effect of lead on children in India. Second, to collect data and samples that will allow us to look at lead's effect on behavior as well as intelligence (the emphasis of past epidemiologic studies), and identify genetic traits that render individuals particularly susceptible to lead."

To lay the foundation for their studies, Hu and Balakrishnan spent four months designing intelligence and behavior assessment tools, piloting a method for measuring blood lead levels using accurate lab protocols, and fine-tuning tools for detecting socioeconomic factors that may influence results. Next they initiated a roughly year-long effort to collect blood and tooth samples and administer a battery of behavioral tests and questionnaires to children and their parents at several local schools in Chennai. The selected schools serve populations typical of urban India. "We'll be looking at parent and teacher ratings of behavior, with the parents and teachers blinded to lead testing results," notes Hu. "The ratings will tell us the extent to which the children exhibit aggressive, internalizing, and other antisocial and delinquent behavior."

Hu will determine if this behavior correlates with higher lead level exposures and apply statistical methods to isolate the effect of lead from other important influences of behavior, such as nutrition, socioeconomic status, parental education, and family structure. Finally, Hu will perform chemical and genetic analyses of blood samples collected in the study. These samples will allow the investigators to look for sub-populations within the study group that are particularlyat risk for lead's effects because of their nutritional or genetic profiles.

In the long run, Hu's findings could help stimulate important environmental policy changes. "The relationship of lead to intellectual and behavioral abnormalities will be quantified so as to allow policymakers to gauge the impact of each increment in lead exposure that is experienced in communities and workplaces,"he explains. "This, in turn, will hopefully allow an appreciation of the enormous economic as well as public health benefits that can be expected from controlling exposure to this toxin."

There's just something about lead that has driven this internal medicine physician to devote much of his career and a year abroad to investigate its health effects. "Lead is a globally distributed toxin that every country has had to deal with," Hu explains. "And while it's the most studied toxin of all, there remain huge gaps in our knowledge of its long-term toxicity after initial exposure." Unresolved questions that continue to command Hu's attention include: What delayed toxicity might be expected from lead that lingers in the body for decades? What genetic traits render a person more susceptible to adverse health effects from lead exposures? To what extent do such exposures contribute to chronic disease conditions such as hypertension, kidney impairment, and progressive loss of intellectual capacity? As Hu sees it, addressing these questions can expand the scope of environmental health research. "The things we discover about lead and the methods we develop to do the research could lay the groundwork for examining other toxins the public is concerned about, such as pesticides, mercury, and PCBs," he notes.

With that philosophy in mind, Hu pursued his lead studies in India while working to boost that country's capacity for environmental health research in general. "By picking a classical toxin that's widely studied," he says, "we're hoping to put the Research Institute and the subject on the map." To that end, Hu also spent part of his Fulbright year assisting in the strategic planning process to possibly create a school of public health at the Institute, and collaborated with Balakrishnan on other projects addressing critical environmental health problems in India.

Back in Boston since April, Hu aims to continue much of the research he began in India and looks forward to returning there to build an environmental health research program with both India- and Harvard-based collaborators. For good reason. "India is an incredibly important place to do environmental health research because of the extent of their problems and the huge population affected," he explains. "This is a propitious moment in the country's development--there's enough economic muscle and intellectual capacity to address these huge problems."

Mark Dwortzan