Indian children are at high risk from lead exposure

mumbai: a recent pilot study measuringthe toxic effects of lead exposure among urban children provides early warningof the devastating impact of leaded gasoline and other environmental toxins inindian cities. blood lead tests of 75 children in the outskirts of chennai foundhalf of them with levels exceeding the maximum allowable level of 10 microgramsper deciliter set by the u.s. centre for disease control and prevention. earlyevidence from this pilot study is part of an ongoing and wider investigationbeing conducted in india by howard hu, associate professor of occupationalmedicine in the department of environmental health, harvard school of publichealth, usa, in collaboration with kalpana balakrishnan of the sri ramachandramedical college and research institute in chennai. dr hu, who has spent 15 yearsstudying the impact of lead on human health, says, “lead stays with you. asingle exposure can get in your bones and linger indefinitely. if you inhalefumes of combusted lead gasoline, for example, or ingest lead-contaminated foodand water, the toxic metal can lodge in your skeleton for decades. repeateddoses can result in high bone lead levels, which may ultimately trigger adversehealth effects. particularly at risk are citizens of developing countries wherelead pollution controls are often lax.’’ india is a case in point,where leaded gasoline is commonplace and a host of poorly regulated industriesroutinely exposes employees and neighbouring communities to lead contamination.very few studies have been done on this problem in india, but some limitedsurveys indicate that the main sources of lead pollution are combustion ofleaded gasoline, exposure to lead-contaminated dust (from lead gasoline fall-out, which is like to continue for decades), exposure to industrial emissionsand contaminated products such as kohl. evidence from a number of epidemiologicstudies from the u.s., australia, britain, taiwan, mexico and elsewhere nowclearly demonstrates that lead exposure from foetal and/or early childhoodexposure reduces subsequent iq levels, says dr. hu. adult exposures, meanwhile,have been firmly linked with an increased risk of developing hypertension,kidney failure, cognitive impairments, reproductive problems (infertility,neurodevelopment impairments etc), anaemia. preventive measures would call for acomplete phase-out of leaded gasoline, education on precautions (such as washingchildren’s hands prior to eating), monitoring lead- polluting industries.meanwhile, further studies are required to identify other sources of leadpollution. dr hu has spent the past year in india on a fulbright grant toprepare the grounds for his collaborative study. its primary focus is the impactof lead exposure on the mental development of children, who are the mostvulnerable to lead’s neurotoxic effects. the two broad aims of theirresearch, he says, is to assess what extent the genetic and nutritional profileof the indian population will modify the toxic effect of lead on children inindia; and to collect data and samples that will allow them to look atlead’s effect on behaviour as well as intelligence, and identify genetictraits that render individuals particularly susceptible to lead. dr hu hopesthat in the long run, the findings from his studies can help stimulate importantenvironmental policy changes. establishing the relationship between lead andintellectual and behavioral abnormalities in a quantifiable manner will enablepolicy makers to gauge the impact of lead exposure experienced in communitiesand workplaces. he hopes that this in turn, would enable them to appreciate theenormous economic as well as public health benefits that can be expected fromcontrolling exposure to this toxin. while lead is the most studied globallydistributed toxin that every country has to deal with, huge gaps in knowledgestill remain about its long-term toxicity after initial exposure, says dr hu.unresolved questions that still remain include: how harmful are foetal exposuresemanating from maternal exposure or mobilisation of maternal bone lead stores,as opposed to early childhood exposures? are these reversible or treatable? whatmakes some individuals particularly vulnerable, for instance do gentic traitshave any role? are populations in developing countries like india, particularlyvulnerable because of interactions with malnutrition or infectious diseases?