Lead Exposure and DALYs

It is well known that exposure to lead can cause a number of health problems, such as cognitive impairment, cardiovascular problems, low birth weight, etc. Exposure is also associated with a decreased life expectancy and economic output. While many countries have banned the use of lead in products such as petrol and paints, leading to significant declines in the levels of lead recorded in a person’s blood (termed blood lead levels – BLLs) there are still numerous other sources of exposure. In India, for example, studies found elevated BLLs in the population more than ten years after leaded petrol was phased out; sources include from lead smelting sites, some ayurvedic medicines, cosmetics, contaminated food, and contaminated tube wells, rivers and soil. In order to assess the extent of elevated BLLs in India, Ericson and colleagues conducted a meta-analysis of 31 studies totalling 67 samples.[1] Overall, they found a mean BLL of 6.86 μg/dL (95% CI: 4.38-9.35) in children, and 7.52 μg/dL (95% CI: 5.28-9.76) in adults (who did not work with lead). As a reference, the CDC deem a BLL of 5 μg/dL as requiring prompt medical investigation, “based on the 97.5% of BLL distribution among children… in the United States”.[2] From these figures the authors estimated that such high levels of exposure resulted in a DALY loss of 4.9 million (95% CI 3.9-5.6) in 2012. Further, data from other studies suggest that a BLL of 0.1-1.0 μg/dl contributes to loss of a single IQ point, meaning the levels of lead seen in these children would result in an average loss of four IQ points (95% CI 2.5-4.7).

The authors fear that a significant amount of the lead exposure stems from used lead batteries used in motor vehicles, which are often processed informally, and thus call for better regulations and larger studies.

Peter Chilton, Research Fellow

References:

  1. Ericson B, Dowling R, Dey S, et al. A meta-analysis of blood lead levels in India and the attributable burden of disease. Environ Int. 2018; 121(1): 461-70.
  2. Centers for Disease Control and Prevention. CDC Response to Advisory Committee on Childhood Lead Poisoning Prevention Recommendations in “Low Level Lead Exposure Harms Children: A Renewed Call of Primary Prevention”. 2012.
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