Waste dumpsites and public health: a case for lead exposure in Zimbabwe and potential global implications

Most waste sites in Zimbabwe are not sanitary landfills but open dumps that indiscriminately receive waste from municipalities, industries, commercial establishments, and social services establishments. People, including children, who eke out a living through scavenging the dumps expose themselves to environmental pollutants at the dumps via inadvertent ingestion and inhalation of contaminated dust, and dermal absorption. The public is potentially being exposed to a slew of the pollutants via air, water, and food, all contaminated by uncontrolled leachates and aerially deposited dust and particulates from the sites. One of the unfortunate consequences of globalization is the sharing of contaminated food and the associated disease burdens; hence, regional contamination can have global impacts. We analyzed the levels of lead at two waste sites in Zimbabwe to assess the daily exposure levels of Pb to children and adults who scavenge the sites as well as determine levels of the heavy metal that are potentially contaminating air, water, soils, and food in the country. Levels of Pb ranged from 23,000 to 14,600,000 µg/kg at one of the sites and from 30,000 to 1,800,000 µg/kg at the other. Inadvertent daily exposure amounts that were calculated by assuming an inadvertent daily ingestion of 20-500 mg of soil/dust were mostly higher than the provisional tolerable daily intake established by the World Health Organization for infants, children, and adults. The XRF measurements were validated using certified reference samples, 2710a (Montana soil) and 2781 (domestic sludge), from the National Institute of Standards and Technology.