Lead in drinking water
The presence of lead in drinking water is not a new problem. Lead was historically used to produce pipes to carry water and later to solder iron and copper pipes. It is a ubiquitous heavy metal that has been used for centuries as a constituent in various products such as face powder, ceramic glazing, gasoline, plumbing, radiation shielding, children's toys and paint. Its long history of use and distribution means lead exposure and its health effects are global.
By following the risk assessment process first established by the US National Research Council,1 this article provides practitioners with information to respond to their patients' concerns regarding lead in drinking water.
Many countries have succeeded in reducing lead exposure through regulation of products. However, according to the World Health Organization, a number of developing countries still allow lead in gasoline. About one-fifth of the burden of disease from lead exposure occurs in Southeast Asia, and another one-fifth occurs in the western Pacific region.2 The burden is also felt in poorer sections of Europe: the World Health Organization estimates that nearly 157 000 days of healthy life are lost among children under 4 years old because of mild retardation from lead poisoning.3 In Central and South America, 33%–34% of children have blood lead levels above 10 µg/dL (0.48 µmol/L), compared with 7% in North America.4
Lead exposure in Canada has decreased significantly over the past several decades, thanks to the introduction of regulations to remove lead from common sources such as paint and gasoline. However, as we control these sources, others, including drinking water, become relatively more important. Homes built before the 1950s were often built with lead plumbing, and those built as recently as 1990 may contain lead solder.3 Many communities in Canada have older sections of their drinking-water distribution systems that have lead pipes or soldering.
The risk assessment process described in this article starts with an exposure and hazard assessment, which in turn informs risk management decisions.