Compounds of Lead

Examples of lead paint flakes at and around the North Chalone Fire Lookout Tower.   Picture from National Park Service

Examples of lead paint flakes at and around the North Chalone Fire Lookout Tower.   Picture from National Park Service

Unlike metallic lead, industrial lead compounds are highly soluble in the digestive tract of wildlife.  Lead compounds are formed when lead is combined with a variety of different elements, which provide favorable industrial characteristics. These lead compounds have long been used in many different applications.  However, use in industrial applications renders the lead in a much more soluble form than metallic lead.  Lead compounds are, therefore, readily absorbed within biological systems.  In other words, the high rate of solubility of industrial lead compounds make them readily bioavailable to humans, plants and animals. It is this ready bioavailability of soluble lead compounds that is responsible for the high toxicity of lead based paints, gasoline and pesticides. Other common applications of lead compounds include ceramic glazes, PVC coatings, and cosmetics.  All of these different formulations of lead compounds drastically increase the solubility and, as a result, the bioavailability of lead. Industrial lead compounds are problematic for wildlife when used in the environment.  Indeed, Condor Recovery Program (CRP) biologists observed California Condors 317 and 318 (all birds are numbered by the CRP) in Pinnacles National Monument eating lead-based paint fragments that had flaked from the North Chalone Fire Lookout Tower. These Condor parents subsequently fed the regurgitated paint fragments to their offspring (550). Condors 317, 318 and 550 were all tested and found to have high blood-lead levels.  Because of the ready bioavailability of lead compounds in lead-based paint, 550 had to be evacuated to the Los Angeles Zoo for intense treatment for lead poisoning.