Heavy metals, pesticides and industrial pollutants can reach unacceptable levels within animals in several ways if their environment is polluted with industrial or agrochemical contaminants.
In some areas, because of the mineral makeup of underlying rocks, soil and grass levels of these agents may be sufficiently high for them to accumulate naturally to unacceptable levels within grazing livestock.
Regulatory limits for these substances are low because many tend to accumulate in fat and other tissues. Consequently, their concentrations will increase in individuals further up the food chain and thus will be higher in humans than in farmed animals. An area of emerging concern is the build up of several agents whose long-term effects may be additive.
