Dietary intake, levels in food and estimated intake of lead, cadmium, and mercury.

Since 1980, systematic efforts have been made by the Joint UNEP/FAO/WHO Food Contamination Monitoring Programme to collect information on dietary intake of various contaminants, exemplified by lead, cadmium and mercury. In 1980-88, average adult intakes of lead varied from 1 to 63 micrograms/kg bw/week, approaching or exceeding the Provisional Tolerate Weekly Intake (PTWI) of 25 micrograms/kg bw in four countries providing data. Major sources in food and drinking water differed from country to country. A downward trend was observed consequent on reduction in use of lead-soldered cans and of lead in petrol. Few countries provided data on intakes by infants and children (more vulnerable groups) but the mean exceeded the PTWI in three countries, heavily influenced by levels in water and lowest in infants consuming only breast milk. Average adult intakes of cadmium were, with one exception, below the PTWI of 7 micrograms/kg bw; intakes by children were higher on a body weight basis but still within the PTWI in countries supplying data. Highest levels occurred in offal (mean 320 micrograms/kg) and shellfish (200 micrograms/kg) but, because of amounts consumed, reduction of concentrations in cereals, roots and tubers would be most effective. Important sources of contamination included phosphate fertilizer sewage sludge, plated/galvanized equipment, enamels and glazes. For mercury, average intakes were below the PTWI (300 micrograms/person; 200 micrograms/person or 3.3 micrograms/kg bw as methylmercury) for adults and for breast-fed infants. Contributions from fish varied from 20 to 85%; in some countries because of different dietary habits, cereals or meat may contribute similar amounts. Because of inadequate data on food other than fish, intake estimates are biassed and sometimes based solely on typical levels in fish.