Cadmium, Environmental Exposure, and Health Outcomes

Soisungwan Satarug; Scott H. Garrett; Mary Ann Sens; Donald A. Sens

Disclosures

Environ Health Perspect. 2010;118(2):182-90. 

In This Article

FAO/WHO Guidelines for Safe Intake

The major issue addressed in this article is whether the guidelines established for the safe intake of cadmium adequately protect individuals from increased health risk. The Food and Agriculture Organization/World Health Organization (FAO/WHO) Joint Expert Committee on Food Additives has defined the provisional tolerable weekly intake (PTWI) for a chemical with no intended function as an estimate of the amount of the chemical that can be ingested weekly over a lifetime without appreciable health risk (WHO 1989). The PTWI value initially set for cadmium was 400500 µg/person/week (WHO 1989). These levels were based on a critical renal concentration of 100200 µg cadmium/g wet kidney cortex weight, attained after a cadmium intake of 140260 µg/day for > 50 years or 2,000 mg over a lifetime (WHO 1989). The PTWI model incorporates an oral absorption rate of 5% and a daily excretion rate of 0.005% of total body burden. In 1992, the PTWI for cadmium was refined and subsequently expressed in terms of cadmium intake per kilogram of body weight (WHO 1993). This refinement also recognized that the model PTWI for cadmium did not include a safety factor and that only a very modest margin existed between the level of exposure in a normal diet and a level predicted to produce a potential effect on the kidney. Despite this narrow safety factor, the PTWI for cadmium was retained at 7 µg/kg body weight, which translates to 70 µg/day for a person who weighs 70 kg. A toxicokinetic model predicts, based on similar assumptions, that the renal cortical cadmium level of 50 µg/g wet weight could be attained at the cadmium intake of 1 µg/kg body weight/day over 50 years (Buchet et al. 1990). The renal cortical cadmium 50 µg/g wet weight corresponds to urinary cadmium 2 µg/g creatinine, but kidney effects have been observed at urinary cadmium levels < 0.5 µg/g creatinine (Table 1). These findings argue that the current safe intake level does not provide sufficient health protection and that it should be lowered.

Satarug et al. (2000, 2003) examined the PTWI model by studying cadmium accumulation in kidneys and livers of environmentally exposed subjects. Their studies suggested that the safe intake level for an adult should be < 30 µg/day. They also showed that cadmium accumulation in the kidney cortex increased with age, reaching a plateau by 50 years of age (Satarug et al. 2002). An estimated dietary intake at 2530 µg cadmium/day for persons in the 41- to 50-year-old age group would give rise to a total cadmium body burden of 18 mg. The studies indicated that the estimated intake of 2530 µg/day may produce adverse kidney effects in about 1% of the adult population when variability in absorption and sensitivity to adverse effects among population members are considered in the analysis.

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