The model on which the WHO PTWI
was based did not include an uncertainty factor to account for smoking or other nondietary routes of exposure, or for factors such as age and sex (WHO 1993).
2000, 2003) examined the PTWI model by studying cadmium accumulation in kidneys and livers of environmentally exposed subjects.
Thus, the PTWI value must be substantiated by additional experimental data, and, if warranted, a larger uncertainty factor should be applied to the value.
To be valid, the threshold-based PTWI model, although appearing to be a reasonable method for deriving a safe exposure level, will require appropriate input from current scientific knowledge.
Our average concentration, 197 ng/g, about 3% of a child's PTWI
, is also comparable with the highest concentration reported for any food (boiled shrimp maximum, 210 ng/g) in the U.
However, Cd-linked kidney toxicity occurred in higher-than-expected frequencies in human populations whose dietary Cd intakes were well within the current PTWI, suggesting that the current PTWI is not sufficiently restrictive to protect the general population.
Such high Cd concentrations in the mollusks and crustaceans have raised considerable concerns for frequent consumers whose dietary Cd intake easily exceed the PTWI for Cd (Kruzynski 2004).
In European countries, dietary Cd intake estimates were between 10 and 30 [micro]g/day, corresponding to 17-50% of the PTWI (Nasreddine and Parent-Massin 2002).
Cd levels in RRT patients were not determined, but the Cd urinary excretion of approximately 1 pg/g creatinine derived from residents of contaminated areas in Sweden suggests intake of less than the PTWI.
5 L consumed per week (49,000 [micro]g/week of intake), this equates to 23 times the intake at the PTWI
for a person weighing 85 kg (2,125 mg intake in 1 weeD.