Gelatin potentiates lead toxicity due to improper preparation of a Chinese tea drug, choreito. A study based on our previously published case report of long-term choreito use.

A woman who had used a Chinese tea drug, choreito, for treatment of chronic renal diseases over years, experienced lead poisoning with blood lead concentration over 600 μg/l on admission to the hospital. We found that one of the ingredients in choreito, kasseki, was commonly contaminated by lead (30-50 μg/g of kasseki), but this level of lead contamination in the drug had never caused poisoning previously. Our experiment indicates that another ingredient, gelatin, has lead-extracting ability and an adhesive quality on the walls of teapots. Thus, the possible causes of the toxicity seemed to be: (1) the lead in the kasseki, which was extracted by gelatin that had adhered to the wall of the pot, accumulated in large quantities for a long period of time (the patient used the same pot for more than a year without washing); and (2) a large quantity of the accumulated lead was released into the decoted drug day by day and induced the intoxication. In all, 37.2 mg of lead was extracted by 10 extractions of 4% acetic acid from the patient's pot. Repeated extraction (four times) of lead from the pot which was made by the same manufacturer in the same lot of the patient's pot with acetic acid, only totally 18.5 μg of lead was detected.Also, it is evident that the intoxication was due to an improper method of decoction, that is, the patient did not prepare the tea according to Japanese pharmsacopoedia. The patient decocted all of the ingredients at the same time.