Safety Regulation by Health Canada of Traditional Chinese Medicines Containing Pyrrolizidine Alkaloids
Canada's Natural Health Products Regulations set out mandatory pre-market licensing requirements for the safety of Traditional Chinese Medicine (TCM) products. Although herbal medicines, including those used in TCM, are in general relatively safe, some constituents such as certain pyrrolizidine alkaloids (PAs) may cause serious risks to consumer safety. PAs are of major concern because they are present in many plants and some exhibit hepatotoxicity and are associated with cancer. As TCM has become more “globalized” in its use, accurate documentation of the names of the more than 40 PA-containing TCM herbs and the concentrations of PAs of concern will be beneficial for international harmonization of risk mitigation. The structural complexity of PAs, in addition to differences in toxicity and the presence of more than one PA in each herb, mean that it is complicated and almost impractical to monitor each specific PA in every herb. For that reason, Health Canada has taken a more conservative and pragmatic approach by setting a limit for all PAs as “non-detectable” based on analysis by conventional high-performance liquid chromatography equipped with a diode array detector (HPLC-DAD) and a detection limit of 0.1 ppm. This approach is in line with recommendations from the WHO, Belgium and Germany. Health Canada's pre-market safety review and post-market compliance enforcement prioritized by risk provide consumers assurance regarding authorized TCM products. Nevertheless, the Department also faces challenges mitigating risks posed by unauthorized health products and certain foods, such as bee products and milk, which may be contaminated with toxic PAs.