CFS announces risk assessment study results on pyrrolizidine alkaloids in food

Hong Kong (HKSAR) -      The Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department announced today (January 6) the results of a recently completed risk assessment study on pyrrolizidine alkaloids (PAs) in food, which was conducted to estimate the dietary exposure of the localadult population to PAs and to assess the associated health risks. The study results revealed that the risk to health from exposure to PAs in food is low.

     A spokesman for the CFS said, "PAs are widely distributed natural toxins that exist in plants.Over 660 PAs have been identified from more than 6 000 plant species. Humans can be exposed to PAs through ingestion of contaminated crops. Overseas studies showed that humans are also exposed to PAs through the consumption of honey, tea, milk, eggs and offal."

     He said that the liver is the main target organ of toxicity.

Currently there are no epidemiological data suggesting that PAs cause cancer in humans but certain PAs can cause cancer in animal experiments.

     A total of 234 samples, covering 48 food items, were tested for 28 individual PAs. The study results showed that of the 234 samples analysed, 118 samples were detected with at least one PA, with the majority of them belonging to the food groups "dried spices", "honey" and "tea leaves (infusion)". Other items with PAs detected included wheat, rye flour, yoghurts, cheeses and tea beverages.

     As regards the concentrations of PAs in different food groups, dried spices contained the highest levels of total PAs, followed by honey and tea leaves (infusion).

The upper bound mean concentrations of the three food groups were 300 micrograms per kilogram for dried spices, 7.5 mcg/kg for honey and 0.46 mcg/kg for tea leaves (infusion).

     The study showed that all "common teas" (i.e. fully fermented, semi-fermented and non-fermented teas) were found to contain relatively low levels of PAs. However, some "specific teas" and dried spices were found to contain relatively higher levels of PAs. Among those "specific teas", a relatively higher level of PAs was found in rooibos tea.

Nevertheless, when compared with overseas studies, the levels of PAs in these specific teas were found to be much lower and therefore a lower level of health concern to local consumers is expected. As regards PAs in some dried species, few species such as cumin seed and oregano were found to contain relatively higher levels of PAs. However, a significant contribution of PAs from dried spices to overall dietary exposure to PAs is not expected since dried spices are normally used in small amounts as minor ingredients during food preparation. 

     According to the information of the Joint Food and Agriculture Organization of the United Nations/World Health Organization (WHO) Expert Committee on Food Additives, dietary exposure to PAs lower than 0.0182 mcg per kg of body weight (bw) per day would be of low concern from a public health point of view.

The CFS study results showed that the lower bound and upper bound dietary exposure estimates of total PAs for average consumers were 0.00033 and 0.0015 mcg/kg bw per day respectively, far below 0.0182 mcg/kg bw per day. Hence, health concern related to PAs for the general population is considered to be low.

     The spokesman said that despite the findings showing that exposure to PAs in food is of low health concern, in view of PAs' capacity to damage genetic materials, the trade is urged to make efforts to minimise PA content in food.

     The spokesman said, "Food manufacturers should investigate the causes of PA contamination in their products and make reference to the Codex Code of Practice for Weed Control to Prevent and Reduce Pyrrolizidine Alkaloid Contamination in Food and Feed with a view to improving their cultivation, harvesting and cleaning methods so as to reduce PA content in their products."

     The spokesman also advised members of the public to maintain a balanced and varied diet so as to avoid excessive exposure to contaminants from a small range of food items.

     "The findings of this study did not provide sufficient justifications to warrant changes to the basic dietary advice on healthy eating. The public is advised to maintain a balanced and varied diet which includes a wide variety of fruits and vegetables so as to avoid excessive exposure to contaminants from a small range of food items," he said.

     The spokesman said that, currently, the information about PAs, for example, the toxicity of different types of PAs, their concentration in different food items, reasons for contamination, differences of PA levels in batches, and the relevant risk assessment reports, is rather limited.

The Codex Alimentarius Commission and different countries have not established standards of PAs in food. Food safety authorities such as those in Europe have conducted relevant risk assessment studies. The WHO has also requested food safety collaborating institutions worldwide to provide data to support its safety assessment studies on the issue in future. The CFS, as a WHO Collaborating Centre for Risk Analysis of Chemicals in Food, conducted this study with a view not only to assessing the health risk posed to the local population from dietary exposure to PAs, but also providing information for reference by the WHO, making a contribution to regional and global food safety.

The CFS will continue to keep in view the relevant international studies and developments and follow up as appropriate.

     The study is available on the CFS' website at" target="_blank">

Published on: 2017-01-06

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