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The eighth report of the First Hong Kong Total Diet Study, which has assessed the dietary exposure of the Hong Kong population to organochlorine pesticide (OCP) residues and their associated health risks, was released by the Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department today (May 29). The findings showed that the dietary exposure of the local population to various OCP residues was far below the respective health-based guidance values and thus unlikely to pose unacceptable health risks.
A spokesman for the CFS said, "OCPs are toxic chemicals mainly consisting of carbon, hydrogen and chlorine and have been widely used in agriculture worldwide. A total of 14 OCP residues, namely aldrin, dieldrin, chlordane, chlordecone, DDT, dicofol, endosulfan, endrin, heptachlor, HCB, HCH, mirex, pentachlorobenzene and toxaphene, were analysed in the study. All except dicofol are persistent organic pollutants (POPs) listed in the Stockholm Convention for elimination or restriction."
The spokesman said that, for the general public, diet is the main source of exposure to OCP residues. In cases of excessive intake, the principal acute toxic effect of OCPs is on the nervous system. Some OCPs have been linked to elevated rates of liver, thyroid or kidney cancer in animals but in humans there is inadequate evidence for their carcinogenicity. Therefore these OCPs were classified as possibly carcinogenic to humans by the International Agency for Research on Cancer.
Most OCPs are no longer allowed to be used in agriculture in many countries nowadays. However, since most of the OCPs analysed in the study are POPs that are persistent in the environment and have potential for bioaccumulation (for example in fat tissue), food commodities may still contain low levels of OCP residues.
"Among 600 composite samples of 150 food items tested, low levels of OCP residues were detected in 55 per cent of the samples (i.e. 332 samples). The three most commonly detected OCPs were DDT, HCB and endosulfan. A higher proportion of samples from animal origin such as 'fish and seafood and their products', 'meat, poultry and game and their products' and 'eggs and their products' had detectable DDT and HCB. Meanwhile, a higher proportion of samples from 'vegetables and their products' had detectable endosulfan. In addition, chlordecone was not detected in any samples. The rest of the OCPs were detected in 10 per cent or less of the composite samples," the spokesman said.
"The estimated dietary exposure to all OCP residues was very low. Even for high consumers, the upper exposure estimates of OCP residues ranged from 0.1 per cent to 13.6 per cent of their respective health-based guidance values (e.g. acceptable daily intake). Hence, it would be unlikely to pose unacceptable health risks," he added.
The CFS conducted a risk assessment study on dietary exposure to DDT in 2006, which found that the mean DDT concentration of "seafood (including fish)" was 29.7 micrograms per kilogram. In this Total Diet Study, the mean DDT concentration of "fish and seafood and their products" was 18 micrograms per kilogram. This finding was consistent with the declining trends of DDT in food reported by different countries since it was banned.
"To avoid excessive intake of OCP residues, people are advised to have a balanced and varied diet which includes a wide variety of fruits and vegetables, and to reduce fat intake," the spokesman said.
He also urged farmers to observe Good Agricultural Practices, such as using only pesticides registered with the competent authority, and applying the minimum quantities necessary to achieve adequate pest control. They should also use the pesticides in strict accordance with the label requirements, e.g. do not harvest the crops within the specified withholding period after the last pesticide application.
The First Hong Kong Total Diet Study was launched by the CFS in March 2010 and will be completed this year. Seven reports have already been released covering the following substances: dioxins and dioxin-like polychlorinated biphenyls, inorganic arsenic, polybrominated diphenyl ethers, pesticide residues, metallic contaminants, acrylamide and mycotoxins.
The Study aims at estimating the dietary exposure of the general population and various population subgroups to a range of substances, including contaminants and nutrients. The purpose is to assess any associated health risks, focusing on the total diet of the population rather than individual foods.
A total of 150 food items were chosen for the study according to the food consumption patterns of the Hong Kong population. They are being used for testing the levels of over 130 substances, including pesticide residues, POPs, metallic contaminants, mycotoxins, macro nutrients and elements. By combining the test results with food consumption data, the dietary exposure of the population to the selected substances may then be estimated.
The full report on the study on OCP residues is available on the CFS' webpage at www.cfs.gov.hk. Study results concerning other substances will be released in phases.
Ends/Thursday, May 29, 2014
Issued at HKT 15:01
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