Knowledge
Biology scholars develop new food safety analysis methods
31 Jan 2013
Professor Chris Wong, Head of Biology, Dr. Alice Law, Post-doctoral Research Fellow, and their team at the Department of Biology have developed a rapid biological screening method for endocrine-disrupting chemicals (EDCs) present in meat. In comparison with the traditional instrumental analyses of food samples, the new techniques take two days and are 500 times less expensive for each sample under analysis when screening for dioxins, for example. The new method also enables measurement of the concentration of various residues and the biological impacts of contaminants on human beings. The findings provide insights on possible ways to develop a cost-effective risk assessment platform for routine monitoring of EDC contaminations in many food products.
Over the years, the team has looked into the endocrine-disrupting effects of environmental chemical contaminants on human beings. In the present study, they used a battery of bioassays to screen 84 local and imported meat samples including chicken, pork, beef, and fish, for the detection of the residual hormonal and dioxin-like activities.
Traditional chemical analyses of food samples by the use of instruments cost around HK$5,000-HK$6,000 per food sample and take four to five days to complete. In addition, instrumental analyses identify only concentration of individual residues. With the new techniques, screening of each sample costs around HK$10 and can be completed in only two days. Measurement of the enormous numbers of chemical contaminants in the environment and EDC-elicited activities in animals were also considered.
The team has applied the use of “reporter-gene” techniques, the first time these techniques have been used, to the measurement of EDC-elicited hormonal activities such as androgenic, estrogenic, dioxin-like, glucocorticoid-like, progesterone-like, peroxisome proliferator-like and retinoid-like activities in the animal meat. Concentration of contaminants is reflected by the amount of light emitted, in other words, a highly chemical-contaminated food sample displays a greater amount of light emitted during the analyses.
The results show that fish samples exhibited the greatest androgenic, dioxin-like, glucocorticoid-like, peroxisome proliferator-like and retinoic acid-like activities. Extracts of chicken skin exhibited the greatest estrogenic effects, followed by dioxin-like and progesterone-like activities. Chicken meat extracts exhibited glucocorticoid-like potency followed by dioxin-like, retinoid acid-like and peroxisome proliferator-like potencies. Beef and pork extracts exhibited lesser hormonal potencies.
The results reveal that fish products contribute the greatest proportion of exposure to pollutants that are active through the screening. This is possibly due to the disposal of chemical pollutants into the water systems of oceanic cities which make fish a source of various environmental toxicants to humans.
The results also show that cells exposed to the extract of chicken skin from Mainland China display the greatest formation of cellular reactive oxygen species (ROS) level. The extracts from all fish samples showed no noticeable effects on cellular ROS level. Excess ROS level may result in significant damage to cell structures or even damage to DNA.
Professor Wong hopes that the rapid and cost-effective screening methods for EDC-elicited activities can be further applied to routine measurement of possible EDC contaminations in other food products, including imported food, in the future. This would also contribute as a gatekeeper of food safety in the region. The team also hopes the findings provide a platform to assess the physiological risks and potential effects of EDCs consumed by human beings, such as body metabolism and homeostasis, can further be assessed in future studies.
The study entitled “Biological analysis of endocrine-disrupting chemicals in animal meats from the Pearl River Delta, China” was published on Journal of Exposure Science and Environmental Epidemiology Vol. 22, No.1, (2012): 93-100.
