31 Jan 2013 (Thursday)

Biology scholars develop new food safety analysis methods
生物系學者研食品安全檢測新法


Professor Chris Wong (left) and Dr. Alice Law have developed a rapid biological screening of endocrine-disrupting chemicals present in food, measuring the concentration of various residues and their biological impacts of contaminants on human beings
生物系主任黃港住教授(左)及博士後研究員羅茹湘博士研發肉類檢測新法,可更快、更全面地評估食物樣本中多種對人體有影響的污染物的濃度

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.

 

Enclosure: The effects of various food-extracts on the promoter-driven luciferase activities; and possible influence of endocrine-disrupting chemicals on human diseases  



浸大生物系學者研發一項快速肉類樣本檢測技術,比傳統以化學儀器檢測時間更快、成本更低。以檢測二噁英為例,新技術比傳統方法快兩天,成本更低五百倍,並可量度食物樣本中多種對人體內分泌有影響的污染物的濃度,檢測範圍更廣泛和全面。研究成果有助應用在更多食品檢測上。

 

生物系主任黃港住教授、博士後研究員羅茹湘博士與團隊一直致力研究食物和化工產品對人體內分泌系統的影響。團隊近期進行一項「測試肉類樣本中各種環境污染物的影響」的研究,對84件本地及入口豬肉、牛肉、雞肉和鹹水、淡水魚樣本進行檢測,並分析它們的毒素、激素等環境污染物的濃度

 

以化學方法檢測食物樣本,每項成本約港幣五千至六千元,需時約四至五天﹔以新的方法進行檢測,每項樣本約港幣十元,檢測時間更可快至兩天。另外,化學儀器僅能量度食物樣本中某一化學污染物的濃度,新方法可評估各種環境毒素對干擾人體內激素合成和代謝的影響程度。

 

黃教授的團隊首次運用「報告基因載體」(reporter-gene)的技術,量度上述各種肉類涉及不同受體的雄激素(androgenic)、雌激素(estrogenic)、二噁英類(dioxin-like)、糖皮質激素(glucocorticoid-like)、孕激素類(progesterone-like)、過氧化物酶(peroxisome proliferator-like)和維甲酸類(retinoid-like)等內分泌干擾物濃度引起的變化。濃度的變化可以從熒光素酶的光度表現出來,換言之,光度愈高,表示肉類樣本受到內分泌干擾物的影響愈大。

 

研究顯示,魚樣本呈現最高雄激素、二噁英類、糖皮質激素、過氧化物酶、維甲酸類等污染物濃度。雞皮樣本呈現最高雌激素濃度,其次是二噁英類及孕激素類。雞肉樣本的濃度最高為糖皮質激素、其次是二噁英類、維甲酸類、過氧化物酶。檢測的豬肉和牛肉樣本則含較少荷爾蒙濃度。

 

研究指出,魚樣本受環境污染的侵害最大,這可能與沿海城市的海水受到排出海面的化學物污染有關。

 

研究亦發現,內地入口的雞皮樣本顯示最高的活性氧水平,魚樣本則沒有明顯活性氧水平。過量的活性氧會損害正常細胞,嚴重更會損害脫氧核醣核酸DNA

 

黃教授期望這項更快、成本更低的檢測技術,可更有效地評估各種食品中的環境污染物,並希望檢測可進一步應用到本港的進口食品,有助食品安全。另外,團隊希望繼續研究和評估進食受環境污染物影響的食品對人體的生理影響,包括新陳代謝、體內荷爾蒙的平衡等。

 

有關〈Biological analysis of endocrine-disrupting chemicals in animal meats from the Pearl River Delta, China〉研究報告,已於《Journal of Exposure Science and Environmental Epidemiology》(201222卷,第1期,93-100頁)上刊登。

 

附件﹕肉類樣本受內分泌干擾物影響的程度及各種毒素、激素水平對相關疾病可能帶來的影響

 

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