Polybrominated diphenyl ethers in foods of animal origin

The Centre for Food Safety (CFS) today (April 29) released results of its recent study on the levels of polybrominated diphenyl ethers (PBDEs) in foods of animal origin.

"PBDEs are a group of chemicals used as flame retardants. They are extensively used in plastics, polyurethane foam and carpets. PBDEs are ubiquitous in the environment, persistent and bioaccumulative, especially in the fat of animals," a CFS spokesman said.

"The main sources of PBDE exposure for humans include indoor air, house dust, and food. Animal studies found that PBDEs affect brain and reproductive organs, neurobehavioural development and thyroxine level, and are toxic to liver."

"The study aims to measure the levels of PBDEs in foods of animal origin, to estimate the potential dietary exposure to PBDEs of secondary school students in Hong Kong from these foods and to assess the associated health risks."

The CFS took 300 samples of foods of animal origin from local markets, including fish, seafood and seafood products, meat and meat products, poultries, eggs, and dairy products, to analyse the levels of 24 PBDEs.

The results indicated that PBDEs were detected in all the samples, and the total PBDE levels of samples in the same food group varied widely. The PBDE levels of fish ranged from 13 to 6,600 pg per gramme (1 pg = 1 trillionth of a gramme), seafood and seafood products (other than fish) 15 to 1,200, meat and meat products 23 to 3,500, poultries 68 to 670, eggs from 280 to 800, and dairy products from 12 to 480. The PBDE levels of foods in Hong Kong were comparable with those reported overseas.

The CFS combined the levels of PBDEs in foods with the consumption data of secondary school students to obtain the daily dietary exposures to PBDEs from individual food items.

The highest PBDE levels on weight basis were found in fish, which was also the major dietary source of PBDEs of secondary school students, representing 38.5% of PBDE exposure among foods of animal origin.

The dietary exposures to PBDEs from foods of animal origin for the average and high consumers of secondary school students were estimated to be 0.0026 microgrammes and 0.0064 microgrammes per kg body weight per day, respectively. These estimated exposures were comparable to those reported by overseas countries.

According to the Joint Food and Agriculture Organisation/World Health Organisation Expert Committee on Food Additives (JECFA), for the more toxic PBDEs, adverse effects would be unlikely to occur in animals at doses of less than approximately 100 microgrammes per kg body weight per day.

The margin of exposure (MOE) approach adopted by JECFA was used to assess the health risk of dietary PBDE exposures in this study. The MOE is calculated by dividing the dose (100 microgrammes per kg body weight) at which adverse effects were observed in laboratory animal studies by the estimated exposure to PBDEs from food. The lower the MOE, the greater the public health risk. The MOE values were 38,000 for average consumers and 16,000 for high consumers, indicating that the estimated exposures of secondary school students were far below the adverse effect dose observed in animals.

"On the basis of the available data, dietary exposure to PBDEs in foods of animal origin is unlikely to pose health risk to average and high consumers of secondary school students." the spokesman said.

"People are advised to maintain a balanced diet as to avoid excessive exposure to chemical contaminants from a small range of food items. PBDEs tend to accumulate in the fat of animals. To reduce dietary exposure to PBDEs, the public should consume low-fat products, trim fat from meat and meat products, use less animal fat in food preparation and adopt fat-reducing cooking methods."

"The food trade should observe good agricultural and manufacturing practices, such as avoiding exposing food animals to PBDE sources such as foams and insulations, obtaining food supplies from reliable sources, and keeping proper records to enable source tracing when necessary."

Ends/Wednesday, April 29, 2009