Hong Kong's Food and Environmental Hygiene Department has warned people to avoid eating too much charcoal-grilled or dried meat as they contain high levels of cancer-causing chemical substances.

The level of polycyclic aromatic hydrocarbons (PAHs), the organic chemicals that are probably carcinogenic to humans, is generally higher in charcoal-grilled or dried meat, according to a risk assessment study on barbecued meat recently completed by the department.

Sixty food samples, including dried meat, barbecued pork and roast pork and duck, cooked in a variety of ways, were collected for testing from food factories and restaurants across the territory.

Announcing the findings of the study on Tuesday, the department's Consultant (Community Medicine) (Risk Assessment and Communication), Ho Yuk-yin, said charcoal grilling, high cooking temperature and close proximity of the meat to heating sources could lead to higher levels of PAHs in barbecued meats.

An analysis of the cooking methods showed that charcoal grilling gave rise to significantly higher levels of PAHs than gas grilling or electric-oven roasting, Ho said.

"The PAH concentrations for charcoal-grilled 'siu mei' ranged from 48.6 to 144.7 micrograms per kilogram, while those prepared by gas grilling or in electric ovens ranged from 5.1 to 10.4 micrograms per kilogram," said Ho.

"The PAH levels in dried meat, cooked by electric or gas grilling were as high as those found in charcoal-grilled 'siu mei'.PAHs levels were found to be generally higher after gas grilling rather than electric grilling," he said.

"Also, dried meats cooked in similar ways were found to contain significantly higher PAH levels than those in barbecued pork due to the close contact of the former to the heat source," Ho said.

In addition, relatively lower levels of PAHs were detected in roast duck samples, which were cooked at a lower temperature, he said.

Ho said the skin and fat of the charcoal-grilled ducks contained significantly higher levels of PAHs than the lean parts,105.6 microgram per kilogram against 2.1 micrograms per kilogram. This was caused by the close proximity of the outer parts of the ducks to the heat source and therefore subjected to a higher temperature.

While PAHs may be toxic to hereditary material, there are not any safe levels of intake of PAHs. Ho said efforts should be made to minimize human exposure to these organic chemicals.

"The trade is therefore advised to use gas grilling or electric-oven roasting to make 'siu mei', and electric grilling to cook dried meat, in order to reduce PAH levels," Ho said.

"In addition, the heating chambers should be properly designed and the fat should be trimmed from the meat before cooking to stop the melted fat dripping onto the heat source," he said.

"Direct contact of the meat with flame and high cooking temperature should also be avoided. Manufacturers are advised to pre-cook the meat so that a lower temperature will suffice for the roasting," he said.

Ho advised consumers not to over-indulge in barbecued meat, particularly charcoal-grilled ones, and the skin and fat, and to remove the charred parts of the meat. "When barbecuing meat, the fat should be trimmed and the meat should be partially cooked beforehand," he emphasized.

(Xinhua News Agency July 14, 2004)