CFS announces First Hong Kong Total Diet Study findings on inorganic arsenic

The Centre for Food Safety (CFS) today (February 20) released the second report of the First Hong Kong Total Diet Study. It reported that the dietary exposure of the population to inorganic arsenic fell within the middle range of levels found in other places (e.g. the US, Canada, Europe, New Zealand, Japan and the Mainland). The CFS advises the public to have a balanced and varied diet.

Announcing details of the study report, a spokesman for the CFS said, "Arsenic is a metalloid that occurs in inorganic and organic forms. It is found in the environment and originates from both natural occurrence and human activities. Low levels of inorganic arsenic in foods may be unavoidable due to its ubiquitous nature in the modern industrial world. Food is also recognised as the major source of inorganic arsenic exposure."

Inorganic arsenic may cause cancer, skin lesions, cardiovascular disease, neurotoxicity and diabetes. Setting a safety reference value for exposure to carcinogens, like inorganic arsenic, is considered not appropriate in the international arena. In 2010, the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives determined the inorganic arsenic benchmark dose lower confidence limit for a 0.5 per cent increased incidence of lung cancer in humans (BMDL0.5) to be at 3.0 microgrammes (μg) per kilogramme of body weight (bw) per day. In other words, at a daily exposure to inorganic arsenic of 3 μg/kg bw, the conservative estimate of the increase of lung cancer incidence in the population would be 0.5 per cent.

The spokesman said the report presents the assessment of the dietary exposure of the population to inorganic arsenic. The dietary exposure to inorganic arsenic for average and high consumers in the population, respectively, were 0.22 μg/kg bw/day and 0.38 μg/kg bw/day, which were below the BMDL0.5. The dietary exposure of the population fell within the middle range of levels found in other countries and regions. Based on these study findings, there is no sufficient evidence to change the basic dietary advice on healthy eating.

A total of 51 per cent of the 600 composite samples tested were detected to contain inorganic arsenic. Among all the food groups, "eggs and their products" contained the highest inorganic arsenic level (mean: 23 μg/kg), followed by "fish and seafood and their products" (mean: 15 μg/kg) and "vegetables and their products" (mean: 9 μg/kg). In addition, the mean inorganic arsenic level in "cereals and their products" was 8 μg/kg. No inorganic arsenic was detected in all samples of dairy products and fats and oils.

In terms of food items, water spinach was found to contain the highest level (mean: 74 μg/kg), followed by salted egg (mean: 58 μg/kg) and oyster (mean: 58 μg/kg), whereas no water and chicken egg samples in this study were found to contain inorganic arsenic.

The spokesman pointed out that "cereals and their products" are staple foods in the population, and the study revealed they were found to be the main dietary source of inorganic arsenic for the local population, contributing 53.5 per cent of the total exposure. Similar findings were also revealed in other places such as the UK and the Mainland. Rice is the major contributor of dietary exposure to inorganic arsenic in the local population, with cooked white rice alone accounting for 45.2 per cent of total exposure. These findings were consistent with data reported in other Asian places where rice is a staple food.

"The findings of the current study are not sufficient to warrant changes in basic dietary advice on healthy eating, i.e. to have a balanced and varied diet, and to have cereals, such as rice, noodles, oatmeal and bread, as the major dietary source. Individuals who wish to reduce exposure to inorganic arsenic can consider choosing other cereals, which generally contain lower levels of inorganic arsenic, as part of their diet. They can also wash rice thoroughly, although without excessive washing as some nutrients may be lost, and discard the washed water before cooking," the spokesman said.

He advised the food trade to observe good agricultural practices to minimise inorganic arsenic contamination of foods, such as avoiding the use of arsenic-contaminated water for irrigation.

The First Hong Kong Total Diet Study was launched in March 2010 and will be completed in 2014.

The Study aims to estimate the dietary exposure of the general population and various population subgroups to a range of substances, including contaminants and nutrients, and thus assess any associated health risks. It focuses 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, persistent organic pollutants, metallic contaminants, mycotoxins, macro nutrients and elements. By combining the test results with food consumption data, the dietary exposure of the population to those selected substances can then be estimated.

The study report on inorganic arsenic is available on the CFS' webpage at www.cfs.gov.hk. Results concerning other substances will be released in phases.

Ends/Monday, February 20, 2012
Issued at HKT 14:51