Fears rise over heavy metals in mainland rice

PUBLISHED : Wednesday, 16 February, 2011, 12:00am
UPDATED : Wednesday, 16 February, 2011, 12:00am

After many food safety scandals - including the infamous melamine-tainted milk that sickened 300,000 children more than two years ago - mainlanders now fear that rice, the major staple in their diets, is also not safe.

Heavy metal contamination of rice has existed for years, but it caused a public outcry in the past two days after mainland media published a survey showing at least 10 per cent of the samples from various provinces contained excessive amounts of cadmium, a heavy metal that can cause bone problems if too much is consumed.

And this affects Hong Kong consumers, with government figures showing rice imports from the mainland have been rising. In 2002, 3.6 per cent of all rice imports were from the mainland, now it is 12.8 per cent.

Most of the rice that comes from the mainland is of the See Mew and Yu Jien type, with the latter being the majority. Two-thirds of rice in the city is from Thailand.

It remains unknown if any of the imported rice in Hong Kong contains excessive amounts of heavy metal.

A team led by Pan Genxing , a professor at Nanjing Agriculture University's Agricultural Resources and Environmental Institute, tested more than 100 rice samples bought from markets in six regions in 2007. They found 10 per cent of them contained higher levels of cadmium than the national standard.

They conducted similar tests the next year on 63 rice samples bought from Jiangxi, Hunan and Guangdong, and found 60 per cent of the samples contained too much cadmium, the mainland-based Century Weekly Magazine said.

Experts said the situation could only be worse now as soil pollution, the main cause of farm product contamination, was spreading hand in hand with rapid industrialisation.

Lin Jingxing, professor at the Chinese Academy of Geological Sciences, said soil pollution had expanded geographically as heavily polluting industries, such as chemical plants, moved inland from coastal regions. Once contaminated, the soil cannot be rehabilitated for years and has a long-term affect on agriculture.

Rice was most susceptible to absorbing cadmium in soil because of its genetic traits, Pan said in the Shanghai Morning Post. He could not be reached yesterday.

He said this absorption would be boosted if the rice was planted in acidic soil, which exists from Jiangxi to Hunan. Hybrid rice, which is common in southern China, also absorbs heavy metals in soil more easily.

A Ministry of Agriculture survey in 2002 also showed that Chinese rice contained excessive amounts of lead and cadmium.

The mainland's food safety rules set caps for heavy metals per kilogram of rice at 0.2 milligrams of cadmium, 0.3 mg of lead and 0.3 mg of arsenic, said Wang Guangyi, a micro-element expert from the Anhui Institute of Chemical Industry.

Heavy absorption of this metal component could lead to bone pain and weak bones, medical experts said. The disease caused by excessive cadmium was recognised in the 1960s when hundreds of farmers in Japan suffered years of bone pain.

Pan Wenjing, director of the food and agriculture team with Greenpeace in Beijing, said excessive use of fertilisers and pesticides also contributed. 'Chinese farmers use seriously redundant fertiliser and pesticide. About 25 to 35 per cent of these chemical materials are absorbed by agricultural products, with the rest either staying in the soil to make it become acidic or clotted, or flowing to pollute nearby rivers.'

In another report on Shanghai-based eastday.com yesterday, Pan Genxing attempted to allay public fears by saying rice in supermarkets in cities had different origins and that reduced the risks of contamination.

But many were not convinced.

Liang Yue, a Shanghai resident, said her family had bought rice from different provinces to 'lower the risk of food poisoning'. They once also paid premium for a top-brand rice, found it had a strange taste and decided to throw it away.

Lee Kwong-lam, a Hong Kong businessman who imports rice from the northeastern part of the mainland, said: 'It shows perhaps the soil was contaminated, but I believe it's an individual case and there's no need to worry.'

Additional reporting by Adrian Yan

Staple concerns

Mainland rice imports to Hong Kong have been on the increase

In 2002, they formed 3.6 per cent of all the city's rice imports. Now, that figure has risen to: 12.8%