Almost every vegetable sample taken from major supermarket outlets in a recent survey contained pesticides - in one case seven times over the safety limit - Greenpeace said yesterday.
Eleven of the 12 samples taken from ParknShop, Wellcome and Jusco in February contained residues of various types of pesticides.
At Jusco's Lai Chi Kok outlet, a long yard bean sample had traces of 12 pesticides. They included the carcinogen chlorpyrifos, at a level seven times above the international standard set by the UN's Codex Alimentarius Commission.
A green Chinese cabbage also contained the chemical, at slightly over the international standard.
Jusco said it removed stocks of the two vegetables from its shelves yesterday and would conduct further tests. Consumers could ask for refunds at any of their stores.
At Wellcome's Liberte Shopping Centre store, residues of four pesticides were found on two samples of flowering Chinese cabbage and Chinese kale. There are no international standards for those pesticides.
At ParknShop's Metro City Plaza store, a flowering Chinese cabbage was carrying residues of up to seven types of pesticide, including fipronil, a pesticide banned on the mainland.
Fipronil remains in the environment for a long time, contaminating soil and water. It can potentially increase cancer risk and damage human organs.
Greenpeace said ParknShop had been importing vegetables from a mainland farm in Huizhou operated by Hong Kong-based Prima Chent Vegetables.
Tests on vegetables, soil and water samples taken at the farm earlier found residues of 13 types of pesticide, including three banned on the mainland, among them the highly toxic carbofuran.
Workers at the farm told the group pesticides were applied daily for periods of more than 10 days. But they said they had no idea what pesticides they were administering, and wore no protective gear.
Greenpeace campaigner Kate Lin Pui-yi said: 'These vegetables are on our menus every day, but before they come into our mouths they are being coated with toxins.'
The group called on the government to step up co-operation with Guangdong on regulating vegetable farms across the border and supermarkets, increase the transparency of their procurement and punish suppliers that abuse pesticides.
A spokeswoman for ParknShop said the company had not imported vegetables from the Huizhou farm this season.
A Wellcome spokeswoman said it would conduct a random check and make the results available in two weeks.
She said the pesticide residues found in vegetables from Panyu and Shaoguan , in Guangdong, were not banned on the mainland or in Hong Kong, and the levels were within European standards.
The Centre for Food Safety said it would take appropriate follow-up action after studying the findings.