The head of China's food safety watchdog stepped down Monday as the number of infants sickened by tainted baby formula in the country jumped to nearly 53,000.
The resignation of Li Changjiang comes after the industrial chemical melamine was found in infant formula and other milk products from 22 of China's dairy companies -- one year after he promised to overhaul the system.
The chemical was blamed for causing kidney stones and kidney failure in babies.
"China hasn't been able to develop strong enough regulatory framework for all of these food products," Queen's University's James Miller told CTV's Canada AM on Monday. "As a result of this we have these increasing numbers of food scares in China in the past few years."
Earlier Monday, the World Health Organization demanded China implement stricter monitoring of the dairy industry.
Melamine has a high nitrogen content, which can make products appear high in protein.
It is alleged that dairy company officials added melamine to watered-down products to make them appear higher in protein content.
Prior to the crisis, China's product quality watchdog had granted the dairy at the centre of the scandal, Sanlu Group. Co., inspection-free status.
Although the status has since been revoked, WHO China representative Hans Troedsson said more monitoring is still needed to raise the country's standards.
"It's clearly something that is not acceptable and needs to be rectified and corrected," he said.
Officially, the number of sick children jumped 6,200 late Sunday to nearly 53,000.
In recent weeks, nearly 13,000 children -- 80 per cent of them just two years old or younger -- have had to be hospitalized. Another 39,965 children received outpatient treatment and were considered "basically recovered," according to the health ministry.
Four deaths have been blamed on the tainted milk powder.
Meanwhile, the Canadian Food Inspection Agency warned Canadians Sunday that a dessert product sold in the country may contain milk contaminated by melamine.
Nissin Cha Cha Dessert is distributed in Ontario, Alberta and British Columbia by Regent Long Marketing and Distribution Ltd., of Richmond, B.C.
Regent is recalling the product voluntarily. CFIA said in a news release that the product was made using Yili Pure Milk, in which melamine was detected by food safety agencies in Hong Kong.
There have yet to be any reports of any Canadians becoming sick after consuming the product. CFIA is monitoring the situation.
With files from The Associated Press
