The tolerable amount of melamine in food a person can ingest without “appreciable health risk” is 0.2 milligrams per kilogram of body weight, according to the latest World Health Organization (WHO) guideline. A person weighting 50kg can tolerate 10mg of melamine per day. It was the first time the WHO had announced the tolerable amount of melamine in food.

“We expect this will better guide the authorities in protecting the health of the public,” WHO's Director of Food Safety Jurgen Schlundt said in a statement.

The TDI (“tolerable daily intake”) released in Ottawa, Canada, during a World Health Organization meeting, is lower than previous levels suggested by some countries’ food safety authorities.

“WHO's daily limit is a guideline for all countries to control their melamine standards. It means normal people can consume up to 10 mg melamine a day without any harmful effects,” Chen Junshi, a senior researcher with the National Institute for Nutrition and Food Safety was quoted as saying. “It also means the country’s existing limit is safe,” he continued.

Melamine, a toxic industrial chemical usually used to produce plastic materials, fertilizers and pesticides, is high in nitrogen and can cause kidney stones and other organ problems. The chemical was added to low-quality milk to boost its protein readings and fetch a higher price.

Melamine-tainted formula was found earlier this year in China, where four babies died and more that 50,000 had become sick with kidney stones or kidney failure associated with the consumption of infant formula contaminated with melamine. It’s not known when the contamination in China started, the WHO said in a statement released earlier this month. Tainted raw material may have been exported as infant formula or other milk- containing products to other countries, according to the statement. The scandal has led many countries to ban Chinese milk imports.

In September, the FDA announced that some instant coffee and tea drinks containing a non-dairy creamer made in China had been recalled for fear of contamination with melamine. FDA's director for Center for Food Safety and Applied Nutrition, Dr. Stephen Sundlof, said that no melamine-induced human illness has been reported in the U.S. In October, the FDA couldn’t set a safety contamination level for melamine.

In November, the agency found trace levels of melamine in several samples of infant formula sold in the United States, but insisted the levels were safe. After reviewing the samples and animal studies, the agency decided that either melamine or cyanuric acid alone is safe in formula at 1 part per million or less. Judy Leon, an agency spokeswoman, suggested the sample that tested positive most likely became contaminated through the manufacturing process or through contact with can liners. Some food processing equipments in manufacturing units are cleaned with a solution that contains melamine, which can easily seep into the products.

International experts say that melamine is a contaminant that should not be in food; however, this situation is sometimes unavoidable.