Melamine
Contamination highlights human food chain risks
Hong Kong mother Shirley Lo stocked her refrigerator with soymilk and
switched to buying imported chocolates for her son after melamine was
found in baby formula and milk products in China.
But when eggs from China tested positive for melamine in Hong Kong
late last month, Lo threw up her hands in despair.
"It's horrifying," she said. "It's clear it has gone into basic foods
and into our food chain. My son has been trying to comfort me, saying he
must be very strong because his body must be full of this stuff and yet
he is not sick".
The discovery of melamine in eggs as well as in baby formula, milk
products, biscuits, chocolates and other foodstuffs containing milk
derivatives confirms what experts have long suspected; that the chemical
is deeply embedded in the human food chain.
And it's not just melamine; heavy metals such as lead and mercury
which can cause brain damage, as well as cadmium, a compound used in
batteries, pesticides and antibiotics are all present in the human food
chain. China is a major transgressor as carcinogenic chemicals are
regularly used as food colouring agents or as preservatives, experts
say.
"In China, food safety is not a concern and all sorts of things like
Sudan red, Malachite green are added in food, so food contamination is
widespread," said Peter Yu, a professor of biology and chemical
technology at the Hong Kong Polytechnic University.
"We also have environmental contamination from pesticides,
formaldehyde (to kill bacteria)," Yu said, citing the use of Malachite
green, a carcinogenic agent, that in 2006 was found in fish from China.
It had been added to eradicate fungal disease in the fish.
Leading food manufacturers regularly test their ingredients and final
products for many of these contaminants, but experts say it's impossible
to keep up with all the foreign compounds that land up on the dinner
table, especially in China where regulation is lax and difficult to
enforce.
In the wake of the melamine scandal, China is reviewing a tougher
draft food safety law following criticism from the United Nations for
its sluggish response to the tainted milk scandal.
The melamine saga has surprised even some food producers, who say
they find it hard to keep up with strange additives that are added to
food. Melamine, for example, was added to baby formula to cheat protein
level tests.
"How did we come up with cadmium or heavy metals? Because we know
they would kill people. That's why we test for them. But we didn't know
melamine would even be in food," said a manager who works for a major
foreign food producer with factories in China.
"We never had melamine in our specifications (contaminants to look
out for). If it is melamine today, it will be something else tomorrow.
We can't possibly test for every toxin in the world," said the manager,
who declined to be named because he was not authorised to speak to
reporters.
Tens of thousands of children in China have fallen ill with kidney
problems in recent months, and at least four have died, after being fed
infant formula that was later found to have been mixed with melamine.
Subsequent tests found melamine in a variety of Chinese-made products
from milk and chocolate bars, to yoghurt and other products exported
around the world, leading to items being pulled from shop shelves and
massive recalls.
But with the discovery of melamine in eggs, apparently due to
contaminated feed given to chickens, the chemical appears to be far more
entrenched in the human food chain than first thought.
Melamine and its derivatives are widely used in animal feed and
pesticides in China but no one knows how harmful they can be to people
after prolonged exposure.
Hong Kong imposed a cap on melamine in September to no more than 2.5
milligrams per kilogram, while food meant for children under 3 and
lactating mothers should be no more than 1 mg per kg. Experts say the
limits are arbitrary and called for more tests and science when imposing
safety limits. "The limits are derived from animal studies but we don't
know what our exposure is. What if we are accumulating more than is
safe?," said Chan King-ming, biochemistry professor at the Chinese
University. "There should be surveys to find out what foods have
melamine and their concentrations. Then we know how serious it is."
A World Health Organisation official said this week some of the
affected children in China, most of whom are believed to be under the
age of 3, have "crystals" in their kidneys. Some might need surgery to
avoid potentially deadly kidney failure.
In Hong Kong, parents have thronged public clinics to get their
children tested for melamine by laboratories that analyse urine samples
with sophisticated spectrometers. "Melamine is not soluble. But if it is
very concentrated as in the case of these Chinese kids (whose diet was
mostly formula), it forms into crystals," said Allen Chan, associate
professor of chemical pathology at the Chinese University.
Permanent liver damage can be caused when crystals suddenly form into
large numbers of tubules in the kidneys of children that have consumed
melamine, causing chronic kidney failure and requiring dialysis and even
kidney transplants later on in life.
The WHO plans to make a detailed assessment of the risks of long-term
consumption of melamine. It has asked China to provide information for a
meeting of experts in December.
REUTERS
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