Asiaweek 25-6-99: THE GREAT DIOXIN

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Subject: Asiaweek 25-6-99: THE GREAT DIOXIN SCARE A persistent problem with

pollutants
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THE GREAT DIOXIN SCARE

A persistent problem with pollutants

WHEN BELGIAN AUTHORITIES FINALLY admitted the country's eggs and poultry were
tainted with carcinogen dioxins, Asia was quick to act. Health regulators from
Bangkok to Taipei imposed a ban on food imports from Europe and ordered a
recall of suspect products such as milk formula. Now officials have added
reason to be glad they did not procrastinate. The source of contamination - an
80,000-kg batch of fat that a Belgium company sold to feed mills supplying
European farms - did not only contain dioxin. There was another class of
hazardous chemical present: polychlorinated biphenyls (PCBs). 


A chicken taken from a Belgian farm in April had 400 parts per million of PCBs
in its fatty tissue. That is 400 times the accepted limit in Holland, say
scientists at a Dutch laboratory, the nearest facility that could test for
dioxins and related chemicals. (The tainted fat was also found to contain 781
parts per trillion of dioxin - 1,500 times higher than the Dutch safe level.)
That was then. But as late as June 11, PCB levels 65 times the German limit
were detected in eggs exported to that country. Belgian chicken burgers were
similarly contaminated. 


How did the toxic chemicals get into the fat? Some suspect that waste
industrial oil containing dioxin and PCBs was placed into a container meant
for
recycled frying fats. PCBs are used in many industries: as heat-exchange
liquid
in transformers, in paint additives and in making plastics. Dioxin, though, is
usually formed as a byproduct in processes such as copper smelting,
paper-production and the making of pesticides and chlorine-containing organic
chemicals. 


Dioxins and PCBs are among a "dirty dozen" dangerous compounds known as
persistent organic pollutants. As the name suggests, their effects are
particularly pernicious because the chemicals are very stable and stay in the
environment for a long time. Dioxin, which is fat soluble, has a
"half-life" of
seven years in the body: It takes that long to break down half the quantity of
the compound. Worse, once absorbed, the chemical is locked into the body's fat
tissue (it is only excreted through the placenta and in breast milk). 



Brief exposure to high levels of PCBs and dioxins may cause skin lesions and
affect the liver (the tolerated daily intake for dioxin is about 1 picogram -
one trillionth of a gram - per kg body weight). Over longer periods, the harm
is transferred across generations. Babies of women exposed to the chemicals
may
suffer impaired memory and learning ability. Damage seems to stem from
dioxin's
interference with crucial biochemical messengers such as the thyroid hormones,
which regulate metabolism and help the brain to develop. Untreated, toddlers
short of the hormones can become mentally retarded. In moderate cases, the
pollutants disrupt youngsters' neurological development. Another effect:
behavioral abnormalities such as attention-deficit disorder. In adults, the
chemicals may disrupt immune systems and reproductive function. And there's no
avoiding increased risks of cancer - to liver, gall bladder and the lymph
system. 


For health officials in Asia, the next pressing task is disposal of
potentially
poisoned foods. Burial in landfills is a common choice. But danger may well
return in another form if the toxic chemicals leach into the groundwater. A
safe food supply requires a clean environment too.