18 February 2008:
As many as 100 million people worldwide are
facing slow poisoning and risk of death from arsenic
in their drinking water and food supply.
That is the conclusion of scientists at the
CRC for Contamination Assessment and Remediation of
the Environment following a global review of the health effects of
arsenic on people in affected countries.
“This is probably the worst mass
poisoning event in history - and in many cases it is
preventable,” says CRC CARE managing director Professor Ravi
Naidu.
“The bad news is that it is spreading
around the world in the expanding global food trade, exposing
millions more people to risk.”
Arsenical poisoning is worst in Bangladesh,
where an estimated 35-77 million people are at risk from drinking
groundwater contaminated by naturally-occurring
arsenic. Another 6 million are at risk in West Bengal,
India. However, numerous cases have now been reported from China,
Chile, Cambodia, Laos, Burma, Pakistan, Nepal, Vietnam, Taiwan,
Iran, Argentina, Finland, the United States and several other
Indian States.
Some groundwaters in Australia are also known
to be contaminated with arsenic, and the landscape contains
‘hot spots’ from its former widespread use as a
insecticide to protect livestock and crops nearly a century ago,
Prof. Naidu says. Concentrations of arsenic are also sometimes
associated with old gold diggings and old rail tracks.
Besides being known to cause cancer of the
skin, lung, bladder, kidney, liver and uterus, arsenic is also
linked to several skin diseases, nerve disorders, diabetes, lung
disease, heart disease, suspected birth defects, liver and blood
disorders, according to a review by Mohammad Rahman and Prof.
Naidu.
“At high doses arsenic is a known
carcinogen and can cause heart attack and diabetes. Much less clear
are the effects of prolonged exposure to low doses in water and
food, and there needs to be a lot more research done globally to
find out,” says Dr Rahman.
“The US National Research Council
estimates that drinking a litre a day of water containing 50
micrograms of arsenic would result in 13 deaths from cancer per
thousand people, but we can only guess the effect for doses greater
or lower than this over time.”
Also diet seems to play a crucial role, he
says. Well nourished people appear more resistant to
the effects of arsenical poisoning, whereas the poor and hungry
experience its symptoms far more acutely.
Work by CRC CARE scientists has revealed that
not only drinking the water is dangerous. Rice and vegetables may
also take up arsenic when grown in contaminated water and small
amounts may pass through the food chain via meat and milk to
people. Rice or vegetables boiled in the contaminated water can
also take up arsenic during the cooking process.
“In Bangladesh, arsenic
levels in rice can range as high as 1770 micrograms
per kilo and in vegetables as high as 3990 micrograms,” Dr
Rahman says. “A level of 1000 micrograms per day is enough to
produce the skin lesions of arsenicosis within a few
years.”
“Also, foodstuffs imported into the
United Kingdom from Bangladesh were found to contain up to 540
micrograms per kilo of arsenic.”
The World Health Organisation recommended
maximum level for arsenic in drinking water is 10 micrograms per
litre.
Professor Naidu says this finding suggests
that with supermarkets now sourcing their fresh fruits, vegetables
and grains worldwide, arsenic poisoning has become a global problem
exposing millions of consumers in countries not significantly
affected by contaminated groundwater.
Ironically, levels of arsenic are found to be
highest in leafy green vegetables, regarded the world over as a
desirable and healthy food and which contains many vital nutrients,
such as iron.
“Due to the growth in the globalised
food trade, the issue of arsenic poisoning is no longer confined to
those countries with contaminated groundwater. Many
consumers in the developed world may be, to some degree, at risk.
This increases the international urgency of overcoming
it.”
Professor Naidu says the arsenic
poisoning calamity is preventable in most areas with a combination
of education and appropriate technologies, such as the use of
domestic rainwater harvesting and simple devices which absorb
arsenic from drinking water. However these do not solve the larger
issue of crops grown on contaminated water, for which the only
solution is to develop improved surface water irrigation and reduce
reliance on groundwater.
“Australia has significant skills in the
management of contaminated soils and water and we should be
stepping up our efforts to help those countries most affected by
arsenic poisoning. At the same time we will be helping
to protect our own consumers.”
More information:
Dr Mohammad Rahman, CRC CARE, 08 8302
5348
Professor Ravi Naidu, CRC CARE, 08 8302 5041
or 0407 720 257
Peter Martin , CRC CARE communication, ph 08 8302 3933 or
0429 779 228. peter.martin@crccare.com
www.crccare.com
