do you have any idea how much rice i eat?

[Guest guest]

gonna have to stick with the organic thai rice i guess

 

Published online: 2 August 2005; | doi:10.1038/news050801-5

US rice may carry an arsenic burden

Mark Peplow

 

 

Legacy of cotton pesticides might be poisoning crops.

 

 

 

 

 

People eating a subsistence diet of American rice could be consuming

a dose of arsenic.

 

© Getty

 

Rice grown in the United States contains an average of 1.4 to 5

times more arsenic than rice from Europe, India and Bangladesh,

according to a survey of grains from around the world.

 

This means that people eating a 'subsistence' diet of 500 grams of

dry American rice a day are probably consuming more than the maximum

intake of arsenic provisionally recommended by the World Health

Organization (WHO), says Andrew Meharg, a biogeochemist from the

University of Aberdeen, UK, and a member of the survey team.

 

Although no one knows whether this level and type of arsenic is

dangerous, Meharg himself has decided to stop eating American

grains.

 

" When we're all paranoid about what's in our food, the question to

ask is, 'Would you like your rice to be grown on arsenic

contaminated soil?', " he says.

 

Low doses of arsenic such as these do not cause acute illness. " It's

more about long term intake that can elevate levels of cancer, " says

Meharg. Research in Taiwan has linked arsenic-contaminated rice to

an increase in bladder cancer, for example1.

 

Poison legacy

 

The survey team thinks that the contamination is a legacy of cotton

farming, which relies on arsenic-based chemicals to kill boll

weevils and to remove plants' leaves before harvest. Quite a lot of

land in Mississippi and Arkansas that previously grew cotton is now

used for rice cultivation, says Meharg.

 

Would you like your rice to be grown on arsenic contaminated soil?

 

Andrew Meharg

University of Aberdeen

 

 

 

When rice was first grown in these soils, the crop often failed

owing to an arsenic-induced disease known as straighthead. So new,

straighthead-resistant rice varieties were bred that could withstand

the arsenic.

 

However, this means that they are more likely to accumulate arsenic

in apparently healthy grains, says Meharg, who is now calling for

change in farming methods. " I don't think they should be growing

rice on old cotton fields, " he says.

 

Of the rice eaten in the United States, the vast majority is home-

grown. About half of all US-grown rice is exported.

 

Gram for gram

 

Meharg tested rice bought from markets in Aberdeen that had been

grown in America, Europe, India, and Bangladesh. He found an average

of 0.26 micrograms of arsenic in each gram of US rice. Indian rice

hit a low of 0.05 micrograms per gram, whereas Bangladesh, which has

had recurring problems with arsenic contamination owing to naturally

high levels of the poison in groundwater, and Europe had about 0.15

micrograms per gram. The results are published in Environmental

Science and Technology2.

 

John Duxbury, a soil chemist at Cornell University in Ithaca, New

York, points out that there are still many gaps to fill in before we

will know whether an overdose of US rice might be bad for you. " The

work is fine as far as it goes, but you can't draw broad conclusions

from such a limited survey, " he says.

 

Others point out that there is no epidemiological evidence that

anyone with a high rice diet, such as those of Asian descent, for

example, is experiencing ill effects. " There simply are no known

negative health issues with US rice, " David Coia, spokeman for the

USA Rice Federation in Washington DC.

 

All tied up

 

The rice may not be particularly toxic, because of the form that the

arsenic takes in the plants. Health effects are diminished if the

arsenic atoms are bound up with carbon-based molecules. Inorganic

arsenic (the form found in drinking water) is estimated by Duxbury

to be five to ten times more toxic.

 

Meharg found that just 42% of arsenic in US rice was inorganic,

compared with 81% of arsenic in Indian rice. But Meharg points out

that organic arsenic can still cause problems3, and could convert

into the inorganic form in the body4.

 

The health effects of arsenic in food are hard to verify because the

increase in cancer risk is small. Meharg estimates that if 10,000

people were exposed to the WHO limit over their lifetime, this would

result in an extra 92 cases of bladder cancer.

 

Given the uncertainties, regulations are few. Even the WHO has not

ratified its provisional guidelines. Australia is the only country

that has a safety limit for arsenic in food.

 

Under review

 

There are a few different types of arsenic pesticides and herbicides

licensed for use in the United States. All are undergoing safety

reviews at the moment, says Enesta Jones, a spokeswoman for the

Environmental Protection Agency, and decisions are planned for next

year.

 

Duxbury cautions that arsenic in US rice might come from natural,

geological sources. It may be that the arsenic in pesticides is in a

form that is harder for the plants to take up, he adds, which could

lower concerns about the chemicals themselves.

 

Although Duxbury doesn't share Meharg's health concerns, he says the

work serves as a good base from which to work out how crops can be

contaminated. This could help to breed plants that tend not to store

arsenic in an inorganic form, he suggests. " There's potential for a

lot of follow up from this. "

 

http://www.nature.com/news/2005/050801/full/050801-5.html

 

 

" God was my co-pilot, but we crashed in the Andes and I had to eat him. "