US rice imports
'contain harmful levels of lead'
By Jason Palmer BBC science reporter,
New Orleans 10.4.2013
The researchers found the highest levels of lead in rice from
China and Taiwan
Analysis of
commercially available rice imported into the US has revealed it contains
levels of lead far higher than regulations suggest are safe.
Some samples exceeded
the "provisional total tolerable intake" (PTTI) set by the US Food
and Drug Administration (FDA) by a factor of 120. The report at the American
Chemical Society Meeting adds to the already well-known issue of arsenic in
rice. The FDA told the BBC it would review the research.
Lead is known to be
harmful to many organs and the central nervous system. It is a particular risk
for young children, who suffer significant developmental problems if exposed to
elevated lead levels. Because rice is grown in heavily irrigated conditions, it
is more susceptible than other staple crops to environmental pollutants in
irrigation water.
Recent studies have
highlighted the presence of arsenic in rice - prompting consumption advice from the UK's Food Standards Agency and more recently from the FDA.
However, other heavy
metals represent a risk as well.
Dr Tsanangurayi
Tongesayi of Monmouth University in New Jersey, US, and his team have tested a
number of imported brands of rice bought from local shops.
The US imports about
7% of its rice, and the team sampled packaged rice from Bhutan, Italy, China,
Taiwan, India, Israel, the Czech Republic and Thailand - which accounts for 65%
of US imports. The team measured the lead levels in each country-category and
calculated the lead intake on the basis of daily consumption. The results will
be published in the Journal of Environmental Science and Health (Part B). "When
we compared them, we realised that the daily exposure levels are much higher
than those PTTIs," said Dr Tongesayi.
"According to the
FDA, they have to be more than 10 times the PTTI levels (to cause a health
concern), and our values were two to 12 times higher than those 10 times,"
he told BBC News.
'Globalised
market'
"So we can only
conclude that they can potentially cause harmful effects."
That factor of 120 is
for Asian children, who are most susceptible by virtue of age and comparatively
high rice intake on average. For non-Asian adults the excesses above the PTTI
ranged from 20 to 40.
Rice from China and
Taiwan had the highest lead levels, but Dr Tongesayi stressed that all of the
samples significantly exceeded the PTTIs.
Dr Tongesayi has also
worked on quantifying arsenic contamination - and is in effect working his way
through the heavy metals one by one to determine their prevalence.
The problem, he said,
is the range of agricultural practices around the world. "If you look
through the scientific literature, especially on India and China, they irrigate
their crops with raw sewage effluent and untreated industrial effluent,"
he explained.
"Research has
been done in those countries, and concerns have been raised because of those
practices, but it's still ongoing." Dr Tongesayi also said that the
increasing practice of sending electronic waste to developing countries - and
the pollution it leads to - exacerbates the problem.
"With a
globalised food market, we eat food from every corner of the world, but
pollution conditions are… different from region to region, agricultural
practices are different from region to region, but we ignore that.
"Maybe we need
international regulations that will govern production and distribution of
food."
So far, such
international oversight exists informally in the form of the Codex
Alimentarius, a collection of food-safety standards first set out by the United
Nations.
FDA spokesman Noah
Bartolucci told BBC News that the "FDA plans to review the new research on
lead levels in imported rice released today".
"As part of an
ongoing and proactive effort to monitor and address contaminants in food traded
internationally, FDA chairs an international working group to review current
international standards for lead in selected commodities, including rice, and
to revise, if necessary, maximum lead levels under the… Codex
Alimentarius," he said.
