farmers |
Nairobi — As food plants suffer more stress, they are producing more health-damaging chemicals, researchers find. As they struggle to
deal with more extreme weather, a range of food crops are generating
more of chemical compounds that can cause health problems for people and
livestock who eat them, scientists have warned.
A new report by the
United Nations Environment Programme (UNEP) says that crops such as
wheat and maize are generating more potential toxins as a reaction to
protect themselves from extreme weather.
But these chemical
compounds are harmful to people and animals if consumed for a prolonged
period of time, according to a report released during a United Nations
Environment Assembly meeting in Nairobi.
"Crops are
responding to drought conditions and increases in temperature just like
humans do when faced with a stressful situation," explained Jacqueline
McGlade, chief scientist and director of the Division of Early Warning
and Assessment at UNEP.
Under normal
conditions, for instance, plants convert nitrates they absorb into
nutritious amino acids and proteins. But prolonged drought slows or
prevents this conversion, leading to more potentially problematic
nitrate accumulating in the plant, the report said.
If people eat too
much nitrate in their diets, it can interfere with the ability of red
blood cells to transport oxygen in the body, the report said. Crops susceptible
to accumulating too much nitrate in times of stress include maize,
wheat, barley, soybeans, millet and sorghum, it said.
DROUGHT, THEN RAIN
Some
drought-stressed crops, when then exposed to sudden large amounts of
rain that lead to rapid growth, in turn accumulate hydrogen cyanide,
more commonly known as prussic acid, the report said.
Prussic acid - one
of the ingredients used in some types of chemical warfare - interferes
with oxygen flow in humans. Even short-term exposure can be debilitating
for people, McGlade said.
Plants such as cassava, flax, maize and sorghum are most vulnerable to dangerous prussic acid accumulation, the report said.
Cases of nitrate or
hydrogen cyanide poisoning in humans were reported in Kenya in 2013 and
in the Philippines in 2005, McGlade said. In Kenya, two children died
in coastal Kilifi after eating cassava that had raised levels of prussic
acid in it following extreme rainfall, according to local media
reports.
Aflatoxins, molds
that can affect plant crops and raise the risk of liver damage, cancer
and blindness, as well as stunting foetuses and infants, also are
spreading to more areas as a result of shifting weather patterns as a
result of climate change, scientists said.
McGlade said about
4.5 billion people in developing countries are exposed to aflatoxins
each year, though the amounts are largely unmonitored, and the numbers
are rising.
"We are just
beginning to recognise the magnitude of toxin- related issues
confronting farmers in developing countries of the tropics and
sub-tropics," the report noted.
"As warmer climate zones expand towards the poles, countries in more temperate regions are facing new threats," it added.
In 2004, Kenya
suffered severe outbreaks of aflatoxin poisoning, which affected more
than 300 people and killed more than 100 following a prolonged drought,
according to the International Livestock Research Institute.
EUROPE AT RISK
The UNEP report
said Europe will be at growing risk from aflatoxins in locally grown
crops if global temperatures rise by at least 2 degrees Celsius. The
world is currently on a path to a more than 3 degree Celsius temperature
rise, scientists believe.
An increase in
toxic compounds in crops is likely to impact heavily on the world's
health system, which are already struggling with the effects of food
insecurity, Dorota Jarosinska of the World Health Organization's
European Center for Environment and Health said in an interview with the
Thomson Reuters Foundation.
Alex Ezeh,
executive director of the African Population Health and Research Center,
said the increase in toxins in crops was a big concern.
"Toxic crops can
lead to neurological diseases among humans but the greatest challenge is
the incidence of cancer," he said in an interview.
The report proposes
a list of eight ideas farmers and agricultural experts can adopt to try
to limit damage from more crop toxins, such as mapping contamination
hotspots and building better evidence about what is happening now with
the toxins in their area.
Scientists also
suggest that developing crop varieties designed to cope with extreme
weather could help reduce the levels of toxic chemicals in food.
"Research centers
with the Consultative Group on International Agricultural Research are
developing seeds that are suitable in various regions that have been hit
by climate change," McGlade said.
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