A fishmonger prepares fish fillets for sale at the City Market in
Nairobi on June 22, 2015. PHOTO | SALATON NJAU | NATION MEDIA GROUP
By GATONYE GATHURA
Some of the fish consumed in Nairobi, Kiambu and Machakos
counties are contaminated with chemicals, including those known to cause
cancer, a research has shown.
While most of fish eaten in Nairobi
comes from Lake Victoria, a significant percentage of farmed tilapia in
neighbouring Kiambu and Machakos Counties is sold and consumed in the
city.
The fish is sold in restaurants, open markets, kiosks, roadside eateries and some at the famous Gikomba market in Nairobi.
An
investigation by researchers from the University of Nairobi tested 213
fish samples from 60 ponds in Kiambu and Machakos and found them to be
contaminated with banned agricultural chemicals.
The findings, published in February in the journal Cogent Environmental Science confirmed residues of DDT, Lindane, Heptachlor and Dieldrin, Endrin in almost all the samples.
Human
poisoning from Aldrin and Dieldrin is characterised by major body
convulsions. Heptachlor is highly toxic to humans and can be absorbed
through the skin, lungs and the food tract.
These chemicals are
banned in most countries and in Kenya by the Pest Control Products
Board. The study led by Dr Isaac Omwenga, showed Lindane and DDT as the
most prevalent in all the samples analysed.
“While the
contamination did not breach international health safety standards, it
is an extremely worrying trend,” Dr Laetitia W. Kanja of the University
of Nairobi and one of the study authors told the Nation.
More
samples from Kiambu were found to be contaminated compared to those
from Machakos, possibly because of the heavy use of agriculture
chemicals in central Kenya.
Kiambu was also found to have more
earth ponds which easily allow for leaching of the agricultural
chemicals into the fish farming environment.
Kiambu County
recently announced a Sh2.6 million fish-farming expansion programme with
Nairobi and locals as the principal markets. Experts say it is
important to factor in the health concerns.
“The issue of chemical
residues must first be addressed maybe through non-leaching ponds and
caveat on dangerous chemicals or both,” says Dr Kenneth Wameyo a
consulting veterinary surgeon in Nairobi.
DDT residue was found in
all tested fish body parts including muscle and liver with the highest
concentration found in the brains. The head usually reserved for those
with best fish eating skills is considered most nutritious.
“Our
evidence suggests recent use of DDT in the study area hence more strict
control measures against the use of this chemical need to be put in
place,” wrote Dr Omwenga and his team.
Last June, the World Health
Organisation (WHO) classified the chemical Lindane as carcinogenic to
humans and DDT as possibly carcinogenic. This week the WHO is meeting to
review the caveats against a number of harmful agricultural products
including Lindane.
DDT has been linked to a cancer which attacks the body’s immune system, testicular and liver.
A
check at the Pest Control Products Board shows Lindane to have been
banned for use as an insecticide in Kenya in 2011 and DDT in 1986 for
use in agriculture. But the board at the same time has registered
several agricultural products such as Acarin, Dicofol and Kelthane,
which contain DDT.
The use of DDT was, however, brought back in
2006 for malaria control through residual indoor spraying especially in
western Kenya. But recent studies show this strategy to have failed
hence putting the lives of Kenyans and the environment at risk.
A
recent Dispatch (Volume 21, Number 12—December 2015) by the US Centres
for Disease Control and Prevention in Nairobi, showed the malaria
mosquito to have developed high levels of resistance against DDT.
Separate studies in Western Kenya have found extensive soil poisoning by
various chemicals.
In January, Dr Elijah Ngumba of the University
of Jyvaskyla, Finland, published a landmark study showing the whole of
the Nairobi River basin to be extensively contaminated with residues
from HIV and Aids drugs.
Residues of three first line HIV and Aids
medicines were found in all rivers in Nairobi including at Athi River’s
Fourteen Falls, a popular fishing and recreation site.
Dr Ngumba
in the study published in Science of the Total Environment demonstrated
that the waters of Nairobi rivers had high concentration of the
antiretrovirals Lamivudine, Nevirapine and Zidovudine and other
antibiotics.
The chemicals, he said were not just affecting fish
in some of the rivers but the waters are also used to raise crops and
livestock whose products are consumed in the city and nearby counties.
A
policy brief by the Ministry of Agriculture estimates about 50,000 bags
of maize and 15,000 bags of beans are produced in Nairobi annually.
The ministry estimates that up to a quarter million chicken are reared within Nairobi and about 45,000 goats and sheep.
Environmentalist
Isaac Kalua, who also chairs the Kenya Water Towers Agency, says there
is inadequate waste water treatment systems for removing chemical
component before the water is returned for use into the environment.
Even
where waste water works exists, a recent Sino-Africa study indicates
they were never designed for the removal of pharmaceutical waste.
Dr
Omwenga and his team argue that, some of the chemicals found in the
fish though banned are bound to linger in the atmosphere for some time
hence remaining a matter of serious concern.
“But these are not
excuses for allowing people to consume chemicals no matter the level of
concentrations, the same fish are also eaten by birds and other life
forms which have a lower tolerance levels,” says Dr Kalua.
NMG
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