Human carcinogen by the oral route
New Delhi/ 25/9/2010: Amidst several crises faced by Commonwealth Games, the Municipal Corporation of Delhi (MCD) is spraying synthetic pyrethroids, potent lipophilic insecticides for mosquito control at the Commonwealth Games sites due to the dengue scare, unmindful of exposure due to inhalation
of ambient air that is also possible after these compounds have been used.
The use of these products can lead to both dermal and inhalation exposure. The fact is that pyrethroids are synthetic analogs and derivatives of the original pyrethrins and represent a diverse group of over 1,000 powerful insecticides. The synthetic pyrethroids are released to the environment due to their use as insecticides.
These compounds are biodegraded in soil and water and can also undergo hydrolysis under alkaline conditions. Since these compounds adsorb strongly to soils, they are not taken up substantially by the roots of vascular plants. These compounds bio-accumulate in aquatic organisms and are extremely toxic to fish.
An expert panel that studied the proposal of spraying synthetic pyrethroids gave its nod to use the particular chemical exclusively at the Commonwealth Games venues to control mosquito breeding. This panel erred in not examining non-toxic measures. For instance, an inch of rain water at the bottom of a cup left outdoors can produce 1 000 mosquitoes every week! Since mosquitoes breed in stagnant water that should have been dealt with.
MCD officials who say that it is safe to use pyrethroids in India as they are considered to be one of the least toxic insecticides to humans and are quickly deactivated by metabolic processes are misleading and have misguided Delhi's Health Minister to approve this proposal. MCD’s Health Department has been quoted as saying that mosquitoes will not breed for about three months after synthetic pyrethroids are sprayed on the walls.
It is being incorrectly argued that synthetic pyrethroids are relatively safe. The general population is primarily exposed to pyrethrins and pyrethroids from the ingestion of foods, particularly vegetables and fruits.
Almost all systemic effects are related to the action of pyrethrins and pyrethroids on the nervous system. Direct skin contact may cause temporary paresthesia (abnormal cutaneous sensations such as tingling, burning, stinging, numbness, and itching) that is limited to the area of contact.
Limited animal data indicate that transfer of pyrethroids across the placenta to the fetus may occur. Although pyrethroids have not been identified in human breast milk, very low levels of pyrethroids (<1% of an
orally administered dose) are excreted into milk of lactating animals. Some animal studies indicate that exposure to pyrethroids may result in other less overt signs of neurotoxicity, such as changes in startle and avoidance responses, altered levels of spontaneous motor activity, and changes inoperant conditioned responses.
As to possibility of Cancer, increased incidences of thyroid follicular cell tumors were reported in male and female rats administered pyrethrins (57.57% pyrethrum extract) in the diet for 2 years. The female rats also exhibited increased incidences of hepatocellular adenomas and combined adenomas and/or
carcinomas. In a review of this rat carcinogenicity study, a Cancer Assessment Review Committee for pyrethrins attributed the increased incidences of thyroid and liver tumors to pyrethrum treatment and classified pyrethrins as “likely to be a human carcinogen by the oral route.” Available data does indicate that pyrethrins may be a carcinogenic concern to humans.
Over the years, first the chemical extracts of pyrethrum, and then more recently, the specific synthetic chemical analogs have been produced. The six active insecticidal compounds of pyrethrum are called pyrethrins. The six individual pyrethrins are pyrethrin I, pyrethrin II, cinerin I, cinerin II, jasmolin I, and jasmolin II. Pyrethrum is the natural extract that occurs in the flowers of Chrysanthemum cinerariaefolium and Chrysanthemum cineum. Pyrethrum is recognized as possessing insecticidal properties of
their causing rapid paralysis of flying insects.
The spraying of synthetic pyrethroids must be stopped immediately and biological and other creative methods must be used for achieving the same end. The authorities should consider ways of warding off adult mosquitoes that did come to be by using many herbs that repel mosquitoes such as cedarwood, garlic, lemongrass, frankincense, cinnamon, geranium, eucalyptus, basil, rosemary, cloves, peppermint, lemon balm, onions, feverfew, thyme and marigold.
*For Details*: Gopal Krishna, ToxicsWatch Alliance, Mb: 9818089660, E-mail: firstname.lastname@example.org
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