toxicity - pesticides, herbicides and insecticides - Blackherbals.com

African Traditional Herbal Research ClinicVolume 8, Issue 6 NEWSLETTER July 2013FEATURED ARTICLESPesticide Issues in the Food ChainPesticide Action Network - UKWhat are pesticides?We use the term pesticide to cover a wide range ofchemicals used to control insect pests (insecticides), plantdiseases (fungicides), weeds (herbicides), rats(rodenticides) or other unwanted organisms.Pesticides are one of the few groups of man-madechemicals that are designed to kill and deliberatelyreleased into the environment. You can tell this from theirname -the ending -cide literally means ‘killer’.Several pesticides were originally developed as nervetoxins to be used as instruments of war. When peacecame, their manufacturers found a ready new market forthese products as pest control agents.The insecticide DDT is probably the best-knownpesticide. It was used in huge quantities for three decadesafter World War Two as a miracle cure for many insectpests in agricultural crops and against household andmosquito pests until the first signs began to appear that itcould have harmful effects on many other animals.Rachel Carson published her famous book.“Silent Spring” in 1962 drew public attention to the factthat DDT was harming birds and lead to declines in theirpopulation. DDT has been banned for 20 years in Britainbut because it breaks down so slowly and builds up in thefatty tissue of all animals, it has left a toxic legacy aroundthe globe- traces of it can be found in polar bears andseals in the Arctic thousands of miles from where itwas sprayed. Almost everyone on the planet has DDTin their body and it gets passed to babies in breast milk.However, many other pesticides are far more‘poisonous’ in immediate terms, what we term acutelytoxic, as opposed to chronic effects that may take yearsbefore they turn into noticeable symptoms.People often don't realise that many pesticides can alsocause harm to human beings. Insecticides in theorganophosphate and carbamate groups work bydisrupting the nervous system. Unfortunately, the wayour nervous system works is very similar to the way itworks in insects and so we are vulnerable to the sameharmful effects.Take the example of chlorpyrifos, an insecticide used ina wide range of crops and in certain UK householdantkiller products. Symptoms of chlorpyrifos poisoningin humans include headache, nausea, dizziness, muscletwitching, weakness, increased sweating and salivation.At very high exposure levels, the damage to thenervous system can lead to unconsciousness,convulsions, respiratory failure and death. Serious andfatal pesticide poisonings occur frequently indeveloping countries, especially among peasant farmersand farm workers who often handle these toxicchemicals without any form of protective clothing.Between 3-25 million people are estimated toexperience some form of acute poisoning each yearworldwide. In industrialised countries, farm workersmust use protective equipment and there are restrictionson how insecticides like chlorpyrifos are handled soserious poisoning cases are much less common. Evenso, chlorpyrifos is one of the major causes of pesticidepoisoning in the US.Long term and low dose effectsLow doses of nerve toxin pesticides can also have moresubtle, longer term effects such as drowsiness,Continued on page 5-4 - Traditional African Clinic – July 2013