Pesticides are Poisons, meant mainly to kill living organisms of different kinds (organophosphate pesticides, for instance, have been originally developed as nerve poisons during World War II).
Synthetic pesticides do have several health impacts which can be broadly classified as Acute (immediate/short-term) and Chronic (long-term). These effects have been explained some more below. It should be remembered that for various reasons, women and children are particularly vulnerable (skin being more permeable, internal organs not fully developed in children, more exposure due to vulnerable behaviour in children, more fat tissue in women, excretory system being less efficient etc.) to toxins like pesticides.
Further, it is reported that malnutrition and dehydration increase the sensitivity to pesticides. It needs no reiteration that India has alarming levels of malnutrition!
(UNEP document on Childhood Pesticides Poisoning, 2004 can be downloaded here
This is the adverse health effect seen of the pesticide due to exposure to the toxic substance in a short span of time, with the effects/symptoms showing up immediately or within a couple of weeks of exposure. Signs and symptoms of systemic poisoning include headaches, dizziness, nausea, vomiting, cramping, breathing difficulties and blurred vision. If the poisoning is severe and proper treatment is not available, death can occur.
There is a widely accepted classification given by World Health Organisation since 1975, based on the acute toxicity level of various pesticides, based on experiments with rats for the purposes of this classification (here, the less it takes to kill, the more toxic in this classification).
Class Ia Extremely Hazardous (red triangle)
Class Ib Highly Hazardous (yellow triangle)
Class II Moderately Hazardous (blue triangle)
Class III Slightly Hazardous (green triangle)
O Hazard unlikely if used safely
Pesticide consumption and subsequent death due to acute poisoning is recorded as a major method of committing suicide, especially of farmers around the country. However, accidental inhalation related to occupational exposure to pesticide is also a major cause for acute poisoning and subsequent illnesses and even death. Agri-chemicals pose the greatest occupational hazard in the field of agriculture and annually, millions of agricultural workers are estimated to be poisoned by pesticides across the globe.
Chronic effects of pesticides are those harmful effects that occur from repeated exposure to small doses of pesticides over a period of time. Some of the chronic poisoning effects from pesticides include birth defects, cancers, blood disorders, neurological problems, reproductive health effects, immune system impairment, effect on growth and development etc.
Pesticides can be classified into different categories depending on their chronic impacts as mutagenic (causing alterations in genetic material which in the next generations can cause irreversible abnormalities), terato-genic (causing physical defects in fetus which leads to congenital or birth defects), neuro-toxic (alters the normal activity of the nervous system), endocrine-disrupting (chemicals that can lead to sexual abnormalities and reproductive failures by interfering with the body's hormones secreted by endocrine glands, also called as hormone disruptors), immuno-toxins or immuno-suppressants (pesticides that affect the body's natural defence responses to invading agents/organisms – this might increase the common disease burden in turn), carcinogenic (cancer-inducing, for instance pesticide exposure having a positive association with leukemia), allergic and so on.
Many chronic effects have been shown to be correlated to/associated with particular pesticides in various scientific studies, whether they are lab-based experiments or epidemiological in nature.
(A review of health impacts of pesticides by Ontario College of Family Physicians, Canada (2004) can be accessed here
It is worth noting that chemical pesticide registration does not depend on testing for all the above potential chronic impacts and does not depend on independent and long term testing before each chemical is allowed to be used (even if done, this does not incorporate possibilities of a cocktail situation of use and exposure!).
It is often argued that the health impacts of chemical pesticides will depend on:
the type of pesticide,
the amount of pesticide you were exposed to (how much),
the concentration/strength (how strong/dose),
the length of exposure (how long/time),
"route of entry" into the body or exposure route (skin, ingestion, or inhalation),
other carriers or chemicals in the pesticide product, and
an individual's predisposition...
However, while it is made to sound as though all the above factors are controllable and can be individually delineated, what we have in reality is an unimaginable cocktail situation of contaminants all around us, in our water, food, soil and air. It is obvious that no scientific testing can ever be comprehensively taken up for all the permutations and combinations of exposures possible in this cocktail situation and the synergistic effects that get produced thereby. SO, SUFFICE IT TO SAY AGAIN THAT PESTICIDES ARE POISONS. MORE AND MORE, THESE ARE POISONS OUT OF OUR CONTROL.