Pesticide Residue is the pesticide that is remaining in a product after a chemical is applied to a crop and is often quantified in terms of amount found through testing. Such residues could be anywhere around us, including the foods that we consume (vegetables, fruits, grains, milk, meat etc.), water, soil etc. Pesticide residues undergo at least two biological processes that are a cause for concern: of accumulation and magnification.
Bio-accumulation and Bio-magnification
Bio-accumulation is the phenomenon when an organism absorbs a toxin at a rate greater than that at which the substance is lost. For instance, when the half life period (the time that it takes to disintegrate or get destroyed by half) is very long, bio-accumulation poses a greater risk of chronic poisoning by that toxin. Those chemicals that are lipid-soluble (fat-soluble) also create bio-accumulation especially in women with more fat-tissue, for example.
Bio-magnification, on the other hand, is the increase in the concentration of a pesticide along the food chain (pesticides ending up in water bodies ending up in fish, eaten by birds, eaten further down by animals and then by humans etc.). The substances become concentrated in tissues or internal organs as they move up the chain. This phenomenon of buildup is usually connected with persistence, slow metabolisation and excretion often due to water insolubility etc.
While bio-accumulation occurs within an organism, bio-magnification occurs across trophic levels (food chain).
It is reported that Indians are exposed to very high levels of pesticide residues in numerous ways. Until the turn of the century, Government of India's own monitoring reports (All India Coordinated Research Project on Pesticide Residues or AICRPPR) indicated that 59% of food samples tested for were contaminated, with 20% of them being above "MRL" (Maximum Residue Limit).
1999 AICRPPR Report had the following findings for instance:
20% samples exceed MRLs (all commodities included)
Finds fruits, vegetables and milk to be highly contaminated
In states like UP and Kerala, more than 40% fruits and vegetable samples exceeded MRLs – finds monocrotophos, DDVP and Methyl Parathion as most prevalent – all 3 WHO class I pesticides
Finds 78% milk samples exceeding HCH MRL and 43.4% exceeding DDT MRL
2001 AICRPPR Report:
Again finds high contamination levels in fruits and vegetables – 61% contaminated – 11.7% failed MRLs
In milk, contamination still high – 15.2% failed HCH MRL and 7.7% failed DDT MRL.
Finds new pesticides like Endosulfan, chlorpyrifos and chlorthalonil in milk.
In 2003, Centre for Science & Environment's findings on pesticides in bottled water
in India, followed by another analysis on pesticides in soft drinks
shook the country. For only the fourth time in Indian history, a Joint Parliamentary Committee (JPC) was set up to look into Pesticide Residues in and Safety Standards for Soft Drinks, Fruit Juice and other beverages (http://parliamentofindia.nic.in/ls/jpc/jpc-prsfb.htm
) as the CSE findings rocked the nation. This is the very first time that a JPC was created to look at health and food safety of Indians.
What is interesting to note however is that in the recent past, the Government of India has been reporting that very little of our food is contaminated and that very few samples that are tested for, under the Ministry of Agriculture's scheme called "Monitoring of Pesticide Residues at National Level" (started in 2005-06, with 21 labs representing various ministries), are found to have pesticide residues above the MRLs fixed.
The main findings of this monitoring scheme for 2010-2011 are:
Out of a total of 15321 samples analysed, residues were detected in 1044 or 6.8% of samples; out of this, residues were detected above maximum residue limit in 188 or 1.2% of samples.
11.5% of the 5170 vegetable samples were contaminated, with 2.3% being above MRL; only 0.9% of 2062 fruit samples were found to fail MRLs.
None of the fish/other marine product samples or CTC tea or pulses samples or milk/meat/eggs/honey/soil samples were found to be contaminated.
These findings however do not reflect or resonate with the findings from various independent studies from around the country, including from various government/public sector institutions.