Use of chemical pesticides is often being considered as the cause of health hazards to human. Effects of pesticide may be short-term or long term depending upon the exposure which results into acute and chronic toxicity respectively. Risk of pesticide injury depends upon both toxicity and exposure and can be lowered down by avoiding such exposure. Pesticide contamination in food and drinking water is quite observed and thus, dietary risk assessment of any pesticide needs to be determined. For assessment of risk, processes have to be followed to determine permissible intake of the pesticide. By comparing this data with residual contribution of that particular pesticide, safety assessment can be judged. However, multi-residue exposure of pesticides needs to be determined critically in future.
Pesticides are indispensible input in modern agriculture. They may be synthesized in chemical laboratory as xenobiotics or can be derived from natural sources of plant or microbial origin. Bio control agents, useful tool in pest management, are also being categorically considered as bio-pesticide. Among these, chemical pesticides are of major concern as they have the potency to cause health hazard in human. They are applied in the field to control major pests of crops, leaving toxic residues in environment. Although, pesticides do benefit the crops; but they impose a serious threat to the ecosystem . The situation gets worsen when these compounds undergo bioaccumulation and enter into food chain. Majority of chemical pesticides are lipophilic in nature and hence, used to be absorbed in human fat.
Started from mixing and applying in the field to consumption of produce, in each step even in routine use, pesticide can cause poisoning. These can be carried away from the site of application through different agents like wind, water, animals etc., and deposited to the non-target area. There could be occupational exposure as found in case of applicator in field, household, greenhouses or worker in industry, sales houses etc. It is evident that who are involved in mixing, loading, transport and application of pesticide are at highest risk of pesticide injury . Apart from that, there are some occurrences of accidental spillage, leakage and faulty applications.
Pesticides can enter into human body in three ways:
a. Through mouth (oral administration),
b. By adsorption through skin or eyes (dermal adsorption) and
Human beings are mostly exposed to pesticides through contaminated food and drinking water. These phenomenons are mainly occurred through non-occupational exposure and leads to low dose-chronic (or semi-chronic) toxicity . However, occupational exposure often leads to acute toxicity which is considered to be more dangerous and found to be lethal at the same time. Symptoms of pesticide poisoning are often misleading. There are some common symptoms observed in case of pesticide poisoning such as nausea, headache, abdominal pain, vomiting tendency, fatigue, loss of appetite, blurred vision etc. But, these symptoms are often confused with general illness which needs medical attention.
Risk related to pesticide poisoning can be defined as the
extent of getting exposed to a pesticide with certain degree of
toxicity. These can be expressed as:
Risk = Toxicity X Exposure 
Avoidance of exposure can definitely lower down the level of
risk that associated with the use of potentially toxic pesticides.
Toxicity of any pesticide cannot be altered but risk can be
managed. Dietary risk assessment of any pesticide is a critical
study in which several processes are involved. Toxicological
tests involving animal laboratory animal are carried out to
calculate Acceptable Daily Intake (ADI) value of a particular
pesticide. At the same time, multi-locational field trials have to
be conducted to find out the residual fate of that pesticide at
recommended dose in a crop. From that experiment, Theoretical
Maximum Residue Contribution (TMRC) of that pesticide can
be determined by multiplying daily consumption of the harvest
product with amount of pesticide residue found . Moreover,
one has to calculate Maximum Permissible Intake (MPI) of that
pesticide for humans by multiplying ADI with average body
weight. Finally, TMRC value has to be compared with MPI value
and if found less than the later, the pesticide may be considered
as safe to consume.
Non-occupational low dose exposure of any pesticide causes
chronic diseases in humans and can be considered as silent
killer. But, almost every crop in its life span faces number of
applications of different pesticide which results into multiresidue
exposure of those pesticides to human being. Effect
of multi-residue exposure could be more dangerous if any
synergistic effects are being observed in causing toxicity effects.
Thus, studies have to be performed to evaluate the effects of
multi-residues of pesticides in human.