Pesticide residue is charactering as those traces of pesticides, toxic metabolites, degradation products and impurities which are not decomposed that left in organism, products, soil, water and atmosphere after the use of pesticides. There are several indices are used to predict pesticide residue intake. The Maximum Residue Limits (MRLs) is one of the indicators of residues level (express as mg/kg), which is recommended by the Codex Alimentarius Commission (CAC) to be the legally permitted in food commodities and animal feeds.
China is a large agricultural county and facing the most severe pesticide residue problems. According to the statistic in China, the most serious pesticide residues are the following three categories of pesticide. The first category is organochlorine pesticides, the DDT and BHC as representatives of this type of pesticide. It is hard to decompose because of the stable chemical properties. Before 1980s, countries around world had been restricted and prohibit the use of DDT and BHC. The second category is organophosphate pesticides include dichlorvos, fenitrothion, etc. Owing to the fact that they are easy to decomposed and has short half-life, resulting in a little bit accumulation of harmful substance in crops, animals and the human body, so that they are widely used. However, the organophosphate pesticides has become the most serious pollution of pesticides in food because of the increasingly range and quantity of usage. The third category is carbamate pesticides. Its mechanism of action is similar to the organic phosphorus pesticides.
The data from Ministry of Agriculture of the People’s Republic of China shows that 433 pesticides in over 13 categories of agricultural products had been set in 2016, containing 4140 MRLs. The National Bureau of Statistics data shows an increasing trend of pesticide use. However, China’s average pesticides utilization rate is only 36.6% in 2015. The excessive use of pesticides not only affects food safety, but also influences farmland ecological security through the runoff, leakage of contaminated soil and water.
According to the 2014 European Union Report on Pesticide Residues in Food, 97.1% of the 82,649 samples analysed in 2014 contained residues within the legally permitted levels or were free of residues or. Particularly, the exceedance rate of pesticide residue in infant foods (4.2%) is serious than organic food (1.2) and conventional food (3.0).
(Comparison of organic and conventional foods in different food groups. Sauce)
In EU, more than 500 pesticides in over 370 food products or groups are set MRLs. Effective control programme is essential to reduce pesticide residues. For instance in EU, Regulation (EC) No 396/2005 imposes on Member States the obligation to carry out controls to ensure that food placed on the market is compliant with the legal limits, involving both EU and national level: EU-coordinated control programme and National control programmes.
Pesticide Residue Hazards
Pesticide residues get into human body through the food chain transmission and enrichment, resulting in health hazards. The degree of harm can be divided into acute toxicity, chronic toxicity and special toxicity (carcinogenic, teratogenic and mutagenic). Consumption of vegetables and fruits with highly toxic pesticides, or death livestock and aquatic products contained poison pesticides could cause acute poisoning. Pesticide residues will be accumulated in human body gradually since contaminated foods intake, resulting in physiological function changes in human body and cause chronic poisoning. Some pesticides such as dichlorvos, trichlorfon and dimethoate have potential ‘carcinogenic, teratogenic and mutagenic’ effects. Highly harmful pesticides may have acute or chronic toxic effects and pose special hazards to children. They are widely used in many parts of the world, often resulting in health problems and death due to exposure to work and accidental or intentional poisoning. Pesticide residue in vegetables and fruits are the most severe situation in China. Over the past ten years, there are approximately 150 food poisoning accidents that are caused by pesticide residues in vegetables and other contaminated foods annually.
The invention and application of pesticides increased crop yields, but due to a large number of unreasonable and incorrect use of pesticide, residues affect both human health and environment.
1. Strengthen training process to farmers. In the vegetable production process, farmers play one of the most critical role. In the vegetable production process, farmers play one of the most critical roles. Therefore, enriching the pesticides using knowledge is essential to control pesticide residue from the beginning of production process. Through the technical training and knowledge propaganda process, guiding farmers to use pesticides in an effective and correct way. In other words, advocating farmers to use the appropriate low-cost non-toxic or low-toxicity pesticides. Furthermore, strictly implement the standards of pesticides use that are stipulated by laws, and resolutely put an end to the use the highly toxic pesticides in fruits and vegetables.
2. Adjusting the structure of pesticide products, and gradually phase out highly toxic residues. Government and markets should accelerate the substitution of highly toxic and highly toxic pesticides, making plans to replace the relevant species gradually. Strengthen the circulation and use of pesticides and other links to ensure that highly toxic and highly toxic pesticides shall not be used in vegetables, melons, tea and other crops. Relevant departments should undertake researches to vigorously promote efficient and non-toxic plant pesticides and biological control techniques to reduce the dependence of vegetable production on chemical pesticides. Taking actions to truly solve the problem from the source of pesticide poisoning and pesticide residues in vegetables.
3. Improving policy and legislation. FAO’s Integrated Production and Pest Management (IPPM) programme has developed and adapted major new tools in collaboration with the Oregon State University’s Integrated Plant Protection Center (OSU) recently. These tools can greatly assist pesticide monitoring in the environment and estimate the potential negative impacts of pesticides on key biodiversity indicators and human health. Increase the punishment of the abuse of pesticides can be a solution to control pesticide residue.
Despite the effective control of pesticide residues, especially in European counties, the accumulation and enrichment of pesticide residues in human body will cause chronic damage that cannot be ignored.