Pesticide residue is a general term for trace pesticide precursors, toxic metabolites, degradation products and impurities that remain in organisms, crops, soil, water bodies and atmosphere after a period of pesticide use.
Some pesticides applied to crops are attached to crops, some are scattered in soil, air and water, and some pesticides remaining in the environment will be absorbed by plants. Pesticide residues directly reach people and animals through plant fruits, water and atmosphere, or are finally transmitted to people and animals through the environment and food chain.
Types of pesticide residues
1. Insecticide and acaricide
1) organophosphorus pesticides can inhibit cholinesterase in many animals and insects, thus affecting the hydrolysis of esters. This pesticide is used in a large amount and in a wide range. Common organophosphorus pesticides are: trichlorfon, dichlorvos, monocrotophos, phoxim, mianan, parathion, methyl parathion, butachlor, fenthion, diazine, phoxim, isocarbophos, vegetable phosphorus, methamidophos, phoxim, dimethoate, phorate and malathion.
2) Pyrethroids were widely used because a number of varieties with high efficiency, low toxicity and wide insecticidal spectrum appeared in the 1970s. At present, these pesticides have been widely used in China, such as fenvalerate, cypermethrin, deltamethrin, cypermethrin, cypermethrin and so on.
3) Carbamate pesticides have been widely used in China since HCH was banned. The toxicity of these pesticides has the following characteristics: first, most varieties have good quick effect, short residue period and strong selectivity; Second, most species have low toxicity to higher animals. Commonly used carbamate pesticides are cicada powder, lacquer tree, aldicarb, fenobucarb, carbofuran, pirimicarb and so on.
4) Nereistoxin-like Nereistoxin is a natural toxic substance with insecticidal activity in Nereis. Since its chemical structure was determined in the early 1960s, this toxin and many derivatives have been synthesized. After a series of experiments, people have developed a kind of nereistoxin insecticide with special insecticidal effect. The characteristic of this kind of pesticide is that it can effectively control a variety of pests. The commonly used varieties are: dimehypo, dimehypo, dimehypo and so on.
5) Commonly used organochlorine pesticides are bhc, ddt, triclosan, heptachlor, aldrin, etc. Among them, organochlorine pesticides HCH and DDT have played an important role in plant protection and health and epidemic prevention since they were used in the 1940s. After discovering that they had high residue and pollution problems in the 1960s, some countries restricted and banned them in the 1970s.
6) The main acaricides are chlordimeform, dicofol, propyl bromide and diflubenzuron.
2. Fungicides
Commonly used varieties are: carbendazim, metalaxyl, triadimefon, tricyclazole, prochloraz, sterile Dan, clonidine, dicyandiamide, herbicide, dipyridamole, trichlorfon, thiophanate-methyl, thiophanate-methyl, chlorothalonil, pentachloronitrobenzene and hexachlorobenzene.
3. Herbicide
Herbicides are widely used, and the main varieties are chlorotoluron, monuron, diuron, diuron, thiabendazole, herbicide, yemaiwei, beet, alachlor, butachlor, methyl chloride, herbicide diethyl ether, sodium pentachlorophenol and so on.
Harm of pesticide residues
The harm of pesticide residues is mainly the harm of pesticide residues to human body, to market economy and to crops.
First, the harm of human pesticide residues:
1, which is easy to cause obesity. When the liver can't detoxify toxic substances, it is wrapped in fat to form cellulite, which is why some people feel sick after losing weight, because the pesticides in it re-enter the human body after losing weight.
2, easy to cause cancer. It is easy to induce body mutation and increase the possibility of cell mutation, thus causing cell malformation and inducing cancer.
3, interfere with endocrine. The molecules of some pesticides are very similar to human estrogen, which makes the hormone balance of human body out of balance. These things will affect our behavior, affect the development of children's brains and organs, and lead to cancer.
4, it will make the human digestive function disorder. Long-term consumption of food with pesticide residues will interfere with the function of our digestive system, mainly manifested as abdominal pain, diarrhea and dry stool. Therefore, we must be careful when eating food.
5, affect the immune system and hematopoietic system. Long-term consumption of food with pesticide residues will easily lead to cancer, gonorrhea and immune system disorder, and will also affect our immune system and hematopoietic system.
6, easy to lead to fetal visceral hypoplasia or deformity. Toxic substances in pesticide residues will be absorbed by the fetus through the placenta or breast milk of pregnant women, resulting in hypoplasia or deformity of some internal organs of the fetus. Some children with birth defects are poisoned in the uterus, which is the reason for the increase of childhood diseases. Be careful when feeding children.
Second, the harm of pesticide residues in crops:
The unreasonable use of pesticides, especially herbicides, leads to frequent injury accidents, which often leads to large-scale production reduction or even complete production, seriously affecting agricultural production. Residual long-acting herbicides in soil is one of the important reasons.
Third, the harm of market economy:
All countries in the world, especially the developed countries, attach great importance to the problem of pesticide residues, and set more and more strict limit standards for pesticide residues in various agricultural and sideline products. Many countries regard pesticide residue limit as a technical barrier to restrict the import of agricultural and sideline products and protect agricultural production. In 2000, the residue limit of fenvalerate in tea was reduced from 10mg/kg to 0. 1mg/kg, which made China's tea export face severe challenges.
Main detection methods of pesticide residues
Biochemical detection method: the biochemical reaction of a biochemical substance extracted from an organism is used to judge whether there are pesticide residues and pesticide pollution. The sample does not need to be purified during the determination, or the purification is relatively simple and the detection speed is fast. Among biochemical detection methods, enzyme inhibition method and enzyme-linked immunosorbent assay are the most widely used.
Related instruments: csy-n 12 portable pesticide residue detector csy-n8/csy-n 16 pesticide residue detector (enzyme inhibition method) csy-n48/csy-96 pesticide residue detector (enzyme-linked immunosorbent assay).
Rapid chromatographic detection method: by simplifying the sample purification steps as much as possible, the organophosphorus pesticide residues in vegetables and fruits can be directly extracted and analyzed. In the specific application, the above rapid detection methods can choose to use related instruments according to the actual situation, and their respective application scope, advantages and disadvantages: csy-ng spectrum pesticide residue detector.