Common pesticide and veterinary drug residues in food and their toxicity

作者：admin  点击次数：17  发布时间：2025-04-11

1. Organophosphates Organophosphates are the most widely used insecticides at present, and the commonly used ones are trichlorfon, dichlorvos, dimethoate, malathion, etc. Some varieties can be used as fungicides (such as chlorpyrifos, isopyruvate, dichlorvos) or nematicides (such as chlorpyrifos, chlorpyrifos, fenamiphos). The chemical properties of this pesticide are relatively unstable and easy to degrade and lose their toxicity, so it is not easy to remain for a long time, and the accumulation in organisms is also low. Organophosphates are neurotoxic agents, which mainly inhibit the activity of cholinesterase in organisms. Some varieties have delayed neurotoxic effects. Chronic poisoning is mainly manifested by damage to the nervous system, blood system and vision. Most organophosphate pesticides have no obvious carcinogenic, teratogenic, or mutagenic effects.
2. Carbamates
This type of pesticide can be used as an insecticide (common varieties include carbaryl, aldicarb, chlorfenapyr, chlorfenapyr, methomyl, chlorfenapyr, etc.) or a herbicide (such as chlorfenapyr, chlorfenapyr, chlorfenapyr, chlorfenapyr, etc.), and some varieties (such as aldicarb and chlorfenapyr) also have nematicidal activity. The advantages of carbamate pesticides are fast efficacy, high selectivity, low toxicity to warm-blooded animals, fish and humans, easy to be decomposed by soil microorganisms, and not easy to accumulate in organisms. Its mechanism of action is similar to that of organophosphates, and it is also a cholinesterase inhibitor, but its inhibitory effect is highly reversible, and the activity of the enzyme can be restored to varying degrees after hydrolysis. Its acute poisoning is mainly manifested by symptoms of cholinergic nerve excitement. Studies have shown that this type of pesticide can generate nitrosamines with nitrite under weak acid conditions, which may have a certain carcinogenic effect.
3. Pyrethroids
This type of pesticide belongs to the high-efficiency and low-residue pesticides, which can be used as insecticides and pesticides. Products developed since the 1980s, such as cypermethrin (Deltamethrin, Kesolin), propylthrin, phenthrin, and cyhalothrin, have an effective use amount of even less than 10g/hm'. The degradation in the environment is mainly photolysis (isomerization, ester bond cleavage, dehalogenation, etc.), followed by hydrolysis and oxidation reactions. The disadvantage of pyrethroid pesticides is high resistance, that is, insects can develop resistance to them in a short period of time, which reduces their insecticidal activity or even completely loses it. The combined use of multiple pesticides can delay the occurrence of resistance.
Pyrethroid pesticides can be divided into two types according to their chemical structure and mechanism of action. [Type does not contain a base, such as allethrin (Bispermum), bifenthrin (Uranus), tetramethrin, ethathrin, permethrin, etc. Its mechanism of action is to cause repeated discharges, that is, the depolarization potential after the action potential increases, and a series of action potentials are triggered when the threshold is exceeded. Type II contains bases, such as cypermethrin (cypermethrin), cypermethrin (cypermethrin, anlubao), pyrethroids, pyrethroids (Baishude pyrethrin), trifluthrin, etc. Its mechanism of action is to cause conduction resistance, prolong the depolarization period, gradually depolarize the membrane without action potential, and block nerve conduction.
Pyrethroid pesticides are mostly moderately toxic or low toxic, and their LD is tens to hundreds of milligrams per kilogram of body weight, which has no inhibitory effect on cholinesterase. Acute poisoning is mostly caused by accidental ingestion or productive contact, mainly neurological symptoms, such as drooling, sweating, impaired consciousness, slurred speech, slow reaction, blurred vision, muscle tremors, dyspnea, etc. Severe cases can cause coma, convulsions, tachycardia, pupil constriction, loss of light reflex, incontinence, and death due to heart failure and dyspnea. Tranquilizers, central muscle relaxants and atropine can relieve symptoms.
Pyrethroid pesticides are irritating and sensitizing to the skin, and can cause paresthesia (numbness, itching) and delayed allergic reactions. Chronic poisoning is rare due to its accumulation and low residual amount.
4. Organochlorine
This is the most important insecticide used in the early days. It is very stable in the environment and not easy to degrade. For example, DDT disappears 95% of the time in the soil in 3 to 30 years (an average of 10 years). It is highly fat-soluble. Therefore, it mainly accumulates in adipose tissue in the body. Organochlorine is mostly low-toxic or moderately toxic. Acute poisoning is mainly manifested by damage to the nervous system, liver, and kidneys. Long-term low-dose intake of organochlorine pesticides in experimental animals can cause chronic poisoning, which is mainly manifested as liver lesions, blood and nervous system damage. Organochlorine can enter the fetus through the placental barrier, and some varieties and their metabolites have certain teratogenicity. Some organochlorine pesticides have certain carcinogenic effects in animal experiments. It is reported that a larger dose of DDT can significantly increase the incidence of liver cancer in animals such as mice and guinea pigs. Since the large-scale use of DDT in the 1940s, organochlorine pollution to the environment has continued to increase. Organochlorine can now be detected in the environment of almost any region in the world. Even in areas where it has never been used (such as the North and South Poles), organochlorine pollution can also be detected due to the carrying of air and water currents.
Since organochlorine pesticides are easy to accumulate in the environment for a long time and can be gradually concentrated through the food chain, they also have certain potential hazards and "three-cause" effects, so they have been stopped in many countries. my country stopped producing in 1983 and stopped using organochlorine pesticides such as 666 and DDT in 1984.
5. Fungicides
Organomercury fungicides, such as silicen (ethyl mercuric chloride) and silicen (phenylmercuric acetate), have been stopped in my country since 1972 because of their high toxicity and difficulty in degradation. Organoarsenic fungicides (such as arsenic, arsenic, and arsenic) can be converted into highly toxic A8+ in the body, causing poisoning. Ethylene bis dithiocarbamate fungicides (zinc, mancozeb, mancozeb, etc.) can be converted into carcinogen ethylene sulfide in the environment and in organisms. Benzamidazole fungicides (carbendazim, thiophanate-methyl, and thiophanate-methyl that can be converted into benzamidazole in plants, etc.) have good control effects on a variety of crop diseases such as wheat fusarium head blight, smut, rice sheath blight, rice blast, and sweet potato black spot. This type of pesticide can cause reproductive dysfunction in rats at high doses, and has certain carcinogenic and carcinogenic effects. 6. Herbicides Most herbicides have low toxicity to animals and humans, and because they are mostly used in the early growth of crops, the residues after harvest are usually very low, and their harm is relatively small. However, some varieties have different degrees of "three-hazard" effects, which should be given sufficient attention. 7. Toxicity of mixed pesticides
The reasonable use of two or more pesticides can improve their effects and delay the resistance of insects and weeds to them. Therefore, the production and use of mixed pesticides have increased in recent years. The mixing or compounding of multiple pesticides can sometimes increase their toxicity (including additive and synergistic effects).