Pesticides mainly refer to drugs used to prevent diseases, bacteria, insects, rats, weeds, etc., which are harmful to the growth of crops and stored in agricultural products. They also include chemical substances such as plant growth regulators, defoliants, and synergists.

One, the main cause

Pesticides may have different classification methods. For example, they may be classified into systemic agents, contact poisons, stomach agents, fumigants, infertility agents, antifeedants, decoys, preservatives, etc., depending on the mode of action; Inorganics, organic mercury, organic tin, organic chlorine, organic arsenic, organic phosphorus, organic sulfur, organic fluorine, organic nitrogen, halogenated hydrocarbons, nitro compounds, phenols, quinones, organic acids, urea and thioureas , esters, indanones, azaheterocycles, etc.; according to the use can be divided into insecticides, acaricides, fungicides, herbicides, rodenticides, plant growth regulators, sterile agents, Defoliants, synergists, repellents, etc. The main cause of acute pesticide poisoning is insecticides, common species are organic phosphorus, carbamates, pyrethroids, organochlorines, insecticides, etc. Followed by fungicides ( common species such as organic mercury, organic tin, etc. ) , rodenticides ( such as organic fluorine, indandione, etc. ) and individual herbicides ( such as paraquat ) .

Second, toxic effects

Pesticides have very different chemical structures, so the toxicity is not the same, but many pesticides, especially organic compounds, can have the following common toxicity characteristics.

(1) Neurotoxicity Most organic compound pesticides, due to their strong lipid-soluble properties, often have varying degrees of neurotoxicity, and some are the main mechanisms by which they exert insecticidal effects. The most toxic organic tin, organic mercury, organic chlorine, organic fluorine, organic phosphorus, halogenated hydrocarbons, carbamate, etc., can often cause toxic encephalopathy, brain edema, peripheral neuropathy, etc., clinically visible headache, nausea, Vomiting, convulsions, coma, muscle tremor, sensory disturbance or paresthesia, spasticity, etc., and some can still cause central hyperthermia, such as 666, Dieldrin, aldrin, toxaphene and other organochlorines.

(2) Skin and mucous membrane irritations Almost all kinds of pesticides are irritant, organic sulfur, organic chlorine, organic phosphorus, organic mercury, organic tin, carbamate, insecticide, phenols, halogenated hydrocarbons, The strongest effects of herbicidal ether and paraquat can cause rashes, acne, blisters, burns, and ulcers.

(3) Cardiotoxicity Many poisons can cause myocardial damage, resulting in ST and T wave abnormalities, conduction disturbances, arrhythmia, even cardiogenic shock, sudden death, especially organic chlorine, organic mercury, organic phosphorus, organic fluorine, insecticide Phosphine etc. are the most prominent.

(4) Digestive system toxicity Oral administration of various pesticides can cause significant chemical gastroenteritis and cause nausea, vomiting, abdominal pain, diarrhea; some such as arsenic, paraquat, propylene oxide, 401 , 402, etc., may even cause Corrosive gastroenteritis, with vomiting blood, blood in the stool and other performance; also some pesticides such as organic chlorine, organic mercury, organic arsenic, organic sulfur, carbamates, halogenated hydrocarbons, propylene oxide, 2 , 4- drop, kill Insect pairs, paraquat, etc. have strong liver toxicity and can cause abnormal liver function and hepatomegaly. Some pesticides also have unique toxicities, such as

1 hematological toxicity: such as insecticidal fleas, azadirachtin, formyl hydrazine, propanil, herbicidal ether can cause significant methemoglobinemia, and even lead to hemolysis; zein can cause sulfidation hemoglobinemia, can also cause hemolysis Indole diketones can cause clotting disorders and can cause severe systemic bleeding;

2 Lung toxicity: chloropicrin, phosphine, thiram, chlorpheniramine, dipyridamole, organophosphorus, carbamate, pyrethroids, halogenated hydrocarbons, paraquat, etc. are strongly irritating to the lung and can cause severe Chemical pneumonia, pulmonary edema, the latter can also cause acute pulmonary interstitial fibrosis;

3 kidney toxicity: the aforementioned can cause acute intravascular hemolysis of pesticides, can be blocked due to hemoglobin tubular tubular, causing acute tubular necrosis and even acute renal failure. In addition, organic phosphorus, organic sulfur, organic mercury, organic chlorine, organic arsenic, dimehypo, safety, propylene oxide, halogenated hydrocarbons, etc. have direct toxicity to the renal tubules and can cause acute tubular necrosis or even acute renal failure. Insecticides can also cause hemorrhagic cystitis;

4 Others: Dinitrophenol, dinitrocresol, lecimaroxime, dichlorprecine, etc. can lead to the uncoupling of oxidative phosphorylation in the body, so that the energy generated in the oxidation process cannot be stored in the form of ATP and converted into heat energy. High fever, convulsions, and coma can occur.

Third, the clinical manifestations

Due to limited space, this section only selects the most common pesticide species for a brief introduction.

1. Organophosphorus

As the most widely used pesticides in China, they can be divided into four categories based on their toxicity.

Highly toxic, such as Trump, phorate (3911), disulfoton, phosphorus Jun (Mevinphos), parathion (1605), demeton (1059), fonofos (large thunder), azinphos-methyl (azinphos-methyl), sulfotepp (3911 sulfoxide), schradan, cotton An phosphorus (phosfolan), azinphos benefits, aphids off the net and the like;

Highly toxic, such as dichlorvos, monocrotophos, ethion (dead aphids full Li, 1240), parathion benzene (Yi Boen, EPN), parathion-methyl (meth 1605), demeton-methyl ( Methyl 1059 , 4044) , Methamidophos, Omethoate, Trithiophos, etc.;

Poisoning categories, such as dimethoate, mahogany, fluvalicarb, fenthion ( baizhitu ) , gengsan, safrole, synergic phosphorus, pilus phosphorus ( Iraqi 57, etc. ) ; 4 low toxicity , such as insecticide fear, housefly phosphorus, chlorenone pine, bromophos and other.

The incubation period of acute poisoning is closely related to the route of intrusion, dose, type of pesticide, and personal status. Generally speaking, the incubation period for oral administration is the shortest, and within a few tens of minutes of onset, fasting or high dose, minutes to ten minutes can be achieved. Incidence; inhalation of the vapor usually occurs in about 30 minutes; skin absorption occurs after 2 hours. The main clinical symptoms are 4 groups, namely:

Muscarinic symptoms are mainly caused by excitatory fibers after the parasympathetic ganglion, and a few sympathetic postganglionic fibers ( such as sweat glands ) are also excited, so there are smooth muscle excitement, glandular hyperactivity and other manifestations, such as nausea, vomiting, abdominal pain, Diarrhea, runny nose, runny nose, tearing, increased trachea secretion, dyspnea, excessive sweating, miosis, and even pulmonary edema and respiratory failure.

Nicotine-like symptoms, mainly caused by motor nerves, sympathetic preganglionic fibers, adrenal medulla excitement, manifested as muscle tremors, severe systemic ankylosing sputum, followed by muscle spasm, respiratory muscle paralysis, can cause respiratory failure, in addition , It can also be seen pale, high blood pressure, rapid heartbeat, heart failure, etc.;

Central nervous system symptoms, mainly caused by the excitation of synapses between central nervous cells, manifested as headache, dizziness, fatigue, irritability, cramps, convulsions, coma, respiratory failure, and even death;

Others, such as toxic myocardial damage, have been found to have a high incidence in recent years and often cause ST-T wave changes, conduction block, arrhythmia or even heart failure, sudden death, such as dimethoate; some types of organophosphorus pesticides such as dimethoate, omethoate, fenthion, monocrotophos, methamidophos, dichlorvos syndrome can cause intermediate (intermediate syndrome, IMS), mainly for about 2 to 4 days after intoxication, the symptoms disappeared after the sudden occurrence Limb proximal muscle weakness, severe death due to respiratory muscle paralysis; some organophosphorus pesticides can induce delayed neuropathy ( delayed neuropathy ) 1 to 2 weeks after poisoning , manifested as distal limb sensory disorders, muscle weakness, lower extremities even worse, severe muscle atrophy occurs, it is difficult to recover. Whole blood cholinesterase (AchE) assay is a specific diagnostic indicator of organophosphorus poisoning, and its activity decreased by more than 70 % can cause symptoms of poisoning. AchE activity in severely poisoned patients is still less than 30 % of normal people . Blood originals, urine metabolites ( such as increased urinary trichloroethanol; parathion, chlorprophos, isophos-phorphine, ipene poisoning, urine can be measured in the nitrophenol, etc. ) measurement also prompts significance. Lymphocytes or platelets neural target esterase (neurotarget esterase, NTE) activity assay is helpful in the diagnosis of delayed neuropathy.

2. Carbamates

Carbamates is second only organophosphorus pesticide most widely used, the common varieties such as for insecticide carbofuran, carbaryl, aldicarb, metolcarb, isoprocarb (Isoprocarb), enemy Fly wei, chlorpromone, dimethylcarbamate, chlorfenone, hexanone oxime, etc.; for herbicides such as Chloropicin, Huangcao Ning, Oatmeal, Oats, Da Zhuang ( grass-killed ) , Beet Ning, Aniline, chrysanthemum, benzalkonium chloride, etc.; used for sterilization are benomyl, carbendazim and so on.

This product enters the body mainly through the digestive tract and respiratory tract, the metabolism is very fast, 24 hours can discharge intake of 70 % to 80% , mainly through the urine. Its toxicity mechanism is similar to that of organic phosphorus, and it can inhibit the function of acetylcholinesterase. However, since it can be rapidly hydrolyzed, the activity of AchE recovers quickly. Oral ones often develop in 10 to 30 minutes, and those who inhale their vapors usually develop in 2 to 3 hours. Symptoms are similar to organophosphorus poisoning. Unless they are taken orally to cause death, they generally recover more quickly.

3. Pyrethroids

This is a kind of simulated natural pyrethrins chemical structure of synthetic pesticides, is the late 1970s developed efficient, broad-spectrum, low toxicity pesticides, our country was introduced in the 1980s, prototype, but has become a widely used third Pesticides. Common varieties of permethrin (fine insecticides, Section permethrin), cypermethrin (Po Hing Cotton, Ann Bao Lu, can eliminate one hundred), pentyl cyhalothrin (fenvalerate, sumicidin) , fluvalinate ( Malprox ) , cyhalothrin ( decubilin, mefluthrin, fluvalinate ) , allethrin, cyfluthrin ( permanthrin ), and the like.

This product can be absorbed through the respiratory tract, digestive tract, and skin. Metabolism is very rapid in the body and is mainly excreted through the urine. This product has a strong neurotoxicity, can cause toxic encephalopathy, peripheral nerve dysfunction, and skin and mucous membranes and respiratory irritation. Skin contact may cause local itching, burning sensation, acupuncture sensation, erythema, herpes, etc. The incubation period is only tens of minutes; field spray application is the most common cause of such pesticide poisoning, and the incubation period for systemic poisoning symptoms is 2 ~ 12 hours, the shortest in the tens of minutes, the main manifestations of dizziness, headache, nausea, loss of appetite, fatigue, apathy, salivation and facial burning sensation is very obvious, severe cases of limb muscle tremors, bursts Sexual convulsions or cramps, miosis, pulmonary edema, dyspnea, palpitations, purpura, and coma may be due to respiratory and circulatory failure. Severe cases are more common in oral poisoning. At this time, the gastrointestinal symptoms are also very prominent. It has been reported that 25 ml of pyrethroids can cause obvious poisoning symptoms.

The diagnosis of poisoning is mainly based on the reliable history of toxic exposure and typical clinical manifestations. The timely determination of the blood and urinary toxicants helps confirm the poisoning.

4. Kill insects

This product is also known as chlorophenyl hydrazine, kill fleas, is a type of oxime ( organic nitrogen ) insecticide acaricide. Because of its high efficiency, broad spectrum, low toxicity, and effective against insecticide-resistant pests, it began to rise to No. 4 soon after it was put into use in China in the 1970s . Later, it was discovered that it has strong toxicity and potential carcinogenic effects on the human body. In 1992 , the country had explicitly banned the production and use of insecticidal lice, but poisoning incidents still occur. This product can be absorbed through the digestive tract, respiratory tract and skin, but productive poisoning is mainly caused by skin contamination. Chlordimeform metabolized in vivo, are discharged very fast, small accumulation, 3 days after the first intake of about 90% can be discharged, mainly excreted in the urine; its main metabolite of chlordimeform demethylation, N- methyl Acyl - p-chloro-o-toluidine, 4- chloro-o-toluidine, and the like.

The main links of poisoning are disturbance of consciousness, hyperferritinemia and hemorrhagic cystitis. Myocardium, liver and kidney also have varying degrees of damage. The incubation period for productive poisoning is about 2 to 6 hours, and the incubation period for oral administration is about tens of minutes. Mainly manifested as dizziness, headache, fatigue, apathy, nausea, anorexia, numbness of the extremities and significant sleepiness, severe cases can occur coma, incontinence, or even respiratory and circulatory failure; at the same time, there are obvious symptoms of cyanosis and hypoxia, and Dose is significantly related; 12 to 48 hours after poisoning , there will be urinary urgency, frequent urination, dysuria, hematuria and other symptoms of hemorrhagic cystitis; heavier patients often have fever, ECG ST-T wave abnormalities, conduction block, arrhythmia , Liver function and abnormal kidney function. The timely determination of the blood and urine protozoa or the determination of metabolites in the urine has important implications for poisoning; determination of methemoglobin in blood can be used as an important reference indicator.

5. Organic fluorine

The common species are sodium fluoroacetate and fluoroacetamide, and the toxicity is very strong.

(1) Sodium fluoroacetate is a highly effective rodenticide that enters the body and binds to coenzyme A to form fluoroacetyl coenzyme A , which in turn synthesizes oxalic acid with oxaloacetate. This reaction is called "lethal synthesis" because The produced fluoro-citric acid can obviously inhibit aconitase, so that citric acid can not be further oxidized, the cycle of three carboxylic acid is interrupted, energy (ATP) is generated, and direct stimulation of a large amount of accumulated citric acid is carried out, thereby enabling the functions of vital organs in the body. Serious obstacles, especially brain and heart muscle damage. Poisoning is mainly caused by oral administration, incubation period is only tens of minutes, common symptoms are nausea, vomiting, salivation, abdominal pain, may have bloody vomitus, and then appear central nervous system and cardiovascular system symptoms such as headache, dizziness, mental paralysis, fear, Facial numbness, unclear vision, muscle tremor, muscle spasm pain, heart palpitations, etc., electrocardiogram examination often have tachycardia, conduction block, atrial fibrillation; severe epileptic seizures, coma, brain edema, pulmonary edema Even respiratory arrest, death. This product has been banned due to its high toxicity. Blood fluoride, increased urinary fluoride, and increased blood citric acid have important implications for diagnosis.

(2) Fluoroacetamide has the same toxicity as sodium fluoroacetate, and it is not currently used for killing rats, but is mainly used for killing insects. This product is not volatile, insoluble in lipids, it is not easy to invade the respiratory tract and skin, poisoning due to misuse or consumption of this product is poisoned dead livestock and poultry, the incubation period is mostly tens of minutes. The toxic symptoms are similar to sodium fluoroacetate. Blood fluoride, urine fluoride, and increased blood citrate have important implications for diagnosis.

6. Paraquat

Mainly used as herbicides, because this product is not volatile, so the main cause of productive poisoning due to skin contamination, misuse is also a common clinical cause of poisoning. Skin contact can cause local burning itching, redness, blisters, ulceration or necrosis, __ This eye also stimulate injury. Symptoms of poisoning are mainly respiratory symptoms such as cough, chest pain, chest tightness, shortness of breath, and purpura on the basis of headache, dizziness, weakness, irritability, etc., may be due to pulmonary edema, early fibrosis of the lungs, respiratory failure, and severe cases. Mental disorders, convulsions, and severe manifestations of myocardial, liver, and kidney damage can occur. Severe patients are mainly seen in oral patients, 3g Can cause death; oral can cause chemical burns of the mouth, esophagus and stomach and severe nausea, vomiting, abdominal pain, diarrhea, hematochezia, vomiting, etc., and combined with abnormal liver function, hepatomegaly tenderness, proteinuria, hematuria and even acute kidney Failure, cardiac arrest, pulmonary edema, early pulmonary fibrosis, and respiratory failure. The mechanism may be related to the production of a large number of oxygen free radicals in the body and the induction of a strong lipid peroxidation reaction.

7. Anticoagulant rodenticides

Common varieties of warfarin (also known Warfarinanion rodent Ling, chemical name is 3-acetonyl-benzyl-4-hydroxycoumarin-generation), diphacinone (chemical name 2-formyl-phenyl - 1 , 3- indanedione ) . The former mainly inhibit formation of prothrombin, and may damage the capillary, which in addition to prothrombin generate impact, but can still competitive inhibition of vitamin K activity, and inhibiting blood coagulation factor â…¡, â…¤, â…¦, â…¨, â…© etc. synthesis.

Poisoning is mainly caused by misuse, mainly nausea, vomiting, abdominal pain, dizziness, fatigue and other symptoms; 2 to 3 days after the occurrence of epistaxis, bleeding gums, vomiting blood, blood in the stool, hematuria, hemoptysis, vaginal bleeding, purpura and other bleeding performance, serious There may be liver and kidney damage. Tests showed that prolonged clotting time and prothrombin time, and severe bleeding time also prolonged.

Fourth, treatment

1. The principle of treatment

The principle of group poisoning can refer to the irritant gas poisoning section. Generally speaking, there are more oral routes in pesticide poisoning cases. Therefore, gastric lavage, vomiting, catharsis and other devices should be well prepared. If they come to the hospital immediately after oral administration, they should be treated with tongue squeezing and root canal syrup (30ml , children minus). Half ) Oral, or subcutaneous injection of apomorphine (5mg) to induce vomiting; for a slight delay, gastric lavage should be used, commonly used gastric lavage fluid is 1/5000 potassium permanganate ( without organophosphorus pesticides ) , 4 % sodium bicarbonate , saline or water, gastric lavage needs to be sufficient, and then poured into activated carbon 30g And sodium sulfate 30g , to adsorb residual poisons and vent. After the above-mentioned treatment, non-specific detoxification treatment such as glucose, VitC , liver tyrol, mannitol, furosemide can be given ; glucocorticoid is an essential drug for chemical poisoning, and should be used in an early and sufficient amount, and the first daily dose should not be less than 60 mg ( Dexamethasone ) ; patients with poor performance in circulatory function can be treated with naloxone early; patients with severe disease can be treated with blood perfusion or hemodialysis early; in addition, calcium channel blockers can be administered early, Oxygen radical scavengers to early block malignant lesions.

Generally speaking, some pesticides need to be treated with a special antidote to be effective, and early and timely administration has a significant impact on the prognosis of the disease, especially organic phosphorus. Therefore, for pesticide poisoning, blood AchE should be measured first. Activity, in order to simply divide the cause into two categories:

Those with decreased AchE activity are mainly caused by organophosphorus and carbamates . The identification of the two can be seen in Table 6.5-1 . After clarifying, specific therapeutic drugs can be immediately administered.

2 If the specific antidote for AchE activity does not change, organic fluorine, organic arsenic and pesticides that can produce degenerative hemoglobin should be used. The rest of the pesticides are mainly symptomatic and supportive treatment. Therefore, special attention should be paid to the protection of the vital organs.

2. Specific treatment and treatment of pesticide poisoning

(1) The main antidotes for organophosphorus compounds are terpenoids, which are mainly used to revive poisoned cholinesterase to combat nicotine-like symptoms such as muscle tremors, tendons, muscle weakness, and muscle palsy. The commonly used drugs are chlorfothodine, pralidoxime, and phosphate, etc. The principle of medication is early enough and there is a first impact. After 48 hours, there should be maintenance therapy until the fibrillation completely disappears. There is no need to rush to stop the drug ( see Detoxification and Special Treatment section ) . The use of drugs at the same time also need to use anti-cholinergic drugs such as atropine to counteract the central nervous system and muscarinic symptoms, medication should be maintained after atropine treatment, until the basic control of symptoms. In recent years, attention has also been paid to the use of calcium channel blockers and diazepam in organophosphorus poisoning, and it is considered important to prevent and reduce central nervous system symptoms, intermediate syndromes and myocardial damage. The former is verapamil (0.1 mg/kg , iv). , nifedipine (0.01mg/kg , iv) , daily 2 to 3 times; stability can be 5 ~ 10mg , im , 2 ~ 3 times / day, convulsions can be 15 ~ 10mg / times, iv .

(2) carbamate atropine anticholinergic drugs that is its specific drug without the need for terpenoids. Mild poisoning can be intramuscular injection 0.5 ~ 1mg ; serious condition can be doubled dose, and can be repeated medication, no atropine, but severe patients require atropine, and maintain atropine treatment.

(3) no specific antidote pyrethroids, except with nonspecific detoxification, lavage or wash the contaminated skin, clothing contamination removal process, the central nervous system symptoms should actively control convulsions, spasms, such as diazepam (10mg , im) , pentobarbital sodium (100mg , im), etc., or artificial hibernation therapy; oxygen should be given and glucocorticoids should be given as soon as possible; closely monitor the function of all vital organs, especially heart and lung function, with early Treatments such as energy mixture, proper rehydration, diuresis and dehydration.

(4) Insecticide should pay attention to contaminated skin thoroughly clean, remove contaminated clothing, oral administration should be gastric lavage, immediate administration of methylene blue (1 ~ 2mg/kg , iv) , if necessary, 1 to 2