Symptoms of mild paraquat poisoning

Speaking of paraquat, it is a lethal herbicide that has a strong killing power on weeds in the fields. Its weed control effect is also very good. It can be quickly absorbed by plants, causing them to wither and die. However, in addition to its high lethality to green plants, it is also extremely toxic to humans, and there is no specific antidote, so the mortality rate is extremely high if taken orally. Therefore, special attention must be paid when coming into contact with or using paraquat. Let’s talk about the symptoms of paraquat poisoning.

The diagnosis is mainly based on the exposure history and clinical manifestations of lung damage accompanied by multi-system damage. Those with obvious lung damage have a poor prognosis. Abnormalities in clinical tests, lung function, chest X-rays, etc. are not specific for diagnosis. Toxicological identification (gastric lavage fluid, blood, urine and residual toxins, etc.) should be performed when necessary. The extinction rate of residual toxins can be measured by spectroscope at 600nm. Residual analysis must first be extracted and reduced by ion exchange column, and then measured at 396nm. There is currently no national standard for the classification of poisoning levels. The reference classification indicators are:

1. Mild poisoning: Paraquat intake is less than 20 mg/kg. Apart from gastrointestinal irritation symptoms, there is no other obvious organ damage, and lung function may be temporarily reduced.

2. Moderate to severe poisoning: Paraquat intake is 20-40 mg/kg. In addition to gastrointestinal symptoms, there are manifestations of multi-system damage. Pulmonary fibrosis will appear after a few days to weeks, and most people die within 2-3 weeks.

3. Outbreak poisoning: Paraquat intake >40 mg/kg, with severe gastrointestinal symptoms, oropharyngeal corrosion and ulceration, accompanied by multiple organ failure, and death within a few hours to a few days.

What are the symptoms of paraquat poisoning?

1. Oral poisoning

There are burning sensation in the mouth, erosion and ulcers of the oral and esophageal mucosa, nausea, vomiting, abdominal pain, diarrhea, and even vomiting and bloody stools. In severe cases, complications such as gastric perforation and pancreatitis may occur. Some patients experience liver enlargement, jaundice, abnormal liver function, and even liver failure. Patients may experience dizziness and headache, and a few may develop central nervous system symptoms such as hallucinations, fear, convulsions, and coma. Renal damage is the most common symptom, manifested as hematuria, proteinuria, oliguria, increased blood BUN and Cr, and in severe cases, acute renal failure. Lung damage is the most prominent and severe, manifested by cough, chest tightness, shortness of breath, cyanosis, and dyspnea. Physical examination may reveal decreased breath sounds and dry and wet rales in both lungs. Those who take large amounts orally will experience pulmonary edema and pulmonary hemorrhage within 24 hours, and often die from ARDS within a few days; those who do not take large amounts will present a subacute course, with chest tightness and shortness of breath occurring in about a week, and dyspnea reaching a peak in 2 to 3 weeks, and patients often die of respiratory failure. A small number of patients developed complications such as pneumothorax, mediastinal emphysema, toxic myocarditis, and pericardial hemorrhage.

2. Local contact with paraquat poisoning

The clinical manifestations are contact dermatitis and chemical burns of mucous membranes, such as skin erythema, blisters, ulcers, etc., burns of the conjunctiva and cornea forming ulcers and even perforations. Prolonged and excessive exposure may cause systemic damage or even be life-threatening.

3. Those who are exposed to paraquat through injection (blood vessels, muscles, skin, etc.)

Exposure to paraquat through injection (blood vessels, muscles, skin, etc.) is rare, but the clinical manifestations are severe and the prognosis is poor.