Objective: Paraquat poisoning occurs worldwide, and both the fatality rate and the number of deaths are out of the ordinary. Japan is one of the few countries in the world that have replaced 24% products with 5% products. This report is an attempt to introduce information about paraquat poisoning in Japan.
Methods: The Japanese Association of Rural Medicine has carried out extensive surveys on clinical cases of pesticide poisoning at its 122 member installations since 2007. Of all the findings, we have picked out and evaluated those concerned with paraquat poisoning.
Findings: Twenty-two out of 28 persons who attempted to commit suicide with paraquat died in 2007-2011. The rate of deaths from suicide attempts with paraquat stands at somewhere near 80% or so even with 5% products, so it appears that the attempts to reduce the death rate did not have the intended effect even with products having a lower concentration.
Conclusion: The “outcome prediction line” propounded in 1979 still stands today, while a wide variety of therapies have been studied. It seems that paraquat should at least be classified into Class Ib (highly hazardous) given that the mortality remains high and efficacious therapies remain elusive.

　　Clinical cases of pesticide poisoning from 2010 through 2012 were analyzed based on data collected from the hospitals affiliated with the Japanese Association of Rural Medicine.　　One hundred and thirty-seven cases of pesticide poisoning were reported from 37 hospitals. By gender, males and females made up almost the same number. By age group, those in the 70-79 age band accounted for 22% of the total number of the cases, followed by those in their 60s (18%) and those in their 80s (18%). By month, the incidence peaked in May, accounting for 16%. When it comes to occupational poisoning, the majority of the cases occurred in spring and summer, when pesticides were used frequently.　　By type of pesticide exposure, suicide accounted for 71%, followed by accidental ingestion (13%) and occupational exposure (12%).　　By type of clinical manifestation, acute poisoning was most frequent (83%), followed by dermatitis (6%) and ocular disorders (5%). When it comes to occupational exposure, the rate of acute poisoning decreased to 42%, and dermatitis and ocular disorders increased to 47% and 11%, respectively.　　Amino acid herbicides topped the list of agricultural chemical compounds causing poisoning (29%), followed by and organo-phosphate insecticides (29%) and bipyridilium herbicide (8%).　　As regards main ingredients, glyphosate was the most frequent inducer (38 cases), followed by fenitrothion (18 cases) and paraquat (12 cases).　　Twenty-two death cases were reported, of which eight cases were by paraquat and three cases by fenitrothion. The death rate from paraquat poisoning was far higher than those from any other pesticides. The death number has been decreased gradually, which was correlated with the downward trend of paraquat sales.

  Clinical cases of pesticide poisoning from 2007 through 2009 were analyzed based on data collected from the hospitals affiliated with the Japanese Association of Rural Medicine.
  Two hundred and twelve cases of pesticide poisoning were reported from 48 hospitals. By gender, males accounted for 54%. By age group, those in the 60-69 age band accounted for 23%, followed by those 70-79 years old (22%) and those 50-59 years old (19%). By month, the incidence peaked in May or August accounted for 12% respectively. When it comes to occupational poisoning, the majority of the cases occurred in spring and summer, when pesticides were used frequently.
  By type of pesticide exposure, suicide accounted for 77%, followed by occupation exposure (16%) and accidental ingestion (4%).
  By type of clinical manifestation, acute poisoning was most frequent (90%), followed by dermatitis (3%) and ocular disorders (2%). When it comes to occupational exposure, the rate of acute poisoning decreased to 70%, and dermatitis and ocular disorders increased to 11% respectively.
  Organo-phosphate insecticides topped the list of agricultural chemical compounds causing poisoning (32%), followed by amino acid herbicides (22%) and bipyridilium herbicide (10%). When it comes to main ingredients, glyphosate was the most frequent inducer (32 cases), followed by fenitrothion (25 cases) and paraquat (21 cases).
  Thirty-six death cases were reported, of which 16 cases were by paraquat and 9 cases by organo-phosphate insecticides. The death rate and number from paraquat poisoning were by far larger than those from any other pesticides. A ban on the use of paraquat must be considered.

  Mass poisoning with an organo-phosphate insecticide occurred at a junior high school in Japan. We collected clinical data from four hospitals, which treated the patients, and investigated this poisoning.
  In late July, the janitor of the school dropped an undiluted solution of 40% methidathion insecticide into the nest of ant near the classroom between 10:00 and 11:00 a.m The volatilized gas spread into the classroom, and many students presented some symptoms of poisonig, 16 students were taken to neighborhood hospitals around noon.
  Of the 16 patients, 13 complained of headache, 11 of nausea, and 4 of dizziness. One patient vomited twice. The serum cholinesterase activities, the pupil diameters and the light reflexes of the patients were normal. Three patients were hospitalized one night for observation. All patients did not get sever poisoning, and recovered and had no sequela.
   It has to be admonished against spraying an undiluted solution of high toxic insecticide near the classroom, and it is necessary to take stern measures to prevent another such accident.

　　Sales of cut flowers depend much on outside appearance. They are not supposed to be, so pesticide is used more liberally for cut flower growing than for other agricultural products. When the annual group health checkups for cut-flower farmers were held in late-August in 2009, 2010, 2011, we sampled spot urines and measured four dialkylphosphates, the metabolites of the organo-phosphorous pesticide.　　At one time, concentrations of dimethylphosphate in 2 males were around 1,000-fold as much as the median of this group. Their serum cholinesterase activity levels at that time declined to 64% and 72% of their average measurements in the other years. These figures were comparable to the level that the pesticide spraying procedure should be revised, as suggested by the agricultural worker health system in California, United States which monitored cholinesterase activity levels in farmers.　　We had interviews with the two Japanese cut flower growers. One of them complained of unbearable cough with pyrethroid insecticide spraying. We advised him some measures in consideration of his history of respiratory disease. He decided not to use pyrethroid insecticides. Another man refused to talk about the pesticide exposure risk at first. But later on, we heard that he had decided to wear dust protective mask.　　The risk communication using the measurement of the index of pesticide exposure seemed to be a effective way to decrease pesticide exposure and its adverse effect. Although this procedure needs some trained interviewers and is sometimes refused by farmer, we are going to continue this type of dialogue from now on.

Pesticide poisoning is one of the most inportant health issues associated with rural medicine, and chronic nervous and mental disorders are its importnat sequelae. We investigated suquela cases nationwide, and reviewed chronic nervous and mental disorders from a clinical and epidemiological point of view.
Our nationwide survey found one reported case of delayed neuropathy. The patient ingested organophosphorus insecticides, and showed delayed neuropathy dozens days after.
Cases of delayed neuropathy attributable to Mipafox was reported in1951.This disease is mainly caused by organophosphorus insecticides. Carbamate insecticides are also known as the agents to induce delayed neuropathy. Herbicide Glufosinate (Basta^TM) was put on the market in 1984. The case reports published during the 1990's pointed out that some Glufosinate poisonings cause amnesia and disorientation. Thesecases were reviewed according to the types of pesticides or their groups.
An epidemiological investigation of neurological and psychiatric desorders among such workers exposed to several types of pesticides as plantation workers and sheep dippers was made. These exposed workers were at high risk of mild cognitive dysfunction, tremor, weakness, and so on to a significant extent. Those children who were exposed to organochlorine insecticide and pollutant via placenta or milk were also surveyed whether they had impairments of nervous and mental development. Highly exposed children were significantly slow in development relative to their peers. The results of these investigations were also reviewed.

　　Soil fumigants are used to control pests, fungi, and weeds before planting crops. As they are highly volatile and acutely toxic, farmers are often exposed to serious risks of poisoning by inhalation and contact. We investigated the use of soil fumigants and subjective symptoms of cut flower farmers by interviewing them.　　The subjects of this study consisted of 69 male farmers who came to health check, and we asked them about the names of soil fumigants they used in recent years, whether or not they wore the gas mask and the goggle, and whether they had had any subjective symptoms, and many other questions.　　Of the subjects, 68% said they used Chloropicrin and 64% gave D-D. Chloropicrin tablet and carbam were used by 15% of them, respectively.　　It was found that 38% of the chloropicrin users put on the gas mask, and that 32% put on the goggle. The occurrences of subjective symptoms differed with whether the farmer put on gas mask or goggle. The farmers without gas mask or goggle complained about watery eye (72%), couch (31%), runny nose (31%), breathing difficulties (21%), and eye irritation (19%).　　The farmers put into practice some measures to prevent chloropicrin exposure, as follows: Using the machine with injector crawls under the ground, working when gentle wind is blowing, working when the temperature of soil is low, and using the refrigerated chloropicrin.　　Some farmers and their wives informed that they had runny eye, sneeze when covering fumigated hillings with plastic films. The workers are recommended to put on the gas mask on working this process.　　The use of low-permeable film, developed in recent years, could economize on soil fumigants for cultivating some corps. It is hoped that the use of this new material will spread in cut flower farming and reduce risks of fumigant exposure.

  Calcium polysulfide, used in early spring as a spray to control insects and fungi, is indispensable for fruit growers. However, this chemical sometimes causes serious burns, as it is notably high in alkalinity.  In early March, a man in his late fifties was spraying this insecticide over his garden trees. With a lack of any background knowledge, he did not wear waterproof protective gear. He carried on his garden work, even though the chemical soaked through his pants. In the evening, he had sharp pains on the posterior surface of each leg. At the time of his first visit to our hospital, he had third degree chemical burns. Necrosis was evident. Debridement was preformed on Day 6. Ulceration was seen from dermis to panniculus adiposus. A skin graft was applied on Day 19. The patient was treated as an inpatient for one month.  Clinical case reports on thise type of burn were cited nearly one per year in Japanese medical study database. More reports were available in 2000s than 1990s. Studies, published abroad showed that these burns have not decreased in recent decades.  For this type of burn, stady priority should be given to preventive measures. Beside general precautions against pesticide poisoning, it is necessary to emphasize the need to (1) wear waterproof protective gear and (2) wash the body immediately after exposure to liquid chemicals. We prepared a brochure as a guideline for prevention.