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Epidemiologic Notes and Reports Organophosphate Insecticide Poisoning Among Siblings -- Mississippi

On August 6, 1984, the Mississippi State Department of Health was informed of the death of an 11-year-old girl from Tunica County, Mississippi, and the hospitalization of her six siblings. The initial clinical diagnosis for the seven children was organophosphate poisoning. Neither the children's mother nor her live-in male companion was ill. Following is a summary of the State Department of Health's investigation.

On August 2, five of the seven children had visited a local physician complaining of abdominal pain of 2 days' duration. One child also had fever and diarrhea. The physician diagnosed viral gastroenteritis and suggested fluids and rest. There was no improvement during the next day, and on the morning of August 4, three children did not respond to vocal sounds, and the others were obviously ill.

Later that day, all seven children presented to a Memphis, Tennessee, hospital with signs and symptoms of organophosphate poisoning. Two were in respiratory arrest, and the other five had various degrees of lethargy, increased salivation, increased respiratory secretions, and pinpoint pupils. All the children had depressed serum and erythrocyte cholinesterase levels (Table 1). One child could not be resuscitated and died. Preliminary autopsy findings were consistent with organophosphate poisoning and suggested ingestion as a primary route of exposure. A second child died August 9, and the other five children recovered and were discharged. A survey of local physicians and emergency rooms revealed no other similar cases.

Because both adults in the household and a nearby adult neighbor were clinically well, it was felt that the source of poisoning was confined to the children's household. The male live-in companion reported having sprayed the inside of the house July 26 with a solution of insecticide in an attempt to control spiders. He had obtained a nearly empty insecticide container from the farm where he worked and had added water to it. He reported using a hand sprayer to spray the solution on the inside upper walls of three of the four rooms (excluding the kitchen) in the house. He reported no subsequent spraying, but the sprayer, still partly filled, was found on the back porch of the house the day after the children became ill. The house had no running water, and drinking water was obtained from the nearby neighbor's well and stored in an open ice chest. Therefore, contamination of the drinking water was considered a strong possibility for exposure.

Samples of insecticide solution from the sprayer, water, prepared food, other liquids, and indoor and outdoor air were obtained (Table 2). The sprayer solution contained the organophosphate insecticide methyl parathion ((CH((3))O)((2))-PS-O-C((6))H((3))(NO((2)))Cl) in a concentration nearly three times that used for outdoor agricultural spraying. The drinking water in the house contained methyl parathion in a concentration above the suggested no adverse response level (SNARL); water from the well was negative for methyl parathion. The air inside the house contained over 100 times the concentration of methyl parathion measured in the air in the same locality during the spraying season (2); the air on the porch contained only one-seventh the amount found inside.

Food histories showed that, since the visit to the doctor August 2, the children had eaten primarily canned soups cooked with water and drunk liquids prepared with the household drinking water. In contrast, the adults apparently ate other foods (e.g., catfish) and drank more bottled soda. Samples of blood and urine from the adults were analyzed for evidence of exposure to organophosphate compounds and compared with those of the children (Table 1). The higher levels of exposure among the children are evident, although the adults were sampled several days later.

It seems likely that the seven siblings were exposed to methyl parathion by multiple routes, primarily ingestion, inhalation, and possibly surface contact via contaminated clothing. The absence of clinical illness in the two adults in the household may reflect lower levels of exposure due in part to different food intake. The 8-day delay between the reported spraying and the manifestation of classic symptoms of organophosphate poisoning is not explained. Efforts are under way to decontaminate the house and to reemphasize to the public the danger of organophosphate insecticides used inappropriately. Reported by A Dean, J Pugh, Tunica County Health Dept, K Embrey, District I Health Office, J Cain, MS, L Lane, PhD, Mississippi State Chemical Laboratory, B Brackin, MPH, FE Thompson, Jr, MD, State Epidemiologist, Mississippi State Dept of Health; Div of Field Svcs, Epidemiology Program Office, CDC.


  1. U.S. Environmental Protection Agency. Advisory opinions for toxic chemicals in drinking water. Criteria and Standards Division, U.S. Environmental Protection Agency, January 19, 1979.

  2. Mississippi State Chemical Laboratory. Mississippi Epidemiologic Studies Program, Annual Report No. 9, Mississippi State University, Starkville, Mississippi, 1976.

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