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Acute Pesticide Poisoning Associated with Use of a Sulfotepp Fumigant in a Greenhouse -- Texas, 1995

Pesticide fumigants that eradicate pests but do not damage flowers or foliage can be used to protect market-ready florals. During November 1995, a pesticide applicator worker in Texas became ill during fumigation despite wearing the personal protective equipment (PPE) recommended on the fumigant product label. This report summarizes the results of the case investigation by the Texas Department of Health (TDH) and CDC's National Institute for Occupational Safety and Health (NIOSH) and a survey of growers about pesticide use. The findings indicate that the recommended PPE may be inadequate to protect workers using sulfotepp fumigants from pesticide poisoning.

Case Investigation

On November 30, 1995, the Environmental and Occupational Epidemiology Program at TDH was notified by the Texas Poison Center Network of a 32-year-old man who had visited an emergency department (ED) because of symptoms consistent with acute pesticide poisoning, including headache, nausea, diarrhea, vomiting, cough, slight dizziness, sweating, fatigue, abdominal pain, anxiety, muscle aches, chest tightness, drowsiness, restlessness, shortness of breath, and excessive salivation. The patient was a pesticide applicator employed at a greenhouse and had applied sulfotepp fumigants (Plantfume 103 and Fulex) * the previous night. Sulfotepp, a highly toxic organophosphate pesticide and cholinesterase inhibitor, is used in greenhouses to control aphids, spider mites, thrips, and whiteflies; sulfotepp does not damage delicate flowers or foliage (1).

The patient reported onset of symptoms shortly after igniting the sulfotepp fumigant canisters in the first of four interconnected greenhouses where chrysanthemums, poinsettias, and other plants were grown. Despite feeling ill and smelling the chemical, he and three other workers completed fumigating all four greenhouses. He did not seek medical care until the following day. Physical examination at the ED was unremarkable, and he was released without treatment.

The patient was a licensed pesticide applicator and had been employed at the greenhouse for 2 years. Although he had applied other fumigants in the past, this was the first time he had applied sulfotepp and the first time the chemical was used in this greenhouse. During the application, he wore the PPE recommended on the product label, including a laminated full-body suit, rubber boots, nitrile gloves, and a full-face air-purifying respirator equipped with a pesticide prefilter and organic vapor cartridge. He had undergone a qualitative (smoke) respirator fit test in November, and no leakage was detected. A qualitative fit test conducted after the incident indicated an adequate fit.

On December 3, TDH and NIOSH interviewed the other applicators, inspected the PPE, and observed the next fumigant application at the greenhouse. All three applicators reported wearing the label-recommended equipment, and two of these three workers reported nausea and detecting the odor of the chemical during application on November 30; however, they did not vomit or seek medical care.

During the second application, unopened canisters of Plantfume 103 and Fulex were set out in a grid-like fashion within each greenhouse. In accordance with the label instructions, a total of 80 canisters were set out (one canister per 20,000 cubic feet). The internal air circulation system and the exhaust ventilation system were turned off. The internal air circulation system had not been turned off during the previous application because the applicators misinterpreted the instructions. To avoid the smoke, the workers ignited the canisters as they exited each greenhouse, but each canister rapidly generated smoke. After the final canister was ignited, the workers moved to a shipping area not being treated with the fumigant, removed their PPE, and left the facility. The time necessary to complete the application was approximately 45 minutes and, even though all product label instructions were followed, the index patient again reported some symptoms.

Survey of Growers

During December, TDH conducted a telephone survey of greenhouse operators in Texas to assess the prevalence of greenhouse fumigant use and the occurrence of possibly related adverse health effects among workers. TDH contacted 413 Texas companies listed under Standard Industrial Classification (SIC) code 5193 (nursery stock for florists and the same SIC code as the greenhouse) and identified 53 companies with greenhouses in which plants were grown. All 53 companies participated in the survey. Of these, 43 (81%) reported ever using fumigants, and 30 (70%) of the 43 reported using sulfotepp. Of the 43 companies using any type of fumigant, 33 (77%) reported that workers used respirators during fumigant application, including five that used respirators with an independent supply of compressed air. Three (7%) companies reported that at least one worker had become ill during the application of fumigants, none of which contained sulfotepp; none of the workers sought medical care for their illness. At two of these three companies, workers wore all label-recommended PPE during the fumigant application; at the third company, workers did not use PPE during the application.

Reported by: T Willis, D Salzman, P Schnitzer, PhD, Environmental and Occupational Epidemiology Program; DM Simpson, MD, State Epidemiologist, Texas Dept of Health. Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health; Div of Applied Public Health Training (proposed), Epidemiology Program Office, CDC.

Editorial Note

Editorial Note: Although pesticide use in the United States has doubled since the 1960s (2), the health effects of pesticide use on agricultural workers has not been well documented. In Texas, where occupationally related acute pesticide poisoning is a reportable condition, 247 cases were reported during 1986-1994. However, during 1989-1990, only 20% of cases were reported (TDH, unpublished data, 1991).

The findings of the TDH investigation indicate that the acute illness among workers in this report most likely was associated with exposure to the sulfotepp fumigant and underscore the importance of reporting pesticide poisonings. Exposure occurred even though the workers followed the pesticide label instructions and properly used all recommended PPE during the second application. Because there was no evidence of oral or dermal contact with the chemical and workers smelled the chemical, inhalation was the most likely route of exposure. Other factors potentially associated with exposure may have included the technique employed in igniting the canisters and operation of the internal air-circulation system during the first application, which may have increased dispersion of the fumigant throughout the greenhouse.

The sulfotepp label instructions state that applicators and other handlers must use "a respirator with either an organic vapor-removing cartridge with a prefilter approved for pesticides (approval prefix TC-23C) or a canister approved for pesticides (approval prefix TC-14G)" (3,4). In general, such filters do not provide adequate protection against the high ambient chemical concentration and small particle size characteristic of fumigants. In addition, a single type of filter may not be appropriate for all types and forms of pesticides and, in July 1995, NIOSH discontinued certifying cartridges specifically for use with pesticides. ** The survey findings in this report indicated that many greenhouses use fumigants, most workers use only a respirator, and other greenhouse workers had become ill during fumigant applications, despite the use of label-recommended PPE.

Neither the product distributor nor the formulators of Plantfume 103 and Fulex had received reports of illness related to these products; however, neither maintained surveillance for potentially related problems or illnesses. During 1985-1992, the U.S. Environmental Protection Agency (EPA) received 23 reports of illness in persons occupationally exposed to sulfotepp (EPA, unpublished data, 1996); 70% of these persons were referred to health-care facilities, and 7% were hospitalized.

As a result of this investigation, TDH and NIOSH recommended to EPA that sulfotepp fumigant labels be amended to indicate the appropriate respiratory protection. Label instructions for other pesticide fumigants also may need to be reviewed for appropriateness. In addition, advertising material and labels for pesticide prefilters, cartridges, and canisters should clearly state they are not for use with fumigants. Professional associations and licensing and regulatory agencies should provide applicators with educational materials regarding the safe use of pesticide fumigants, including appropriate PPE, efficient fumigant application procedures, and less toxic pest-control options. Employers should implement comprehensive PPE programs, including selection of appropriate respirators by qualified staff using NIOSH-recommended procedures (5).


  1. Plant Products Corporation. Plantfume 103 -- plantfume tedion dithio and nicotine smoke generators {Supplemental product information}. Vero Beach, Florida: Plant Products Corporation.

  2. Ridgway RL, Tinney JC, MacGregor JT, Starler NJ. Pesticide use in agriculture. Environ Hlth Perspect 1978;27:103-12.

  3. Plant Products Corporation. Supplemental labeling for Plantfume 103 smoke generator. Vero Beach, Florida: Plant Products Corporation.

  4. Fuller System, Inc. Supplemental labeling for Fulex dithio insecticidal smoke fumigant. Woburn, Massachusetts: Fuller System, Inc.

  5. NIOSH. NIOSH guide to industrial respiratory protection. Cincinnati: US Department of Health and Human Services, Public Health Service, CDC, 1987; DHHS publication no. (NIOSH)87-116.

    • Use of trade names and commercial sources is for identifcation only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services. ** 42 CFR 84.

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