NIOSH Publication No. 99-126:
NIOSH Alert: Preventing Phosphine Poisoning and Explosions during Fumigation
|Alerts briefly present new information about
occupational illnesses, injuries, and deaths. Alerts urgently request
assistance in preventing, solving, and controlling newly identified occupational
hazards. Workers, employers, and safety and health professionals are asked
to take immediate action to reduce risks and implement controls.|
|Current Exposure Limits|
Esta Pãgina en Español
99-126.pdf (Full Document)
The National Institute for Occupational Safety and Health (NIOSH) requests help in preventing worker exposures to phosphine gas during the application of phosphide fumigants. These products are often used to fumigate agricultural products and to control rodents.
This Alert describes 205 cases of illness or injury in workers exposed to phosphine gas associated with phosphide fumigants. Information about these exposures is urgently needed by agricultural workers, employers, cooperative extension agents, physicians, and other health care providers. NIOSH therefore requests that editors of trade journals, safety and health officials, labor unions, and agricultural employers bring this Alert to the attention of all workers who handle products that generate phosphine gas.
Phosphide fumigants release toxic phosphine gas (PH3) when they contact moisture in the air. When phosphine is inhaled, it can react with moisture in the lungs to form phosphoric acid, which can cause blistering and edema. These effects can be serious or fatal. Exposure to phosphine has also been linked with other effects such as chest tightness, headache, dizziness, and nausea. Also, improper handling of aluminum and magnesium phosphide has caused injuries from flash fires and explosions.
In 1988, NIOSH published survey results showing that worker exposure to phosphine often substantially exceeded the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) [Zaebst et al. 1988]. The case reports described in this Alert clearly illustrate the hazards to workers who handle or work near phosphide fumigants.
Aluminum and magnesium phosphide containers
may flash on opening. Pay careful attention to
handling procedures on labels
Commonly Used Fumigants
Commonly used fumigants include the following:
Phosphine has been reported to have the odor of decaying fish at concentrations below the OSHA PEL of 0.3 parts per million (ppm). However, Zaebst et al.  reported that workers noticed no odor when they worked in phosphine concentrations as great as 50 ppm for several minutes with no respiratory protection. This lack of apparent odor may be attributable to olfactory fatigue (inability to detect an odor following exposure).
Others have reported that phosphine has a garlic-like odor, but this may be due to the use of technical grade phosphine fumigants that contain impurities. These impurities can produce substituted phosphines, diphos- phines, methane, and most important, arsine (AsH3). Arsine is a highly toxic gas with a garlic-like odor. In 1979, NIOSH published Current Intelligence Bulletin 32, which fully describes the hazards of arsine.
Thus workers should not rely on odor to warn them about the presence of phosphine.
Significant Chemical Reactions
On contact with oxygen, phosphine tends to decompose to more stable forms of phosphorusultimately to phosphoric acid. This process may occur explosively at concentrations above 1.8%, especially when trace amounts of diphosphine are present [Cotton and Wilkinson 1972]. Phosphine gas also reacts violently with compounds containing fluorine, chlorine, bromine, and iodine (halides). Furthermore, phosphine gas can react with a variety of metals, including copper, brass, gold, and silver.
Symptoms of Exposure
Phosphine gas irritates mucous membranesespecially those of the deep lungs and upper airways. Because phosphine gas releases highly acidic forms of phosphorus when it contacts deep lung tissues, it tends to cause pulmonary edema (fluid in the lungs) [Parkes 1982]. Once absorbed into the body, phosphine can damage cell membranes and enzymes important for respiration and metabolism.
Intermittent, low concentrations of phosphine gas (probably 0.08 to 0.3 ppm) have been associated with mild headaches. Higher intermittent concentrations (0.4 to 35 ppm) have been linked to the following symptoms [Jones 1964]:
*Code of Federal Regulations. See CFR in references.
The U.S. Environmental Protection Agency (EPA) has established regulations governing the use of phosphide fumigants [40 CFR 152].
The NIOSH recommended exposure limit (REL) for phosphine is 0.3 ppm as a TWA for up to 10 hours per day during a 40-hour workweek, and 1 ppm as a 15-minute short- term exposure limit (STEL) that should not be exceeded at any time during a workday. In addition, NIOSH has established 50 ppm as the immediately dangerous to life and health (IDLH) concentration for phosphine gas. The IDLH is the concentration that could (1) result in death or irreversible health effects, or (2) prevent escape from the contaminated environment within 30 minutes.
The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) is 0.3 ppm as an 8-hour TWA; the ACGIH STEL is 1 ppm [ACGIH 1998].
The case reports described here were reported by the California Pesticide Illness Surveillance Program (PISP). This program has received 29,863 reports of pesticide-related illness or injury for the period 19821992. These reports include 205 cases associated with exposure to phosphine gas and solid forms of aluminum, zinc, and magnesium phosphide [Mehler et al. 1992].
Types of Fumigants InvolvedAmong the 205 cases reported here, the primary fumigant was
The 23 not determined cases included
ApplicatorsFumigant applicators reported numerous symptoms of illness after exposure to phosphide fumigants. Symptoms included skin irritation, rash, headache, nau- sea, vomiting, throat irritation, chest tightness, shortness of breath, dizziness, faintness, and incoherence. Two applicators required hospitalization, and four applicators lost work days (5, 7, 11, and 14 days, respectively).
Two applicators involved in phosphide fires and explosions reported chest pains, lightheadedness or dizziness, and difficulty in breathing or talking.
NonapplicatorsNonapplicators reported nausea, headache, chest tightness, and stomach cramps after exposure to phosphide fumigants. One death also occurred (see Case 7). Reported illnesses in nonappli- cators often occurred in clusters, accounting for 123 (79.9%) of the 154 reported cases.
Thirty-eight nonapplicators involved in phosphine fires and explosions reported symptoms of illness. Fire fighters were frequent victims. Of these cases, more than 20 were fire fighters who became ill during 6 phosphine exposure incidents. Others included a television reporter, a nearby mechanic, workers, a homeowner, and neighborhood residents.
Two applicators were injured when phosphide fumigants spontaneously caught fire or exploded. They reported facial burns, hair loss, a broken leg, cuts, and a perforated ear drum.
Examples of Case Reports
Six workers reported illness after they applied aluminum phosphide to rodent burrows in a field of tall, wet grass. No air samples were taken, but the employers concluded that application conditions had produced more rapid release of phosphine gas than expected.
Case 2Rodent Control
A rodent control worker wearing coveralls, rubber gloves, and goggles noticed an onion/ garlic odor while applying aluminum phosphide tablets. He soon developed tightness in his chest. Though he was not hospitalized, he missed 11 days of work.
Case 3Walnut Fumigation
A worker wearing cloth and leather gloves placed Phostoxin® tablets into bins of walnuts at a greater rate than recommended on the label. He then secured a plastic liner on top. One hour later the worker developed dizziness, headache, faintness, incoherence, and shortness of breath. He lost 5 days of work.
After a fumigation, workers placed unused Phostoxin pellets in a 4-cubic-foot bin and covered it with a tarpaulin. The bin exploded while two workers were checking it to see whether combustion was complete. One worker suffered facial burns, hair loss, a broken left leg, and a perforated eardrum. The other worker received facial cuts and burns.
At a North Hollywood spaghetti sauce factory, two explosions occurred during attempts to dispose of unused material from 62 trays of aluminum phosphide. First, a small explosion resulted when 20 trays were placed in a barrel with liquid and a detergent. A second explosion occurred when 42 trays were placed in a dry barrel.
Four fire fighters at the scene were hospitalized for 40 hours with nausea. Plant workers were treated and released at a nearby emergency room. And four neighborhood residents were briefly hospitalized.
Case 6Grain Elevator
Workers at a grain elevator developed headache, nausea, tightness of the chest, and stomach cramps after collecting grain samples and noting a foul odor. A colorimetric tube sample showed a phosphine gas concentration of about 25 ppm.
Case 7Railcar Fumigation
An unemployed man stowed away in a rice- filled railcar that was being fumigated in transit from Houston, Texas. He was found dead several days later when the train arrived in Colusa, California [CDC 1994].
Fires and explosions due to the mishandling of fumigant products have particularly disastrous consequences.
Workers are often unaware of the risks of working with or near phosphide fumigants. These risks can be greatly minimized by following the recommendations outlined in this Alert.
Summary of RecommendationsWorkers
These recommendations are discussed in more detail in the following subsections.
Aeration and Reentry
Take the following steps before permitting workers to reenter the area after fumigation.
Do not expose workers to phosphine gas at concentrations greater than 0.3 ppm during the moving, storage, or processing of incompletely aerated products.
Industrial Hygiene Monitoring
Do not use respirators as the primary means of controlling worker exposures to phosphine gas. Instead, use effective engineering controls and work practices to minimize worker exposures.
Workers may use respirators when engineering controls are being implemented and when intermittent tasks expose them to concentrations that cannot be kept below the NIOSH REL by engineering controls alone.
All respirators should be used in conjunction with a formal respiratory protection program
Important elements of the OSHA respiratory protection standard are as follows:
Employers should evaluate the respiratory protection program regularly. Table 1 lists the NIOSH-recommended respiratory protection for workers exposed to phosphine gas.
Please direct comments, questions, or requests for additional information to the following:Director
Division of Respiratory Disease Studies
National Institute for Occupational Safety
1095 Willowdale Road
Morgantown, WV 26505-2888
Telephone: 1-304-285-5894, or call
UC Davis Agricultural Health
and Safety Center
Old Davis Road
University of California
Davis, CA 95616-8757
We greatly appreciate your assistance in protecting the lives of American workers.Linda Rosenstock, M.D., M.P.H.
Director, National Institute for
Occupational Safety and Health
Centers for Disease Control and Prevention
CDC (Centers for Disease Control and Prevention) . Deaths associated with exposure to fumigants in railroad cars. MMWR 43(27):489-491.
CFR. Code of Federal regulations. Washington, DC: U.S. Government Printing Office, Office of the Federal Register.
Cotton FA, Wilkinson G, eds. . Advanced inorganic chemistry. A comprehensive text. 3rd ed. New York: Interscience Publishers, pp. 367-402.
Eller P, Cassinelli M, eds. . NIOSH manual of analytical methods. 4th ed. Cin- cinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113.
Hayes WJ, Laws ER . Handbook of pesticide toxicology. Vol. 2. San Diego, CA: Academic Press, pp. 657-661.
Jones AT, Jones RC, Longley EO . Environmental and clinical aspects of bulk wheat fumigation with aluminum phosphide. Am Ind Hyg Assoc J 25:376-379.
Mehler LN, OMalley MA, Krieger RI . Acute pesticide morbidity and mortality: California. Rev Environ Contam Toxicol 129:51-66.
NIOSH . Current Intelligence Bulletin 32: arsine (arsenic hydride) poisoning in the workplace. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 79-142.
NIOSH [1987a]. NIOSH guide to industrial respiratory protection. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 87-116.
NIOSH [1987b]. NIOSH respirator decision logic. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 87-108.
Parkes WR . Occupational lung disorders. 2nd ed. London: Butterworths, pp. 472.
Zaebst DD, Blade LM, Burroughs GE, Morelli-Schroth P, Woodfin WJ . Phosphine exposures in grain elevators during fumigation with aluminum phosphide. Appl Ind Hyg 3:146-154.
Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health.