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 SACRAMENTO, Calif., April 2 /PRNewswire/ -- A recent review of toxicology studies has prompted Cal/EPA's Department of Pesticide Regulation to issue regulations that change the way homes and other structures are fumigated for wood-destroying insects like termites. The new regulations will be in effect early next week.
 "When we recently reviewed animal studies on the pesticide, methyl bromide, we found that present application methods did not provide an ample enough margin of safety," said DPR Director James W. Wells. "Although we have no evidence that current methods result in illness in the residents of fumigated homes, we feel it is necessary to provide a greater margin of safety."
 The new regulations affect only structural applications of methyl bromide. The chemical is also used to fumigate ships and railroad cars; stored grains, processed food and fresh produce; and bare soil before planting. It is used to kill insects, mites, rodents, plant diseases, nematodes, termites, and weeds.
 DPR made its findings available to the U.S. Environmental Protection Agency, and the two regulatory agencies have been in close coordination. USEPA is announcing a nationwide change in methyl bromide structural application methods, after methyl bromide registrants agreed to adopt in large measure the changes being implemented in California.
 "Methyl bromide is one of the two major chemicals available to fumigate houses and other structures to kill termites, powder post beetles, and other wood-destroying insects," said Wells. "According to representatives of the structural pest control industry, there are approximately 150,000 dwellings fumigated each year in California, about half with methyl bromide, and the remainder with sulfuryl fluoride.
 "In many instances, these treatments are required when homes are sold, and escrow cannot close until they are done," said Wells.
 The two chemicals are applied in a similar manner. Dwellings are cleared of residents, and some furniture, clothing, and other items are removed. The structure is completed covered with a large tarp, which is weighted to seal in the chemical. The pesticide--in the form of a gas--is then pumped into the structure. Because both methyl bromide and sulfuryl fluoride are odorless, a small amount of an odorous warning agent, chloropicrin, is also added to the mixture.
 The tarp is removed after 24 to 48 hours, and windows and doors opened by a trained applicator, wearing self-contained breathing apparatus. In some instances, fans are used to accelerate clearing the gas from the dwelling.
 According to present use practices throughout the country, the dwelling can be reoccupied when the ambient level of methyl bromide inside drops to 5 parts per million. Fumigators use a hand-held gas monitoring device to determine this level. The 5 ppm level, known as the threshold limit value (TLV), had been considered to be health-protective, based on historical data.
 However, recent DPR review of animal toxicology studies submitted under the mandates of the 1984 Birth Defect Prevention Act (SB 950, Petris) indicated that the TLV does not provide an adequate margin of safety for persons reoccupying the structure. The studies indicate that exposure to excessive doses of methyl bromide can cause neurotoxic effects, such as tremors and blurred vision. Excessive doses of methyl bromide also cause birth defects in animals.
 "Scientists from DPR, the state Department of Health Services, and Cal/EPA's Office of Environmental Health Hazard Assessment support these actions and agree that what we are doing is making home fumigation a lot safer than it was," said Wells.
 The new regulations impose interim risk reduction measures that will be in effect for several weeks, while new tests are conducted by DPR to develop improved aeration techniques.
 These tests are prompted by recent studies that indicate that, after structures are cleared for reoccupancy and windows and doors closed, methyl bromide levels tend to rise. This is because the gas is adsorbed during treatment by walls, ceilings, furniture, carpet and other items, and slowly releases into the living space. It can take several days to dissipate completely.
 The interim measures impose mandatory aeration intervals, ranging from 72 hours to 7 days after the tarps are removed, depending on whether the pest control companies use fans to force fresh air into the house.
 The interim measures also require pest control companies to provide residents of structures to be fumigated with a handout explaining the potential hazards of methyl bromide fumigation. This handout is being prepared by DPR scientists in consultation with the Cal/EPA's Office of Environmental Health Hazard Assessment and the state Department of Health Services.
 The new regulations also require that pest control companies file a written notice with the county agricultural commissioner 24 hours before a dwelling is to be fumigated. This is to allow the commissioner--the state's local pesticide enforcement agent--to inspect and monitor applications.
 DPR studies are also underway to determine if mitigation measures are necessary to provide a greater margin of safety for agricultural workers applying methyl bromide soil treatments. Few such treatments are done until mid-April, just before planting. Although there are alternatives for methyl bromide available for most agricultural uses, many are less effective and may require multiple applications. In addition, methyl bromide is also widely used to fumigate commodities, stored spices, and processed foods. Many states and countries require such fumigation before export. DPR also plans studies to determine whether these uses pose a risk to workers. and if additional protective measures are necessary.
 Q. What is methyl bromide?
 A. Methyl bromide, in use since 1932, is a pesticide that kills insects, mites, rodents, plant diseases, nematodes, termites, and weeds. It is registered as a preplant soil fumigant; as a fumigant for stored commodities (both raw agricultural commodities and processed foods and feeds); to treat ornamentals in greenhouses; for termite control in homes and other structures; and to fumigate mills, ships, railroad cars and other transportation vehicles.
 It is a colorless, odorless gas that is normally mixed with another chemical warning agent, chloropicrin, which has a very noticeable odor and irritant properties.
 There were 20.1 million pounds of methyl bromide used in California in 1990. The most significant uses were: 26 percent for structural fumigations; 21 percent to treat strawberry fields before planting; 8 percent to treat nursery stock; 7 percent to treat processed grapes; 4 percent for treatment of soil before planting; and 3 percent to treat almond acreage before planting and nuts after harvest.
 Q. How is methyl bromide used in structural fumigations?
 A. Fumigation is the method of choice for extensive infestations of controlling wood-destroying insects, like termites and powder post beetles. Homes must often be fumigated before property title can be transferred.
 There are two chemicals used to fumigate homes: methyl bromide and sulfuryl fluoride (trade name, Vikane). According to industry estimates, there are approximately 150,000 dwellings fumigated each year in California, about 95% of them for termites. Other target pests may include powder post beetles and cockroaches. About half the structural fumigations in California are done with methyl bromide, half with sulfuryl fluoride. More fumigations occur in Southern California, because of its greater population (and, therefore, higher number of dwellings), and because wood-destroying insects flourish in warmer temperatures.
 For the average homeowner, application of sulfuryl fluoride is about three to five times as costly as methyl bromide. In addition, methyl bromide is more effective against insects in the egg stage of the life cycle, and is more effective against wood-destroying powder post beetles.
 Under standard industry practices, both materials were applied similarly. Infested structures are sealed and enclosed in large tarps, usually for 24 to 48 hours. Warning signs are posted during the fumigation period. After the tarps are removed, a worker wearing self-contained breathing apparatus opens doors and windows to aid ventilation. Powerful fans may also be set up to push fresh air into the house. The worker, using direct-reading instruments, regularly monitored the levels of fumigant in the tion, there is concern that the TLV may not protect against certain neurotoxicity effects (e.g., tremors or blurred vision).
 These findings may also have implications for methyl bromide applicators working in agriculture, since application techniques and protective measures are based on the same historical data.
 2) DPR also reviewed a study conducted in Florida by a pesticide registrant which concluded that, after doors and windows of fumigated homes were closed following aeration down to the label-required 5 ppm level, methyl bromide levels could gradually build back up to as much as 25 ppm. Preliminary results from a study conducted by DPR earlier this month under California conditions confirms this phenomenon. These data indicated that improved aeration procedures will have to be developed to ensure homes are adequately cleared of fumigant.
 Q. Why not suspend methyl bromide until these improved aeration procedures are in place?
 A. DPR has not yet completed a full, peer-reviewed assessment of the risks posed by current methyl bromide use practices. The interim measures are precautionary in nature, and we believe that they will result in acceptable risk reduction without depriving homeowners of a tool critical to exterminating wood-destroying pests. While there is a chemical alternative to methyl bromide, it is not as effective against some pests, and is three to five times more costly. We believe we shouldn't increase fumigation costs to homeowners unnecessarily.
 In addition, we have no way of determining if the alternative chemical (Vikane) would be available in sufficient quantities to avoid disruption of the housing market should methyl bromide use be suspended. (Fumigation of termite-infested homes may be a prerequisite of closing escrow in sale of a home.)
 Q. What are the changes DPR is implementing?
 A. As a precautionary measure, structural fumigators will be required to follow these interim aeration procedures:
 1) If a pest controlwelling, ventilation must be maintained for a minimum of 72 hours after the tarps are removed. Two air samples from within the spaces in the walls behind the faceplates are then tested, and aeration must continue until the level is below 3 ppm.
 The regulations also allow alternative aeration procedures to be implemented, based on new data that may be developed, upon approval by the DPR Director.
 In addition, the new regulations require that all occupants of a dwelling be provided with a handout, now being written by DPR in conjunction with state health officials, outlining possible risks associated with exposure to structural fumigants. This handout must be presented before a contract is signed for fumigation services.
 Pest control companies must also notify the county agricultural commissioner (the state's primary pesticide enforcement agents) 24 hours before each fumigation. This will allow county biologists to inspect applications.
 Q. What studies does DPR plan to do?
 A. Working with the pest control industry, DPR scientists will monitor levels of methyl bromide within homes during the aeration period. This will assist in the development of improved aeration methods. These studies are expected to take several weeks.
 Q. What are the symptoms of methyl bromide poisoning?
 A. Methyl bromide used in structural fumigations is always mixed with a warning agent, chloropicrin, which has a noticeable odor and irritant properties. Exposure to chloropicrin caus To encourage this dissipation, tarps are opened from the roof downward, allowing the gas to escape upward.
 Q. Have there been problems in the past with methyl bromide?
 A. Unfortunately, there have been deaths associated with structural fumigations with methyl bromide or sulfuryl fluoride, none in some years, as many as five in 1989. Historically, these have been intruders (often transients or burglars) who ignored the posted warning signs and pushed past the tarp to enter a house, apartment or railroad car under fumigation. In 1989, a applicator died while using liquid nitrogen in a structural fumigation.
 In January of this year, a Redwood City man died after going back into his apartment building, which had been fumigated and cleared for reoccupancy. This death--the first in at least a decade in a dwelling that had been cleared for reoccupancy--is under investigation by the Department of Pesticide Regulation and the San Mateo County District Attorney's Office for possible violations of the clearance procedures. DPR sent a staff physician and certified industrial hygienist to San Mateo County in January to perform an on-scene investigation.
 Q. What about alternatives to fumigation?
 A. Homeowners should always investigate alternatives to pesticide use. In some cases, fumigation is necessary. In other cases, it may be possible to rip out and replace pest-infested portions of the home.
 A good source for advice on possible alternatives to pesticide use is your county office of the University of California Cooperative Extension, listed in the government section at the beginning of the white pages of your phone directory.
 Q. Are there any problems associated with the use of sulfuryl fluoride, the alternative to methyl bromide?
 A. Sulfuryl fluoride (trade name, Vikane), like methyl bromide, is subject to the data call-in requirements of the Birth Defect Prevention Act of 1984 (SB 950, Petris). SB 950 required that chemicals registered before 1984 be fter a home is cleared for reoccupancy. Although sulfuryl fluoride levels do not increase as much as methyl bromide levels do after the doors and windows are closed, the Department of Pesticide Regulation has mandated new aeration procedures for sulfuryl fluoride. These procedures were recommended by the chemical's manufacturer, DowElanco, which has asked USEPA to change the product's label to require these ventilation methods.
 Q. What other uses does methyl bromide have?
 A. Methyl bromide is widely used in agriculture to treat for nematodes, diseases, weeds and insects before planting. It is applied directly to the soil and usually covered with a tarp to enhance its pesticidal properties. As a heavy gas, it is applied in varying amounts, often at 300 to 500 pounds per acre.
 After California suspended the use of another widely used fumigant, 1,3-dichloropropene (brand name, Telone) in 1990, many farmers turned to methyl bromide as the most efficacious and cost- effective alternative. Although there are alternatives available for most uses, many are less effective and may require multiple applications. In some instances, such as heavy infestations of nematodes affecting carrots, the alternatives are not effective. In California, methyl bromide is registered to treat soil before planting of 23 vegetable crops (including broccoli, carrots, celery, lettuce, and tomatoes) and 23 fruit and nut crops (including almonds, cherries, grapes, citrus, oranges, peaches, pears, plums, and walnuts).
 In addition, many farm commodities must be treated before the commodity can be transported across county, state or international borders, to prevent the spread of pests and plant diseases. Methyl bromide, which replaced the banned ethylene dibromide fumigant, is one of the few products left on the market to fumigate produce (fruit, vegetables, nuts and nursery products) for export. The fumigation requirement is imposed by the country or state of destination. The cancellation of methyl bromide would severely disrupt California's export of farm goods.
 Methyl bromide is also used to treat soil in which nursery stock is to be planted. In order to prevent the spread of serious nematode pests, California law requires that certain nursery stock be grown on soil treated in an approved manner. This applies to fruit and nut trees, grapevines, berry vegetable plants, kiwi and other nursery stock sold for on-farm planting. Since the loss of 1,3- dichloropropene, the only approved treatment for fields is fumigation with methyl bromide under tarp. (Soil in beds, flats or containers may be treated with steam.)
 Q. Why is the state taking regulatory action against structural uses of methyl bromide, and not the agricultural uses?
 A. The Department of Pesticide Regulation plans to issue new rules governing the use of methyl bromide in field fumigations within the next few weeks, before heavy use of the pesticide (typically just before spring planting) begins.
 Workers in commodity fumigation situations at a lower risk of exposure since most fumigations occur in airtight chambers, and workers are exposed for only short periods. However, DPR scientists will be studying these uses to determine if changes are necessary to protect workers.
 Q. Whom can I call for more information about health effects of pesticides?
 A. The U.S. Environmental Protection Agency has a toll-free information service, the National Pesticide Telecommunications Network Hotline, at 800-858-7378, or you can call Worker Health and Safety Branch of the California Department of Pesticide Regulation in Sacramento, 916-654-0455.
 Alameda 32,092
 Amador 1,524
 Butte 496
 Calaveras 532
 Colusa 416
 Contra Costa 8,693
 Del Norte 80
 El Dorado 1,553
 Fresno 10,091
 Humboldt 1,318
 Imperial 80
 Inyo 14
 Kern 3,535
 Kings 279
 Lake 2,466
 Los Angeles 4,087,879
 Madera 922
 Marin 11,207
 Mendocino 4,330
 Merced 3,234
 Monterey 11,372
 Napa 1,625
 Nevada 1,430
 Orange 421,415
 Placer 3,278
 Plumas 671
 Riverside 73,380
 Sacramento 24,458
 San Benito 1,022
 San Bernadino 129,690
 San Diego 151,913
 San Francisco 3,301
 San Joaquin 19,879
 San Luis Obispo 11,590
 San Mateo 20,224
 Santa Barbara 28,473
 Santa Clara 49,491
 Santa Cruz 15,410
 Shasta 189
 Sierra 50
 Siskiyou 145
 Solano 4,438
 Sonoma 16,223
 Stanislaus 4,368
 Sutter 1,914
 Tehama 159
 Trinity 214
 Tulare 1,747
 Tuolumne 329
 Ventura 52,997
 Yolo 7,119
 Yuba 69
 TOTAL: 5,229,324
 There were no structural applications of methyl bromide reported in the following counties in 1990: Alpine, Del Norte, Glenn, Lassen, Mariposa.
 -0- 4/2/92
 /CONTACT: Veda Federighi of the Department of Pesticide Regulation, 916-654-1117/ CO: Department of Pesticide Regulation ST: California IN: SU:

MM -- SF007 -- 4662 04/02/92 20:05 EST
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Date:Apr 2, 1992

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