WASHINGTON (AP) — An odorless pesticide sprayed at a Caribbean resort has left three members of a Delaware family hospitalized for weeks after they became seriously ill during their Virgin Islands vacation, and federal officials said Tuesday that investigators found the toxic chemical has been used at the resort several times before. 
 
 U.S. Environmental Protection Agency officials said the agency is looking into the use of the pesticide methyl bromide at the Sirenusa Condominium Resort in Cruz Bay, St. John. The agency is contacting people, including resort employees, to determine how many others might have been exposed to the pesticide, which is prohibited in residential settings. The Justice Department also is investigating the company that may be responsible. 
 
 The Esmond family of Wilmington, Delaware, was staying at the resort when they began having seizures March 20. 
 
 A family spokesman said Steve Esmond, his wife, Theresa Devine, and their two teenage sons were airlifted to hospitals on the U.S. mainland. The sons are in critical condition. Esmond has regained consciousness, but his sons have remained in a coma weeks after the exposure, family spokesman James Maron told The News Journal of Wilmington. Devine was treated and released. 
 
 "They are confident in their medical professionals and are hopeful for a full recovery," Maron said in a written statement Tuesday. "The Esmond family thanks everyone for their support and concern for their recovery from this unthinkable tragedy of pesticide poisoning." 
 
 Esmond is head of a private middle school in Wilmington, and Devine is a dentist. 
 
 Use of the pesticide was confirmed the day after the family became ill, which has helped inform doctors on how to treat the family, said Judith Enck, the EPA's regional administrator in New York City, which has jurisdiction over the U.S. Virgin Islands. 
 
 "We have confirmed that the problem is indeed methyl bromide," she said. "Methyl bromide is a potent neurotoxin. It's a gas. It can cause convulsions, coma, cognitive deficits, inflammation of the lungs. A lot depends on how much a person is exposed to and for what period of time." 
 
 The EPA banned the chemical for residential use in 1984 primarily for health concerns. That ban extends to U.S. territories, including the Virgin Islands, Enck said. 
 
 So far the investigation has revealed a certified applicator working for Memphis, Tennessee-based Terminix applied the methyl bromide in the complex while targeting an indoor beetle that consumes wood, Enck said. The company is now under a criminal investigation led by the U.S. Justice Department. 
 
 Terminix issued a statement saying the safety of its customers and employees is a top priority. 
 
 "First and foremost, the family is in our thoughts and prayers," spokesman Michael Wassmer said. "We're cooperating with authorities in their investigation, and we're conducting our own thorough internal investigation." 
 
 Investigators also learned methyl bromide has been used in the complex before, the EPA said, but it's not clear why the ban was ignored. 
 
 "Certified pesticide applicators know this is not approved for indoor residential use," Enck said. "The health effects are quite serious." 
 
 Sea Glass Vacations LLC, which rents units at Sirenusa, said in a statement that it has terminated its contract with Terminix and the home under investigation is unoccupied. The rental company earlier said the unit below the Esmond family's dwelling was treated for pests by Terminix. 
 
 "We are sending our thoughts and prayers to the family impacted by this tragic incident," the company said. "We remain committed to full cooperation with all local and federal authorities." 
 
 The EPA is continuing to test and monitor the property and is continuing to investigate the details of the family's exposure, Enck said, "to make sure it never happens again anywhere." 
 
 ___ 
 
 Associated Press writer Danica Coto in San Juan, Puerto Rico, contributed to this report. ||||| Story highlights Chemical damages ozone and is being phased out, though it's used in strawberry fields, EPA says 
 
 A Delaware family becomes ill at a resort in the U.S. Virgin Islands 
 
 Preliminary EPA results find methyl bromide was present in the unit where they stayed 
 
 (CNN) A Delaware father is in stable condition and improving as his two boys remain in critical condition after they became sick -- perhaps from pesticide exposure, federal officials say -- during a trip to the U.S. Virgin Islands. 
 
 Steve Esmond, his teenage sons and the teens' mother fell ill more than two weeks ago in St. John, where they were renting a villa at the Sirenusa resort. 
 
 The family has confidence in their medical professionals and is hopeful for a full recovery, according to a statement released Monday from the family's attorney, James Maron. 
 
 The teens' mother, Theresa Devine, was treated at a hospital and released, and is in occupational therapy, Maron said. 
 
 The U.S. Environmental Protection Agency said Friday that the presence of a pesticide at the rented villa in St. John may have caused the illnesses, which were reported to the EPA on March 20. 
 
 Paramedics were called to the villa, which the family was renting. 
 
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 Esmond was found unconscious; the boys and their mother were having seizures, Maron said. The lawyer did not say who called the paramedics. 
 
 Elias Rodriguez, an EPA spokesman, said the agency's preliminary test results "do show that there was a presence of methyl bromide in the unit where the family was staying." 
 
 Exposure to methyl bromide can result in serious health effects, including central nervous system and respiratory system damage, according to the EPA. 
 
 The use of the pesticide is restricted in the United States because of its acute toxicity. It's not allowed to be used indoors. Only certified professionals are permitted to use it in certain agricultural settings. 
 
 In strawberry fields 
 
 For example, the pesticide is injected into the soil of some U.S. strawberry fields, said Judith Enck, an EPA regional administrator. 
 
 "We trust that the strawberry producers are making sure that there's not excess pesticide residue on strawberries," Enck said. "You definitely want to wash them really good. 
 
 "This is a pesticide that's been around for a long time, and ironically because of its impact and damage to the ozone layer, it's being phased out because of the air impacts of this fumigant," Enck added. 
 
 Field workers at a Connecticut nursery were poisoned by the chemical in 1990, according to the Journal of Industrial Medicine. 
 
 In 2011, warehouse workers in California fell ill after exposed to grapes imported from Chile fumigated with methyl bromide, the U.S. Centers for Disease Control and Prevention said. 
 
 Banned in many places 
 
 Dr. Sanjay Gupta, CNN's chief medical correspondent, said many parts of the world banned the chemical, a neurotoxin. The agent is to be used only outdoors. 
 
 The chemical is also odorless and colorless, Gupta said. 
 
 JUST WATCHED What can you do to prevent pesticide poisoning? Replay More Videos ... MUST WATCH What can you do to prevent pesticide poisoning? 02:13 PLAY VIDEO 
 
 "It's not something that you would have any warning of," Gupta said. 
 
 The chemical is often mixed with tear gas so people can be aware of its presence, he added. 
 
 The EPA said it is working with local government agencies to investigate whether the family was made ill after a fumigation at the resort on March 18 and whether any environmental regulations or laws were violated. 
 
 Enck, the EPA regional administrator, said paramedics were called early on March 20. 
 
 Sea Glass Vacations, which acts as a rental agent for several units at Sirenusa, said the unit directly below the one where the family stayed was recently treated for pests, but that the family's unit was not treated. 
 
 The company said it licensed an outside company, Terminix, for the pest control services. 
 
 On Monday, it ended its contract with Terminix. 
 
 In an email to CNN before the termination, a spokesman for Terminix wrote that the company is "committed to performing all work ... in a manner that is safe for our customers, employees, the public and the environment" and is "looking into this matter internally, and cooperating with authorities." 
 
 The U.S. Department of Justice has initiated a criminal investigation. 
 
 "Many questions remain why an odorless pesticide of this level of toxicity could be manufactured, distributed and applied in a residential area resulting in this family's injuries," Maron said. 
 
 The attorney added: "The family is confident that the responsible parties will be brought to justice and held accountable." ||||| Play Facebook 
 
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 The toxic chemical that sickened a Delaware family at a Virgin Islands resort last month had been used there other times over the past year, the Environmental Protection Agency said. 
 
 The EPA was notified on March 20 that the family was hospitalized after a fumigation days earlier at Sirenusa Resort in Cruz Bay, St. John. The agency found that the apartment below where the family stayed had been fumigated with methyl bromide. 
 
 An EPA spokeswoman said Thursday that the chemical was also used in other units in October 2014. 
 
 Methyl bromide, an odorless pesticide and neurotoxin, was banned for indoor residential use in 1984 by the EPA, which also holds authority over the U.S. Virgin Islands. 
 
 Initially, the EPA had said methyl bromide had been used in more than one apartment in March. But on Thursday, spokeswoman Mary Mears clarified that it was just one that month. 
 
 Inhaling the chemical can "be fatal or cause serious acute illness or delayed lung or nervous system injury," according to the EPA. 
 
 Stephen Esmond, his wife Theresa Devine, and their two teenage sons were hospitalized in Philadelphia after their exposure. Devine had been discharged as of Monday and Esmond is in stable condition — but the two boys are still in critical condition, a family spokesman told NBC News. 
 
 Methyl bromide was used in a first-floor apartment. Esmond and his family were staying on the second floor of that unit, Enck said. 
 
 Enck said the chemical was used by pest control company Terminix. 
 
 Sea Glass Vacations LLC, the company that manages many of the rental units at Sirenusa, said it was unaware Terminix allegedly used the chemical, and it has cancelled all of its contracts with Terminix. 
 
 The United States Department of Justice has also opened a criminal investigation into the case, according to a Securities and Exchange Commission report filed by ServiceMaster Global Holdings, Inc., the parent company of Terminix. 
 
 "We are sending our thoughts and prayers to the family impacted by this tragic incident, as well as those around them," Sea Glass Vacations said in a statement. "We remain committed to full cooperation with all local and federal authorities currently investigating this matter." 
 
 The company said only one unit was fumigated by Terminix in the recent case. Sea Glass Vacations said Terminix may have used the chemical when fumigating four other units in October. Terminix has been providing pest control at the property since late 2013. Terminix did not respond to a request for comment. 
 
 The EPA is investigating whether there have been any other reports of medical symptoms in the complex over the past year. The Agency for Toxic Substances Disease Registry is interviewing tourists who stayed in the apartments where methyl bromide was used and interviewing housekeeping staff, Enck said. 
 
 The Department of Justice could bring criminal charges forward if the EPA investigation finds evidence of wrongdoing. 
 
 "The first and top priority is protecting public health," Enck said. "Second is told responsible parties accountable for any violation of environmental laws." 
 
 IN-DEPTH 
 
 — Elizabeth Chuck
– A Delaware family that became seriously ill in the US Virgin Islands was poisoned by an odorless and highly toxic pesticide that should never have been used indoors, according to Environmental Protection Agency investigators. Methyl bromide was used to fumigate a unit at the Sirenusa resort on St. John days before the family was hospitalized on March 20. It was also "used in other apartments around the same time that it was applied here, and also in different apartments in the complex within the past year," an EPA official tells NBC News. Weeks after they became ill, two teenage boys are still in critical condition after being airlifted to a hospital on the US mainland; their father is in stable condition. "We have confirmed that the problem is indeed methyl bromide," which was banned from indoor use in the US—including the Virgin Islands—decades ago, an EPA official tells the AP, describing the gas as a "potent neurotoxin" that "can cause convulsions, coma, cognitive deficits, inflammation of the lungs." The Justice Department has begun an investigation and Terminix, the pest control company involved, says it is cooperating, CNN reports. "Many questions remain why an odorless pesticide of this level of toxicity could be manufactured, distributed, and applied in a residential area resulting in this family's injuries," the family's lawyer said in a statement.