A Delaware family has been hospitalised after it is believed they were exposed to a toxic pesticide while on holiday in the US Virgin Islands . Headteacher Steve Esmond , his wife , Dr Theresa Devine , and their two teenage sons fell seriously ill during their stay at the Sirenusa Condominium Resort on the Caribbean island of St. John . The family were airlifted to separate hospitals in Philadelphia suffering major respiratory trauma , with 11th and ninth grade sons , Sean and Ryan , in critical care . Headteacher Steve Esmond and his wife , Dr. Theresa Devine , were on holiday with their two sons . The family was staying at the $ 800-a-night Sirenusa Condominium Resort on the Caribbean island of St. John . It is believed the harmful chemical was used to disinfect a neighbouring suite at the complex the day the family arrived for their eight-night stay , 6ABC reported . The family 's attorney , James Maron , said the Esmonds began to have seizures on Friday , and they were taken to island hospitals and airlifted back to the Philadelphia area by Monday . 'Their conditions , while serious , are stable and improving , ' the attorney said in a statement issued to The News Journal . 'The boys remain in critical condition . ' The odourless pesticide used inside a suite at the complex was reported to be methyl bromide , which is used to treat mould , insects and rodents . The Environmental Protection Agency ( EPA ) are investigating whether the family was poisoned by a pesticide . According to the US Environmental Protection Agency , the odourless pesticide can be fatal or cause serious central nervous system and respiratory system damage . As it is acutely toxic , use of the pesticide is restricted to outdoor use only in the United States . Investigators confirmed that the chemical was applied 'to deal with indoor bugs , ' said Judith Enck , an administrator for the EPA , to USA Today . 'Their conditions , while serious , are stable and improving , ' a statement from Maron 's law office said . 'The boys remain in critical condition . ' Steve Esmond is the administrator of Tatnall Middle School in Wilmington , Delaware , and his wife , Theresa , is a dentist . Sea Glass Vacations , which acts as a rental agent for several units at Sirenusa Condominium Resort , told 6ABC that it is aware that the family became seriously ill , but that the unit where they stayed was not treated with a pesticide . It said that pesticide was used to treat the unit immediately below the suite where the Esmonds were staying .
Esmond resorts began to have seizures at their resort at US Virgin sites . It is suspected that bromide was used at the resort Resort . Use of the chemical is restricted to outdoor use in America . patients are in a serious condition and teenage sons in a critical state .