-- The deaths of four family members in a Texas mobile home that authorities said was due to fumes from a rodenticide have put the spotlight on a chemical called aluminum phosphide, which can turn into a deadly gas called phosphine gas.
Aluminum phosphide is often used in pellet form to kill burrowing rodents, according to Dr. Edward Otton, a toxicologist at the Cincinnati Poison Control Center.
"The moisture in the ground will convert that [buried] pellet into gas and kill the rodent," Otton said.
In Monday's deadly incident in Amarillo, Texas, surviving family members said they had used a pesticide containing the chemical to kill mice under the home, according to local fire officials. Authorities said the chemical turned deadly when a family member sprayed water on the pesticide to try and clear it from under the mobile home.
"At some point, a family member tried washing the chemical from underneath the house with water," the fire department said in a statement on Monday. "When this chemical comes in contact with water, it creates phosphine gas, which is highly poisonous and can cause pulmonary edema and respiratory failure."
Pulmonary edema occurs when fluid collects around the lungs and makes it difficult or impossible to breathe.
All four reported deaths were minors and six other people in the family were hospitalized, according to fire officials.
Jesse Patton, a spokesman for the City of Amarillo Office of Public Communications and Community Engagement, said due to the toxic nature of the pesticide, those using it are are supposed to have a license. Patton said he did not believe the family member who spread the pesticide was licensed to use it.
The gas is toxic when inhaled because it starts to break down the mitochondria, which are contained in every cell in the body, according to Otton. As the mitochondria break down first in the lungs and then in other organs, it can quickly lead to multi-organ failure and death.
"You can expect to see just about every organ in your body [affected] by a massive inhalation of phosphine gas," Otton said, noting that the gas "commonly causes death when people are exposed to concentrated amounts of it."
Once a person inhales the toxic gas, there is little that doctors can do except give supportive care such as ventilation or intravenous fluids.
"There's no real antidote that you can give for this [to] reverse it," Otton explained.
Otton said while cases of toxic exposure to this gas are not very common, they are "an annual occurrence."
It's "usually people who are not professionals and use it incorrectly."
Not all cases occur near a home, Otton said, noting that many involve workers at factories where the chemical is used. In a 2013 report in the Journal of Agromedicine, researchers looked at the effects of the chemical on 10 workers exposed at a pistachio plant. Six of the workers exposed to the gas had respiratory distress as well as chest pain, shortness of breath. In some cases they had decreased oxygen saturation.
The researchers of the 2013 report found children may be especially susceptible to the chemical. However, due to the limited material on the subject, the researcher didn't theorize why children seemed to have worse outcomes when exposed to the gas.
While the gas can be irritating to the throat and lungs, Otton said it can also break down into a substance called phosgene, a gas that can smell pleasant but cause deadly reactions in the body.
"If it smells good, you take a deeper breath," said Otton , who explained phosgene is so dangerous it was even used as a chemical weapon during World War I.
Any family concerned about properly using a rodenticide should call their local poison control center, which can advise them on how to use it safely, Otton said.
"Poison centers are here to help people with this stuff," Otton said.
The national number for the American Association of Poison Control Centers is (800) 222-1222.