Methyl bromide is still used on food in the US, despite being ‘banned’

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By Barbara Kessler
GRN Reports

Methyl bromide, the chemical suspected of sickening and paralyzing members of a Delaware family vacationing in St. John, is commonly used in growing and storing certain US produce.

This toxic chemical, capable of severely harming people neurologically, is banned by an international agreement known as the Montreal Protocol. But it has continued to receive “critical use” exemptions from the US EPA so that it can be used as a soil fumigant in strawberry fields and on other crops to prevent spoilage during storage.

This exemption for agricultural use does not have a “specified end date,” an EPA spokeswoman said, “but the amount of methyl bromide allowed for critical uses has declined from 7,659 metric tons in 2005 to 376 metric tons in 2015. The agency is still working to determine how much methyl bromide to allow for critical uses in 2016 and 2017.”

Methyl bromide gas is pumped into food storage units to kill a certain mite found on grapes imported from Chile. It is also used in the food processing of rice, pet food, walnuts, plums, figs, raisin, dates and dried pork products to keep pest infestations down, according to EPA documents.

In strawberry fields, methyl bromide is used to kill soil life that  produces bugs that could eat or leave imperfections on the fruit. The prescribed application of methyl bromide (MeBr) is carefully regulated to prevent exposure to the gas by farm workers or bystanders.

Applicators are specially trained and wear gas masks, and farms are required to set up buffer zones based on the amount of the toxic being used. Typically, the chemical is injected into the ground, sometimes under a tarp, but off-gassing from the application can harm people nearby. Eventually, methyl bromide breaks down in the soil into bromide and methanol.

Methyl bromide had been used to fumigate to residential and commercial buildings to kill termites, spiders, mites, rodents and snakes, but this type of use was stopped in the US when the ban of methyl bromide went into effect in 2005, according to the EPA spokeswoman and the EPA’s registration document detailing allowed uses for this compound.

A 2006 image of the ozone hole from a NASA photo.
A 2006 image of the ozone hole from a NASA photo.

Under the 1987 Montreal Protocol, all United Nations-recognized countries agreed to ban methyl bromide and other gases because they were depleting the ozone layer, which acts as a filter against the sun. The “ozone hole” caused by these gases allows harsher UV rays to reach the earth, harming the planet and hurting humans and animals in numerous ways. Ozone depletion is blamed for rising skin cancer in humans and as a contributor to cataracts and macular degeneration.

“Ozone-depleting substances, including methyl bromide and other halogenated gases such as chlorofluorocarbons (CFCs), halons, and hydrochlorofluorocarbons (HCFCs), are very stable in the lower atmosphere. They eventually drift into the stratosphere, where they undergo a series of cyclical reactions that destroy ozone,” the EPA explains on its website.

Back at ground level, methyl bromide is acutely toxic if inhaled.

Delaware family poisoned, Theresa Devine, Stephen Esmond

The Delaware family, Steve Esmond, Theresa Devine and their teenage sons, fell seriously ill on March 20 at Sirenusa resort in St. John, two days after the condo unit below theirs was treated for pests with methyl bromide gas. Theresa, a dentist, has been released from the hospital; Steve, a private school administrator, remains paralyzed and the boys remained unconscious, according to news reports this past weekend when details of this case became public. The EPA is investigating the use of “Meth-O-Gas” at the resort.

Methyl bromide is “an extremely toxic vapor,” according to Extonet, a consortium of universities (Cornell and others) that combined resources to analyze and report on toxic chemicals.

“In humans, methyl bromide is readily absorbed through the lungs. Most problems occur as a result of inhalation. About 1,000 human poisoning incidents caused by methyl bromide exposure have been documented, with effects ranging from skin and eye irritation to death. Most fatalities and injuries occurred when methyl bromide was used as a fumigant,” the group reported back in 1993.

Most incidents of sickness have involved agricultural workers, such as a pair of men in California who fell ill in 2010 after working in close quarters with grapes being treated with methyl bromide gases. The men suffered from neurological effects, such as dizziness, memory difficulties and loss of balance. One of the men recovered, and the other had continuing effects, according to the Centers for Disease Control.

Methyl bromide gas is especially insidious because it is odorless and can accumulate in the human system for a short time before its effects are noticed.

“First symptoms often are due to damage to the nervous system, and may be delayed from 48 hours to as long as several months after exposure. This delay, combined with methyl bromide’s lack of odor, means that the victim may not realize that exposure is occurring until much time has passed,” Extonet reports.

This gradual poisoning, combined with the neurological confusion, puts people at risk of continued exposure.

“Soon after inhalation of large doses, symptoms may include headache, dizziness, nausea, chest and abdominal pain, and a dry throat. Three to 12 hours after vapor inhalation, symptoms include slurred speech, blurred vision, temporary blindness, mental confusion, and sweating. More severe symptoms may include lung swelling; congestion; hemorrhaging of the brain, heart, and spleen; severe kidney damage; and numbness. Death may occur within 1-30 hours, usually from respiratory failure.”

The slowed onset of symptoms could fit with the timing of the St. John incident, in which the neighboring condo unit was treated on March 18 and the family was so sick they were taken to the hospital by paramedics on March 20.

Terminix, the company responsible for treating the condo, has said they’re investigating what happened.

As for those strawberries grown in fields treated with methyl bromide, the main danger from this practice appears to be during the immediate off-gassing that occurs right after the chemical application. The EPA requires that applicators have annual training and has a long list of rules for how to use the chemical without causing workers or bystanders any harm.

After the fumes dissipate, the methyl bromide breaks down in the soil, posing little risk of runoff or water contamination, according to the EPA. The strawberry fruits are untouched by the chemical because the application is done before planting.

Tarp removal after methyl bromide application. (Photo: USDA)
Tarp removal after methyl bromide application. (Photo: USDA)

Methyl iodide was considered a promising replacement for methyl bromide in strawberry fields, because it did not have the same effect on the ozone layer. But methyl iodide is carcinogenic and damages DNA. Environmentalists and farm worker groups united to stop its use, which one scientist with the Pesticide Action Network predicted would increase cancer, miscarriages and thyroid disease.  They won that fight in 2012.

A non-toxic alternative being used by some strawberry growers involves solarizing the soil in their fields by covering them. The heat produced reduces the soil pests. Strawberries grow well in field prepared this way and growers save on chemical costs, according to one study in California.

For consumers worried about pesticides on their fruits and vegetables, there are several chemicals, applied during the growing season, that can potentially end up on your strawberries.

Chemicals used on non-organic or “conventional” strawberries are numerous and according to the US Department of Agriculture include these:

Acetamiprid, Azoxystrobin, Bifenethrin, Boscalid, Captan, Carbendazim, Cyprodinil, Fenhexamid, Fludioxonil, Imidacloprid, Malathion, Malathion oxygen analog, Methoxyfenozide, Myclobutanil, Propiconazole, Pyraclostrobin, Pyrimethanil, Quinoxyfen, Spinosad A, Spiromesifen, Tetrahydrophthalimide, Triflumizole.

The USDA reports show that for any given pesticide on the list above, 10 to 55 percent of the strawberries the agency sampled tested positive for that chemical, though that doesn’t necessarily mean it was present in an amount considered dangerous. The high use of chemicals on conventional strawberries, however, has placed them on the “Dirty Dozen” list of fruits and vegetables compiled by the Environmental Working Group (EWG) to highlight the problem of pesticide residues.

A single sampling of strawberries by the EWG found traces of 13 or more different pesticides. The advocacy group advises consumers to buy Organic certified produce which are not treated with pesticides or to take special care in buying the fruits and vegetables that make its “Dirty Dozen” list, which includes along with strawberries, apples, peaches, grapes and potatoes.

Yes, potatoes. By weight, the average potato contained more pesticides than any other produce, according to EWG’s testing.




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