Why NAFDAC banned use of methyl bromide as fumigant for pest control

More explanations have emerged on why the National Agency for Food and Drug Administration and Control (NAFDAC) banned the use of methyl bromide as a fumigant in pest control.

Director General (D.G.) of NAFDAC, Prof. Moji Christianah Adeyeye, told journalists that methyl bromide causes toxic health effects and hastens ozone layer depletion.

Adeyeye said methyl bromide is a Class I Ozone Depleting Substance (ODS). “It depletes the ozone layer due to release of bromine atom upon the break down of the molecule,” she explained.

The NAFDAC DG said methyl bromide is a scheduled chemical under the Montreal Protocol for Substances that Depletes the Ozone Layer and was placed on a Phase out Procedure from 2001. She said Nigeria effected the phase out of methyl bromide by January 2015 and since then the product has not been permitted for importation into the country.

Ozone layer depletion is one of the major causes of global warming and its attendant negative effects on health, food production and environment.

According to the United States Agency for Toxic Substances and Disease Registry (ATSDR), methyl bromide, also known as bromomethane, monobromomethane, isobrome, and methyl fume, is a neurotoxic gas that can cause convulsions, coma, and long-term neuromuscular and cognitive deficits.

Exposure to high concentrations of pure methyl bromide may cause inflammation of the bronchi or lungs, an accumulation of fluid in the lung, and irritation of the eyes and nose. Tearing agents added to methyl bromide to provide warning of its presence can also cause these symptoms, even at very low concentrations.

Skin contact with high vapour concentrations or with liquid methyl bromide can cause systemic toxicity and may cause stinging pain and blisters.

According to ATSDR, the most serious effects of acute inhalation exposure involve the Central Nervous System (CNS).

Depending on the concentration and duration of exposure, initial neurologic effects may be delayed for two or more hours after exposure and may include headache, nausea, vomiting, dizziness, malaise, and visual disturbances.

Examination may reveal involuntary movements of the eyes, dilated pupils, slurred speech, trembling of the extremities during movement, impaired gait, impaired sensation of touch, brain damage (that is, cerebellar abnormalities), motor deficits, and decreased reflexes.

Neuropsychiatric abnormalities often occur after acute exposure, although onset may be delayed for days to weeks.

In some cases, mental disturbances may predominate with only mild neurologic signs and no seizures; in others, severe and prolonged seizures may occur. Motor and cognitive deficits may persist indefinitely.

Peripheral Neurologic Peripheral neuropathy may develop after acute exposure to methyl bromide and may persist indefinitely.

The NAFDAC DG told journalists: “Information is available to the Agency that some unscrupulous individuals have been illegally importing methyl bromide for use as pesticide in Nigeria.

NAFDAC is currently carrying out surveillance to identifying such illegal importers and they would be severely sanctioned in line with our extant laws.

“Farmers, exporters of agricultural produce and agro input dealers are hereby advised to desist from using methyl bromide as a pesticide. Safer alternatives are available. Contact nearest NAFDAC office for advice on safer alternatives.

Anybody in possession of methyl bromide should submit it to the nearest NAFDAC office.”

Adeyeye added: “Methyl bromide is colourless, odourless, noncorrosive and non-flammable, highly toxic to a broad spectrum of insects from egg to the adult stage. It was primarily used as a fumigant in stored product pest management.

“Methyl bromide is an extremely toxic vapour. In humans, Methyl bromide is readily absorbed through the lungs. Most problems occur as a result of inhalation. Methyl bromide is a dangerous cumulative poison.

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 odour, means that the victim may not realize that exposure is occurring until much time has passed.”