Which gas helps farmers by killing harmful diseases in the soil?
A: Propane. B: Ethyl alcohol. C: Methyl bromide. D: Alka Seltzer.
The Answer is C! Methyl bromide is injected into the ground when planting and has effects that last for the whole growing season. Methyl bromide can take out most anything alive. Most of the state's almonds, grapes and ornamental flowers also depend on methyl bromide. In Florida, more than 50,000 acres of tomato fields are treated every year with the gas. In the United States, fruits and vegetables worth hundreds of millions of dollars are treated with methyl bromide before export or import.
The U.S. Department of Agriculture has estimated that up to $1.5 billion in revenue would be lost each year if methyl bromide were not employed. California calculates that its agricultural losses without the gas could exceed $300 million. Experts in Florida say their stated is looking twice at that.
But by January 1, 2001, the manufacture and importation of methyl bromide is to be banned in the United States.
Methyl bromide has acute effects. In high doses it acts like a nerve gas as it has killed people. In low doses it may be developmental toxin, if the findings from tests on pregnant rabbits and rats extend to humans. But these hazards have not blocked its use. The substance hasn't been shown to cause cancer, the public's deepest fear. But conclusive data may be hard to come by because, paradoxically, the chemical is so deadly. Scientists administering it to dogs, for example, had trouble keeping their subjects alive long enough for the effects of chronic exposure to arise.
The use of methyl bromide increased in the 1970s and '80s as other compounds earned environmental black marks. Today, the strawberry and tomato growers are fighting to keep methyl bromide because there are no good alternatives left, or so they claim.
Methyl bromide's great advantage over other chemicals is that it leaves no toxic residue in the soil. Yet it has fallen afoul of regulators because of an unusual environmental twist. According to the Environmental Protection Agency, the compound can cause cancer all right, but by indirect means. Having gassed its targets, methyl bromide escapes the soil and rises to the stratosphere, where its bromine atoms attack the ozone layer. The breakdown of ozone allows more skin cancer for human beings.
By U.S. law, methyl bromide must go, not because it's too toxic but because it's been declared an ozone-depleting substance. Globally, the chemical is scheduled to be phased out by the year 2010.
Ironically, stopping the manufacture of methyl bromide won't end its story. The oceans and forest fires also produce the stuff, together injecting into the atmosphere perhaps twice as much as human use of the fumigant. The oceans apparently now absorb and destroy at least as much methyl bromide as they emit, but the various natural processes at play are not well understood.
