is evidence implicating the oceans as a major contributor to stratospheric concentrations of

methyl bromide (Sze and Ko, 1991).

 Ozone depletion potential (ODP) is a factor which determines how much a chemical

contributes to the depletion of the ozone. As a result of the U.S. Clean Air Act of 1990, a

chemical with an ODP of 0.2 or higher must be phased out of production and use by the year

2000 (Chemically Speaking, 1992b). Based on knowledge about removal of methyl bromide

from the atmosphere, the atmospheric life expectancy of methyl bromide has been calculated to

be 1.6 years, with an uncertainty factor of about 4 (Sze and Ko, 1991).

 "Methyl bromide emissions from fumigation application may have accounted for

 1/10 to 1/20 of the current global ozone loss, according to the modeling

 calculations discussed at an international science workshop in Washington, D.C.

 convened at UNEP's request" (Chemically Speaking, 1992b).


Legal Developments Surrounding Methyl Bromide

 The Clean Air Act of 1990 (CAA) is a U.S. federal law, whose primary objective is to

maintain and to enhance the quality of the earth's atmosphere. Title VI of the CAA, called the

"Stratospheric Ozone Protection", lists ozone-depleting substances in either Class I or Class II.

If the substance is classified as Class I, then its ozone depletion factor is greater than 0.2, and

the substance will be required to be phased out by the year 2000. However, if the substance

falls under Class II, then it has a ozone depletion factor less than 0.2 and will be required to be

phased out by the year 2015 or 2030 depending on the situation.

 The Clean Air Act allows anyone to petition the Environmental Protection Agency (EPA)

in order to list a substance to be classified as a ozone depletor (EPA, 1993). After being