Problems with the solution. (Chemical Exposures).

Two chemicals singled out by the United Nations Environment Programme (UNEP) for their potential to damage the ozone layer may also cause human health problems. Based on animal data, one of these chemicals, 1-bromopropane (1-BP), was recently reviewed by the National Toxicology Program Center for the Evaluation of Risks to Human Reproduction (CERHR) for its potential to harm human reproductive health, with the conclusion that more research is needed on its human health effects. Due to evidence of kidney tumors in animals, the other chemical, hexachlorobutadiene (HCB), has been classified by the U.S. Environmental Protection Agency (EPA) and the National Institute for Occupational Safety and Health as a possible human carcinogen.

UNEP issued a warning in September 2001 about 1-BP and HCB following reports of their increasing use as alternatives to hydrochlorofluorocarbons, which are banned and being phased out under the Montreal Protocol, an international agreement to discontinue use of ozone-depleting chemicals. 1-BP and HCB are not yet included in the Montreal Protocol, and because they break down close to the earth's surface, scientists believed they pose only a neglible threat to the ozone layer. But recent studies indicate that their long-term use under certain conditions actually may contribute to ozone layer damage.

A CERHR expert panel recently reviewed 1-BP for reproductive and developmental toxicity and is scheduled to release its final report in early spring 2002. A draft report points to the need for a well-designed human study with adequate exposure measurements. The NIEHS Environmental Toxicology Program, in conjunction with the National Institute for Occupational Safety and Health, is already funding some occupational exposure studies of 1-BP, says John Bucher, the program's deputy director.

In 2001, two manufacturers--Albemarle Corporation and Atofina--recommended that 1-BP not be used in applications in which worker exposure can't be tightly controlled, such as certain solvent or adhesive uses. Also, UNEP has asked parties to the Montreal Protocol to encourage industries to use 1-BP only when there is no alternative.

1-BP is known to be toxic in animals. Gaku Ichihara, a professor in the department of occupational and environmental health at Japan's Nagoya University, wrote in the May 2000 issue of Toxicological Sciences that after inhaling 1-BP, rats showed muscle weakness and deterioration of motor nerve function. Inhalation of 1-BP has also been shown to decrease fertility in male and female rats.

1-BP is used in spray adhesives and as a solvent in cleaning electronic components. People working with such applications can be exposed to 1-BP by inhalation or skin contact. There is currently no information indicating public exposure to 1-BP through air, food, or water, says CERHR director Michael Shelby.

According to Shelby, current usage of 1-BP is less than 5 million pounds per year. Although this may increase somewhat if 1-BP continues to be substituted for hydrochlorofluorocarbons, large increases in production don't seem likely because the chemical is very expensive compared to many other organic solvents and cleaners.

Although a December 2000 report from the California EPA titled Evidence on the Carcinogenicity of 1,3-Hexachlorobutadiene states that no data on long-term effects of human exposure to HCB have been found, there is evidence of toxicity in animals. Short-term skin contact with HCB has resulted in kidney, brain, and liver damage in rabbits, and rats and mice that ingested low concentrations of HCB over short and long periods developed kidney tumors and liver damage.

HCB is used as a solvent and to make lubricants and rubber compounds. The public could be exposed to HCB released into air, water, or soil during disposal of industrial waste, according to a toxicologic profile released by the Agency for Toxic Substances and Disease Registry. Some public drinking water contains HCB in amounts under the U.S. EPA maximum contaminant level of 1.0 ppb. The EPA Toxics Release Inventory for 2000 projected that 4,488 pounds of HCB would be released as waste that year in the United States.