Negotiators from 43 nations neared agreement today on a treaty to first limit and later roll back global consumption of chemicals that threaten the earth's protective ozone shield.
But several serious obstacles remained in the way of a treaty signing ceremony, scheduled for this Wednesday. One major roadblock is a demand by the United States that no country be bound by the treaty until countries representing 90 percent of world production sign it.
Manfried Lang, head of the Austrian delegation and chairman of the working group that drafted the protocol said today that ''there will be no protocol'' if the United States insists on the 90 percent figure.
At the end of today's meeting of chief delegates, Lee M. Thomas, administrator of the Environmental Protection Agency and head of the United States delegation, said that there was room for compromise on the United States position.
Another problem is the insistence of the Soviet Union that its production of ozone-destroying chemicals be frozen not at 1986 levels, sought by the other countries, but at consumption levels prevailing when its current five year plan expires in 1990.Continue reading the main story
But most of the delegates and observers here said they were optimistic that the protocol would be adopted and ratified. ''We must not fail, for nothing less than the future of the planet earth is at stake,''said Canada's Environment Minister, Tom McMillan.
The proposed treaty deals with chlorofluorocarbons or CFC's, chemicals used in refrigeration, air conditioning, plastic foams, aerosol sprays, cleaning agents for electronic products and a wide variety of other products. Their use in aerosol sprays has been banned in the United States.
The draft protocol would freeze consumption by developed countries at 1986 levels starting Jan. 1, 1990; it would reduce consumption by 20 percent by Jan. 1, 1994, and by as much as an additional 30 percent by Jan. 1, 1999.
However, the draft would allow total global production of these chemicals go up by as much as 10 percent over the next 10 years in order to meet the needs of the developing countries for industrial growth. The draft protocol would also freeze consumption of halons, chemicals used as fire supressants, by Jan. 1, 1994, but would not require any rollbacks in their use. Dire Predictions
Both CFC's and halons combine chemically with and destroy ozone in the upper atmosphere. That ozone shields the earth's surface from ultraviolet radiation from the sun.
The United States Environmental Protection Agency has projected that if the deterioration of the ozone layer is unchecked, the result will be millions of addditional cases of skin cancer and cancer deaths, increased eye disease, damage to human immune systems, crop losses, depletion of aquatic resources and an increase in global warming.
Mustafa K. Tolba, executive director of the United Nations Environment Program, under whose auspices these negotiations were convened, said that if the protocol were adopted it would be a signal achievement because ''it proves that we can act when our scientists tell us that we are facing a distant threat; it proves that we can move before the full magnitude of the disaster is upon us.''
But Dr. Tolba also pointed out in a speech opening today's meeting of chief delegates, that the formula envisioned in the draft protocol ''is not enough to stop ozone modification entirely.'' He said that even if the agreement takes effect, the earth's ozone shield will be depleted by at least 2 percent by the middle of the next century. Scientists say such a decrease would lead to increased cases of skin cancer and other human illness as well as damage to natural systems.
Both environmental and industry groups attending this meeting as observers praised the draft protocol although both had reservations.
Rafe Pomerance, a senior associate of the World Resources Insitute, an environmental research and policy group based in Washington, called the agreement a ''significant first step.'' He noted that only a year ago that there was not a single proposal before the governments of the world to limit production of ozone-destroying chemicals. Proposal Is Called Inadequate
But Mr. Pomerance and other environmental representatives here said that the actions called for in the draft protocol would not be enough to stabilize the ozone layer. They insisted that an 85 percent reduction in CFC production over the next five years is necessary to stop further deterioration of the ozone layer.
Mr. Pomerance said that because of anticipated increases in consumption by the developing countries, total global consumption is likely to decrease by only 35 percent by the end of the century rather than by the 50 percent specified by the protocol. A United States official said that actual reduction by the year 2000 is likely to be in the 40 to 45 percent range if the protocol is observed.
The preamble to the draft agreement says sets as an ''ultimate objective'' the elimination of chemicals that deplete the ozone layer, but only if technically and economically feasible. The agreement leaves open, however, the possibility of new mandatory reductions in the consumption of these chemicals if new scientific evidence indicates that such action is required.
Scientists are gathering data about the growing hole in the ozone layer that appears over the Antarctic each year. Environmentalists here said that their findings could provide the basis for additional restrictions on CFC's and halons.
Representatives of United States and European chemical trade associations said today that the provisions of the draft protocol could help protect the environment without any undue economic or trade disruptions.
However, Kevin Fay, executive director of the Alliance For Responsible Trade Policy, a United States trade group, said that its adoption could cost industry and ultimately the consumer, billions of dollars for the development of safe, alternative products.
The industry representatives said that an international industry group was being formed to study cooperatively the toxicology of alternatives to CFC's.Continue reading the main story