Jay Angoff, counsel to the National Insurance Consumer Organization, is so used to attacking the insurance industry that he says he feels funny being on the industry's side for once.

But his group, self-styled watchdogs of the nation's insurers, has found itself supporting the views of industry representatives on a precedent-setting bill passed by the City Council aimed at preventing discrimination in insurance coverage for persons who have tested positive as having been exposed to the virus that causes acquired immune deficiency syndrome.

"We scream at them insurance companies for cutting off day care centers and midwives, but on AIDS we are on the same side," Angoff said. "With AIDS, they are trying to make rates based on risk," which, he added, is what his organization has pushed for other types of insurance.

The united front presented by the industry and a group that considers the industry its archenemy is just one indication of the complex issues involved with the legislation and the many uncertainties over AIDS that different parts of society are trying to deal with.

The council unanimously approved the measure, which the gay community had been pushing. While the bill would not extend its protections to persons who actually have AIDS, it would prevent life and health insurers in the District from making anyone take a test for exposure to the virus or, if a person had taken the test, from denying coverage on the basis of a positive result.

The bill would for five years prevent insurers from charging higher premiums to someone with a positive test, but after that time the insurers could make a case to the D.C. superintendent of insurance for higher charges if an accurate test is available and the risk of developing AIDS can be assessed according to experience.

City Council members said they want to protect persons who test positive for exposure to the virus from being unfairly discriminated against in what some called an atmosphere of rising public hysteria over the disease. They questioned the reliability of current tests and said there is little evidence to justify treating persons who test positive differently from others.

Representatives of the national insurance industry, which spent $200,000 in a media campaign against the bill, argued that rates would have to rise for all persons to make up for the added risks and costs thrust upon the industry by the bill. They cited figures that between 5 and 19 percent of those who test positively for exposure to the virus contract the disease itself in two to five years, and that health care costs for an AIDS victim average $140,000.

Some predict that people testing positive will go out and get a million-dollar life insurance policy, which the industry will have to sell at the same price as for someone who has no evidence of exposure to the virus, and that several years down the road the payouts on these policies could skyrocket.

As a result, some insurance companies simply will pull out of the District and refuse to write policies in the city, it was said.

But now that the bill has passed, and the mayor has indicated he will sign it, most insurers seem to be taking a wait-and-see attitude.

Dr. Neal Pickett, medical director for Metropolitan Life Insurance Co., one large national insurer, said that the company is having some internal discussion of the ramifications of the bill but that "we don't have any plans to pull out . . . . We are not even considering it." Such a decision might be made if several years from now the company found that its mortality risk had substantially increased as a result of the legislation, he added.

"There has been a lot of talk about pulling out of the city, but I just don't see it happening," commented Leslie H. Jackson of the D.C. Life Underwriters Association.

Jackson did predict that insurers would see more applications for large policies from persons with positive tests, however. A million-dollar whole-life insurance policy for a 30-year-old male now would cost about $15,000 a year, but a million dollars in term insurance would start at a rate of about $1,330 for a nonsmoking 30-year-old, Jackson said.

While there were rumblings at one point that the insurance industry might make an attempt to get the legislation overturned on Capitol Hill, the industry lobbyists at the forefront of the effort to defeat the bill are backing off.

"The decision was made here that that isn't a good use of our time and efforts . . . . We are going to sit tight for the time being," said Debbie Chase, spokeswoman for the American Council of Life Insurance, whose media blitz against the legislation offended several council members.

Chase said the group now has started talking with gay rights organizations and wants to keep in touch with them about the impact of the bill. "We will work with our former rivals. The proof will be down the road," she said.

On the mayoral campaign front, Mayor Marion Barry netted the endorsement of the Food and Allied Service Trades Metro Washington Council last week at a rally held by the rank and file members of the group, which includes building, food, hotel, communications and other unions in the District.

FAST President Minor Christian labeled Barry a "friend of the worker" and Ron Richardson, leader of the Hotel and Restaurant Employees local here, said the union group, which supported Barry opponent Patricia Roberts Harris in 1982, switched to the incumbent this year because "he has been there when we needed him . . . . He is a winner."