All-terrain vehicles are three- or four-wheeled first cousins of the motorcycle, with huge balloon tires, designed to bounce over sand dunes and hilly countrysides at speeds that, one current ad claims, "will embarrass the wind."

But a windstorm of legal opposition to the vehicles is gathering just as fast, and the industry -- almost exclusively U.S. subsidiaries of Japanese motorcycle manufacturers -- is about to have its own hurricane of litigation and legislation to cope with.

State attorney generals, the Justice Department and Congress are all drawing up attacks designed to, at the least, cut out a substantial part of the market for the machines, which have some commercial uses in remote territories but are primarily sold as fun machines. At the same time, plaintiffs attorneys for victims of ATV accidents have filed hundreds of damage suits that have the potential of eating up much of the profits from the $750 million in sales racked up by the product. It is the accidents that are at the heart of the pending legal actions.

ATVs are accused of adding to noise pollution and speeding land erosion, but the safety issue is the one that has grabbed the enforcers. "These are killer machines," argues Texas Assistant Attorney General Stephen Gardner. "I think they ought to be yanked off the market."

Figures compiled by the Consumer Product Safety Commission indict ATVs in 883 fatal accidents since they became popular in 1982. Most alarming: one-fifth of those deaths were of children age 11 or younger, and another fifth were children between 12 and 15. Over 300,000 injuries requiring treatment at emergency rooms have been blamed on ATV accidents, and 15 percent of those patients were hospitalized -- an unusually high percentage.

Ironically, the determination of the law enforcement officials to do something about the safety problem comes as the accident rate has leveled off. Preliminary 1987 figures suggest that it is even declining. Sales of ATVs are off from their peak, too, and the manufacturers say that with fewer inexperienced riders, there are fewer accidents.

The companies have also been careful recently to run advertising featuring helmeted riders and containing warnings to take safety precautions. They have also suggested that states license drivers and requiring some training before youngsters power up.

Honda Motor Co. once had the ATV market to itself, and still controls more than half of the annual sales of the vehicles. Earlier this month, Honda made just those points in an all-day closed-door meeting with a delegation of state law enforcement officials led by Missouri Attorney General William L. Webster.

Webster warned the company in advance that unless it was ready to promise "a number of measures designed to eliminate needless deaths and injuries," the state attorney generals would begin "protracted and expensive lawsuits." The legal theory: In not spotlighting the hazards, the manufacturers have misled buyers. A total of 26 states have agreed to act together on the problem.

After the meeting with Honda, "All of the states agreed that we were all very disappointed" that the company emphasized driver mistakes as a cause of accidents and denied any design defects in the products themselves, said California Senior Assistant Attorney General Herschel Elkins, who hosted the session. Some of the AGs believe that the tendency of the vehicle to flip over is so great that they should be banned entirely.

The state officials are now hammering out a unified litigation approach, which may be ready to be debated at a Dec. 10 meeting of the National Association of Attorneys General. The CPSC, after failing to get a promise from manufacturers to limit sales to buyers 16 and older, last year asked the Justice Department to sue the companies. That request is still being formulated into a suit, which will ask for warning labels, driver training, and, perhaps, a mandatory refund to unsatisfied customers.

The suit will be legally tricky, because it will be the first to try to use the consumer product safety law against a product whose alleged defect is not in the design but in the marketing approach. But the department is taking a lot of political flak for not moving faster; Democratic presidential candidates Albert Gore Jr. and Paul Simon are making an issue of ATV safety and what they view as a sluggish approach by the administration.

The state officials say they will back off if Justice gets tough with the manufacturers. The industry is in the process of adopting formal standards for ATVs, and already the major companies are complying with some aspects of the proposals, such as labeling machines by the age of driver -- 8 and older -- for whom they are appropriate.

But if the firms substantially redesign the vehicles that could be taken as an admission that the models already sold were less safe than they should have been.

That's a serious concern because the manufacturers already have their hands full with product liability damages suits brought on behalf of accident victims.

Moskowitz covers legal affairs for McGraw-Hill World News.