For parents wanting to provide their children some good, clean off-roading fun, the Fushin,

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a smaller-than-normal all-terrain vehicle, seemed just the thing.

Except the Chinese product with jaunty yellow paint and a low$250 price tag was missing one feature: front brakes.

In the $5 billion market for A.T.V.’s, the huge growth of Chinese imports into the United States is becoming the latest challenge for the Consumer Product Safety Commission, which is starting a global campaign to improve the safety of a product that kills about 900 people a year—more than any of the 15,000 other products the agency regulates.

Fushin, whose A.T.V. also had sharp handlebars that could cause injury, agreed to a voluntary recall of the models marketed for children. But that did not solve the larger problem. A few weeks ago, at the port of Houston, a shipload of Chinese A.T.V.’s that did not meet United States safety standards was seized by customs officials. Fushin’s office in the United States declined to comment.

The Consumer Product Safety Commission is creating new rules under a law passed last year that took voluntary industry standards for A.T.V.’s and made them mandatory. It is scrutinizing sales of Chinese A.T.V.’s over the Internet.

‘‘We’ve seen cases where the Chinese manufacturers have not met our standards,’’ said Inez Tenenbaum, the agency’s chairwoman, who led a 10- member U.S. delegation that met last month with government officials and A.T.V. manufacturers in the industrial city of Taizhou in Jiangsu Province.

‘‘We explained to them, here are the specs that we have and you will have to build based on our standards.’’ But while the legislation passed last year gave the commission broad new powers to regulate A.T.V.’s, both imported and American-made, the Chinesemade vehicles present a special problem.

As is the case with otherChinese imports, like tainted toys and drywall, legal accountability can prove hard to establish, and the commission often can clamp down on problem products only after the damage has been done and reported.

A big concern is that most of the Chinese A.T.V.’s are used by children, some as young as 6. The legislation expanding the commission’s purview was the result of tainted imports from China in the first place — contaminated pet food and toys coated in lead paint—and covers items used by children under 12, including A.T.V.’s.

‘‘As with other products that come in from China,’’ said Russ Reiner, a trial lawyer in Redding, California, who specializes in vehicle rollover cases, ‘‘it is difficult for the commission to have a mandate that will really affect Chinese manufacturers. It is difficult to police.

Many times, productscomehere through shell corporations. The commission can warn the public about products that are not safe. But generally there is no action until after consumers make complaints.’’ Unlike automobiles, which face strict U.S. government safety standards and whose users must be licensed, safety requirements for off-road vehicles are far more limited. Drivers of A.T.V.’s generally need no license, and teenagers frequently post videos on YouTube showing off their daring stunts.

For the most part, the A.T.V. market is divided into two groups: The first, in industry jargon, are the traditionals, which are big American and Japanese companies like Polaris,Honda, Yamaha, Arctic Cat, Kawasaki and Suzuki. The traditionals make and sell their products in the United States.

Chinese imports, which began to enter the market in the last decade, make up the second group. In 2002, fewer than 100,000 A.T.V.’s were imported into the United States and sold, compared with 800,000 sold by the traditional sellers.

That gap has narrowed. Last year, according to a report from Power Products Marketing, a research firm in Minneapolis, the traditionals sold only 220,000 more units than the Chinese, though both groups’ sales have suffered in the economic downturn.

Chinese A.T.V. makers specialize in the smaller, less-powerful vehicles that are usually used by children, from6 to 16 years old. More than 83 percent of all youth vehicles are imports, while the traditional makers cater to the adult market and manufacture the bulk of the bigger models. For parents, the appeal of a Chinese A.T.V. is its flashy design and a price tag that is a third to a half lower than its domestic counterparts.

‘‘It’s basically a race to the bottom to see who can get the cheapest machine,’’ said Matthew Camp, an industry analyst with Power Products. ‘‘For some Chinese companies, it is how many units can they pump out in order to survive.

Margins are thin, and they have to pump them out to make money.’’ On average, the commission reports, more than 100 children are killed each year in A.T.V. accidents; 40,000 are sent to the emergency room. The commission does not break down whether those accidents occurred on Chinese A.T.V.’s or domestic ones.

Until the Consumer Product Safety Improvement Act was enacted last year, A.T.V. safety standards were strictly voluntary and followed only by the traditional sellers. The trade association representing traditional A.T.V.

makers welcomed the mandatory standards as a way of leveling the playing field with the imports.

Paul Vitrano, general counsel for the trade association the Specialty Vehicle Institute of America, accompanied Mrs.

Tenenbaum on her trip to China.

‘‘Our trip to China showed therewas a lack of understanding or information about the new standards,’’ Mr. Vitrano said. ‘‘We told the Chinese that there can be virtually no Chinese exports to the U.S. without compliance. Some companies are ahead of the game in complying. Others are not aware of it or don’t understand what to do.’’