A chemical manufacturer has decided to keep six new chemicals off the market rather than go through a testing process to convince the Environmental Protection Agency that they are safe, the EPA said yesterday.

Refusing because of legal restrictions to disclose the name of the company, ERA Assistant Administrator Steven Jellinek praised the firm for "good, responsible action" in response to a recent EPA pre-production ban on the chemicals.

Jellinek's office of toxic substances control prohibited manufacture of the six industrial plasticizers last month after a National Cancer Institute study of a closely related plasticizer found strong indications that it caused cancer in laboratory animals.

Jellinek noted the company had not known about the cancer study, but it had not reported any safety stuides of its own.

Plasticizers are among the chemicals added to products that require some flexibility, such as garden hoses, refrigerator gaskets and floor tiles. More than 1.5 billion pounds of plasticizers were produced last year.

The EPA prohibited the company from manufacturing the new chemical until it produced safety reports that would satisfy the agency of the substances, relative harmlessness to humans and the environment.

But the firm told EPA this week that it had decided to withdraw the chemicals altogether. "They said the testing would be too expensive . . . and they were also concerned that their identity and the volume of chemicals they were going to produce be kept secret," Jellinek said in an interview.

The April 28 ban was the first such EPA action under the 1976 Toxic Substances Control Act for which regulations have yet to be issued. The company had the option under the law of appealing the decision through federal courts.