Ralph Nader's Public Citizen Health Research Group announced yesterday it will take court action against the Labor Department's Occupational Safety and Health Administration unless the agency reinstates standards governing exposure of humans to MOCA, a widely used chemical that causes cancer in animals.

MOCA, or methylene-bis 2-chloroaniline, is used in the processing of many types of common plastic and rubber goods, such as polyurethane chair padding, refrigerator insulation and skateboard wheels.

In yesterday's statement, Health Research Group Director Sidney M. Wolfe claimed that despite animal studies linking MOCA with cancer in animals, "OSHA has done nothing since 1975 to regulates this powerful carcinogen."

Wolfe cited an unpublished study by E. I. Du Pont de Nemours & Co. that shows that large doses of MOCA, administered orally, caused bladder cancer in four of six dogs tested. Three of the six dogs "developed premalignant liver changes," according to Wolfe's statement, and one developed cancer of the urethra.

Based on an earlier MOCA study involving rats, OSHA had issued an emergency temporary standard in 1973 for MOCA and 13 other substances considered probable cartinogens. The emergency standard set up regulations requiring manufacturers to establish hygiene standards and set aside restricted areas for the use of carcinogens.

MOCA, to which an estimated 18,000 workers are exposed annually, can be ingested through the skin as well as by inhalation. No MOCA-related deaths or cases of cancer in humans have been documented.

However, in December of 1974, the emergency standard covering MOCA was remanded by a circuit court on the basis of a complaint brought by the Polyurethane Manufacturers of America.

The reason for the court's decision was a legal technicality. The court invalidated the MOCA rule because OSHA's proposed rule on the chemical was made public before an advisory committee had submitted its recommendation on the matter.

Eulah Bingham, now director of OSHA, was then chairman of the advisory committee that recommended that MOCA be treated as a carcinogen and regulated by standards.

Yesterday's statement by Wolfe charged that "OSHA has done nothing since 1975 to regulate" MOCA.

"Since the court threw MOCA standards out in 1975. OSHA's gone to sleep," said Peter A. Greene, an attorney with the Nader group.