A House subcommittee is looking into allegations that John A. Todhunter, the Environmental Protection Agency's assistant administrator for toxic substances and pesticides, may have been unduly influenced by his frequent contacts with chemical industry officials.

As part of the inquiry, Rep. Mike Synar (D-Okla.) asked for Todhunter's appointment calendars last week, but was told that Todhunter has torn up his calendars and telephone logs for all but the last two months and also has destroyed separate lists he kept of meetings with industry representatives.

Todhunter began ripping up his calendars last spring, according to an EPA spokesman. At that time, House Democrats questioned appointments showing that Todhunter had breakfasts and dinners with chemical industry officials before making major regulatory decisions regarded by the industry as favorable.

John W. Hernandez Jr., who was then the EPA's second-ranking official and is now its acting director, also attended some of these private meetings with industry representatives, according to Todhunter.

After the resignation this week of EPA Administrator Anne M. Burford, House Democrats are continuing to sift allegations about other members of Burford's senior staff who remain at the agency.

Synar and other congressional critics are questioning whether Todhunter and other officials, through a combination of previous employment, current social ties and philosophical outlook, may be too close to the industries they regulate.

Todhunter, 33, a former professor at Catholic University here, said he has not designed EPA policies to suit the chemical industry, but has tried to ensure that agency regulations are based on careful and objective reviews of scientific evidence.

"I don't particularly care which way the science comes out, as long as it's correctly done," he said. "The agency's credibility in the scientific area needed to be bolstered quite a bit."

Before joining the EPA, Todhunter was a Washington lobbyist for the American Council on Science and Health, a group partially funded by chemical, food and drug companies.

Congressional inquiries have focused on private meetings that Todhunter and Hernandez held with the Chemical Manufacturers Association and other industry groups before deciding not to regulate certain toxic chemicals.

After one series of meetings, Todhunter decided not to restrict the use of formaldehyde, an ingredient in products ranging from plywood to toothpaste. Formaldehyde has been shown to cause cancer in animals and nausea, dizziness and eye and skin irritation in people. These studies prompted the Consumer Product Safety Commission to ban formaldehyde insulation in residences.

In late 1981 EPA staff scientists recommended that formaldehyde be given priority for some action by the agency within six months. Soon afterward, Todhunter and Hernandez held three private meetings on formaldehyde with industry officials.

These meetings, known informally as the "Science Court," included S. John Byington, then the chief lobbyist for the Formaldehyde Institute, and several of the group's lawyers and scientists.

Todhunter later told a House hearing that he has long been friendly with several of the chemical company officials with whom he dined during that period, including Byington, who called the meetings with Todhunter "a significant regulatory breakthrough . . . . All the institute was doing was petitioning EPA to be heard before it made a decision."

Richard Dailey, an EPA scientist who attended the sessions, said, "Todhunter agreed with the industry's point of view more than he agreed with his staff scientists."

Dailey, who later resigned in disagreement with Todhunter, said he and other agency scientists were directed to revise their original assessment that formaldehyde was hazardous and needed prompt regulation.

"We were trying to find a way to write up the data that would reflect the political decision that had been made," Dailey said. "I said Todhunter's interpretation was wrong, but I was told, 'Don't worry about it. The word is down. Just put it in the report.' I felt I had been compromised. I had written things I didn't believe in."

In February, 1982, Todhunter decided that formaldehyde did not present a significant risk because, he said, it was not a proven carcinogen in humans and the levels of exposure were uncertain.

"The program did not have enough information to make that finding at that time," Todhunter said. "The exposure numbers were of dubious quality. We didn't have great confidence in them."

During the same period, Todhunter altered a Carter administration proposal that would have required removal of all asbestos found in school buildings. Asbestos, which causes cancer and lung disease, has been found to flake off from ceilings and walls in some classrooms, where it can be inhaled.

Todhunter decided instead on a voluntary approach that had been urged by an asbestos trade group. He directed the EPA to help all schools inspect their buildings, but not to require them to remove any asbestos they found.

Todhunter said he would have "a horrible time" writing a mandatory standard to cover all schools. He said it was sufficient to notify parents' groups, which would place "societal pressure" on the schools where asbestos was found.

More recently, Todhunter proposed exempting about half of all new chemicals from legal requirements that they be thoroughly reviewed by the EPA before being marketed. The exemptions would cover about 500 chemicals a year and would exclude those whose production totals less than 10 tons a month, which is 10 times larger than the volume qualifying for such exemption in Europe.

"Smaller amounts of chemicals are not going to present sufficient exposure to be hazardous , even if they were of sufficient toxicity," Todhunter said, adding that these chemicals still would receive "an abbreviated review."

Todhunter also has negotiated agreements with chemical companies for voluntary testing of more than two dozen chemicals that EPA scientists regard as suspect.

"A rule-making procedure won't work. It's very hard to write a rule to govern a scientific study," he said, while a voluntary approach "avoids a lot of administrative fluff."

But Jacqueline Warren of the Natural Resources Defense Council said some of the voluntary tests are inadequate and not subject to court review. "Todhunter is an ideologue who feels that the benefits of most new chemicals outweigh the risks," she said. "He starts with that bias. He's much more solicitous of the chemical industry than of the public health."

Todhunter also has speeded up the EPA's approval of pesticides, which congressional critics said has led to the marketing of hundreds of banned or unregistered products without adequate safety reviews. In several cases, according to congressional testimony, EPA employes have submitted "cut-and-paste" reviews of pesticide safety that were rewrites of industry summaries.

One of Todhunter's most persistent critics, Rep. James J. Florio (D-N.J.), has called his regulatory approach "a prescription for neglect of existing chemical hazards."

Todhunter's ties to his former employers also have come under scrutiny. Rep. Synar recently questioned a $40,000 noncompetitive contract that Todhunter's office awarded to Andrulis Research Corp. of Bethesda for undefined research. The Andrulis company paid Todhunter $5,700 in 1981 for his assistance in preparing proposals for government contracts.

Todhunter said he obtained an opinion from EPA's general counsel that the award would be proper as long as Todhunter was not personally involved. "I didn't want to be seen as getting into anything that might involve a conflict of interest," Todhunter said.

A Todhunter aide, John Ritch, said Todhunter had suggested the work at a time when company treasurer Peter Andrulis repeatedly was pressing Ritch for a contract. Ritch said he made the award as a minority set-aside because the firm is headed by a woman.

Andrulis said he told Todhunter about the pending contract "in passing conversation," but that "we have stayed away from Todhunter, except socially."

Todhunter also helped place Elizabeth Whelan, president of the American Council on Science and Health, as a "consumer" representative on EPA's advisory panel on toxic substances, along with other industry officials. The council paid Todhunter $1,000 a month when he worked for it in 1981.

The council, which Todhunter called "basically a balanced group," has received about a third of its funding from such companies as Hooker Chemical Corp., Dow Chemical, Monsanto, American Cyanamid Co., Mobil Foundation, Tenneco, Bethlehem Steel Corp., Chevron USA and the Formaldehyde Institute. The council has argued that such substances as saccharin and formaldehyde are relatively safe.

Whelan, who maintained that her group remains independent from industry, said Todhunter has helped combat "a lot of misinformation in the area of chemicals . . . which can blossom into headlines that create anxiety. His philosophy is that one should not alarm the public on the basis of sketchy and preliminary data."