Of the hundreds of federal agencies, the Federal Trade Commission, the Consumer Product Safety Commission, the United States Department of Agriculture, the Food and Drug Administration and the National Highway Traffic Safety Administration are taking the leading role in reexamining the government's consumer-protection programs.

Here is a close look at what these agencies are doing:

FTC

Even before Reagan's choice to head the Federal Trade Commission, James C. Miller III, arrived at the agency this fall, the commission was busy rolling back many of its controversial rules and investigations.

Among other things, it:

* Dropped its controversial proposal to ban all television advertising aimed at children.

* Dismissed its eight-year-old antitrust complaint against the nation's eight largest oil companies. The complaint sought to break up the companies into several smaller ones on the ground they violated antitrust laws.

* Appeared to be on the verge of ending its eight-year-old novel antitrust case against the nation's three largest ready-to-eat cereal manufacturers.

* Adopted a modified rule that would require used-car dealers to disclose more information to consumers about the condition of the cars they sell. Deleted from the rule was the provision, contained in the original proposal, that dealers also conduct and then disclose the results of detailed inspections of the cars they sell.

* Approved a rule requiring funeral directors to give customers more price information about the services they provide. Deleted from the final rule was a requirement that directors follow a standard itemized pricing form to disclose this information.

On the job for only a month, Miller now wants to go even further in reversing commission policy.

Last week, in his first press conference since taking office, Miller expressed grave doubts about one of the agency's chief advertising rules: the requirement that companies substantiate as true all the statements they make about their products in all advertisements.

"Consumers are not as gullible as many people and many regulators tend to think they are," Miller said, adding his belief that ad-substantiation only adds to the cost of a product. "There's no such thing as a free lunch."

Unlike many other regulators who are fighting Reagan's budget cuts, Miller is also eager to go along with the administration's budget restraints.

At the administration's request, Congress has already agreed to reduce the commission's fiscal 1982 budget by nearly 17 percent, from $84 million to $71.9 million. Now, Miller has agreed to accept an additional 12 percent cut, even though two FTC commissioners have said such a move could jeopardize many of the commission's basic activities.

"We can operate a lean and productive agency on less resources," Miller maintained last week.

CPSC

One of the youngest and smallest regulatory agencies in government, the Consumer Product Safety Commission has been under fire from the very first days of the Reagan administration.

The administration has:

* Succeeded in getting Congress to approve a 30 percent cut in the agency's $45 million budget.

* Urged Congress to abolish the agency altogether, arguing that "the public benefits likely to be secured by the agency in the future are not likely to exceed the costs."

* Appointed as chairman Nancy Harvey Steorts, whose regulatory philosophy emphasizes voluntary industry standards over mandatory commission rules.

Of all these actions, the budget cut has had the greatest impact on the agency's actions.

First, the CPSC had to cut 145 employes from its 728-member workforce. Doing so has required such a juggling act of employes that the commissioners have had little time to spend on substantive issues.

What's more, to meet their lower budget, the agency has had to drop many ongoing investigations, such as those looking into the fire hazards of electric clothes dryers, electric light fixtures and kerosene lamps.

And a final decision on one of the commission's biggest and most controversial proceedings--its proposed rule to ban home insulation made with formaldehyde--has been delayed for six months.

In the few substantive decisions the commission has taken, it has refused to ban reversible lids for pill bottles--lids that used one way meet the agency's child-proof requirements, but turned another way do not comply but are easy to open.

The commissioners have also rejected a mandatory standard for children's projectile toys, voting instead to address their hazards through a voluntary consumer information campaign.

It has also refused to require special labeling on children's thermal underwear to alert parents that the clothing does not comply with the agency's flammability standards for children's sleepwear.

USDA

Only days after John R. Block was nominated as secretary of Agriculture, he told a press conference that the main difference between himself and his predecessor, Bob Bergland, would be a reduced emphasis on consumer issues.

"The best things for consumers is a good healthy agriculture," Block said.

Since then, USDA has:

* Announced plans to make major changes in the way meat is inspected, primarily because of the budget cuts. Instead of having federal inspectors on site in every processing plant to inspect each carcass, the USDA wants to set up a quality-control system in which only random inspections will be made.

* Indicated plans to change its beef-grading standards so beef now marked "good" will be moved to the higher grade of "choice."

* Said it may relax cooking requirements for tubercolosis-infected hogs.

* Proposed to lift its labeling rules for mechanically deboned meat so manufacturers no longer would have to note in large type that their product may contain bone particles.

* Announced plans to lift a rule that bans the sale of soda, candy and other "junk food" in school cafeterias.

* Proposed new standards for school lunches to reduce the minimum requirements. The original proposal--which drew so much criticism that it had to be pulled back--would have allowed ketchup to be considered a vegetable in school lunches.

* Indicated it wants to revise the law banning the use of any food additive that has been found to cause cancer in animals.

* Dropped plans to issue a new food dietary guideline book to give consumers menu guides and recipe ideas for low-fat, noncholestoral diets.

At same time, the USDA has also set for review its age-old system of marketing orders in which the agency determines the amount of fruit and vegetables that may be shipped at a particular growing time. Farmers have contended that the system has guaranteed consumers a steady supply of produce at steady prices. However, many consumer groups have argued that the system helps keep produce prices artificially high.

FDA

"For many years the food industry has been saying that government regulation is too burdensome, and if industry were permitted to confront and resolve important public health issues, the public would be better served," the new head of the Food and Drug Administration recently told Congress.

Arthur Hull Hayes is determined to give the food and drug industries their chance to prove their claim--so long, he says, as the public health needs are met.

In an effort to meet that difficult balance, FDA has:

* Launched an overall review of its drug-approval process to see how it can be speeded up to encourage the development of new drugs.

* Stopped consideration of new labeling requirements that would have given consumers a better indication of the contents of the food they eat. Instead, FDA said it will consider labeling rules on a case-by-case basis, for individual ingredients when they are found to be health hazards.

* Proposed a voluntary instead of a mandatory labeling program for food products high in sodium.

* Ordered a new review of the agency's evaluaton of nonprescription drugs.

But it is two other decisions that consumer advocates are watching to see how consumer-oriented the FDA will be.

The first decision involves the agency's three-year-pilot program that would have required drug manufacturers and pharmacies to dispense special inserts on the proper use and possible side effects of several prescription drugs they sell.

Hayes has administratively delayed the program--one heavily criticized by drug manufacturers--and is expected to decide this month whether it should go forward or be stopped, possibly to be replaced with another patient-information program.

Also expected this month is the administration's policy statement on what its position will be on the current major congressional effort to rewrite the nation's food-safety laws.

NHTSA

Long before President Reagan took office, he made the National Highway Traffic and Safety Administration a target for change.

In campaign handouts and speeches, Reagan said he would "act immediately to relieve the distress of the auto industry."

To accomplish this, NHTSA has so far:

* Repealed the requirement that all cars be equipped with airbags or automatically closing seatbelts.

* Slated 15 other rules for review and possible elimination. Among the major items on the review list are the fuel-economy standards for post-1985 model-year cars and the new bumper-design standard that was developed to reduce the amount of damage that occurs from low-speed collisions.

* Not brought pressure on the auto companies to announce the voluntary recalls they undertake.

* Decided not to reissue The Car Book, which compares fuel-efficiency performance and lists crash-test results of a variety of car models.

* Launched four formal investigations into car defects. In the Carter administration, an average 15 formal investigations were begun each year.

* Agreed to have its budget cut for traffic safety programs by 42 percent from $177 million to $100 million.

Additionally, the Reagan administration is proposing to cut the agency's current budget by 48 percent, from the $289 million proposed by President Carter to $150 million.

Assessing NHTSA's actions to date, consumer advocates are not counting on winning any battles at NHTSA during the Reagan administration. "It's quite clear to me that they're not going to set a single standard during their administration--and where they can, they're going to try to roll back every single standard they can," said Clarence M. Ditlow, director of the Center for Auto Safety.

Raymond A. Peck, Reagan's choice to head NHTSA, contends, however, that his moves have not been intended to reduce car safety. Although many rules may be lifted, Peck said he is confident passengers will have even more protections than they have now under the "aggressive program of consultation, persuasion and encouragement" he plans to undertake to get auto companies to develop "advanced technologies" to make cars safer.