With a dozen shiny new metal cars lined up on a table, a score of cuddly, plush animals crammed into a bookcase and an assortment of colorful rattles scattered about, the room looks like Santa's workshop.

But Manuel Karos, the man in charge here, doesn't make toys. He tests them to determine if they meet federal safety standards.

Working under guidelines established by the Consumer Product Safety Commission, the agency that operates the lab, Karos subjects the toys to a variety of punishments: they are dropped on the floor and then attached to machines that twist them, try to pull them apart and try to push them together.

The question is whether the toy will hold up when a child uses--or abuses--it, or whether it will break in pieces small enough for a child to swallow.

Karos, who has been working full time on children's products for four years, also tests toy sizes. A rattle, for example, fails the size test if it passes through an opening the size of a small child's mouth--specifically, 2 inches wide by 1.4 inches tall by 1.2 inches deep.

Other tests are designed to find out if the toy's edges and points will cut or puncture small hands and faces.

Last year, an estimated 128,000 children were treated in hospital emergency rooms for injuries resulting from the use of toys, bicycles and other children's products, according to CPSC statistics.

The CPSC laboratory, which is in Gaithersburg on a former military base, tests about 200 product lines each year, only a fraction of the 150,000 toys on the market. Each manufacturer is responsible for making sure his product meets CPSC safety standards. The commission tests only to monitor compliance with the standards and to follow up consumer complaints.

When a toy fails the tests, the CPSC can ban the toy or convince the manufacturer to recall it.

Since Oct. 1, 10 toys have been recalled because of questions about their safety. One of the most publicized was the Playmobile toy figures given away by McDonald's to children ordering its "Happy Meal" combination of a hamburger, French fries and a soft drink.

McDonald's voluntarily recalled 30 million of the toys, which included a sheriff, an Indian and four other characters, after some failed the size tests and were found to pose a choking hazard for children 3 and under.

Of 18 employes in the lab, Karos is the only one who spends all his time on toys. One recent day, Karos was testing toy cars sent in by a CPSC inspector who was concerned about their sharp edges. In testing any toy, CPSC examines 12 samples. Since there were nine styles of this car, the inspector had sent 108 cars for testing.

To test for sharpness, Karos used a motorized tool the size of a shoebox, with a metal spoke on one end that simulates a child's finger. Karos wrapped tape around the spoke and turned on the motor, causing the spoke to move in much the same way that a child would stroke a toy with his finger.

Karos selected a gray car and briefly touched it with the machine's rotating spoke. After a few seconds, just long enough for the metal probe to make one revolution, he turned off the machine and examined the tape to see if it had been cut by any of the gray car's surfaces. There were no cuts, so this car passed the sharpness test.

But more than half of the cars tested later failed.

"By our criteria, this is not a biggie -- because it isn't life-threatening," said David Schmeltzer, director of compliance for the safety commission. The sharp edges would probably result in nothing more serious than a child cutting his finger, Schmeltzer said.

Because the injury is so minor, Schmeltzer said, the CPSC will take two steps to correct the problem. The first is to ask the manufacturer to stop importing toys of this type; the second is to ask the trade representative from China to contact his manufacturers and remind them of the CPSC rules on sharpness.

When sharp edges are more dangerous, CPSC may ask the company to recall the product, Schmeltzer said. If the problem is serious enough, CPSC also can ban the item and require the company to recall the toy.

"But we prefer -- when there is only a Band-Aid injury like this -- to prevent any more toys like this from coming into the market rather than spend time and effort and go through a cumbersome statutory action to get the problem fixed retroactively," Schmeltzer said.