Lead poisoning is a serious and underrecognized hazard to automobile radiator repair mechanics, a Massachusetts study found.

Researchers surveyed 27 automobile repair shops in the Boston area, most of which were small and poorly ventilated. They interviewed and tested 75 workers.

Of the 56 workers who had actually repaired radiators, 39 percent had blood lead levels higher than 40 micrograms per deciliter. A variety of effects, including kidney and brain damage, are known to develop at or above that level of lead in the blood.

Lead poisoning is a risk for many kinds of workers, but car radiator mechanics are especially vulnerable because they rely continually on soldering and heating of soldered metal joints.

About 6 percent of male workers tested in the 1983 national health survey had blood lead levels above 30 micrograms per deciliter, a level considered to be cause for concern. In the Massachusetts study, 80 percent of the radiator workers tested exceeded that level.

Automobile radiator repair can also pose a risk of lead poisoning to the children of workers. A case of childhood lead poisoning was traced by Virginia health officials to the contaminated clothing of the father, a radiator mechanic.

The Massachusetts study, conducted by researchers at the state departments of Labor and Public Health, the Harvard School of Public Health and Cambridge Hospital, was reported in the New England Journal of Medicine.

The federal Occupational Safety and Health Administration (OSHA) standard for lead exposure on the job is poorly enforced, and many small businesses are poorly informed about the hazard, the researchers concluded.

The car repair shops surveyed were "often small, dirty and poorly ventilated," researchers reported. Workers frequently ate and smoked in the work area. Even if air-cleaning equipment was available, it was often poorly maintained or unused.

Only 10 of the 27 shops surveyed had done any blood lead testing of employes, and none of those had done so in compliance with the OSHA standard.

The prevalent and excessive exposure to lead among radiator repair workers, the researchers said, should be "prevented by improved ventilation, engineering controls and the use of respirators."