A lawn mower not only cuts grass, it also can mangle a finger or a foot. That's why the Consumer Product Safety Commission (CPSC) requires manufacturers to equip power mowers with a device that stops the blade when you let go of the handle.

Blade-stop systems, mandated in 1982, seem to have helped make mowers safer:

The number of people treated in hospital emergency rooms for mower-related injuries peaked at about 44,500 in 1984. By 1989, injuries had dropped to about 26,000.

The number of injuries probably would have been reduced further if the CPSC's original safety standard had remained intact. The agency had specified two types of blade-stop systems.

One would stop the blade but leave the engine running. The other, which entailed electric restarting, would stop both engine and blade. If both the engine and blade stop when the deadman control is released on a mower without an electric starter, the CPSC reasoned, some people would disable the controls rather than have to repeatedly restart the engine by hand.

But Congress, caving in to both industry pressure and the anti-regulatory sentiment of the early 1980s, amended the standard:

Congress permitted the use of a system on manual-start mowers that stops both the blade and engine. The more convenient safety designs are available only on relatively expensive mowers. So low-priced mowers with disabled deadman controls may well contribute to the toll of mower injuries.

When you mow, follow these rules:

Mow only when and where it's safe. Don't mow when the grass is wet.

If you have a push mower, move it across the slope of a hill, not up and down. If you have a sit-down mower, travel up and down, not across. If the slope is more than about 15 degrees, don't mow at all.

Be sure to dress for the job and wear sturdy shoes and close-fitting clothes. Wear long pants instead of shorts. Avoid loose jewelry or anything else that can get caught in a moving part.

Prepare the area. Before you start, pick up toys, garden hoses, rocks and twigs. Banish anyone close to where you're cutting -- flying objects can be hurled from the mower.

Fill the fuel tank before you start, while the engine is cold. When you refill, wait for the engine to cool.

Keep hands and feet away from moving parts.

Don't defeat safety devices.

Don't let youngsters use a mower.

1990 Newspaper Enterprise Assn.