Carol Ann Rinzler does her own housework. The New York-based science writer turned that fact into the basis of research for her new book, which explains how nearly 100 of the most common household products work, what's in them, what they can do to you, and what's better, safer or cheaper.

During her research Rinzler said she never came across a product that didn't do the job it was designed for -- but she did discover that you may be paying for fancy packaging and frangrances when a more ultilitarian substitute might do the trick.

"You do need something to clean your bathroom," she says. "But you should know that plain old chlorine bleach can do the job as well as the white foam in the aerosol container. I simply want people to make informed choices."

Rinzler does come off as a partisan for those standbys, chlorine bleach and ammonia. The former she says, can be cheaply substituted for disinfectant cleaner, mildew remover, mildew preventive, toilet-bowl cleaner and tub and tile cleaner. And ammonia can take the place of coppoer cleaner, window cleaner, some jewelry cleaners, liquid household detergents, and some stain removers.

But don't think you'll get double cleaning power by mixing bleach and ammonia: What you'll get is a faceful of toxic fumes.

The household favorites, scouring powder and drain cleaner, come in for some caustic criticism from Rinzler. If you're cleaning your bathroom fixtures with scouring powder, stop. The powder causes pits and crevices that dirt and germs love. Instead, use either bleach or an all-purpose cleaning powder such as Spic and Span.

Drain cleaners, whose primary ingredient is lye, are the most dangerous product in general home use, Rinzler says. And if a child happens to swallow some of the stuff, there is no effective antidote.

Rinzler recommends preventive action on the drain: 1. Use a drain strainer (a net-like device which traps debris). 2. Run hot tap water down the sink for at least five minutes after washing the dishes, or your hair. 3. Pour a kettleful of boiling water down the drain once or twice a week. For temporary clogs, try a plunger.

Most of the precautions in her book, "The Consumer's Brand-Name Guide to Household Products" (Lippincott & Crowell, $10.95), are aimed at households with young children. Rinzler's obvious advice is to keep these potentially lethal products far out of an exploring child's reach. (Under the kitchen sink is not an example of such a place.)

If a child does ingest some household product, Rinzler says to call the local poison control center immediately. "Tear up your antidote lists," she advises, warning that some manufacturers' listed antidotes can actually compound a problem.

Because household products are so familiar, Rinzler says adults tend to take their safety for granted. But as her book points out, precautions are necessary.

For example, that lemon-scented oven cleaner is really full of lye. And, as simple-minded as it seems, Rinzler says to check where the nozzle of any aerosol can is pointing before spraying.

Other ideas:

For a coffepot cleaner, substitute vinegar and water or any dishwashing liquid. Laundry pre-soak, simply pour some extra liquid laundry detergent on the spot.

Products for which Rinzler says there are no cheaper or safer substitutes include glue, fabric dye and wood polish.