The womb acts as a wonderfully protective cushion between the fetus and the jolts and bumps of the outside world. On the inside, though, the placenta simply cannot shield the womb from all of the man-made chemicals that have, according to the U.S. Centers for Disease Control, collected in our bodies. You can, however, take simple steps to reduce the risk to your offspring by paying special attention to what you eat, drink and breathe.

You probably already know to avoid alcohol, cigarette smoke, caffeine and kitty litter. Unfortunately, prenatal exposures to other common contaminants can affect the fetus during critical windows when vital systems are developing, says pediatrician Philip Landrigan, M.D., director of the Center for Children's Health and the Environment (CCHE) at the Mount Sinai School of Medicine in New York City. Below are 10 kinds of toxins capable of crossing the placenta and how to avoid them.

1. Trim consumption of animal fats

When you're pregnant, it's more important than ever to choose lean cuts of meat, trim away fat and opt for fat-free dairy products. Here's why: Some toxins linked to prenatal nervous system and hormonal damage are stored in fatty tissue. These include polychlorinated biphenyls (PCBs), which pose risks of reduced intelligence to the developing fetus; brominated fire retardants (see Green Guide 106); dioxins and other pollutants that persist in our air and water.

2. Put a stop to insecticides in your home and office

Organophosphates are a family of insecticides that attack the nervous system. In two New York City studies conducted last year, babies of women who had been most exposed to two organophosphates, chlorpyrifos (Dursban and Lorsban) and diazinon (Spectracide), had significantly lower birth weights. Fortunately, these insecticides were phased out of residential and school use by the EPA in 2001-03. However, other organophosphates are still in circulation, as are similar compounds called pyrethroids. Pesticides also release inhalable volatile organic compounds (see below).

What to do instead? Researchers at the Columbia Center for Children's Environmental Health (CCCEH) recommend that pregnant women switch to sticky traps and other bait stations, "which are safer, last longer and are more effective," while keeping surfaces clean of food residue, removing trash and treating cracks with boric acid, classified by the EPA as of low toxicity, then sealing with caulk. (Keep boric acid and baits out of the reach of children and pets.)

3. Select foods to minimize pesticide residues

Chlorpyrifos and diazinon (see above), along with many related toxic pesticides, are still used widely on food crops. Prioritize your grocery list to allow for the purchase of the following organic fruits and vegetables that, when conventionally grown, tend to harbor the most pesticide residue: apples, bell peppers, celery, nectarines, peaches, pears, potatoes, spinach, strawberries and peppers.

4. Pass on high-mercury fish

Mercury is a potent neurotoxin that can harm a developing fetus. Say "no" to high-mercury fish such as fresh tuna, canned albacore, wild bass, swordfish and tilefish. (One meal of moderate-mercury fish, such as canned light tuna, can be eaten once a month.) Eat up: low-mercury "yes" fish such as sardines, wild salmon and farmed striped bass. For a complete list, download the Green Guide's wallet-sized Fish Picks Smart Shopper's Card.

5. Let Old Paint Lie

Since lead has been banned from gasoline (in 1996) and paint (in 1978), most exposures now come from old lead-based paint. This heavy metal, which can also contaminate water and soil, can interfere with nearly every aspect of fetal development, causing brain and kidney damage, according to the CCHE. If your old house has lead paint in good condition, cover it with fresh paint rather than removing it, which releases lead dust into the air. To test paint for lead, see www.epa.gov/lead/leadinfo.htm#buy or call the EPA's lead hot line at 800-426-4791.

6. Make sure your water is safe to drink

Your local utility must by law provide you with an annual "Right to Know" report listing the EPA-recognized pollutants that exist in your water at potentially unsafe levels. Trihalomethanes, for instance, can increase the risk of miscarriage. See Green Guide No. 101 for contaminants to avoid and best filters. If you suspect there's lead in your pipes, allow the tap to run for 30 seconds to clear them before using water. Find lead-testing services at www.epa.gov/safewater/faq/sco.html.

7. Avoid the VOCs that offgas from paints, glues, air fresheners Toxic volatile organic compounds (VOCs) can evaporate from many conventional building, decorating and other household products, including air freshener sprays. Exposure to air fresheners during pregnancy and within the first six months of life was associated with diarrhea and earache in infants and headaches and depression in mothers, according to a study published in the October 2003 Archives of Environmental Health.

What to Do: For a shopping list of no- or low-VOC pressed woods, paint, stains and varnishes, see Green Guide No. 96. Remember, even when the safest products are used, pregnant women should stay away during renovations and until finished rooms are well ventilated.

If exposed to fumes at work, speak up: Thirty-two children exposed in utero to organic solvents had lower scores on language and other developmental tests, according to a study published in the October 2004 Archives of Pediatric and Adolescent Medicine. In the workplace, their mothers had come into contact with such solvents as toluene, xylene, mineral spirits, isopropyl alcohol and trichloroethylene. See Green Guide No. 92 "Sick at Work?" or contact the National Institute for Occupational Safety and Health, 800-35-NIOSH, www.cdc.gov/niosh.

8. Steer clear of vehicular and smokestack emissions

Research conducted by Columbia University links "combustion-related" chemicals called polycyclic aromatic hydrocarbons (PAHs) with shorter gestation periods for pregnant women, resulting in smaller babies. PAHs are in car or bus exhaust and emissions from residential heating and power generation. Before exercising outdoors, check the EPA's Air Quality Index at epa.gov/airnow. Keep windows closed during peak traffic hours. For the best air filters, see our Air Purifiers product report.

9. Stay away from phthalates in vinyl, personal-care and cleaning products

Chemicals called phthalates, known hormone-system disruptors that have caused birth defects in lab animals, are widely used as plasticizers in nail polishes and vinyl and as solvents in synthetic fragrances. Avoid soft vinyl products and cosmetics containing "Fragrance"; also see lists of phthalate-free cosmetics at nottoopretty.org and Green Guide No. 94 "Beauty Tips" and Green Guide No. 99 "Soap and Shampoo: Personal Best." See also, "Nail Products", "Household Cleaning Supplies", "Lip and Eye Makeup" product reports.

10. Get rid of those crumbling foam cushions, already!

The latest chemicals found to be approaching possibly unsafe levels in American women's breast milk, as well as umbilical-cord blood, are fire retardants known as polybrominated diphenyl ethers, or PBDEs. Furniture foam tends to release PBDEs into house dust when it breaks down. For solutions, see Mattresses and Box Springs and Computers product reports and Green Guide No. 97 "PBDE Fire Retardant and Health Risks."

The Green Guide and www.thegreenguide.com - published by The Green Guide Institute, an independent media service - together serve as consumers' go-to source for practical and reliable green homes tips, product reviews, environmental health reporting and green living advice. For more information, please visit http://www.thegreenguide.com/about/ .