The hidden toxins in your home are quite harmful as they leak into the air and contact your skin. This is scarey when you hear scientists admitting that we don't know for sure how bad these chemicals are for you. In fact, most of the 18,000 chemicals that are produced each year have never been tested by humans. Many of these toxins are lurking just behind your front door. You may be surprised to hear, but it is true, that the air inside your home can be more polluted than what's outside your home, even if you live in a busy urban area. This is because modern building materials, furniture, everyday cleaning solutions and other household products release chemicals that linger in the still air of a well-insulated home.

So, you say you'll be vigilant... Well, chemicals can still enter your home in unexpected ways. For instance, while labels advise us to use paint strippers, adhesive removers and spray paints in well-ventilated areas, gases can still leak out of the closed containers. These products are known to contain methylene chloride which causes cancer in animals.

Carbon monoxide and benzene are known human carcinogens that are present in auto exhaust. These chemicals can leak from an attached garage right through porous drywall and into the house.

The glues, paints and adhesives holding your house together can pollute the air, too. New construction gives off gases that can irritate the eyes, nose and throat.

Pressed-wood products emit formaldehyde, which at elevated levels can cause wheezing in people with asthma. Thankfully, there are usually no permanent effects.

Plug-in air fresheners release a steady stream of pleasantly scented formaldehyde into your home.

Scientists admit that they are uncertain as to how much exposure, or how long, is necessary for many of these chemicals to harm your health. This is especially true since some people are more sensitive than others. For instance, those persons who have asthma or pulmonary conditions often react more strongly. Some symptoms that you want to pay special attention to include feeling nauseous, weak, or always sneezing. If you're concerned about these things, but lacking funding, it is nice to know that you don't have to gut your house to make it healthier. Simply use air cleaners, clean your ducts, and keep the windows open so that fresh air can flush out toxic chemicals. However, your biggest problem may be with the harsh chemicals that are found in cleaning products.

Some toxins arrive incognito, in products without ingredient labels. For instance, did you know that the flame-retardant chemicals that are used in thousands of household appliances and textiles can leach out into your home? Polybrominated diphenyl ethers, or PBDEs, build up in your body over a lifetime. In lab animals, they've been shown to disrupt thyroid hormone balance and alter brain development. Scientists have detected them in women's breast milk, human hair and fat cells. Several states are actually phasing 2 of these toxins out. The third 1 shouldn't be far behind in also being phased out. There are less-toxic flame retardants, as well as chemicals that are bonded to products so they don't leach out, available for use.

Convenience also comes at a cost. Did you know that nonstick and stain-resistant coatings typically contain perfluorochemicals, or PFCs? They're found in Teflon, Scotchguard, Stainmaster and Gore-Tex. They're found in cookware, clothing, wallpaper, paint and food packaging. They're also found in us. This is scarey when you consider that in animals they cause cancer, birth defects and developmental problems, as well as high cholesterol. These chemicals are turning up in unexpected places, including the water supplies of cities with no large-scale commercial use. This could be due to 1 known source: cooking. (Heating Teflon-coated pans to high temperatures releases the fumes that kill pet birds and sicken people temporarily.)

Even plastic baby products aren't necessarily safe. Phthalates are found in some soft vinyl toys, as well as in cosmetics such as nail polish and hair spray. Studies have already proven that infant boys who are born to mothers that have been exposed to phthalates had a higher chance of genital abnormalities. Phthalates are found in baby bottles, food storage containers and water bottles. It's also used in resins that coat the inside of food cans and in dental sealants for children. At low doses, this chemical causes reproductive abnormalities in lab animals. This is because this chemical acts like the estrogen that can be found in birth control pills. When heated, more of this chemical will actually leak into your food. Some studies have detected leaching even at room temperatures. You also should take note that heavily scratched or worn plastic degrades faster.

The long-term health effects of small doses of chemicals are difficult to study since they don't always show up in blood tests, and if they do, effects might take decades to develop. Animal studies don't necessarily translate into equivalent effects on human health either. This is why we urgently need more data. The hard thing is sometimes the data come too late. The other challenge is that there are definite trade-offs in choosing to use these materials (ie cooking your eggs in a nonstick pan means you can use less artery-clogging oil; extra-strength cleaners make housework go faster; plastic baby bottles don't break). A lot of these chemicals truly have made it more tolerable to live in our environment. Nevertheless, we should always approach their use with caution. Where clear, better alternatives exist, we need to choose the alternatives.