Fiberboard glue, particle board and plywood articles are the biggest offenders but new clothing, upholstered furniture and carpeting all release significant amounts, especially when new. Latex paint, cosmetics, paper and plastic products all contain formaldehyde. The list is endless, and you need to learn it to reduce exposure. Use clean water and test it for chemical contaminants that can leach into ground water. Chlorine is great for controlling bacterial infection but can react with organic matter and form small amounts of cancer-causing Trihalomethanes.
People also develop sensitivity to chlorine.
I have several patients with proven chlorine sensitivity that are tremendously improved by simply removing it from their spas and water sources. Fluoridation of water does help decrease tooth decay but also contributes to leaching of aluminum from cookware. Aluminum has been implicated in hyperactivity and early onset of Alzheimer's, although conclusive proof of this is not yet available. All drinking water should be filtered if supplied by a city source. Adopt the Japanese custom of keeping shoes worn outside at the door when you enter your home to reduce lead and pesticides in your house dust.