Formaldehyde is a naturally occurring chemical used in the manufacture of other chemicals and in cosmetics, fungicides, fabrics, embalming fluids, wood resins, carpeting, and some cleaning products.
The most common route of human exposure is through inhalation, especially inhalation of cigarette smoke and fuel exhaust, but it can also arrive through food packaging and cosmetics. According to the World Health Organization, it arrives in drinking water most commonly as a byproduct of water treatment involving ozonation or chlorination.
Exposure to large amounts of formaldehyde can cause skin irritation. In animal studies, long term exposure to ingested formaldehyde was shown to cause incidences of weight loss and damage to the stomach and digestive system.
The International Agency for Research on Cancer reports that there is “sufficient evidence” that formaldehyde is carcinogenic to humans, but by inhalation rather than ingestion. According to the WHO, drinking-water exposure to formaldehyde is not likely to cause cancer:
The weight of evidence indicates that formaldehyde is not carcinogenic by the oral route.
According to the WHO, formaldehyde levels may be reduced with granular activated carbon (GAC) or through changes in disinfection methods.
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