F

Fluorine, Hydrogen Fluoride, Fluorides

CASRN 7782-41-4, 7664-39-3

Physical Properties

Fluorine is an element that rarely exists in elemental form naturally, but is normally combined with other chemicals because of its high reactivity. Elemental fluorine is a pale-yellow gas with a pungent odor. Hydrogen fluoride is a colorless, corrosive gas or liquid that is made up of a hydrogen atom and a fluorine atom. Hydrogen fluoride fumes strongly, readily dissolves in water, and the liquid and vapor forms will both cause severe burns upon contact. Fluorides are salts of fluorine and another element. Examples of fluorides are sodium fluoride and calcium fluoride. Both sodium and calcium fluoride are white solids.

Uses

Fluorine gas is primarily used to make other chemical compounds. Hydrogen fluoride is used in the production of fluorocarbon chemicals. Hydrogen fluoride dissolved in water (hydrofluoric acid) is used for stainless steel pickling or cleaning, glass etching, and metal coating. Fluorides, such as sodium fluoride and hydrofluorosilicic acid, are added to drinking water supplies and to a variety of dental products, including toothpastes and mouth rinses to prevent dental cavities. The fluoridation of drinking water to optimal levels that prevent tooth decay is considered by the Centers for Disease Control and Prevention to be one of the ten great public health achievements in the United States of the 20th century.

Source of Exposure in Iowa

Because fluorides occur naturally in the environment, everyone is exposed to very low levels in air, water, and food. Exposure to fluorides also occurs through the use of fluoride-containing dental products and through the consumption of public drinking water. People who work in industries that utilize fluorine, hydrogen fluoride, and other fluorides are potentially exposed to the highest levels of these chemicals. Hydrogen fluoride and other fluorides are released from coal during its combustion at power plants and from brick and tiles works. The concentration of hydrogen fluoride within the air would be highest in areas closest to these facilities.

Health Effects from Large Acute Exposures

Direct contact with large amounts of fluoride can result in tissue damage. At high concentrations, fluoride can cause irritation and damage to the respiratory tract, stomach, and skin following inhalation, oral, and dermal exposure, respectively. At very high fluoride doses, fluoride can bind with serum calcium resulting in hypocalcemia (low levels of calcium in the blood). The severe cardiac effects in an individual observed at or near lethal doses are probably due to this electrolyte imbalance.

Health Effects from Smaller Chronic Exposures

The recommended level of fluoride in drinking water is about 1 part per million (ppm). This level has been found to prevent tooth decay and optimal oral health. Exposure to fluoride at about 5 ppm in drinking water can cause denser and more brittle bones and exposure to fluoride greater than 2 ppm may cause brown staining and pitting of permanent teeth, if the exposure is long enough. These adverse health effects could also happen if the exposure to hydrogen fluoride through the air is high enough. These adverse health effects would only be seen in people who worked in industries that use or manufacture fluorine or hydrogen fluoride. The level of hydrogen fluoride within the outside air, even near coal combustion power plants or brick and tile works, is generally below levels that would adversely impact human health. There is no association between exposure to fluorine or fluorides and developing cancer.

Protection from Exposure

It is recommended that the levels of fluoride in drinking water be maintained with the range of 0.7 to 1.2 ppm. It is recommended that individuals who work within industries that use of produce fluorine, hydrogen fluoride, or fluorides use personal protective equipment such as respirators in areas where the potential of exposure to high levels of these substances exist.

Formaldehyde

CASRN 50-00-0

Physical Properties

Formaldehyde (HCOH) is a nearly colorless gas at room temperature with a pungent, suffocating odor.

Uses

Formaldehyde is used as part of many building materials including the glue or adhesive in pressed wood products (particle board, hardwood plywood, and medium density fiberboard), preservatives in some paints and coatings, and some foam and fiberglass insulation materials. Formaldehyde is also used in many household products such as antiseptics, medicines, cosmetics, dish-washing liquids, fabric softeners, shoe-care agents, carpet cleaners, paper, and plastics.

Source of Exposure in Iowa

People are normally exposed to low levels (less than 0.03 ppm) in both indoor and outdoor air. Indoors, formaldehyde released from building products poses the greatest risk of exposure. People living in mobile homes may be exposed to higher levels of formaldehyde because manufactured wood products are used extensively in mobile homes. New permanent press fabrics release some formaldehyde. Burning materials, such as wood, kerosene, and cigarettes can increase indoor air formaldehyde levels.

Health Effects from Acute or Large Exposures

Formaldehyde can affect people differently. Some people are very sensitive to formaldehyde while others may not have any noticeable reaction to the same levels. When present in the air at levels above 0.1 ppm, formaldehyde can cause watery eyes, burning sensations in the eyes, nose and throat, nausea, coughing, chest tightness, wheezing, skin rashes, and allergic reactions. Formaldehyde is just one of several gases present indoors that may cause illness. Many of these gases, as well as colds and flu, can cause similar symptoms.

Health Effects from Smaller, Chronic Exposures

The major concerns of repeated formaldehyde exposure are sensitization and cancer. In sensitive people, formaldehyde can cause asthma and contact dermatitis. People sensitive to formaldehyde can also experience increased headaches, depression, mood changes, insomnia, and irritability. In people who are not sensitive, prolonged inhalation of formaldehyde at low levels is unlikely to result in any chronic lung problems. Attention deficit, impaired dexterity, and loss of memory and equilibrium have been reported to result from long-term exposure.

The National Toxicological Program within the Department of Health and Human Services (DHHS) has determined that formaldehyde is a known human carcinogen based upon sufficient evidence of carcinogenicity in individuals occupationally exposed to larger amounts of formaldehyde.

Protection from Exposure

Since formaldehyde is found in so many in-home products, the best way to reduce exposure is by circulating large amounts of fresh air into the home. Increase ventilation by opening doors and windows, and turning on exhaust fans. Sealing unfinished manufactured wood surfaces can help lower exposure to formaldehyde from building materials. Since formaldehyde is used in some fabrics, washing clothing before wearing can also help lower exposure. By not smoking and not using unvented heaters indoors, you can reduce formaldehyde levels in your home. People sensitive to formaldehyde may need to avoid many everyday items to reduce symptoms.