Chemistry CH 2 O, mol. wt. = 30 g/mol Aldehyde Pungent, colorless gas Bpt. -19 °C Soluble in water Formalin, 37 % solution Used as preservative or fixative in biology, polymer chemistry (banned in Europe)
Exposure Sources: (natural + manmade) Urea-formaldehyde foam insulation (UFFI); Urea-formaldehyde, melamine and phenol-formaldehyde resins (aggregated pressboard and plywood - engineered wood products); carpeting; clothing; cigarettes; gas stoves; cosmetics; Formalin Production: 1.4 x 10 6 tons y -1 (US) Leslie and Lunau, 1992
Quote Formaldehyde offers a classic example of a product with obvious problems ignored by the industries proffering from it. Formaldehyde is cheap and easy to obtain and at one time had no environmental baggage to carry. So, sell it and ignore complaints from customers about headaches and nausea; that’s the business way. Later, when the nasty facts are made public, deny any knowledge and plead ignorance; that’s the business way. When the problem has to be corrected, establish new companies to provide the cleanup services; that’s also the business way. The whole formaldehyde mess has been a wonderful business opportunity. Turco, R.P., 2002
Emissions ProductRange of emission rates (10 -6 g per g material per day Particleboard0.4 – 8.1 Plywood Imitation wood paneling Fiberglass insulation Clothing Carpeting0 – 0.06 Paper products0.03 – 0.4 Source: Data from Gammage, R.B. and Gupta, K.C., “Formaldehyde”, in: Walsh, P.J., Dudney, C.S., and Copenhaver, E.D., eds. (1984) Indoor Air Quality. CRC Press, Boca Raton, Florida.
A Note on Units Usually expressed as a mixing ratio: volume analyte/total volume of sample - ppm (v/v) May find mg m -3 Conversion (at 25 ºC and 1 atm): concentration (ppm) = concentration (mg m -3 ) x 24.0 Molar mass For formaldehyde ppm = mg/m 3 x 0.8
Exposure Natural background 0.1 μg/m 3 – 1.0 mg/m 3 from decomp. organic matter Industrial areas 0.04 mg/m 3 Indoor levels 0.1 – 0.8 mg/m 3 ( ppm) Mobile homes > 1 mg/m 3 (due to tight space and more wood products) High indoor levels attributed to particle board and plywood products Leslie and Lunau, 1992 (see also previous ref.)
Uptake Major pathway: Vapor phase Target organs: lungs Symptoms: irritation eyes, nose, throat, lungs Symptoms exhibited above 1 mg/m 3 Absorbed by mucous membrane of nasal cavity
Health Effects Acute Exposure Inhalation > 15 mg/m 3 lethal dose Irritant effects at 0.5 mg/m 3 to severe at 10 mg/m 3 Coughing, wheezing, chest pain, inc. heart rate, bronchitis No federal limits for residences and offices EPA allows no more than ppm in new EPA buildings (0.020 mg/m 3 ) EPA ambient air action level 0.1 ppm WHO safety std. 82 ppb (0.082 ppm) Carcinogenicity Probable human carcinogen (EPA) Forms methylene crosslinks in DNA Short half-life limits DNA exposure
Health Effects Acute Exposure Hess-Kosa, 2002
Risk Assessment Lab studies show formaldehyde to be a mutagen, carcinogen, irritant and allergen in one or more species No evidence from industrial worker surveys (>2 mg/m 3 ) for carcinogenity to humans
Controls Occupant activities, Temperature, RH, ventilation rate 2 Week period – energy efficient, single-family house –50% fluctuation over 24 hr period –Range μg/m 3 Diurnal – model homes –concentrations inc. with T –Inverse relationship in Non-UFFI home –Max in morning when home is closed up –Shows that variations are normal Gammage and Gupka, 1984
Controls Seasonal –Temperature, RH, ventilation rate –Levels double for every 10 °F –RH inc. 30 – 70 % exposure levels inc. by 40 % (Hess-Kosa, 2002) Turco, 2002 Gammage and Gupka, 1984
Measurement UV-Vis, HPLC, GC (see Hess-Kosa for more details) Electrochemical (passive and active) Photometric
Measurement UV-Vis –Nash, 1953 –Shimadzu method uses Hantzsch reagent (acetylacetone reagent) –NIOSH 3500 method uses chromotropic acid –Formaldehyde is highly water soluble gas, forms formalin
Sampling Sample during times and conditions similar to when complaints occur Complaint area, non-complaint area and outside Vicinity of occupants breathing zone
Summary Used in a wide variety of processes and products Carcinogenic, irritant poses safety hazard Max permissible exposure 2.0 – 0.1 mg/m 3 very close to demonstrated rodent carcinogenic dose of 5.6 mg/m 3 and NOEL of 2 mg/m 3
Books Hess-Kosa, K. (2002) Indoor Air Quality. Lewis Publishers. Leslie, G.B. and Lunau, F.W. (1992) Indoor Air Pollution: Problems and Priorities. Cambridge University Press. Turco, R.P. (2002) Earth Under Seige: From Air Pollution to Global Change. Oxford University Press, London.
References Potted Plants aren’t the answer to sick building syndrome: Gammage, R.B. and Gupta, K.C., “Formaldehyde”, in: Walsh, P.J., Dudney, C.S., and Copenhaver, E.D., eds. (1984) Indoor Air Quality. CRC Press, Boca Raton, Florida.