Transcript Environmental Chemistry - Robert Morris University

Industrial Hygiene
Formaldehyde
Copyright © 2008 by DBS
Contents
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Chemistry
Sources
Uptake
Health Effects
Risk Assessment
Measurement
Summary
Chemistry
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CH2O, 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)
NYT 100481
NYT 100481
Exposure
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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
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Production: 1.4 x 106 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
Product
Range of emission rates (10-6 g per g
material per day
Particleboard
0.4 – 8.1
Plywood
0.03 - 9.2
Imitation wood paneling
0.8 - 2.1
Fiberglass insulation
0.3 - 2.3
Clothing
0.2 - 4.9
Carpeting
0 – 0.06
Paper products
0.03 – 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/m3 x 0.8
Exposure
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Natural background 0.1 μg/m3 – 1.0 mg/m3 from decomp. organic matter
Industrial areas 0.04 mg/m3
Indoor levels 0.1 – 0.8 mg/m3 (0.1 - 0.6 ppm)
Mobile homes > 1 mg/m3 (due to tight space and more wood products)
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High indoor levels attributed to particle board and plywood products
Leslie and Lunau, 1992
(see also previous ref.)
Uptake
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Major pathway: Vapor phase
Target organs: lungs
Symptoms: irritation eyes, nose, throat, lungs
Symptoms exhibited above 1 mg/m3
Absorbed by mucous membrane of nasal cavity
Health Effects
Acute Exposure
Inhalation
• > 15 mg/m3 lethal dose
• Irritant effects at 0.5 mg/m3 to severe at 10 mg/m3
• Coughing, wheezing, chest pain, inc. heart rate, bronchitis
• No federal limits for residences and offices
• EPA allows no more than 0.016 ppm in new EPA buildings (0.020 mg/m3)
• 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
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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/m3) for
carcinogenity to humans
Controls
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Occupant activities, Temperature,
RH, ventilation rate
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2 Week period – energy efficient,
single-family house
– 50% fluctuation over 24 hr period
– Range 140-300 μg/m3
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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
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Seasonal
– Temperature, RH, ventilation rate
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Levels double for every 10 °F
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RH inc. 30 – 70 % exposure levels
inc. by 40 % (Hess-Kosa, 2002)
Gammage and Gupka, 1984
Turco, 2002
Measurement
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UV-Vis, HPLC, GC (see Hess-Kosa for more details)
Electrochemical (passive and active)
Photometric
Measurement
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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
Measurement
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Electrochemical:
– 3M Formaldehyde Monitor
– Enmet Formaldemeter htV
– Hal Technology HFX105 Formaldehyde Monitor
http://www.enmet.com/pers_formald.shtml
Measurement
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Photometric
Hess-Kosa, 2002
http://www.formaldehydedetector.com
Sampling
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Sample during times and conditions similar to when complaints occur
Complaint area, non-complaint area and outside
Vicinity of occupants breathing zone
Summary
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Used in a wide variety of processes and products
Carcinogenic, irritant poses safety hazard
Max permissible exposure 2.0 – 0.1 mg/m3 very close to
demonstrated rodent carcinogenic dose of 5.6 mg/m3 and NOEL
of 2 mg/m3
Books
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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
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Potted Plants aren’t the answer to sick building syndrome:
http://www.scienceblog.com/community/older/2000/D/200003104.html
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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.