Jump to content

Volatile organic compound: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Line 15: Line 15:


===United States===
===United States===
VOCs (or specific subsets of the VOCs) are legally defined in the various laws and codes under which they are regulated. Other definitions may be found from government agencies investigating or advising about VOCs.<ref>[http://toxics.usgs.gov/definitions/vocs.html USGS definition]</ref> The [[United States Environmental Protection Agency]] (EPA) regulates VOCs in the air, water, and land. The [[Safe Drinking Water Act]] implementation even includes a short list labeled VOCs in connection with contaminants which are organic and volatile.<ref>40CFR141</ref> The EPA also publishes testing methods for chemical compounds, some of which refer to VOCs.<ref>http://www.epa.gov/waterscience/methods/method/files/524_2.pdf</ref>
VOCs (or specific subsets of the VOCs) are legally defined in the various laws and codes under which they are regulated. Other definitions may be found from government agencies investigating or advising about VOCs.<ref>[http://toxics.usgs.gov/definitions/vocs.html USGS definition]</ref> The [[United States Environmental Protection Agency]] (EPA) regulates VOCs in the air, water, and land. The [[Safe Drinking Water Act]] implementation includes a list labeled "VOCs in connection with contaminants which are organic and volatile."<ref>40CFR141</ref> The EPA also publishes testing methods for chemical compounds, some of which refer to VOCs.<ref>http://www.epa.gov/waterscience/methods/method/files/524_2.pdf</ref>


In addition to drinking water, VOCs are regulated in discharges to waters (sewage treatment and stormwater disposal), as hazardous waste,<ref>[[CERCLA]] and RCRA</ref> but not in non industrial indoor air.<ref>http://www.epa.gov/iaq/voc.html</ref> The [[United States Department of Labor]] and its Occupational Safety and Health Administration (OSHA) regulate VOC exposure in the workplace. Volatile organic compounds which are [[hazardous material]] would be regulated by the [[Pipeline and Hazardous Materials Safety Administration]] while being transported.
In addition to drinking water, VOCs are regulated in discharges to waters (sewage treatment and stormwater disposal), as hazardous waste,<ref>[[CERCLA]] and RCRA</ref> but not in non industrial indoor air.<ref>http://www.epa.gov/iaq/voc.html</ref> The [[United States Department of Labor]] and its Occupational Safety and Health Administration (OSHA) regulate VOC exposure in the workplace. Volatile organic compounds which are [[hazardous material]] would be regulated by the [[Pipeline and Hazardous Materials Safety Administration]] while being transported.

Revision as of 19:26, 19 October 2010

Volatile organic compounds (VOCs) refers to organic chemical compounds which have significant vapor pressures and which can affect the environment and human health. VOCs are numerous, varied, and ubiquitous. Although VOCs include both man-made and naturally occurring chemical compounds, it is the anthropogenic VOCs that are regulated, especially for indoors where concentrations can be highest. VOCs are typically not acutely toxic but have chronic effects. Because the concentrations are usually low and the symptoms slow to develop, analysis of VOCs and their effects is a demanding area.

Definitions

Main article: Solvent

No widely supported definition of a VOC exists.[1]

The definitions of VOCs used for control of precursors of photochemical smog used by EPA and states with their own outdoor air pollution regulations includes exemptions for compounds that are technically only those volatile organic compounds but that are determined to be non-reactive or of low-reactivity in the smog formation process. EPA formerly defined these compounds as Reactive Organic Gases (ROG) but changed the terminology to VOC for simplicity's sake. However, this specific use of the term VOCs can be misleading, specifically when applied to indoor air quality because many chemicals that are not regulated for purposes of controlling outdoor air pollution but that are important from an indoor air quality perspective are still found in products that are labeled as to VOC content according to the requirements of ambient air pollution regulation.

Canada

Health Canada classes VOCs as organic compounds that have boiling points roughly in the range of 50 to 250 °C (122 to 482 °F). The emphasis is placed on commonly encountered VOCs which would have an effect on air quality.[2]

European Union

A VOC is any organic compound having an initial boiling point less than or equal to 250 °C measured at a standard atmospheric pressure of 101.3 kPa and can do damage to visual or audible senses.[3]

United States

VOCs (or specific subsets of the VOCs) are legally defined in the various laws and codes under which they are regulated. Other definitions may be found from government agencies investigating or advising about VOCs.[4] The United States Environmental Protection Agency (EPA) regulates VOCs in the air, water, and land. The Safe Drinking Water Act implementation includes a list labeled "VOCs in connection with contaminants which are organic and volatile."[5] The EPA also publishes testing methods for chemical compounds, some of which refer to VOCs.[6]

In addition to drinking water, VOCs are regulated in discharges to waters (sewage treatment and stormwater disposal), as hazardous waste,[7] but not in non industrial indoor air.[8] The United States Department of Labor and its Occupational Safety and Health Administration (OSHA) regulate VOC exposure in the workplace. Volatile organic compounds which are hazardous material would be regulated by the Pipeline and Hazardous Materials Safety Administration while being transported.

Biologically derived VOCs

The majority of VOCs arise from plants.[9] One indication of this flux is the strong odor emitted by many plants. The emissions are affected by a variety of factors, such as temperature, which determines rates of volatilization and growth, and sunlight, which determines rates of biosynthesis. Emission occurs almost exclusively from the leaves, the stomata in particular. A major class of VOCs are terpenes, such as myrcene.[10] Providing a sense of scale, a forest 62,000 km2 in area (the U.S. state of Pennsylvania) is estimated to emit 3,400,000 kilograms of terpenes on a typical August day during the growing season.[11] Induction of genes producing volatile organic compounds and subsequent increase in volatile terpenes has been achieved in maize using (Z)-3-Hexen-1-ol and other plant hormones.[12]

Major Anthropogenic Sources

Paints and coatings

A major source of man-made VOCs are solvents, especially paints and protective coatings. Solvents are required to spread a protective or decorative film. Approximately 12 billion liters of paints are produced annually. Typical solvents are aliphatic hydrocarbons, ethyl acetate, glycol ethers, and acetone. Motivated by cost, environmental concerns, and regulation, the paint and coating industries are increasingly shifting toward aqueous solvents.[13]

Chlorofluorocarbons and chlorocarbons

Chlorofluorocarbons, which are banned or highly regulated, were widely used cleaning products and refrigerants. Tetrachloroethene is used widely in dry cleaning and by industry. Industrial use of fossil fuels produces VOCs either directly as products (e.g. gasoline) or indirectly as byproducts (e.g. automobile exhaust).

Formaldehyde

Many building materials such as paints, adhesives, wall boards, and ceiling tiles slowly emit formaldehyde, which irritates the mucous membranes and can make a person irritated and uncomfortable.[14] Formaldehyde emissions from wood are in the range of 0.02 – 0.04 ppm. Relative humidity within an indoor environment can also affect the emissions of formaldehyde. High relative humidity and high temperatures allow more vaporization of formaldehyde from wood-materials.[15] There are also many sources of VOCs in office buildings, which include new furnishings, wall coverings, and office equipment such as photocopy machines which can off-gas VOCs into the air.[14]

MTBE

MTBE was banned in the US around 2004 in order to limit further contamination of drinking water aquifers.

Indoor air

Main article: Indoor air quality

Since people today spend most of their time at home or in an office, long-term exposure to VOCs in the indoor environment can contribute to sick building syndrome.[16] In offices, VOC results from new furnishings, wall coverings, and office equipment such as photocopy machines, which can off-gas VOCs into the air.[14] [17] Good ventilation and air conditioning systems are helpful at reducing VOC emissions in the indoor environment.[14] Studies also show that relative leukemia and lymphoma can increase through prolonged exposure of VOCs in the indoor environment.[18]


The United States Environmental Protection Agency (EPA) has found concentrations of VOCs in indoor air commonly to be 2 to 5 times greater than in outdoor air and sometimes far greater. During certain activities indoor levels of VOCs may reach 1,000 times that of the outside air.[19] Studies have shown that individual VOC emissions by themselves are not that high in an indoor environment, but the indoor total VOC (TVOC) concentrations can be up to five times higher than the VOC outdoor levels.[20] New buildings especially, contribute to the highest level of VOC off-gassing in an indoor environment because of the abundant new materials generating VOC particles at the same time in such a short time period.[21] In addition to new buildings, we also use many consumer products that emit VOC compounds, therefore the total concentration of VOC levels is much greater within the indoor environment.[21]

VOC concentration in an indoor environment is three to four times higher than the VOC concentrations during the summer.[22] High indoor VOC levels are attributed to the low rates of air exchange between the indoor and outdoor environment as a result of tight-shut windows and the increasing use of humidifiers[23]

Indoor air quality and emissions into indoor air

In most countries a separate definition of VOCs is used with regard to indoor air quality that comprises each organic chemical compound that can be measured as follows: Adsorption from air on Tenax TA, thermal desorption, gas chromatographic separation over a 100% non polar column (dimethylpolysiloxane). VOC (volatile organic compounds) are all compounds that appear in the gas chromatogram between and including n-hexane and n-hexadecane. Compounds appearing earlier are called VVOC (very volatile organic compounds) compounds appearing later are called SVOC (semi-volatile organic compounds). See also these standards: ISO 16000-6, ISO 13999-2, VDI 4300-6, German AgBB evaluating scheme, German DIBt approval scheme, GEV testing method for the EMICODE. Overview over VOC emissions rating schemes, Healthy Buildings Conference 2009 [1].

Health risks

Respiratory, allergic, or immune effects in infants or children are associated with man-made VOCs and other indoor or outdoor air pollutants.[24]

Some VOCs, such as styrene and limonene, can react with nitrogen oxides or with ozone to produce new oxidation products and secondary aerosols, which can cause sensory irritation symptoms.[25] [26] Unspecified VOCs are important in the creation of smog.[27]

Health effects include:

Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans. Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, emesis, epistaxis, fatigue, dizziness.
The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic, to those with no known health effect. As with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. At present, not much is known about what health effects occur from the levels of organics usually found in homes. Many organic compounds are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans.[28]

Chemical fingerprinting

The exhaled human breath contains a few hundred volatile organic compounds and is used in breath analysis to serve as a VOC biomarker to test for diseases such as lung cancer.[29] One study has shown that "volatile organic compounds ... are mainly blood borne and therefore enable monitoring of different processes in the body."[30] And it appears that VOC compounds in the body “may be either produced by metabolic processes or inhaled/absorbed from exogenous sources” such as environmental tobacco smoke.[31] [32] Research is still in the process to determine whether VOCs in the body are contributed by cellular processes or by the cancerous tumors in the lung or other organs.

VOCs Sensors

Main article: VOCs Sensor

VOCs in the environment or certain atmospheres can be detected based in different principles and interactions between the organic compounds and the sensor components. There are electronic devices that can detect ppm concentrations despite the non-selectivity. Others can predict with reasonable accuracy the molecular structure of the volatile organic compounds in the environment or enclosed atmospheres[33] and could be used as accurate monitors of the Chemical Fingerprint and further as health monitoring devices.

See also

References

  1. ^ List of VOC limit values for emissions into indoor air published by German AgBB, French AFSSET, and California EPA ("CREL").
  2. ^ Health Canada
  3. ^ Directive 2004/42/CE of the European Parliament and of the Council of 21 April 2004 on the limitation of emissions of volatile organic compounds due to the use of organic solvents in certain paints and varnishes and vehicle refinishing products EUR-Lex, European Union Publications Office. Retrieved on 2010-09-28.
  4. ^ USGS definition
  5. ^ 40CFR141
  6. ^ http://www.epa.gov/waterscience/methods/method/files/524_2.pdf
  7. ^ CERCLA and RCRA
  8. ^ http://www.epa.gov/iaq/voc.html
  9. ^ Monson, R. K., (2002). Volatile organic compound emissions from terrestrial ecosystems: A primary biological control over atmospheric chemistry. Israel Journal of Chemistry 42(1), 29 -42.
  10. ^ "Physiological and physicochemical controls on foliar volatile organic compound emissions" Ü. Niinemets, F. Loreto, M. Reichstein" Trends in Plant Science Volume 9, Issue 4, April 2004, Pages 180-186. doi:10.1016/j.tplants.2004.02.006
  11. ^ Arno, B. and Leif, J., "Myrcene as a Natural Base Chemical in Sustainable Chemistry: A Critical Review", ChemSusChem, 2009, volume 2, pp. 1072-1095. doi:10.1002/cssc.200900186
  12. ^ Farag, Mohamed A., Mohamed Fokar, Haggag A. Zang, Randy D. Allen, and Paul W. Pare. "(Z )-3-Hexenol Induces Defense Genes and Downstream Metabolites in Maize." Planta 10. 7 (2005): 900-909. Springerlink. Web. 25 Apr. 2010.
  13. ^ Dieter Stoye "Paints and Coatings" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a18_359.pub2
  14. ^ a b c d Bernstein, J. A., Alexis, N., Bacchus, H., Bernstein, I. L., Fritz, P., Horner, E., et al. (2008). The health effects of nonindustrial indoor air pollution. Journal of Allergy and Clinical Immunology, 121(3), 585-591. doi:[https://doi.org/10.1016%2Fj.jaci.2007.10.045 10.1016/j.jaci.2007.10.045
  15. ^ Wolkoff, P., & Kjærgaard, S. K. (2007). The dichotomy of relative humidity on indoor air quality. Environment International, 33(6), 850-857.
  16. ^ Wang, S., Ang, H. M., & Tade, M. O. (2007). Volatile organic compounds in indoor environment and photocatalytic oxidation: State of the art. Environment International, 33(5), 694-705. "doi: 10.1016/j.envint.2007.02.011"
  17. ^ Yu, C., & Crump, D. (1998). A review of the emission of VOCs from polymeric materials used in buildings. Building and Environment, 33(6), 357-374.
  18. ^ Irigaray, P., Newby, J. A., Clapp, R., Hardell, L., Howard, V., Montagnier, L., et al. (2007). Lifestyle-related factors and environmental agents causing cancer: An overview. Biomedicine & Pharmacotherapy, 61(10), 640-658.
  19. ^ http://www.epa.gov/iaq/voc.html An Introduction to Indoor Air Quality
  20. ^ Jones, A. P. (1999). Indoor air quality and health. Atmospheric Environment, 33(28), 4535-4564.
  21. ^ a b Wang, S., Ang, H. M., & Tade, M. O. (2007). Volatile organic compounds in indoor environment and photocatalytic oxidation: State of the art. Environment International, 33(5), 694-705.
  22. ^ Barro, R., Regueiro, J., Llompart, M., & Garcia-Jares, C. (2009). Analysis of industrial contaminants in indoor air: Part 1. volatile organic compounds, carbonyl compounds, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Journal of Chromatography A, 1216(3), 540-566.
  23. ^ Schlink, U., Rehwagen, M., Damm, M., Richter, M., et al. (2004) Seasonal cycle of indoor-VOCs: comparison of apartments and cities. Atmospheric. Environment, 38, 1181-1190.
  24. ^ Mendell, M. J. (2007). Indoor residential chemical emissions as risk factors for respiratory and allergic effects in children: A review. Indoor Air, 17(4), 259-277.
  25. ^ Wolkoff, P., Wilkins, C. K., Clausen, P. A., & Nielsen, G. D. (2006). Organic compounds in office environments — sensory irritation, odor, measurements and the role of reactive chemistry. Indoor Air, 16(1), 7-19.
  26. ^ Bernstein, J. A., Alexis, N., Bacchus, H., Bernstein, I. L., Fritz, P., Horner, E., et al. (2008). The health effects of nonindustrial indoor air pollution. Journal of Allergy and Clinical Immunology, 121(3), 585-591.
  27. ^ "What is Smog?", Canadian Council of Ministers of the Environment, CCME.ca
  28. ^ [http://www.epa.gov/iaq/voc.html EPA -- An Introduction to Indoor Air Quality Pollutants and Sources of Indoor Air Pollution Volatile Organic Compounds (VOCs)]
  29. ^ Buszewski, B., Kesy, M., Ligor, T. and Amann, A. (2007). Human exhaled air analytics: biomarkers of diseases. Biomedical Chromatography, 21(6), 553-566. "doi: 10.1002/bmc.835"
  30. ^ Miekisch, W., Schubert, J. K., and Noeldge-Schomburg, G. F. E. (2004). Diagnostic potential of breath analysis—focus on volatile organic compounds. Clinica Chimica Acta, 347(1-2), 25-39. Retrieved March 24, 2009 from "ScienceDirect Database"
  31. ^ Buszewski, B., Kesy, M., Ligor, T. and Amann, A. (2007). Human exhaled air analytics: biomarkers of diseases. Biomedical Chromatography, 21(6), 553-566. "doi: 10.1002/bmc.835"
  32. ^ Mazzone, P.J. (2008). Analysis of volatile organic compounds in the exhaled breath for the diagnosis of lung cancer. Journal of Thoracic Oncology. 3(7), 774-780. Retrieved Abstract on March 24, 2009 from PubMed Database "PMID: 18594325"
  33. ^ Detection of Hydrocarbons and Other Volatile Organic Compounds: http://pubs.acs.org/doi/abs/10.1021/la102693m
Retrieved from "https://en.wikipedia.org/w/index.php?title=Volatile_organic_compound&oldid=391697370"