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Environmental impact of DCM


Uses

Chlorinated solvents are organic solvents containing chlorine atoms in their molecular structure. They have a huge range of uses by individuals, professionals, and industry.

The chlorinated solvent DCM has been used in industry for over 80 years. Its unique combination of properties - low boiling point, high solvency power, relative inertness, low toxicity and non flammability - has led to its wide variety of applications. It is the most widely-used of the chlorinated solvents, particularly for pharmaceutical production, and is as well used as an extraction medium/process solvent.(Eurochlor). For these reasons, our team has chosen to use DCM as the case study chemical for which we will develop a bioremedication mechanism eventually applicable to all chlorinated solvents.

Who produces chlorinated solvent waste, and why?

Eurochlor, the EU body responsible for the European Chlorinated Solvents Association) analyses the uses and impact of chlorinated solvents in three categories:
  • Industrial
    Chlorinated solvents have too many industrial applications to list. Amongst the most essential are food production, cleaning, the textile industry, manufacturing, foam blowing, fire extinguishers, and as an extraction solvent and functional fluid.

  • Professional
    These solvents are widely used in laboratories, as well as extensive use in dry cleaning, film cleaning and copying, aerosols, adhesives, and packaging.

  • Consumer
    Prominent uses include aerosols (despite controversies chlorinated solvents remain present in a wide range of aerosol products including hairspray and deodorant), glue and other home decorating products such as paint and paint stripper. Chlorinated solvents are also common in home-use pest control sprays and in various washing and cleaning products.
  • Environmental Impact

    Current disposal methods for chlorinated solvents are inadequate on every level. Because individual users may use chlorinated solvents infrequently or in very small amounts, they make not think it worthwhile, may not have the means, or may lack the knowledge/understanding of chlorinated solvents to ensure waste is disposed of properly. Cumulatively these small incidents amount to a large volume of chlorinated solvents which are simply poured down the drain or otherwise dangerously disposed of, leading to grave and often long-lasting environmental damage.

    For worse is the impact of the much greater volumes of chlorinated solvents used professionally and in industry. Although disposal is regulated and there are high penalties for failure to deal properly chlorinated waste, contamination remains an issue. Meanwhile, even that waste which is disposed of in accordance with procedure caused environmental harm; currently chlorinated solvents which can no longer be recycled are simply incinerated released damaging compounds into the atmosphere.

    “Quote from EA how bad chlorinated solvents are, how many hundreds of thousands/millions it costs to clean them up, & this is paid by taxpayers, how standards are lower in other countries…”

    British Environment Agency

    Click the images below to discover more about the damage caused by chlorinated solvent waste to the atmosphere, biosphere, ground and surface water, and to the marine environment.


    Atmosphere


    The Environmental Protection Agency has expressed fears that even short lived halocarbons may have a significant detrimental effect on the global atmosphere, as well as concerns about our relative lack of understanding of the environmental effects of these compounds2. Several chlorinated solvents are listed by the U. S. Environmental Protection Agency (U.S. EPA) as a hazardous air pollutant (HAP) under the U.S. Clean Air Act. However, various environmental NGOs and organisations maintain that current regulation of chlorinated solvent disposal is inadequate - for example, chlorinated solvents are not regulated under the Montreal Protocol despite evidence that they may contribute to ozone depletion.

    Photochemical Smog

    TCE and PBRC have both been linked to photochemical smog - both used in textiles industry.

    Global Warming

    Dichloromethane has a Global Warming Potential (GWP) ten times greater than that of carbon dioxide, whilst trichloromethane has a GWP 30 times greater. At the time of writing the GWPs of tetrachloroethene and trichloroethene are not known, but are expected to be comparable to those for DCM and TCM.

    Acid Rain

    In the lower atmosphere degradation of chlorinated solvents is initiated by a reaction with the hydroxyl radical, and forms a variety of products including hydrochloric acid, formic acid, and phosgene (the colourless gas infamous for its use as a chemical weapon during World War One). These compounds dissolve in cloud and rain water and are ultimately deposited from the atmosphere in acid rain and snow.

    Further, trichloroacetic acid (TCA) can be formed as a minor product in the atmospheric deg-radation of some chlorinated solvents. Studies have shown that TCA is broadly distributed in precipitation, surface water and soil on a global scale. Since the observed levels in soil in some areas have been found to exceed the accepted 'safe' levels (2.4 μg/kg for terrestrial organisms) the European Commission instructed producers of the relevant solvents to carry out extensive studies of the origin and fate of environmental TCA. Although the results of these studies suggest that TCA levels in soils could not be explained by precipitation alone, the European Union Risk Assessment on nevertheless concluded that “it is considered unlikely that depo-sition of TCA from the atmosphere will by itself lead to levels of TCA in soil that pose a risk for ter-restrial organisms”.




    Atmosphere


    The Environmental Protection Agency has expressed fears that even short lived halocarbons may have a significant detrimental effect on the global atmosphere, as well as concerns about our relative lack of understanding of the environmental effects of these compounds2. Several chlorinated solvents are listed by the U. S. Environmental Protection Agency (U.S. EPA) as a hazardous air pollutant (HAP) under the U.S. Clean Air Act. However, various environmental NGOs and organisations maintain that current regulation of chlorinated solvent disposal is inadequate - for example, chlorinated solvents are not regulated under the Montreal Protocol despite evidence that they may contribute to ozone depletion.

    Photochemical Smog

    TCE and PBRC have both been linked to photochemical smog - both used in textiles industry.

    Global Warming

    Dichloromethane has a Global Warming Potential (GWP) ten times greater than that of carbon dioxide, whilst trichloromethane has a GWP 30 times greater. At the time of writing the GWPs of tetrachloroethene and trichloroethene are not known, but are expected to be comparable to those for DCM and TCM.

    Acid Rain

    In the lower atmosphere degradation of chlorinated solvents is initiated by a reaction with the hydroxyl radical, and forms a variety of products including hydrochloric acid, formic acid, and phosgene (the colourless gas infamous for its use as a chemical weapon during World War One). These compounds dissolve in cloud and rain water and are ultimately deposited from the atmosphere in acid rain and snow.

    Further, trichloroacetic acid (TCA) can be formed as a minor product in the atmospheric deg-radation of some chlorinated solvents. Studies have shown that TCA is broadly distributed in precipitation, surface water and soil on a global scale. Since the observed levels in soil in some areas have been found to exceed the accepted 'safe' levels (2.4 μg/kg for terrestrial organisms) the European Commission instructed producers of the relevant solvents to carry out extensive studies of the origin and fate of environmental TCA. Although the results of these studies suggest that TCA levels in soils could not be explained by precipitation alone, the European Union Risk Assessment on nevertheless concluded that “it is considered unlikely that depo-sition of TCA from the atmosphere will by itself lead to levels of TCA in soil that pose a risk for ter-restrial organisms”.




    Atmosphere


    The Environmental Protection Agency has expressed fears that even short lived halocarbons may have a significant detrimental effect on the global atmosphere, as well as concerns about our relative lack of understanding of the environmental effects of these compounds2. Several chlorinated solvents are listed by the U. S. Environmental Protection Agency (U.S. EPA) as a hazardous air pollutant (HAP) under the U.S. Clean Air Act. However, various environmental NGOs and organisations maintain that current regulation of chlorinated solvent disposal is inadequate - for example, chlorinated solvents are not regulated under the Montreal Protocol despite evidence that they may contribute to ozone depletion.

    Photochemical Smog

    TCE and PBRC have both been linked to photochemical smog - both used in textiles industry.

    Global Warming

    Dichloromethane has a Global Warming Potential (GWP) ten times greater than that of carbon dioxide, whilst trichloromethane has a GWP 30 times greater. At the time of writing the GWPs of tetrachloroethene and trichloroethene are not known, but are expected to be comparable to those for DCM and TCM.

    Acid Rain

    In the lower atmosphere degradation of chlorinated solvents is initiated by a reaction with the hydroxyl radical, and forms a variety of products including hydrochloric acid, formic acid, and phosgene (the colourless gas infamous for its use as a chemical weapon during World War One). These compounds dissolve in cloud and rain water and are ultimately deposited from the atmosphere in acid rain and snow.

    Further, trichloroacetic acid (TCA) can be formed as a minor product in the atmospheric deg-radation of some chlorinated solvents. Studies have shown that TCA is broadly distributed in precipitation, surface water and soil on a global scale. Since the observed levels in soil in some areas have been found to exceed the accepted 'safe' levels (2.4 μg/kg for terrestrial organisms) the European Commission instructed producers of the relevant solvents to carry out extensive studies of the origin and fate of environmental TCA. Although the results of these studies suggest that TCA levels in soils could not be explained by precipitation alone, the European Union Risk Assessment on nevertheless concluded that “it is considered unlikely that depo-sition of TCA from the atmosphere will by itself lead to levels of TCA in soil that pose a risk for ter-restrial organisms”.




    Atmosphere


    The Environmental Protection Agency has expressed fears that even short lived halocarbons may have a significant detrimental effect on the global atmosphere, as well as concerns about our relative lack of understanding of the environmental effects of these compounds2. Several chlorinated solvents are listed by the U. S. Environmental Protection Agency (U.S. EPA) as a hazardous air pollutant (HAP) under the U.S. Clean Air Act. However, various environmental NGOs and organisations maintain that current regulation of chlorinated solvent disposal is inadequate - for example, chlorinated solvents are not regulated under the Montreal Protocol despite evidence that they may contribute to ozone depletion.

    Photochemical Smog

    TCE and PBRC have both been linked to photochemical smog - both used in textiles industry.

    Global Warming

    Dichloromethane has a Global Warming Potential (GWP) ten times greater than that of carbon dioxide, whilst trichloromethane has a GWP 30 times greater. At the time of writing the GWPs of tetrachloroethene and trichloroethene are not known, but are expected to be comparable to those for DCM and TCM.

    Acid Rain

    In the lower atmosphere degradation of chlorinated solvents is initiated by a reaction with the hydroxyl radical, and forms a variety of products including hydrochloric acid, formic acid, and phosgene (the colourless gas infamous for its use as a chemical weapon during World War One). These compounds dissolve in cloud and rain water and are ultimately deposited from the atmosphere in acid rain and snow.

    Further, trichloroacetic acid (TCA) can be formed as a minor product in the atmospheric deg-radation of some chlorinated solvents. Studies have shown that TCA is broadly distributed in precipitation, surface water and soil on a global scale. Since the observed levels in soil in some areas have been found to exceed the accepted 'safe' levels (2.4 μg/kg for terrestrial organisms) the European Commission instructed producers of the relevant solvents to carry out extensive studies of the origin and fate of environmental TCA. Although the results of these studies suggest that TCA levels in soils could not be explained by precipitation alone, the European Union Risk Assessment on nevertheless concluded that “it is considered unlikely that depo-sition of TCA from the atmosphere will by itself lead to levels of TCA in soil that pose a risk for ter-restrial organisms”.