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Dictionary

Hazardous Substances in the Environment

Hazardous substances are so classed because they must be prevented from entering the environment. In an ecosystem they may bioaccumulate, with tragic results for both humans and nature.

  • Persistent Organic Pollutant
    • Persistent Organic Pollutants are a classification of organic compounds, typically pesticides, herbicides, and similar products, which have long biodegradation half-lives.

      These pollutants typically transport and bioaccumulate and biomagnify well, and are found in dangerous concentrations in animals, fish and birds far from the source.

      Regulated by the Stockholm Convention on POPs (2001).

      List of POPs
      • Organochlorine Insecticides
        • Chlordane
        • DDT Dichlorodiphenyltrichloroethane
        • Dieldrin
        • Toxaphene
      • Industrially produced chemicals
        • PCB
      • Process Secondary Products
        • Dioxins
  • Pollutants in arctic ice
    • Persistent pollutants can travel in clouds and water far from their source. These can become trapped in ice in the Arctic. Now, climate change is causing these deadly pollutants to re-enter the arctic ecosystem at unprecedented rates.

      An extensive research programme in Canada* has shown that a number of persistent chemicals, such as DDT, PCBs, and mercury, have precipitated in the Arctic, where they has remained in ice for decades. The Arctic is warming twice as fast as the global average, so these pollutants are coming back with a vengeance.

      The research found that the concentration of the POPs and heavy metals in seal meat increased in low-ice years. The pollutants bio-accumulate in cod, which is eaten by the seals.

      * Gary Stern and colleagues at Canada's Department of Fisheries and Oceans, Winnipeg, Manitoba: ringed seal study 1973 - 2007.

  • Chlorinated paraffins
    • A group of organic substances classed as hazardous due to their toxicity, persistence in the environment, and potential for bioaccumulation.

      Chlorinated paraffins are alkanes with a variable number of chlorine (Cl) and carbon (C) atoms. CPs are liquid or solid, colorless or yellowish, depending on the mix and number of C and Cl in the chain. CPs in commercial products have many forms, and are used in flame retardants, sealants, paints, adhesives, textiles, and plasticisers.

      Short-chain CPS (SCCPs) are classified as toxic to aquatic organisms and carcinogenic to lab animals. They are classified by the IARC (International Agency for Research on Cancer) as possibly carcinogenic to humans. The parties to the Stockholm Convention on Persistent Organic Pollutants are currently evaluating a global ban on SCCPs.

  • Radon
    • Radon is a chemical element (atomic number Z=86, mass number of most stable isotope A=222, ), a noble gas, and a source of hazardous, naturally-occurring radioactive pollution.

      Radon is colourless, odourless and tasteless. It occurs in some soils and can migrate into buildings through cracks in walls and flooring, and structural gaps, such as electrical wiring and water pipe ducts. In enclosed spaces it can accumulate and presents an invisible hazard for occupants. Radon exposure is linked to cancer.

      22286Rn has a half-life (t½) of 3.8 days. Although it does not last long in the environment as radon gas, it is continuously being generated as part of the decay sequence of thorium/uranium → radium (Ra: Z=88, A=226). When radon decays it produces further radioactive elements, which are solids and adhere to surfaces such as dust particles. Among the longer lasting decay elements are 21083Bi (Bismuth t½ = 5 days) which beta decays into 21084Po (Polonium t½ = 138 days), and lead (Pb).

      The US EPA ranks radon as the second greatest cause of lung cancer (21k deaths p.a. in the USA), after cigarette smoke. Radon decay products on dust particles will also provoke cancer if inhaled.

      Switzerland: in the Radiation Protection Ordinance of 1994 the following limit values were set for Radon-222: 1000 Bq/m³ for residential and residential areas and 3000 Bq/m³ for workrooms. For new buildings a guideline value of 400 Bq/m³ applies.

      Germany: For the time being, the maximum value of 400 Bq / m³ applies to Germany as well as to the entire EU. In the meantime, the new Euratom standard is in force, which must be transposed into national law by 6 February 2018, according to which the maximum exposure in buildings and rooms in the annual average is max. 300 Bq. This Euratom standard applies to the whole EU.