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  1. Phenols

  2. Phenols and their close derivatives are molecules which are widely distributed in nature. They are widespread contaminants whose sources are both natural and industrial (Fahmida Karim A. N. M. Fakhruddin, 2012).
    The largest use of phenols is as an intermediate in the production of phenolic resins, which are low-cost, versatile, thermo set resins used in the plywood adhesive, construction, automotive, and appliance industries.
    Phenols can be used as a general disinfectant, as a reagent in chemical analysis and it's also a major chemical intermediate for the manufacture of artificial resins, fertilizers, explosives, pharmaceuticals and textile. Consequently, aquatic organisms including fishes are subject to these pollutants. (Nahed S. Gad and Amal S. Saad 2008).

    Excessive exposure to elements of this diverse group of chemicals may induce a variety of health effects depending on the particular chemical. It may cause severe damages to many organs and also genetic impairment.
    Beyond being harmful for humans, phenols also appear to be toxic to aquatic animals. Chlorinated phenols are the most noxious to aquatic life (more informations here).
    Moreover phenol is categorized as a Volatile Organic Compound (VOC) contributing to photochemical smog which threaten phytoplankton.

    Figure2: Phenol chemical structure

    Phenol is a priority substance for a lot of countries in the world which have edited rules and safety thresholds.

    *European list of priority substances according to the European Union Commission: EC 1179/94, under Regulation 793/93 (OJ L131, 26.5.94, p.3 - link here)
    *Substances Priority List 2013 according to the Agency for Toxic substances and disease registry: Phenol is ranked at the 180th but we can find phenolic compound at rank 54 and 89 (link here).
    *European Council Directive 80/778/EEC relating to the quality of water intended for human consumption. (link here)
    *Phenol - US Environmental Protection Agency (link here)

  3. PCBs

  4. Polychlorinated biphenyls (PCBs) are synthetic organic compounds forming a family of 209 elements which derive from biphenyl and of chemical formula C12H(10-n)Cln. Every core can have up to 5 chlorin groups. They are known to be the most environmental contaminants persisting in the biosphere. Due to their thermal resistance and chemical stability, they are commonly considered as indestructible. Hydroxylated polychlorinated biphenyls (OH-PCBs) are derivatives of PCBs and have also been identified as environmental contaminants.

    Due to years of intensive use by industries, PCBs are found in large quantities in natural environment (air, water and soils). Since the 80’s, their production has been banned because of their toxicologic properties causing cancers, reproductive impairment, neurodevelopmental anomalies, and immunologic deficiency.

    Figure3: PCBs chemical structure

    PCBs are now considered as extremely dangerous and a lot of countries have established rules and safety thresholds.

    *Substances Priority List 2013 according to the Agency for Toxic substances and disease registry: PCBs are ranked at the 5th (link here).
    *Chemical quality of marine sediments in France: Synthesis of the available databases, INERIS, 2010 (link here)

  5. Nitrite

  6. Nitrites are completely natural compounds that are parts of the natural nitrogen cycle and they are nitrates reduction products.
    The nitrate ion is one of the principal azote sources for plants. Thus natural or synthetic commercial fertilizers contain a lot of these compounds and are largely used to increase crops yield from 30 to 50% (Stewart,2005).

    High nitrate water concentration have effects on living organisms. In fact, nitrites are nitrates reduction products that are responsible for Blue Baby Syndrome. This syndrome can occur when nitrate level is above 100 mg/L (SNIDE) in groundwater.
    Symptoms start from a cyanosis and if it is not treated on time, can cause cerebral lesions and death.

    Figure4: Nitrites chemical structure

    Most of the rules and strict safety thresholds about these compounds concern drinking water.
    *French government: The quality of the drinking water in France - Sanitary and statutory aspects (link here)
    *Basic Information about Nitrite (Measured as Nitrogen) in Drinking Water according to United States Environmental Protection Agency. (link here)
    *Substances Priority List 2013 according to the Agency for Toxic substances and disease registry: Lead is ranked at the 214th (link here).

  7. Heavy metals

  8. Heavy metals are one of the most important family of pollutants. For our project, we chose to focus on two of them, lead and cadmium. All heavy metals exist in surface waters in colloidal, particulate, and dissolved phases.

    Majority of lead in the environment comes from human activity such as burning fossil fuels, mining, and manufacturing. It is used in the production of batteries, ammunition, metal products etc... Because of health concerns, use of lead has been dramatically reduced in recent years.
    Cadmium does not corrode easily and has many uses, including batteries, pigments, metal coatings, and plastics. Moreover, all soils and rocks, including coal and mineral fertilizers, contain some cadmium.
    Living organisms require trace amounts of some heavy metals (cobalt, copper, iron, manganese, etc...), excessive levels of essential metals, however, can be detrimental to the organism.
    Non-essential heavy metals like cadmium, lead, mercury, or arsenic are toxic compounds for all living organisms. According to the Agency for Toxic Substances and Disease Registry, lead and cadmium are considered as carcinogens and can damage all vital or non vital organs. (Lead, Cadmium)

    Figure5: Periodic symbols of Cadmium and Lead

    All heavy metals and their uses are now very supervised and companies which use them have to follow rules and strict safety thresholds.

    *French government publication of 01/01/2014 by law of 02/02/1998 in relation to water sampling and consumption as well as to all residues of classified installations for environment protection subject to authorisation (link here)
    *European Council Directive 83/513/EEC of 26 September 1983 on limit values and quality objectives for cadmium discharges (link here)
    *EPA numeric aquatic life criteria (60 FR 22230) promulgated by EPA on May 4, 1995 (link here).
    *Substances Priority List 2013 according to the Agency for Toxic substances and disease registry: Lead is ranked at the 2nd and Cadmium is ranked at 7th (link here).