Team:Evry/Project/Compounds/Targets

Phenols and their close relatives 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 also a major chemical intermediate for the manufacture of artificial resins, fertilizers, explosives, pharmaceuticals and textile. Consequently, aquatic organisms including fish are subjected to these polluants. (Nahed S. Gad and Amal S. Saad 2008).

Excessive exposure to elements in this diverse group of chemicals may cause a variety of health effects depending on the particular chemical. It may health effects on the brain, digestive system, eye, heart, kidney, liver, lung, peripheral nerve, skin and the unborn child. Phenol may also cause genetic damage.
Phenols are toxic to aquatic animals and in general fish appear to be the most sensitive. Chlorinated phenols are the most toxic to aquatic life (more informations here).
Phenol is categorized as a Volatile Organic Compound (VOC) that can contribute to photochemical smog.

Figure2: Phenol chemical structure

Polychlorinated biphenyls (PCBs) are synthetic organic compounds which formed a family of 209 elements which derived of biphenyl and with the chemical formule C12H(10-n)Cln. Every core can have up to 5 chloro. They are known like being the most widely identified environmental contaminants persisting in the biosphere. Due to their inherent thermal and chemical stability, it is commonly considered as indestructible under normal incineration or burial. Hydroxylated polychlorinated biphenyls (OH-PCBs) are metabolites of PCBs and have also been identified as environmental contaminants.

Due to years of intensive use in industrial applications, PCBs are found in large quantities in natural environment (air, water, soils, wildlife, food chain, on the surface of sediments at the bottoms of rivers). Since the 80’s, their production is banned because of their toxicologic properties causing carcinogenicity, reproductive impairment, neurodevelopmental anomalies, and immunologic deficiency.

Figure3: PCBs chemical structure

Nitrites are completely natural compounds that takes part of the natural nitrogen cycle read circle Figure 3. Nitrites are natural nitrates reduction products.
The nitrate ion is one of the principal azote sources for plants. Natural or synthetic commercial fertilizers are largely used to increase crops yield and be responsible from 30 to 50% of yield (Stewart,2005).

high nitrate water concentration have effect on human and animal health. In fact, nitrites are nitrates reduction products that are responsible to Blue Baby Syndrome. This syndrome can occur when nitrate level is above 100 mg/L (8) in groundwater.
Symptoms start from a gently cyanosis and if it is not treated on time, can cause cerebral lesions and death.

Figure4: Nitrites chemical structure

Most of 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).

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 productsetc... Because of health concerns, using 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, chromium, mercury, arsenic, and antimony 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).