Nonylphénol

Nonylphénol, or NP, is synthetic chemicals pertaining to the family of the alkylphénols. The name of Nonylphénol gathers the various forms in which one finds it, i.e., 2,3 or 4 nonylphénol. Nonylphénols are the precursors in the manufacture of the polyéthoxylés nonylphénols, or NPE, by addition of éthoxylates groups (until a hundred) largely used in industry

The worldwide production of Nonylphenol is estimated around 600,000 tons per annum.

Nonylphénol is a toxic substance bioaccumulable and Biodégradable but persistent. Indeed, they are completely degraded only after several weeks according to the medium in which they are what allows the contamination of the environment and certain organizations.

Industrial applications and uses

The NPE are synthesized because of their surface-active properties which allow a better dispersion of the liquids and the miscibility of certain substances such as oil and water. Thus, they are largely used in industry. Indeed, industries of the textile employ them like agents of damping, dispersants, emulsifiers or like detergents. They are also used in paintings, the production of pastes and papers, the treatment of metals, the extraction and the production of oil like in certain cosmetic products such as the shampoos and certain cleaning products domestic. This indicates that the NPE are present at the private individuals in great quantity.

Origin

The NPE are rejected into the environment mainly by the industrial effluents, the effluents of the municipal stations of purification of waste water, by forward thrust in the aquatic environments but also by the private individuals since they are present in maintenance products (ref. 3). They are thus rejected into the sewers then the effluents are treated in the purification plants. According to the treatment applied, only 20 to 80% of the NPE are eliminated. However, it is possible to eliminate the NPE up to 90%. In the majority of the cases, the primary education Traitements which consist of a simple decantation which makes it possible to remove the major part of the suspended matter are only carried out because the more powerful treatments are expensive. The NPE then undergo a biological degradation by micro-organisms. At the time of a first stage, the degradation of the NPE involves the formation of under products and the regeneration of NP. The intermediate and final products of the metabolism are more persistent than the NPE parents. After several weeks, these under products are completely degraded in particular by CO2 and photodegradation. They are thus found in the environment in particular in the grounds, muds of spreading, subterranean water, the rivers and the sediments. NP are persistent under conditionins anaerobic (in subterranean water, the sediments and the discharges) but much less seem the being in the ground in aerobic medium (ref. 3). The presence of NP and NPE in the sediments are explained by the fact why they are adsorbed by particles which settle then at the bottom of the rivers. Their adsorption depends in particular on the percentage of total organic carbon of the sediments. Thus, the watery plants, the fish and at the organizations coming into contact with the sediments can absorptive NP and NPE which they contain. NP are known to accumulate in fabrics of fish and other living organisms, and to follow a process of biomagnification in the food chain. They are thus found in the food chain in many products such as the pork-butchery, tomatos or apples.

Toxicity

NP and the NPE being every two present in the environment, the toxicity of the two made up ones is taken into account and is expressed in toxic equivalent of NP or AND. NP are known to have disturbing effects on the system endocrinien and an estrogen activity, i.e. the capacity to imitate the natural sex hormones, which can involve the feminization of fish. They can also cause a reduction in the success of reproduction, a deceleration of the growth, a reduction in the size and can result in the death of certain watery organizations. NP is relatively toxic for the fish (17-1 400 μg/L), the invertebrates (20-3 000 μg/L) and the algae (27-2 500 μg/L). The toxicity of the NPE increases in a way inversely proportional to the length of the chain ethoxyl. NP are from 2 to 200 times more toxic than NPE (ref. 4).

The effects of NP on the Man are still known little about for lack of studies. However, of recent work showed effects on the functions of sperm in the mammals and a deterioration of the DNA in human sperm, the human lymphocytes

The estimate of the possible exposure to NP and the NPE is difficult because of the many potential sources of exposure to these compounds. Indeed, it is necessary to take into account the indirect exposure due to the rejections in the environment caused by various industrial activities and servants but also the direct exposure of human to these various compounds present in many consumables. The data of monitoring of the mediums to which the human ones are most likely to be exposed are extremely limited. Because of these limitations, it is not possible to estimate with confidence the exposure of the population to NP and the NPE. (ref. 4)

Techniques of analyzes

NP can be analyzed by several methods such as colorimetry, the chromatography coupled to a detector of selective mass (GC-MSD) or by Liquid Chromatographie High efficiency with detection of fluorescence preceded by an extraction of the solid phase (SPE/HPLC-fluorescence)

Studies

In 2004, a study carried out in France by bearing Greenpeace on 50 hearths and an elementary school, made it possible to highlight the presence of NP in certain pyjamas for children, toys, cleaning products or paintings whereas since 2003, they are prohibited in Germany because the research center of Jülich found remainders of Nonylphenol in food products such as the chocolate, apples and the pork-butchery. This research center also found NP traces in the mother's milk. (ref. 2) Always according to Greenpeace, more than 25% of the rivers of the European Union present rates of Nonylphénols `regularly higher than the `concentration for null purpose'.

In Canada, the NP concentrations in the sediments of the basin of the Big lakes and the St-Laurent river varied between values lower than the levels of detection (<0,02 μg/g of dry weight) and 110 μg/g of dry weight. These concentrations exceed the Provisional Canadian Recommendation for the Quality of the Sediments (RCPQS) which is of 1.4 Mg ET/kg indicating that harmful effects can occur (ref. 3).

Alternative

In the majority of the fields in which the NPE are used, the substitution of the latter is possible by fatty alcohols ethoxyls. These substitute products do not have any more the function phenol which would be responsible for toxicity and ecotoxicity. They would not thus have any more disturbing effects endocriniens and would not present any other major disadvantage. The majority of industries for which the replacement of the NPE has an accessible cost implement this substitution. However, in the sector of industrial cleaning, the costs seem high but set up of the substitute products is all the same to adopt even if it will take more time for this sector for that. On the other hand, in the industry of the textile, it would seem that alternatives are possible at a bearable cost but that the profession did not still implement anything to adopt them.

Thanks to these possibilities of replacement, a reduction of 98% of the NP rejections in the water of industries of pastes and papers were observed between 2001 and 2003 in Canada.

References

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