CARNIVAL OF CHEMISTRY, endocrine disruptors.
Pera who first
A sad idle the fetid waters and silt
My citizen exposed;
And profit was a vile
health calendar. "
G. Parini, Odi
" The clean air"
1761
1. Trace contaminants in wastewater: the case of endocrine disruptors
1.1 FEATURES AND DEFINITIONS
In the industrialized world of the twenty-first century, some chemicals that come from the use and disposal of uncontrolled resins, solvents, detergents, food, plastics, adhesives, paints, dyes, solvents, cosmetics, home accessories, toys and products for children may accumulate in the environment and pose a significant risk to human health because it can interfere with the functioning of endocrine systems. The substances referred to are countless and poorly biodegradable, accumulate, and persist in the environment due to their nature poorly polar-polar or otherwise tend to be concentrated in body fluids and tissues rich in animal fats such as milk and meat. Unlike occupational exposure "classical" in which people are exposed to large amounts of individual substances known, the absorption occurs in the general population unknowingly, many times because these compounds are odorless, colorless, low-dose exposure is, compounds are different and the accumulation is continuous and "silent". Internationally, endocrine disruptors are defined as "any exogenous agent that interferes with the production, release, transport, metabolism, binding, action and the elimination of natural hormones in the body responsible for maintaining homeostasis and regulation of developmental processes. "This definition, however, dates back to 1996, appears to be whooping and verbose. For this reason, in May 1997, the task force on endocrine disrupters in the U.S. Evironmental Protection Agency ( EDSTAC ) was agreed on the following definition: "An endocrine disruptor is an exogenous chemical substance or mixture that alters the functioning of endocrine system and consequently cause adverse effects on an organism, its progeny or (sub) population. " Although many interfering Endocrine be released into the atmosphere as a result of combustion (polycyclic aromatic hydrocarbons, dioxins etc.). the main sectors in which the EDCs are found are groundwater and surface water and foods. The urban sewage and industrial especially those containing a multitude of persistent organic compounds derived from industrial and domestic applications. Recently, the presence of EDCs was also reflected in municipal sewage treatment plants.
1.2 The main EDCs: general description and
1.2.1 Alkylphenol ethoxylates
alkylphenol ethoxylates are one of the largest groups of chemical compounds. They are used in many domestic and industrial applications and can cause sewage treatment plants or the environment due to bacterial degradation, alkylphenol polyethoxylate: for example, nonylphenol (NP), nonylphenol mono-and di-ethoxylate (NP1EO and NP2EO) nonylphenol carboxylates (NpnECs) (fig 1) are generally found all'inerno treatment plants.
Fig 1 Process of degradation of apnea in the aquatic environment. (Ning B, Graham NJD, Zhang Y. (2007). Degradation of Nonylphenol and octylphenol by
ozone. Part I: direct reaction . Chemosphere, 68, 1163-1172.)
r epresentation one of the most important categories among the EDCs. In fact, as you can see in Figure 2 the structure of Nonylphenol is very similar to the general formula of sex hormones. Alkylphenols show estrogenic activity only if the alkyl chain is in position para and in any case with the alkyl chain alkyl with less than 4 atoms carbon are inactive (Lintelmann et al. 2003) The alkyl compounds are hydrophobic, the solubility increases with 'increase of ethoxyl group, the toxicity in the aquatic environment is higher with a low number of ethoxy groups and a greater length of the hydrophobic chain. Consequently nonylphenol (NP) and octylphenol (OP), but also alkyl carboxylates are known to be more toxic than their precursors ethoxylates. With regard to the toxicity in the aquatic environment, it turns out to be higher with a low number of ethoxyl groups and with a greater length of the hydrophobic chain. Because of their lipophilicity and persistence, the APs have a relatively high bioconcentration factors and tend to bioaccumulate in aquatic organisms, both vertebrates and invertebrates, causing an increase in river pollution. Are considered ubiquitous contaminants of the aquatic environment, where they tend to be associated with particulates and sediments (Auriol et al., 2006; Bertanza and Pedrazzani, 2006; Fountoulakis et al., 2005). Specific attention they deserve in vivo studies on endocrine effects in teleosts. In particular, both through experimental observations in the field tests are consequences were identified on reproduction and development due to estrogenic activity. In most studies, these effects were observed at concentrations of 10-20 g / L. In male trout (Onchorinchus mykiss) exposed to NP, there was a No Observed Effect Concentration (NOEC) of 5.02 g / L for the increase in plasma vitellogenin. However, a NOEC for the effects of estrogen has not been determined yet for octylphenol as increases in plasma vitellogenin and testicular atrophy were observed even at concentrations of 3 g / L. Planas et al. (2002) argue that the aquatic toxicity of NPnEO varies according to the organism in question and the number ethoxyl groups added to the molecule of NP: NP,
NP1EO, NP2EO, and NP1EC NP2EC compounds are more toxic and persistent. In particular NP1EO, NP2EO and NP are hydrophobic and are found mainly in the solid particles are hydrophilic and NPnEO are detected predominantly in the aqueous phase. In Canada, the concentration of NP considered to be critical towards the environment and was fixed in 1 Jg / L (Sabik et al., 2004).
A risk scenario can be derived from those data and to those on fish consumption for the Italian population, produced by the National Institute of Nutrition (1995). Based on the assumptions:
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that the full rate of fish consumed is made up of only shellfish;
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that the rate of contamination is at levels equal to the highest found in molluschiesaminati (700 g / kg);
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c he considered the population is made up of high consumers (95th percentile) for which ilconsumo of fish and was estimated to be approximately 120 g / person / day (while stood taleconsumo for the general population of about 40 g / person / day);
resulting daily intake of about 80 g, approximately 1 , 3 g / kg body weight. Finally, based on available data, we estimate that the contribution of intake drinking water is much lower and probably represents less than 10% of intake in the diet. Overall, the levels of certain alkylphenols in fish of the Adriatic indicate a significant health risk for high consumers of these products.
1.2.2 Phenols and substituted phenols.
Phenols and substituted phenols are a broad category of substances used in various industrial and manufacturing fields, such as additives in plastics and rubbers. The compound most representative of this group, and also the most studied is found to be bisphenol A (BPA) (Fig. 3). The BPA because of its significant solubility in water, its low value of Henry's constant and appreciable values \u200b\u200bof Koc and log Kow, water is mainly implemented in the environment, is persistent and is adsorbed by organic matter. Can be degraded by microorganisms acclimated: The half-life depends on the environmental sphere and varies from about a week to a year. (Lintelmann et al., 2003).
BPA is one of the most important chemical compounds throughout the world: the release into the wild and in surface waters can occur by leaching from the final product. The potency of the estrogen BPA was evaluated by four orders of magnitude lower than the natural hormone E2 (17 β - estradiol) and equal to that of 4NP. Studies have shown that BPA can determianre alteration of a few cycles of mitotic aberrations in cells producing cromoscomi (Facker et al. 2000). It was also shown that BPA, when present in the linings of food cans can enter the product giving the same estrogenic activity, it can also be released from dental fillings and epoxy resins used to renew the water mains. Unlike what obtained alkylphenol ethoxylates, the study of degradation and by-products degradation has not achieved the results that can be considered definitive and more accepted. In reality, little is known about the byproducts of BPA. The main reason probably lies in the fact that, in the recent past, were not considered toxic or hazardous to the environment and organisms. Although the most recent publications are beginning to assume the effects of estrogen compounds that are derived from the degradation of BPA, in general the fate of BPA in wastewater treatment plants and the environment is still limited to the study of the presence of BPA itself. Within the group of phenols, chlorophenols, which also includes a group of organic substances are introduced into the environment Following a number of human activities, such as waste incineration, uncontrolled use of protective agents for wood, fungicides and herbicides, or as by-products of bleaching paper with chlorine and disinfection of water through chlorination. In particular, the 2,4-dichlorophenol has a key role in the synthesis of chlorinated herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) acid 2 - (2,4-diclorofenossi) propionic acid (2 ,4-DP) (Contreras et al., 2003).
1.2.3 natural and synthetic hormones.
The most important compounds present in municipal sewage that have estrogenic activity are naturally occurring hormones estrone (E1), 17 β - estradiol (E2), estriol (E3) and the synthetic hormone 17 β -ethinylestradiol (EE2) used for birth control. (Rudder et al. 2004; Liu et al. 2005). The hormones are excreted by humans and animals primarily in conjugated form, the deconjugation may occur in the environment leading to the reactivation of the substance or mixture for processing in a different (and Bertanza Pedrazzani, 2006). E1, E2, E3 are normally excreted from the body of women in varying amounts depending on the phase of the menstrual cycle and / or are pregnant or breastfeeding.
1.2.4 Polychlorinated
Polychlorinated biphenyls (PCBs) (Fig. 4) are classified as persistent organic pollutants ( POPs). The greater the degree of chlorination, the higher the lipophilicity and the tendency to accumulate, the less are the biodegradability and solubility in water. They tend to undergo bioaccumulation and biomagnification (Bertanza and Pedrazzani, 2006) The PCBs were used in the production of trasmormatori, accumulators, condensers, hydraulic oil additives to insecticides. Their use is banned since 1996 (Directive 96/59/EC).
1.2.5 Polychloro dibenzo-dioxins and furans
the polychlorinated-dibenzo-dioxins (PCDD) and polychlorinated-dibenzo-furans (PCDF ) are included in the list of POPs. They are not used in production processes, but may develop during the production or use of chlorine-containing compounds, for example in the production of herbicides, insect and disinfectants (Mantovani and Piccinini, 2005). The number of chlorine atoms affects the vapor pressure and water solubility. Because of their lipophilicity, they accumulate in aquatic organisms and the food chain.
1.2.6 Pesticides
in pesticides, includes all substances capable of control, limit, deny, or destroy living organisms (micro-animals, plants) which are regarded as harmful, or to oppose their development. Among the pesticides, those with endocrine disrupting effects may include aldrin, atrazine, benthiocarb, p, p'-DDT, p, p'-DDD, p, p'DDE, 2,4-D, dieldrin, endosulfan ( α, β ), endrin.
1.2.7 Polycyclic Aromatic Hydrocarbons
PAHs, arise from incomplete combustion or pyrolysis of materials such as waste or fossil fuels. Solubility and decrease with increasing hydrophilicity of carbon atoms in the chain. Among those with suspected IPA endocrine disruptor effect is reminiscent of benzo (a) pyrene, benzo (a) anthracene and fluoranthene. (Fig. 6)
1.2.8 Phthalates
Phthalates ( PAES) are used industry as additives for plastics because of their excellent properties (such as increased flexibility) and their compatibility with the vinyl and other polymers. They are also used in the production of paper, cardboard, foam, capacitors (as dielectric) and wood (as protective agents), it is possible to infer the composition of phthalates in polyvinyl chloride (PVC), coatings, paints, glues and adhesives, cosmetics ( nail polish) dye, shampoo and bubble bath. Among the phthalates considered endocrine disruptors can remember butyl-2-ethylhexyl acrylate, butylbenzylphthalate, diisottilftalato, and dimetilpropilftalato dipropilftalato
1.2.9 Organotin compounds
Organotin compounds (OTs) play a key role in the chemical industry of the past few years, they are used as a stabilizer for light and heat, such as anti-fouling, moth repellents, disinfectants. Although widely used, is still on them today is difficult to obtain precise data on their toxicology and ecotoxicology.
NOTE: This is an introductory part of broader research work, for questions, concerns or reliability of analytical, are available upon request full data.
