Alkylphenol Ethoxylates Research Articles

Effects of surfactant concentration and sorbent properties on the sorption and transport of ethoxylated nonionic surfactant mixtures

Ethoxylated nonionic surfactants are widely used for industrial applications and have been considered for environmental remediation applications. As a result, an understanding of the sorption and transport of nonionic surfactants is important, both for their efficient use during remediation applications and for understanding their potential fate in the environment. Because ethoxylated nonionic surfactants are typically broadly-distributed mixtures containing a substantial number of components, an understanding of the influence of the surfactant component distribution on the overall mixture behavior is also required. In this paper, the sorption behaviors of linear alcohol ethoxylates and alkylphenol ethoxylates are examined in the presence of three different sorbents, a crushed natural silica, an organic-coated crushed natural silica, and a river sediment. Similar sorption behavior is observed for all surfactants on all three sorbents, although the magnitudes of sorption trends vary with sorbent and surfactant properties. In general, sorbed surfactant is enriched in high-EO surfactant components at low concentrations, and is enriched in low-EO surfactant components at intermediate concentrations. At high concentrations, sorbed and solution surfactant compositions approach the initial surfactant composition. This behavior is attributed to mixed aggregate formation on the solid surface and in solution. The varying magnitudes of observed behavior are attributed to differences in surface site energies and to surface site heterogeneity. Column transport data are presented for a nonionic surfactant mixture, and the results are discussed in terms of mixed sorption behavior. Implications of transport results for the fate and transport of surfactants in the environment are also discussed.

Degradation of Alkylphenol Ethoxylate Surfactants in Water with Ultrasonic Irradiation

During the last years, many efforts have been devoted to the elimination of alkylphenol ethoxylate surfactants from aqueous systems. In this paper, the sonochemical degradation of aqueous solutions of Triton X-100 was performed at an ultrasonic frequency of 358 kHz and an applied power of 50 W. Analysis of the reaction products by HPLC-ES−MS suggests that the hydrophobic alkyl chain is the preferential site for oxidation. Alkylphenol, or short-chain ethoxylated phenols, were not generated as byproducts. To verify this hypothesis, the sonochemical degradation of the corresponding alkylphenols (e.g., tert-octylphenol) was performed under the same conditions; in these cases, similar rate constants and products were observed. These results differ from those reported for the biodegradation of alkylphenol ethoxylates. A substantial increase in the rate constant was observed for the degradation of Triton X-100 below its critical micelle concentration. This observation indicates that micelle formation serves to effectively isolate the free surfactant monomers from the water−air interface of the oscillating cavitation bubbles, thus decreasing the overall efficiency of the sonochemical process. The hydrophobic tail of the molecule is no longer exposed directly to the bubble “hot spot” when it is pointed into the core of the micelles.

99/03586 Effect of water vapor on the pyrolysis of the Moroccan (Tarfaya) oil shale: El harfi, K. et al. J. Anal. Appl. Pyrolysis, 1999, 48, (2), 65–76

This paper describes the synthesis and characterization of a series of TRITON™ X-based surfactants with a predominantly alkyl phenol ethoxylate (APE) backbone and a phosphate ester chain end. Four phosphate-terminated TRITON™ X (or APE) derivatives (OPE2–OPO(OH)2, OPE5–OPO(OH)2, OPE10–OPO(OH)2, and NPE10–OPO(OH)2) were prepared from commercially available octyl phenol ethoxylate (OPE) of different oxyethylene units (n = 2, 5 and 10), nonyl phenol ethoxylate (NPE) of 10 oxyethylene units and phosphorous pentoxide via a simple condensation reaction. Depending on their composition and chain length of oxyethylene units used in the reaction, the surfactants show different self-charring behaviors. The phosphate-terminated TRITON™ X of the lowest number of oxyethylene units (i.e. OPE2–OPO(OH)2) gives the largest amount of char (up to 23 wt%) at 600 °C under air condition. The carboxylic acid-terminated TRITON™ X derivatives (i.e. OPE–COOH) were also tested for comparison.

The effects of 4-nonylphenol in rats: a multigeneration reproduction study.

The alkylphenol breakdown products of alkylphenol ethoxylates have been shown in in vitro studies to be weakly estrogenic, but few in vivo data address this issue in mammals. Because estrogens have been found to be most potent during developmental/perinatal exposures, this study maximized developmental exposure to nonylphenol (NP) by treating 3.5 generations of Sprague-Dawley rats to NP in diet at 200, 650, and 2000 ppm to determine the range and severity of any toxicity. Dose rate was higher for younger rats; calculated dose ranges were 9-35, 30-100, and 100-350 mg/kg/d for the low (200NP), middle (650NP), and high (2000NP) dose groups, respectively. There were adult (F0, F1, F2) and postnatal day (pnd) 21 (F1, F2, F3) necropsies; the oldest F3 rats were killed on pnd 55-58. Body weight gain was reduced by 8-10% in the 650NP and 2000NP groups. Vaginal opening was accelerated by approximately 2 days (650NP) and approximately 6 days (2000NP) in F1, F2, and F3 generations. Uterine weights at pnd 21 were increased in 650NP (14%) and 2000NP (50%) F1 females, but not in other generations. Testis descent, anogenital distance, and preputial separation were not consistently changed. No consistent changes were seen in pup number, weight or viability, litter indices, or other functional reproductive measures. Relative ovary weight in F2 adults was decreased at 650NP and 2000NP by 12%; relative ovary was unchanged in other generations. Follicle counts were unchanged in F2 adults. Sperm indices, including CASA measures, were unchanged in F0 and F1 males. In F2 rats, epididymal sperm density was reduced by 8% and 13% at 650NP and 2000NP, respectively. Testicular spermatid count was reduced by 13% in 2000NP F2 males; testis and epididymis weights were unchanged. Erosion of gastric and duodenal mucosa was monitored grossly and microscopically, and never found. Kidney weights were increased in 650NP and 2000NP males, and renal medullary tubular dilatation and cyst formation were noted in all generations of males, and often at the lowest dose tested. These data show that NP had limited effects on the reproductive system in the presence of measurable nephrotoxicity. The F2 sperm effects are either statistical/biological "noise," or imply heretofore unknown pharmacokinetics or toxicodynamics. These sperm data should be interpreted cautiously until the findings are repeated.

Induction of hepatic estrogen receptor in juvenile Atlantic salmon in vivo by the environmental estrogen, 4-nonylphenol

Alkylphenol ethoxylate degradation products such as nonylphenol and octylphenol are shown to have estrogenic effects. Nonylphenol induces synthesis of vitellogenin (a precursor of egg yolk proteins) and zona radiata proteins (eggshell proteins) in juvenile and/or male fish. Little is known about the molecular mechanisms of estrogenicity of environmental chemicals such as nonylphenol. To study the mechanisms of estrogenic effects of 4-nonylphenol (NP), we examined its in vivo effects on the expression of the estrogen receptor (ER), vitellogenin (Vtg) and zona radiata protein (Zrp) genes in juvenile Atlantic salmon liver. We show that the ER mRNA synthesis is induced by NP in a dose-dependent manner in juvenile Atlantic salmon liver. The induction of the ER mRNA synthesis is followed by the induction of Zrp and Vtg mRNA synthesis. The ER transcripts reach peak levels earlier than the Zrp and Vtg mRNA and proteins, which is in agreement with the physiological effects of estradiol during zonagenesis and vitellogenesis. Various studies have also shown that NP competitively inhibits the binding of 17β-estradiol (E2) to ER. Our results further suggest that NP directly mimics E2 in inducing the ER, Zrp and Vtg genes in salmon liver.

The environmental fate of the primary degradation products of alkylphenol ethoxylate surfactants in recycled paper sludge

Alkylphenol ethoxylates (APEOs) are a group of non-ionic surfactants that are degraded microbially into more lipophilic degradation products with estrogenic potential, including nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), octylphenol (4-tOP) and nonylphenol (4-NP). Nonylphenol ethoxylates are used in paper recycling plants for de-inking paper and have the potential to be released into the environment through spreading of wastewater treatment sludge for soil amendment. Three samples of recycled paper sludge were collected from farmers' fields and analyzed for concentrations of NP1EO, NP2EO, 4-NP and 4-tOP. Each sample differed in the amount of time elapsed since the sludge was placed on farmers' fields. Primary degradation products of APEOs were present at low μg/g concentrations in the sludge samples. Differences in the concentrations of these analytes in sludge samples indicated that APEO concentrations declined by 84% over a period of 14 weeks on farmers' fields. Changes in the chromatographic patterns of acetylated 4-NP indicated that there is a group of recalcitrant nonylphenol isomers that degrades more slowly than other isomers. These data indicate that microbial degradation may reduce the risk of environmental contamination by these compounds, but more work is required to assess the toxic potential of APEOs in sludges used for soil amendment.

Molecular distribution of some commercial nonylphenol ethoxylates using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Nonylphenol ethoxylates (NPEs) belong to a group of nonionic surfactants that are collectively referred to as alkylphenol ethoxylates (APEs). APEs find widespread use in heavy-duty commercial and household cleaning formulations, shampoos, and industrial processing, i.e. textile manufacture. Their environmental impact depends on the molecular distribution and the extent of their biodegradation in municipal sewage systems, waterways and rivers. We have established two sample preparation methods that have enabled the determination of the molecular distributions of six commercial nonylphenol ethoxylates using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). In both methods, alpha-cyano-4-hydroxycinnamic acid, dissolved in acetonitrile/tetrahydrofuran, was used as the matrix. In one set of experiments, the NPEs were dissolved in an acetonitrile/tetrahydrofuran solvent system prior to mixing with the matrix solution, and the resulting MALDI-TOF mass spectra produced mostly sodiated molecules [M + Na](+). The NPEs, all having the formula 4-(C(9)H(19))-C(6)H(4)-(OCH(2)CH(2))(n)-OH, are Surfonic (R)N-95, N-100, N-102, N-120, N-150 and N-300. Surfonic N-95 and N-100 gave n values of 5-20; Surfonic N-102, N-120, N-150, and N-300 gave n values of 5-21, 5-22, 8-25 and 15-40, respectively. In order to develop a sample preparation method that could be used with less polar NPEs, we dissolved the NPEs (except N-300) in pentane prior to mixing with the matrix solution, and found that the MALDI spectral quality was unaffected by the solvent systems. Copyright 1999 John Wiley & Sons, Ltd.

Optimization of a matrix solid-phase dispersion method with sequential clean-up for the determination of alkylphenol ethoxylates in biological tissues

A modified Matrix Solid-Phase Dispersion (MSPD) method with sequential clean-up has been developed to isolate and purify alkylphenol ethoxylates (APEs) and alkylphenols in biological tissues. Elution profile, sequential clean-up adsorbent and experimental set up were optimized. Octadecylsilica was used as the solid-phase for matrix dispersion. Methanol was found to be the optimal eluting solvent for APEs. Aluminum oxide was quite efficient for removing the coeluting interferences. Quantitative analysis was done by reversed-phase HPLC with fluorescence detection. The optimized procedure was applied to analyze both fish and mussel samples. Average recoveries for all spiked tissue samples were greater than 90%. Typical limits of detection amount to tens of ppbs on a wet weight basis.

Review of the Environmental Occurrence of Alkylphenols and Alkylphenol Ethoxylates

Abstract Alkylphenol ethoxylates and, in particular, nonylphenol ethoxylates have found many industrial, commercial, institutional and household uses in Canada. These nonionic surfactants are very efficient and cost effective. Their widespread use has led to the detection of the parent surfactants and their degradation products in various environmental matrices. Alkylphenol ethoxylates can be degraded aerobically and anaerobically in natural environments and sewage treatment plants.. The resulting degradation products are more persistent, more toxic, more lipophilic, less water soluble and more estrogenic than their parent compounds. This article reviews the occurrence of nonylphenol polyethoxylates and their degradation products as well as octylphenol poly-ethoxylates and their degradation products. There is limited information available about the concentrations of these substances in their original product formulations. The highest levels of the degradation products, especially nonylphenol, occur in the anaerobically digested sludge of sewage treatment plants. Sludge from these sewage treatment plants may be used as an amendment to agricultural soils. Various sewage treatment plants have wide ranges of discharged effluent concentrations of these compounds — some appear to be very efficient at removing alkylphenolics from their effluent stream. Little information is available about the fate of these substances in their receiving environment, and environmental concentrations and bioaccumulation factors of these contaminants in aquatic biota. More research is required on the uptake, persistence and bioaccumulation of alkylphenolic metabolites in fish, mussels and other aquatic organisms

Review of Analytical Methods for the Determination of Nonylphenol and Related Compounds in Environmental Samples

Abstract Analytical methods published in the last 20 years for the extraction, chromato-graphic separation, and quantification of alkylphenol ethoxylates (APEO) and related compounds in environmental samples are reviewed. Examples of various isolation and preconcentration techniques for water, effluent, sediment and sludge are presented. This includes procedures from the classical liquid-liquid and Soxhlet extraction to the up-to-date solid phase and supercritical fluid extraction. Chromatographic separation of APEO by normal and reversed phase liquid chromatography (LC) and capillary column gas chromatography (GC) is compared. A variety of quantification methods involving the common LC and GC detectors as well as various mass spectrometric techniques are also discussed.

Adverse Effects of Alkylphenol Ethoxylates on the Endocrine System

Alkylphenol ethoxylates (APE) are widely used as industrial surfactants owing to their high performance as wetting agents, emulsifiers and so on, and fairly low cost. Just after “Our Stolen Future” was published in 1996, “Endocrine Disruptor” became a global issue. APE and its metabolites (alkylphenol (AP) etc.) have been shown to possibly have adverse effects on the endocrine system of wildlife and these compounds include DDT, PCB and DES. This paper reviews this problem. The estrogenic activity of AP and APE, suspected as “endocrine disruptors” is much weaker than endogenous hormones in animals, and their effects are not strong enough to disrupt the hormone balance in a living body. “Endocrine disruption” by AP would thus not be a possibility. Environmental data on AP and APE are not sufficient and additional study should be made of the effects of AP and APE. Replacement of APE is examined in the present study.

Reproductive Endocrine Disruption by Environmental Xenobiotics that Modulate the Estrogen-Signaling Pathway, Particularly Tetrachlorodibenzo-p-dioxin (TCDD)

Environmental pollutants are known to exert endocrine-disrupting effects on several hormonal axes of animals, including reproduction and development. Many of these xenobiotics modulate the estrogen-receptor signaling pathway(s) in agonistic or antagonistic ways. Some of the compounds are themselves estrogenic (so-called xenoestrogens, environmental estrogens, or ecoestrogens), and are classified as synthetic estrogens, phyto- or fungal estrogens, alkylphenol ethoxylates; certain non-coplanar polyclorinated biphenyls (PCBs), etc. Other molecules are anti-androgenic, e.g., p, p'-dichloro-diphenyl-dichloroethylene (DDE); while still others disrupt estrogen function in a manner that is dose, species and tissue specific, e.g., certain co-planar PCBs and dioxin-like molecules (e.g., tetrachlorodibenzo-p-dioxin [TCDD]). Exposure to some compounds has been correlated with skewing of sex ratios in aquatic species, and feminization and demasculinization of male animals; declines in human sperm counts; and overall diminution in fertility of birds, fish, and mammals. This review will cover these various xenobiotics and evaluate them for their estrogen-modulating effects; and then further concentrate on TCDD specifically. Dioxins are produced as by-products of herbicide overuse, from paper bleaching, plastics manufacture, and waste incineration. TCDD has been correlated with altered fecundity and endometriosis in monkeys, and with certain cancers in experimental animals and humans. TCDD is also correlated with reproductive deficits in many laboratory species. In summary, we believe that some of the reproductive deficits from endocrine-disrupting xenobiotics may be attributable to the modulation of the estrogen-signaling pathway, in positive and negative manners, depending on dose, species, and tissue specificity.

Evaluation of aquatic toxicity and bioaccumulation of C8‐ and C9‐alkylphenol ethoxylates

AbstractThe extensive database of acute and chronic aquatic toxicity data for alkylphenol ethoxylates (APEs) and selected biodegradation intermediates was reviewed and summarized for freshwater and saltwater aquatic microorganisms, algae, invertebrates, and fish inhabiting cold and warm water bodies. Most acute toxicity studies that tested APE‐9 and APE‐10, the most common commercially relevant APEs, reported results that ranged from about 1,000 to 10,000 μg/L. Results from studies testing alkylphenols, intermediate by‐products of APE biodegradation, ranged from about 20 to 3,000 μg/L. Chronic values are a factor of about 2 to 10 lower. Although most studies used one of several common species and standard protocols to assay conventional endpoints, many nontraditional species and toxicological endpoints were also used. This toxicological database encompasses virtually all important types of aquatic habitats and classes of aquatic species. Bioaccumulation data from both laboratory and field studies indicate that alkylphenols have a low to moderate bioaccumulation potential. Fresh weight, nonlipid‐based bioconcentration factors (BCFs) measured in the laboratory ranged from < 1 to 1,250 for fish and 1 to 3,400 for invertebrates, whereas field bioaccumulation factors (BAFs) ranged from 6 to 487, with most values < 100. Overall, these data provide an extensive and useful database to support environmental risk assessment activities.

Chlorphenole und Nonylphenole in Klärschlämmen. Teil II: Hat die Belastung mit Pentachlorphenol und Nonylphenolen abgenommen?

Klärschlämme der Jahre 1994 und 1995 wurden auf Pentachlorphenol und isomere 4-Nonylphenole untersucht, zwei Umweltchemikalien, die nicht durch die Klärschlammverordnung, aber durch die Pentachlorphenol-Verbotsverordnung und eine freiwillige Verzichtserkärung geregelt sind. Die Ergebnisse werden in Form von Histogrammen unter Angabe von Median und 90%-Percentil dargestellt und den Untersuchungsergebnissen von Klärschlämmen der Jahre 1987 bis 1989 gegenübergestellt. In den meisten der 101 untersuchten Klärschlammproben ließ sich Pentachlorphenol mit einem Median von 19 μg/kg, bezogen auf Trockensubstanz (TS), nachweisen. Damit ergibt sich keine statistisch gesicherte Abnahme der Gehalte im Ver-gleich zu früher, allerdings eine Tendenz zu niedrigeren Gehalten. Dagegen hat die Belastung mit Nonylphenolen, bei einem Median von 4.6 mg/kg, bezogen auf TS, imVergleich zu früheren Jahren signifikant abgenommen. Dies sehen wir als Hinweis darauf, daß die freiwillige Verzichtserklärung der Industrie bezüglich Einsatz und Verwendung von Alkylphenolethoxylaten eingehalten wurde. Chlorophenols and Nonylphenols in Sewage Sludges. Part II: Did Contents of Pentachlorophenol and Nonylphenols Reduce? Sewage sludges were analyzed for pentachlorophenol and isomeric 4-nonylphenols. These environmental pollutants are not regulated by the German sewage sludge regulations (Klärschlammverordnung) but are subsequently controlled by the pentachlorophenol prohibition ordinance and the industry’s voluntary declaration of renouncing the use of alkylphenol ethoxylates. The samples analyzed originated from sewage treatment plants in the state Rheinland-Pfalz from 1994 till 1995. The analytical results are presented graphically by histograms and numerically by quantiles (median, 90%-percentile).The results are compared to those we formerly obtained from all West German states from 1987 till 1989. To verify the statistical significance of median differences, we used the Wilcoxon test suitable for non parametric data distributions. All histograms show non symmetrical frequency distributions. In almost all 101 analyzed samples, pentachlorophenol was found at a median of 19 μg/kg related to dry matter (d.m.) and a 90%-percentile of 86 μg/kg related to d.m. Compared with the past, there seems to be a tendency to lower values which, however, cannot be proved statistically. In almost all sewage sludge samples, nonylphenols could be found at a median of 4.6 mg/kg related to d.m. and a 90%-percentile of 24.8 mg/kg. In contrast to the past, these values are very low; nonylphenols in sewage sludges have significantly reduced. This may be a hint that the industry’s voluntary dec-laration has been taken seriously.

Degradation Photoinduced by Fe(III): Method of Alkylphenol Ethoxylates Removal in Water

The photoinduced degradation of an alkylphenol ethoxylate (APE) (Igepal CA 520) by Fe(III) in aqueous solution has been investigated. A complete characterization of the commercial product showed the presence of a mixture of compounds with various ethoxy and alkyl chain lengths. The photodegradation study was carried out with the major fraction of ethoxymers having an alkyl chain length of 8 carbon atoms and n ethoxy units E (C8PhEn). We have demonstrated that the Fe(III) sensitized degradation of this fraction occurs efficiently both at 365 nm and under sunlight. The rate of degradation depends on the concentration of Fe(OH)2+, the most photoreactive species in terms of •OH radical formation. The primary step of the decomposition of Igepal involves the hydrogen abstraction on one carbon of the ethoxy chain. The shortening of the ethoxylated chain all along the degradation process was observed. The identified photoproducts are aldehyde ethoxylates, formate ethoxylates, and octylphenol that is a persistent ...

Nonylphenol Ethoxylates, but Not Nonylphenol, Are Substrates of the Human Multidrug Resistance P-glycoprotein

Alkylphenol ethoxylates are surfactants that are commonly used in industry and in home care products. They are broken down by anaerobes to yield toxic environmental pollutants such as nonylphenol. In this study, we tested whether nonylphenol ethoxylates and their most common biodegradation product, nonylphenol, were substrates of human P-glycoprotein.In vivoandin vitroassays showed that the enzyme interacts with a wide variety of nonylphenol ethoxylate compounds, but not with nonylphenol. These results suggest that P-glycoprotein can protect organisms from the toxic and estrogenic effects of nonylphenol ethoxylates, but not from the major biodegradation product, nonylphenol.

Oxidation of Nonionic Detergents by Cytochrome P450 Enzymes

Nonionic phenolic detergents are commonly used in the purification of membrane-associated proteins. Triton N-101 was shown to be oxidized by NADPH-fortified human liver microsomes and recombinant human cytochromes P450 (P450). Oxidation was monitored using HPLC and the fluorescence properties of Triton N-101 and other alkylphenol ethoxylate detergents, which are similar to those of anisole. Human liver microsomes and recombinantly expressed reconstituted P450 3A4-oxidized Triton N-101 in a concentration-dependent manner which could be inhibited by ketoconazole, a P450 3A4-selective inhibitor. Triton N-101 inhibition of testosterone oxidation by human liver microsomes was of a mixed nature but mainly non-competitive. Electrospray ionization mass spectrometry and tandem mass spectrometry indicated that the major product formed was hydroxylated on the alkyl moiety. Human liver microsomes also oxidized other Tritons (X-100 and X-114), Emulgens 911 and 913, and Tergitol NP-10 to a similar extent. P450s 1A1, 1A2, and 2C9 also oxidized Triton N-101 but to a lesser extent than P450 3A4. We conclude that Triton N-101 and similar nonionic detergents are oxidized by P450 3A4 and some other P450s.

Exposure of female juvenile rainbow trout to alkylphenolic compounds results in modifications to growth and ovosomatic index

AbstractThe alkylphenol ethoxylates (APEOs) are a major group of nonionic surfactants. Biodegradation of these compounds is incomplete during sewage treatment; thus, they are ubiquitous aquatic pollutants. All the main degradation products of APEOs were recently demonstrated to have estrogenic properties in vitro, but their effects in vivo remain to be established. In this study, female juvenile rainbow trout (Oncorhynchus mykiss Walbaum) were exposed to octylphenol, nonylphenol (NP), nonylphenol diethoxylate, and nonylphenol mono‐carboxylic acid (NP1EC) at environmentally relevant concentrations (Experiment 1: 1, 10, and 50 μg/L; Experiment 2: 1, 10, and 30 μg/L). Exposure to APEOs commenced at hatch (day 0) and was terminated on day 22 (Experiment 1) or day 35 (Experiment 2). Body weight and fork length of representative samples offish from each treatment group were recorded at intervals up to 108 d (Experiment 1) or 466 d (Experiment 2). In Experiment 1, significant differences in size of the exposed fish, related to treatment, were still apparent on day 108, 86 d after withdrawal of the treatments. These observations were confirmed during Experiment 2, in which significant changes in body weight and fork length as a consequence of exposure to the compounds were observed approx. 15 d after exposure was terminated. These differences were sustained for at least 466 d in the case of NP and NP1EC. In addition, the ovosomatic index (OSI) offish exposed to NP and NP1EC was significantly affected zby the treatment. Survival of fish in the natural environment is strongly influenced by body size, and an appropriate OSI is a crucial factor in successful reproduction. Therefore, exposure of natural populations of fish to these chemicals at concentrations currently measurable in the aquatic environment may have an impact on the performance of those populations.

Occurrence of Alkylphenoxyacetic Acids in Canadian Sewage Treatment Plant Effluents

Abstract Alkylphenoxyacetic acids such as 4-tert-octylphenoxyacetic acid (OP1EC) and nonylphenoxyacetic acid (NF1EC) are metabolites of non-ionic surfactants derived from the ethoxylation of 4-tert-octylphenol (OP) and nonylphenol (NP). Although the occurrence of OP1EC and NP1EC was suspected in many Canadian sewage treatment plant effluents due to the extensive use of the alkylphenol ethoxylate surfactants and their degradation under sewage treatment conditions, the acids have never been reported due to the lack of authentic standards. In this work, OP1EC and NP1EC were synthesized by the condensation of OP and NP, respectively, with chloroacetic acid in the presence of a base. With these standards, the occurrence of OP1EC and NP1EC in Canadian sewage treatment plant effluents was confirmed for the first time. The level of OP1EC ranged from 0.18 to 1.2 μg/L and from 0.45 to 6.8 μg/L, in the primary and final effluents, respectively. In contrast, the level of NP1EC in the same sample was much higher and it ranged from 2.4 to 17.7 μg/L in the primary effluents and from 3.2 to 703 μg/L in the final effluents.

EXPOSURE OF FEMALE JUVENILE RAINBOW TROUT TO ALKYLPHENOLIC COMPOUNDS RESULTS IN MODIFICATIONS TO GROWTH AND OVOSOMATIC INDEX

The alkylphenol ethoxylates (APEOs) are a major group of nonionic surfactants. Biodegradation of these compounds is incomplete during sewage treatment; thus, they are ubiquitous aquatic pollutants. All the main degradation products of APEOs were recently demonstrated to have estrogenic properties in vitro, but their effects in vivo remain to be established. In this study, female juvenile rainbow trout (Oncorhynchus mykiss Walbaum) were exposed to octylphenol, nonylphenol (NP), nonylphenol diethoxylate, and nonylphenol mono-carboxylic acid (NP1EC) at environmentally relevant concentrations (Experiment 1: 1, 10, and 50 μg/L; Experiment 2: 1, 10, and 30 μg/L). Exposure to APEOs commenced at hatch (day 0) and was terminated on day 22 (Experiment 1) or day 35 (Experiment 2). Body weight and fork length of representative samples offish from each treatment group were recorded at intervals up to 108 d (Experiment 1) or 466 d (Experiment 2). In Experiment 1, significant differences in size of the exposed fish, related to treatment, were still apparent on day 108, 86 d after withdrawal of the treatments. These observations were confirmed during Experiment 2, in which significant changes in body weight and fork length as a consequence of exposure to the compounds were observed approx. 15 d after exposure was terminated. These differences were sustained for at least 466 d in the case of NP and NP1EC. In addition, the ovosomatic index (OSI) offish exposed to NP and NP1EC was significantly affected zby the treatment. Survival of fish in the natural environment is strongly influenced by body size, and an appropriate OSI is a crucial factor in successful reproduction. Therefore, exposure of natural populations of fish to these chemicals at concentrations currently measurable in the aquatic environment may have an impact on the performance of those populations.