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Acrylonitrile removal from synthetic wastewater and actual industrial wastewater with high strength nitrogen using a pure bacteria culture.

A gram-negative rod-shaped bacteria (strain AAS6), capable of utilizing acrylonitrile as the sole source of both carbon and nitrogen, was utilized to investigate the removal of acrylonitrile in ABS resin manufacturing wastewater. Both synthetic wastewater, containing a high concentration of acrylonitrile, and actual wastewater obtained from an ABS manufacturing factory were used. The result indicated that strain AAS6 was capable of completely removing acrylonitrile from synthetic wastewater containing less than 889 mg/l acrylonitrile and from actual industrial wastewater containing less than 400 mg/l acrylonitrile. Whether in synthetic wastewater or actual industrial wastewater, strain AAS6 showed approximately the same ability for acrylonitrile removal and used acrylic acid, a metabolic by-product of acrylonitrile, as the carbon source and ammonium as the nitrogen source. The bacteria could not directly metabolize other chemicals found in the actual industrial wastewater. However, its metabolic activities were not inhibited by the presence of compounds such as butadiene, styrene or acrylonitrile-styrene polymer. Thus, this strain is expected to play an important role in aeration tanks for treating ABS resin manufacturing wastewater.

Acrylonitrile↗

Species differences in acrylonitrile metabolism and toxicity between experimental animals and humans based on observations in human accidental poisonings.

The high acute toxicity of acrylonitrile may be a result of its intrinsic biological reactivity or of its metabolite cyanide. Intravenous N-acetylcysteine has been recommended for treatment of accidental intoxications in acrylonitrile workers, but such recommendations vary internationally. Acrylonitrile is metabolized in humans and experimental animals via two competing pathways; the glutathione-dependent pathway is considered to represent an avenue of detoxication whilst the oxidative pathway leads to a genotoxic epoxide, cyanoethylene oxide, and to elimination of cyanide. Cases of acute acrylonitrile overexposure or intoxication have occurred within persons having industrial contact with acrylonitrile; the route of exposure was by inhalation and/or by skin contact. The combined observations lead to the conclusion of a much higher impact of the oxidative metabolism of acrylonitrile in humans than in rodents. This is confirmed by differences in the clinical picture of acute life-threatening intoxications in both species, as well as by differential efficacies of antidotes. A combination of N-acetylcysteine with sodium thiosulfate seems an appropriate measure for antidote therapy of acute acrylonitrile intoxications. Clinical observations also highlight the practical importance of human individual susceptibility differences. Furthermore, differential adduct monitoring, assessing protein adducts with different rates of decay, enables the development of more elaborated biological monitoring strategies for the surveillance of workers with potential acrylonitrile contact.

Acrylonitrile↗

Effect of chronic exposure to acrylonitrile on subjective symptoms.

A cross-sectional study was performed to clarify the relationship between exposure to acrylonitrile (AN) and its effect on subjective symptoms by using a modified Cornell Medical Index (CMI) health questionnaire. The 7 acrylic fiber manufacturing factories surveyed were classified into 3 groups, namely, group L with a mean environmental acrylonitrile concentration of 1.8 ppm, group M with 7.4 ppm, and group H with 14.1 ppm. The total number of workers engaged in acrylic fiber manufacturing processes (acrylonitrile workers) and reference workers analyzed were 504 and 249, respectively. These consisted of 92 acrylonitrile workers and 108 reference workers in group L, 304 and 102 respectively in group M, and 108 and 39 respectively in group H. The mean values for length of exposure to acrylonitrile were 5.6 years in group L, 7.0 years in group M, and 8.6 years in group H. Neurotic status as determined by Fukamachi's criteria and Cornell Medical Index profiles did not show any AN-related differences between AN workers and reference workers in any of the groups. The subjective symptoms with significantly high prevalences in AN workers were "headache", "tongue trouble", "choking lump in throat", "fatigability", "general malaise", "heavy arms", and "heavy sweating". Except for "choking lump in throat" there was no relationship between the prevalence of symptoms and the length or level of exposure to acrylonitrile. These results suggested that long-term exposure to acrylonitrile at levels up to 14.1 ppm did not induce neurotic effects in acrylonitrile workers, but might cause some reversible subjective symptoms.

Acrylonitrile↗

[Application of micronucleus test of buccal mucosal cells in assessing the genetic damage of workers exposed to acrylonitrile].

OBJECTIVE: To investigate the application of micronucleus test of buccal mucosal cells in monitoring the genetic effect of acrylonitrile in the population exposed to the acrylonitrile. METHODS: Forty-one healthy male workers in a chemical factory in Shanghai were selected as the low concentration acrylonitrile exposed group while forty-seven healthy male workers in an acrylonitrile factory in Shanghai were selected as the intermediate concentration acrylonitrile exposed group. At the same time, thirty-one male workers who had no toxicant exposure and lived in the same community were selected as the control group. The micronucleus test in buccal mucosal cells and lymphocytes were used respectively for assessing the genetic damage status of these men. RESULTS: The rate of micronucleus in buccal mucosal cells in both acrylonitrile groups (the low concentration group: 3.68% +/- 2.72%; the intermediate concentration group: 4.00% +/- 2.38%) was significantly higher than that in the control group (2.03% +/- 2.20%) (P < 0.05). The rate of micronucleus in the intermediate concentration group (4.23% +/- 3.34%) was significantly higher than that in the control group (2.48% +/- 1.46%) (P < 0.05). There was the correlation between the micronucleus test of buccal mucosal cells and the micronucleus test of the lymphocytes in the peripheral blood in the acrylonitrile exposed population (r = 0.299-0.359, P < 0.05). CONCLUSION: The micronucleus test of buccal mucosal cells replacing the micronucleus test of the lymphocytes in the peripheral blood can be used as one of the screening indexes in the surveillance of the genetic damage in the acrylonitrile exposed population.

Acrylonitrile↗

Clinical toxicology of acrylonitrile.

Acrylonitrile monomer is used in the production of artificial fibres and resins. It has been used as a fumigant. Acrylonitrile has acute toxic effects for men and animals on over-exposure by inhalation of the vapor, dermal absorption of the liquid and oral intake. Symptoms in men are non-specific and predominantly related to the central nervous system, the respiratory tract, the skin and to the gastrointestinal tract. Severe acrylonitrile intoxication is followed by loss of consciousness, convulsions, respiratory arrest and death. The detailed investigation of a patient with complaints after chronic exposure demonstrates the necessity of objective neurophysiologic studies. Acrylonitrile has carcinogenic properties in animals. It is also embryotoxic and teratogenic. Epidemiological studies in men exposed to acrylonitrile are not convincing. There may be a slight excess of deaths from lung cancers and other malignant tumors. Effects of potential antidotes were studied in animal experiments. Rats were intoxicated with lethal doses of acrylonitrile by different routes of application. The cyanide antidotes 4-dimethylaminophenol plus thiosulfate showed some protective effect only after oral but not after i.p. or inhalational acrylonitrile administration. Of the sulfhydryl compounds cysteine, N-acetyl-cysteine, cysteamine and diethyldithiocarbamate, the two antidotes cysteine and N-acetylcysteine proved to be especially effective. From these experiments a tentative schedule of antidotal therapy for humans accidentally intoxicated with acrylonitrile is inferred, using N-acetylcysteine by analogy with the therapeutic regimen effective in cases of paracetamol poisoning.

Acrylonitrile↗

Possible role of lipid peroxidation in the actions of acrylonitrile on the adrenals, liver and gastrointestinal tract.

Acrylonitrile-induced adrenal necrosis is associated with the early depletion of adrenal glutathione and elevation of adrenal dopamine. These biochemical events could result in increased susceptibility to free radical-mediated lipid peroxidation which may play a role in the pathogenesis of adrenal injury caused by acrylonitrile. In the studies reported here we found no elevation in malonaldehyde or conjugated diene concentrations of adrenal glands (or of glandular stomach and duodenal mucosa which may be other targets of acrylonitrile action) from rats given acrylonitrile. Conjugated diene concentrations in liver microsomes were significantly elevated (132%) 60 min after administration of carbon tetrachloride or 15 (38%), 30 (58%), and 60 (46%) min after injection of acrylonitrile whereas mitochondrial conjugated diene concentrations were not significantly altered by acrylonitrile. Our results suggest that while lipid peroxidation may not be involved in the pathogenesis of acrylonitrile adrenal injury it may occur in other tissues after acrylonitrile administration.

Acrylonitrile↗

Modulation of acrylonitrile-induced embryotoxicity in vitro by glutathione depletion.

The effects of glutathione (GSH) depletion on the embryotoxicity of acrylonitrile were assessed in vitro using the rat whole-embryo culture system. Day 10 rat embryos were cultured in rat serum medium for 6 h in the presence of 250 microM L-buthionine-S,R-sulfoximine (BSO), a specific inhibitor of GSH synthesis, to deplete GSH in both embryo and visceral yolk sac. Following pretreatment, conceptuses were cultured for an additional 21 h in the presence of 152, 228, or 304 microM acrylonitrile. At the end of the culture period, conceptuses were assessed for survival, growth and development, malformations, and the protein and glutathione content of embryos and yolk sacs were assayed. Acrylonitrile alone produced concentration-related and statistically significant decreases in yolk sac diameter, crown-rump length, head length and number of somite pairs, as well as in embryonic and yolk sac proteins. The chemical also caused dysmorphogenesis of the brain and of the caudal extremity, and a concentration-related and statistically significant increase in GSH content in the yolk sac. Pretreatment with BSO significantly enhanced the embryotoxic effects of acrylonitrile. The conceptuses displayed further decreases in functional yolk sac circulation, yolk sac diameter, crown-rump and head length, when compared to either acrylonitrile or BSO alone. The incidence of caudal malformations and the severity of brain malformations produced by acrylonitrile were also increased. Marked decreases in embryonic and yolk sac GSH contents were observed after exposure to BSO alone or in combination with acrylonitrile.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced↗

Urinary metabolites of [1,2,3-13C]acrylonitrile in rats and mice detected by 13C nuclear magnetic resonance spectroscopy.

Acrylonitrile, a carcinogen in rats, undergoes extensive metabolism via two routes: direct glutathione conjugation or epoxidation. Metabolism to cyanoethylene oxide may mediate the carcinogenic and toxic activity of acrylonitrile. To characterize comprehensively the metabolism in vivo of acrylonitrile, the detection and identification of metabolites in urine of rodents dosed with acrylonitrile have been carried out using NMR spectroscopy. Following administration of [1,2,3-13C]acrylonitrile to male Fisher 344 rats (10 or 30 mg/kg, po) or B6C3F1 mice (10 mg/kg, po), urine samples were collected for 24 h. Carbon-13 NMR spectra were acquired directly on the urine samples after centrifugation and addition of 10-25% D2O. Resonances were assigned to carbons of acrylonitrile metabolites on the basis of chemical shift, proton multiplicity, carbon-carbon coupling, and calculated values of shift, and by comparison with standards. The proton multiplicity of each carbon was determined by heteronuclear 2D J-resolved spectroscopy (HET2DJ), and the carbon-carbon connectivities of resonances were determined using incredible natural abundance double quantum transfer spectroscopy (INADEQUATE). The metabolites identified in rat urine were thiocyanate, N-acetyl-S-(2-cyanoethyl)cysteine, N-acetyl-S-(2-hydroxyethyl)cysteine, N-acetyl-S-(1-cyano-2-hydroxyethyl)cysteine, thiodiglycolic acid, thionyldiacetic acid, and S-(carboxymethyl)cysteine or its N-acetyl derivative. These metabolites were also identified in mouse urine. Metabolites were quantitated by integrating metabolite carbon resonances with respect to that of dioxane added at a known concentration. Thiodiglycolic acid and (carboxymethyl)cysteine (or its N-acetyl derivative) were the major metabolites in the mouse, while N-acetyl-S-(2-cyanoethyl)cysteine and N-acetyl-S-(2-hydroxyethyl)cysteine were the major metabolites in the rat. Metabolites derived from cyanoethylene oxide (CEO) accounted for approximately 60% of the products excreted in rat urine, compared with 80% in the urine from mice. Differences between rat and mouse in the further metabolism of CEO were also observed. The proportion of the dose metabolized via CEO may be an important determinant of the toxicity and carcinogenicity of acrylonitrile.

Acrylonitrile↗

Activity of sulphate reducing bacteria according to COD/SO4(2-) ratio of acrylonitrile wastewater containing high sulphate.

This study was performed to evaluate the biodegradability of acrylonitrile wastewater, microbial inhibition effect of acrylonitrile wastewater on removal efficiency and the activity of sulphate reducing bacteria (SRB) according to COD/sulphate ratio. Acrylonitrile wastewater was hardly biodegradable in a biodegradability test, however, SRB activity was 57% for overall consumption of electron donor and it was relatively high value compared to 17% of reference test with glucose. COD removal of acrylonitrile wastewater was improved to 57% and 61% from 20% as the COD/sulphate ratio were 0.5 and 0.3 by sulphate addition to acrylonitrile wastewater. First order reaction rate constants k on organic removal of acrylonitrile wastewater were 0.001, 0.004 and 0.004 at each COD/sulphate ratio of 0.9, 0.5 and 0.3. Thus it was suggested that the activity of SRB was a significant factor for removing organics and sulphate simultaneously in acrylonitrile wastewater.

Acrylonitrile↗

Gene and protein expressions in human cord blood cells after exposure to acrylonitrile.

Acrylonitrile is a very high volume industrial chemical used primarily in the manufacture of plastics and rubber, which displays a pronounced acute toxicity and may be carcinogenic. The damage to the hematopoietic function by acrylonitrile may result from interference with cytokine production and cytokine receptor binding. Our present data show that acrylonitrile modulates the expression of some genes implicated in cell differentiation, cell-cycle progression, and clonogenic potential of human cord blood cells. A macroarray hybridization analysis showed that expression of the CXCR4, MCP-1, and MRP8 genes was modified by acrylonitrile exposure. Moreover, the acrylonitrile cell target seems to be the myeloid compartment, as assessed by a CFU-GM assay. In particular, the downregulation of CXCR4, MCP1, and MRP8 can be responsible for the observed reduction of cell proliferation and clonogenic capability of CFU-GM precursors. A Western blot assay showed an acrylonitrile-dependent induction of Bax, while Bcl-2 expression changed only after 48 h of chemical exposure. Bax was overexpressed in respect to Bcl-2, and this fact can be responsible for the induction in cell death after 24 h of treatment. C-fos and c-jun were also downregulated after 24 h and 6 h of treatment, respectively.

Acrylonitrile↗

Acrylonitrile: a suspected human carcinogen.

The literature on carcinogenicity of acrylonitrile (an important intermediate in the chemical industry) is reviewed. The three main conclusions are: (1) Acrylonitrile has genotoxic effects in various tests in microorganisms and in mammal cells. (2) Chronic exposure to acrylonitrile causes tumours in rats. (3) Results of epidemiological studies indicate that acrylonitrile may be a human carcinogen. From this it is clear that acrylonitrile is very probably carcinogenic to humans. Therefore the authors plead for a reduction of acrylonitrile standards to the lowest practicable limit.

Acrylonitrile↗

Influence of simultaneous exposure to acrylonitrile and styrene on the toxicity and metabolism of styrene in rats.

Nine groups of adult male rats were given different combinations of styrene and acrylonitrile and each chemical was administered at three doses (styrene 0, 5.8, and 11.6 mmol/kg, ip; acrylonitrile 0, 0.3, and 0.6 mmol/kg, po). The animals were killed 24 hr later and blood and urine samples were collected. The results of biochemical analyses due to the toxicity of both chemicals and of the determination of urinary metabolites of styrene were then subjected to a factorial (3 X 3) analysis of variance. There was: (1) a significant elevation of blood urea nitrogen (BUN) and serum glutamic-pyruvic transaminase (SGPT), and a diminution of urinary creatinine due to styrene; (2) an increase in serum creatinine and serum glutamicoxaloacetic transaminase (SGOT) due to styrene that was further increased by acrylonitrile; and (3) an increase in the concentrations of urinary metabolites (thioethers, mandelic, phenylglyoxylic, and hippuric acids) due to styrene that was considerably reduced by acrylonitrile. These results suggest that styrene causes renal toxicity which may be potentiated by acrylonitrile; furthermore, the significant diminution of the urinary metabolites of styrene due to acrylonitrile obscures interpretation of the results of the biological monitoring of exposure to styrene.

Acrylonitrile↗

Effect of glutathione depletion on the irreversible association of acrylonitrile with tissue macromolecules after oral administration to rats.

Binding of acrylonitrile and its reactive metabolites to tissue macromolecules, especially nucleic acids, may be responsible for its carcinogenicity in rats. Both acrylonitrile and its primary metabolite, 2-cyanoethylene oxide, also react with glutathione. To better understand the role of glutathione in the manifestation of acrylonitrile toxicity, the irreversible binding to tissue macromolecules was assessed in control and glutathione-depleted F-344 rats treated with a 4 mg/kg dose (po) of [2,3-14C]acrylonitrile. Glutathione was depleted in rat tissues by the administration of a combined intraperitoneal phorone/buthionine sulfoximine treatment (300 mg/kg and 2 mmol/kg, respectively) given 30 min prior to acrylonitrile administration. The amount of total radioactivity recovered from brain, stomach (target organs), liver, kidney, lung, and blood (nontarget organs) was similar between control and glutathione-depleted rats. However, stomach, lung, blood, and liver showed an increase in total radioactivity content after glutathione depletion by phorone/buthionine sulfoximine treatment. Glutathione depletion also caused an increase in acrylonitrile-derived non-dialysable radioactivity (MW greater than 3500 Da) in liver, lung, kidney, stomach, blood, and brain macromolecules between 6 and 24 hr after the dose. There was no organ-specific accumulation of radiolabel in RNA in control rats. However, an increase in the radiolabel associated with nucleic acids in the target organs but not in the nontarget organs was measured in glutathione-depleted rats. Urinary excretion of thiocyanate, a metabolite derived from the epoxide pathway, was also increased by 300% in glutathione-depleted rats. These results suggest that glutathione might play a role in the extent of 2-cyanoethylene oxide formation and in the distribution of the radiolabel among tissues.

Acrylonitrile↗

Mortality update of workers exposed to acrylonitrile in The Netherlands.

To study the possible carcinogenic effects of acrylonitrile, we updated the follow up of a cohort of 2842 acrylonitrile workers. The comparison group consisted of 3961 workers from a nitrogen fixation plant. Industrial hygiene assessments quantified past exposure to acrylonitrile, 8-hour averages as well as peak exposure, the use of personal protective equipment, and exposure to other potential carcinogenic agents. Standardized mortality ratios were calculated to adjust for the effect of age distribution, length of follow up, and temporal changes in background mortality rates. Cumulative dose-effect relations were determined for 3 exposure categories and 3 latency periods. The results show that no cancer excess seems related to exposure to acrylonitrile. This additional follow up of a cohort of 2842 workers exposed to acrylonitrile further supports the notion that occupational exposures to acrylonitrile that have occurred in the past have not noticeably increased workers' cancer mortality rates.

Acrylonitrile↗

Report of an independent peer review of an acrylonitrile risk assessment.

A peer review panel made up of experts in toxicology, epidemiology, cancer mode of action (MOA), cancer mechanisms, carcinogenicity, genotoxicity, dose-response, US Environmental Protection Agency (EPA) cancer and noncancer methods, pharmacokinetic modeling and acrylonitrile, met on 22-23 September 2003 in Cincinnati, OH. The purpose of the meeting was to provide an independent review of a risk assessment of acrylonitrile that had been prepared by the Acrylonitrile Group (AN Group). Toxicology Excellence for Risk Assessment (TERA) organized the peer review and selected the panel. The panel discussed the toxicity and epidemiology literature of acrylonitrile and MOA information, and reached conclusions regarding its MOA, weight of evidence (WOE) for carcinogenicity, preferred approach for dose-response assessment and risk values. This paper summarizes the discussion and conclusions of the panel regarding the acrylonitrile assessment. Subsequent to the peer review, the authors of the acrylonitrile assessment revised their report and the panel reviewed the revised report. A manuscript of the revised assessment is being published in Regulatory Toxicology and Pharmacology.

Acrylonitrile↗

Irreversible binding of acrylonitrile to nucleic acids.

1. [2,3-14C]Acrylonitrile was incubated with rat-liver microsomes, NADPH and either DNA, RNA or bovine serum albumin. Irreversible binding occurred to the macromolecular targets. Binding was lower when incubations were performed without microsomes. 2. Most of the 14C bound to DNA, RNA or polynucleotides (poly-A, poly-C, poly-G, poly-U) after incubation of [2,3-14C]acrylonitrile with rat-liver microsomes and 'conventional' re-isolation of the nucleic acids was removed from the macromolecular target when subsequently chromatographed on hydroxyapatite. 3. Radioactivity attached to DNA after prolonged non-enzymic incubations with [2,3-14C]acrylonitrile was also removed from the DNA by chromatography on hydroxyapatite. 4. When [2,3-14C]acrylonitrile was administered to rats (i.p.), incorporation of 14C into the natural bases of hepatic RNA was observed. In contrast with previous experiments with [1,2-14C]vinyl chloride, no radioactive [1-N6]etheno-adenine could be detected in RNA. 5. After administration of [2,3-14C]acrylonitrile to rats, hepatic DNA was isolated and hydrolysed by a modified enzymic procedure. Chromatography on PEI-cellulose showed two 14C peaks which did not co-chromatograph with any known standard. The amount of 14C in these presumed alkylation products was too low to allow chemical identification. 6. It is concluded that acrylonitrile, either itself or its metabolites, can alkylate nucleic acids. However, the extent of irreversible nucleic-acid binding is quantitatively much less than that observed with vinyl halides.

Acrylonitrile↗

In vivo interaction of acrylonitrile and 2-cyanoethylene oxide with DNA in rats.

Several approaches were used to probe aspects of the mechanism of acrylonitrile carcinogenicity in rats. Acrylonitrile did not appear to increase the rate of DNA synthesis resulting from tissue injury and regeneration in liver or brain, the latter being a target organ. The chemical did cause unscheduled DNA synthesis in rat liver but not brain. The epoxide of acrylonitrile, 2-cyanoethylene oxide, was formed in perfused rat liver; this metabolite accumulated in the perfusate as long as acrylonitrile was available to the organ. When 2-cyano[2,3-14C]ethylene oxide was administered to rats i.p., covalent binding to both liver and brain protein was found, but no covalent binding to nucleic acids could be detected at the level of 0.3 alkylations per 10(6) bases. No 1,N6-ethenoadenosine or 1,N6-ethenodeoxyadenosine was found in liver nucleic acids after administration of either acrylonitrile or 2-cyanoethylene oxide to rats, with the limits of detection being 0.3 alkylations per 10(6) RNA bases and 1 alkylation per 10(6) DNA bases. However, low levels of N7-(2-oxoethyl)guanine were detected in the livers of these rats by means of a radiometric derivative assay (0.014-0.032 alkylations per 10(6) DNA bases). In the brains of the treated rats the levels of N7-(2-oxoethyl)guanine were not above the limit of detection. These results show that acrylonitrile has some limited potential for genotoxicity in vivo and that the epoxide, with its ability to leave the liver and possibly to enter the brain, can interact with nucleic acids to a limited degree.

Acrylonitrile↗

Toxicologic profile of acrylonitrile.

Acrylonitrile is a monomer used extensively as a raw material in the manufacturing of acrylic fibers, plastics, synthetic rubbers, and acrylamide. It has been classified as a probable human carcinogen according to the results of numerous chronic rat bioassays. The present report summarizes the toxicity data on acrylonitrile and reviews available data concerning the mechanism (genetic versus epigenetic) by which acrylonitrile is carcinogenic in rats. From the evaluation of the relevant toxicity data, it can be concluded that acrylonitrile is indeed carcinogenic to rats after either oral or inhalational exposure. However, information on other mammalian species is lacking, and, moreover, the exact mechanism of the carcinogenic process is unclear. Therefore, it is recommended to conduct an additional long-term inhalation carcinogenicity study with acrylonitrile in mice, as well as studies into the mechanism by which acrylonitrile induces (brain) tumors in rats (genetic versus epigenetic).

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