Application of screening tools for environmental hazard and risk to support assessment and subsequent prioritization of effluent discharges from the oil and gas industry

Assessment and management of effluent discharges are key to avoiding environmental deterioration. Often compliance with discharge regulations and permits is based on a limited set of chemical parameters, while information on whole effluent hazardous properties (toxicity, bioaccumulation potential, persistence) and environmental risks is lacking. The need to collect those data and to become more effective in quickly identifying high-risk activities, without extensive laboratory testing, has led to the development of screening tools to complement information on chemical composition. A simple, Tier 1 screening "toolbox" is proposed which is comprised of solid-phase microextraction with gas chromatographic (SPME-GC) analysis, the in-vitro ecotoxicity assay Microtox, and a simple weathering assay. When combined with dilution modeling, screening-level risk assessments can be performed, providing additional lines of evidence to support a weight of evidence type of analysis. Application of the toolbox enables prioritization of discharges that may be deemed to require higher tier assessment. The toolbox was trialed on a number of produced water samples collected from offshore oil and gas facilities and effluents from petroleum processing and manufacturing sites. In contrast to what has been reported for petroleum products, results showed only moderate correlation between bioavailable hydrocarbons (bHCs) and toxicity, which might be related to the possible presence of toxic contaminants from other chemical classes or to methodological issues such as suboptimal conditions during transport. The methods employed were quick, inexpensive, and simple to conduct. They require relatively small volumes of sample, which is especially advantageous when evaluating discharges from remote offshore facilities. The toolbox adds valuable information on whole effluent properties to existing data, for example, on chemical composition, which can improve understanding of which discharges are more likely to pose a risk to the environment and so require further investigation or risk management. Integr Environ Assess Manag 2021;17:1025-1036. © 2021 Shell International B.V. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Re-evaluation of target lipid model-derived HC5 predictions for hydrocarbons

The target lipid model (TLM) has been previously applied to predict the aquatic toxicity of hydrocarbons and other nonionic organic chemicals and for deriving the concentrations above which 95% of species should be protected (HC5 values). Several concerns have been identified with the TLM-derived HC5 when it is applied in a substance risk assessment context. These shortcomings were addressed by expanding the acute and chronic toxicity databases to include more diverse taxonomic groups and increase the number of species. The TLM was recalibrated with these expanded databases, resulting in critical target lipid body burdens and acute-to-chronic ratios that met the required guidelines for using species sensitivity distributions in substance risk assessment. The HC5 equation was further revised to consider covarying model parameters. The calculated HC5 values derived from the revised TLM framework were validated using an independent data set for hydrocarbons comprising 106 chronic values across plants, invertebrates, and fish. Assuming a sum binomial distribution, the 95% confidence limit for a 5% failure is between 0.8 and 9.2%. Eight chronic values fell below the HC5, corresponding to an excursion of 7.5%, which falls within the expected uncertainty bounds. Thus, calculated HC5s derived from the revised TLM framework were found to be consistent with the intended protection goals. Environ Toxicol Chem 2018;37:1579-1593. © 2018 SETAC.

A Review of the Environmental Degradation, Ecotoxicity, and Bioaccumulation Potential of the Low Molecular Weight Polyether Polyol Substances

"Polyalkylene glycol" is the name given to a broad class of synthetic organic chemicals which are produced by polymerization of one or more alkylene oxide (epoxide) monomers, such as ethylene oxide (EO) and propylene oxide (PO), with various initiator substances which possess amine or alcohol groups. A generalization of this polymerization reaction is illustrated in Fig. 1.

Critical micelle concentration values for different surfactants measured with solid-phase microextraction fibers

The amphiphilic nature of surfactants drives the formation of micelles at the critical micelle concentration (CMC). Solid-phase microextraction (SPME) fibers were used in the present study to measure CMC values of 12 nonionic, anionic, cationic, and zwitterionic surfactants. The SPME-derived CMC values were compared to values determined using a traditional surface tension method. At the CMC of a surfactant, a break in the relationship between the concentration in SPME fibers and the concentration in water is observed. The CMC values determined with SPME fibers deviated by less than a factor of 3 from values determined with a surface tension method for 7 out of 12 compounds. In addition, the fiber-water sorption isotherms gave information about the sorption mechanism to polyacrylate-coated SPME fibers. A limitation of the SPME method is that CMCs for very hydrophobic cationic surfactants cannot be determined when the cation exchange capacity of the SPME fibers is lower than the CMC value. The advantage of the SPME method over other methods is that CMC values of individual compounds in a mixture can be determined with this method. However, CMC values may be affected by the presence of compounds with other chain lengths in the mixture because of possible mixed micelle formation. Environ Toxicol Chem 2016;35:2173-2181. © 2016 SETAC.

PETRORISK: a risk assessment framework for petroleum substances

PETRORISK is a modeling framework used to evaluate environmental risk of petroleum substances and human exposure through these routes due to emissions under typical use conditions as required by the European regulation for the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH). Petroleum substances are often complex substances comprised of hundreds to thousands of individual hydrocarbons. The physicochemical, fate, and effects properties of the individual constituents within a petroleum substance can vary over several orders of magnitude, complicating risk assessment. PETRORISK combines the risk assessment strategies used on single chemicals with the hydrocarbon block approach to model complex substances. Blocks are usually defined by available analytical characterization data on substances that are expressed in terms of mass fractions for different structural chemical classes that are specified as a function of C number or boiling point range. The physicochemical and degradation properties of the blocks are determined by the properties of representative constituents in that block. Emissions and predicted exposure concentrations (PEC) are then modeled using mass-weighted individual representative constituents. Overall risk for various environmental compartments at the regional and local level is evaluated by comparing the PECs for individual representative constituents to corresponding predicted no-effect concentrations (PNEC) derived using the Target Lipid Model. Risks to human health are evaluated using the overall predicted human dose resulting from multimedia environmental exposure to a substance-specific derived no-effect level (DNEL). A case study is provided to illustrate how this modeling approach has been applied to assess the risks of kerosene manufacture and use as a fuel.

Development of a chronic fish toxicity model for predicting sub-lethal NOEC values for non-polar narcotics

To comply with the REACH (Registration, Evaluation, Authorisation and restriction of Chemicals) regulations, the generation of chronic fish toxicity data is required for chemicals produced or imported within or into the EU in quantities greater than 100 tonnes per year. This comes at a great cost to industry and consumers alike and requires the sacrifice of many vertebrates. In acknowledgment of these issues the REACH regulations encourage the use of non-testing methods (NTM). These include read-across, weight-of-evidence and QSAR (quantitative structure-activity relationship) techniques. There are many QSAR tools available to generate predictive values for a number of physico-chemical properties, as well as human and environmental health end points; however, close analysis of the currently available chronic fish models identified room for improvement in both the selection of data used and in its application in model creation. In light of this a model was developed using only sub-lethal no-observed-effect concentration (NOEC) end-point data according to best practice QSAR development. Only the lowest value was taken for each compound, in line with the conservative approach taken by the European Chemicals Agency (ECHA). The model developed meets the Organisation for Economic Co-operation and Development (OECD) principles, has strong internal and external validation statistics, and can reliably predict sub-lethal chronic NOEC values for fish within its defined applicability domain.

Environmental properties of long-chain alcohols. Part 2: Structure-activity relationship for chronic aquatic toxicity of long-chain alcohols

Daphnia magna reproduction tests were performed with C(10), C(12), C(14) and C(15) alcohols to establish a structure-activity relationship of chronic effects of long-chain alcohols. The data generation involved substantial methodological efforts due to the exceptionally rapid biodegradability of the test substances and the need to test as close as possible to their water solubility limits. Test concentrations were determined by GC-MS before and after test solution renewal. Whereas apparent toxicity based on survival and reproduction increased with increasing C-chain lengths up to C(14), observations of toxicity to C(15) alcohol were not in line with lower chain lengths due to the lack of toxicity below the level of water solubility. When omitting C(15), the slope of most (Q)SARs approach -1, being consistent with the expectation of a non-polar narcotic mode of action. Further testing at higher chain lengths is not sensible due to progressively lower solubility, at remaining biodegradability. Effects on mortality and reproduction are not expected below the level of water solubility.

Determination of the fate of alcohol ethoxylate homologues in a laboratory continuous activated-sludge unit study

Environmental monitoring indicates that the distribution of alcohol ethoxylate (AE) homologues in wastewater treatment plant (WWTP) effluents differs from the distribution in commercial AE products, with a relative higher proportion of fatty alcohol (AOH, which is AE with zero ethoxylation). To determine the contribution of AE-derived AOH to the total concentration of AE and AOH in WWTP effluents, we conducted a laboratory continuous activated-sludge study (CAS). This consisted of a test unit fed with AE-amended synthetic sewage and a control unit fed with only synthetic sewage to avoid AE contamination from the feed. The removal efficiencies of some 114 AE homologues were determined by the application of a specific and sensitive analytical method. The extent of the removal of AE ranged from 99.70% for C18 compounds to > 99.98% for C12-16. Relatively high-AOH concentrations were observed in the effluents from blank and test units. By building the concentration difference from the test minus the control unit, the AE in the CAS effluent originating from AE in the influent was determined. Thus, it could be shown that AOH represented only 19% of the total AE (EO0-18) in the CAS, while monitoring in 29 WWTP effluents (European, Canadian, and US) revealed in total a mean AOH fraction of 55% (5-82%) of the total AE (EO0-18). This shows that only a small fraction of AOH in WWTP effluents originates from AE entering the WWTP.

Monitoring of environmental fingerprints of alcohol ethoxylates in Europe and Canada

Recent improvements in methodology for the determination of alcohol ethoxylates (AE) in effluents now enable measurement of the full range of AE components, at ng/L levels, in the same analysis. This approach was deployed in effluent monitoring of biofilm and activated sludge wastewater treatment plants from Europe (n = 12) and Canada (n = 8) receiving predominantly municipal effluent. Individual component or "environmental fingerprint" analyses for alkyl carbon numbers C12-C18 and ethoxylate numbers 0-18 were conducted using a derivatization procedure with liquid chromatography/mass spectrometry determination. The AE results were very similar with an overall mean level of 5.7 microg/L (range 1.0-22.7 microg/L). The major contribution to the total AE content was from fatty alcohol, which constituted, on average, 43% of the total. The exposure data can then be corrected to account for alcohol derived from sources other than AE and for sorption to particulate matter to determine AE concentrations in undiluted effluents. These data can be used with site-specific dilution information to estimate river water exposure in mixing zones and then to determine aquatic risk by integrating normalized AE effect concentrations determined through quantitative structure-activity relationships.

An improved analytical method, based on HPLC with electrochemical detection, for monitoring exposure to 3-chloro-4-fluoroaniline

An HPLC method for monitoring exposure of workers to 3-chloro-4-fluoroaniline (CFA) is described. It is based on the detection of a major urinary metabolite, 2-amino-4-chloro-5-fluorophenyl sulphate, and is superior to the previously adopted GC method. The limit of detection for the metabolite, 2-amino-4-chloro-5-fluorophenyl sulphate, is less than or equal to 0.01 mg/L (as CFA equivalent), with a coefficient of variation obtained over the range 1-15 mg/L of 4%. The HPLC method avoids the need for derivatization (cf. GC) and is consequently a much quicker and cheaper monitoring method. Urine samples from plant workers may be stored at 4 degrees C for a period of three months without loss of the metabolite.

Human dose-excretion studies with pyrethroid insecticides cypermethrin and alphacypermethrin: relevance for biological monitoring

1. Dose-excretion studies with cypermethrin (as a 1:1 cis/trans mixture) and alphacypermethrin (one of the two disastereoisomer pairs which constitute cis cypermethrin) were carried out with, in each case, two volunteers per dose level. The studies included (a) single oral alphacypermethrin doses of 0.25 mg, 0.50 mg and 0.75 mg followed by repeated alphacypermethrin doses at the same levels, daily for five days, (b) repeated oral cypermethrin doses of 0.25 mg, 0.75 mg and 1.5 mg daily for five days, and (c) a single dermal application of 25 mg cypermethrin to the forearm. Urine was monitored for the free and conjugated 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid before and after dosing. 2. Metabolism and rate of excretion of a single oral dose of alphacypermethrin was similar to that of cis cypermethrin, on average, 43% of the dose was excreted as the cyclopropanecarboxylic acid in the first 24 h urine. There was no increase in urinary metabolite excretion when alphacypermethrin was administered as a repeated oral dose. Subjects excreted, on average, 49% of the dose as the cyclopropanecarboxylic acid in the subsequent 24 h periods after dosing. 3. There was no increase in the urinary cyclopropanecarboxylic acid excretion when cypermethrin was administered as a repeated oral dose. Subjects excreted, on average, 72% of the trans isomer dose and 45% of the cis isomer dose respectively in the subsequent 24 h periods after dosing. 4. Approximately 0.1% of the applied dermal dose of 25 mg cypermethrin was excreted within 72 h as the urinary cyclopropanecarboxylic acid. No conclusions can be drawn from such urinary excretion data as to the concentration of cypermethrin and its metabolites in the skin or other organs, or the possibility of other routes of metabolism or excretion.

The metabolism of o-fluoroaniline by rats, rabbits and marmosets

o-Fluoroaniline is rapidly metabolized and excreted in rats, rabbits and marmosets. Following a single oral dose of 14C-fluoroaniline of about 20 mg/kg, more than 80% of the dose is excreted in 0-24 h, the urine being the major route of excretion for all three species. For all three species, 4-amino-3-fluorophenyl is a major metabolite, conjugated at oxygen with either sulphate or glucuronic acid. 4-Acetylamino-3-fluorophenyl sulphate or glucuronide are also significant metabolites. An h.p.l.c. method with electrochemical detection was developed for monitoring exposure of plant workers to o-fluoroaniline, based on 4-amino-3-fluorophenyl sulphate.

The metabolism of n-butyl glycidyl ether in the rat and rabbit

[1-14C]Butyl glycidyl ether administered orally to male rats and rabbits (20 mg/kg) is rapidly absorbed and metabolized. Most of the administered compound, 87% (rat) and 78% (rabbit), is eliminated in the 0-24 urine. Major metabolites in the rat include 3-butoxy-2-hydroxypropionic acid (9%), 3-butoxy-2-acetylaminopropionic acid (23%) and butoxyacetic acid (10%). 3-Butoxy-2-hydroxypropionic acid (35%) and butoxyacetic acid (5%) are also major metabolites in the rabbit. Biotransformations of the glycidyl ether and their likely biochemical mechanisms are discussed.

2,4-Difluoroaniline and 4-fluoroaniline exposure: monitoring by methaemoglobin and urine analyses

Two possible methods for monitoring exposure to 2,4-difluoroaniline and 4-fluoroaniline have been investigated: measurement of methaemoglobin content in blood and measurement of urinary metabolites. Experiments using rats dosed by the oral route as a model system show that measurement of methaemoglobin content provides a very rapid and simple monitoring method, but is not very sensitive. Measurement of the ortho-hydroxy metabolites of the two compounds, as their benzoxazole derivatives, provides a much more sensitive, but complicated technique. Details of both methods are presented.

Human dose-excretion studies with the pyrethroid insecticide, cypermethrin

1. An analytical method for monitoring human exposure to cypermethrin has been developed, based on the detection of the free and conjugated forms of the urinary metabolite, the cyclopropanecarboxylic acid. 2. Four male subjects were given a single oral dose, ranging from 0.25 mg to 1.5 mg, of a 1:1 cis/trans mixture of cypermethrin, and urine was monitored for the free and conjugated cyclopropanecarboxylic acid. Urinary excretion of the individual metabolites (cis and trans isomers) was similar for the different dosages. Subjects excreted, on average, 78% of the trans isomer dose, and 49% of the cis isomer dose respectively in 24 h. 3. Thus, as in other mammals, ester cleavage and elimination of the cis and trans cyclopropanecarboxylic acid moieties in the free and conjugated form is a major route of metabolism of cypermethrin in man.

Interactions of alkyl sulphates with bovine-serum albumin studied using eaq--as a probe

The reactions of hydrated electrons produced during pulse radiolysis habe been used to investigate the binding of a range of alkyl sulphates to bovine-serum albumin. Binding to ten high-affinity sites is detectable for all compounds (methyl, hexyl, octyl, decyl, and dodecyl sulphates) studied. Sodium dodecyl sulphate, in contrast to the other analogues, causes large increases in the reactivity of BSA as a result of further binding. Possible mechanisms for this increase are discussed.

Investigation of the interaction of alkyl sulphates with serum albumin using the thiocyanate radical ion (SCN)2

The reaction of the radical anion -(SCN)2-, produced during pulse radilysis of aqueous KCNS solutions, have been used to study the binding of a range of alkyl sulphates to bovine (BSA) and human (HSA) serum albumin. At neutral pH, -(SCN)2- reacts chiefly with trytophan residues. Approximately ten high-affinity binding sites are detectable for compounds of chain length greater than C7. The results are interpreted in terms of a model in which one hydrophobic region in the protein, containing the tryptophan residues, can accommodate the ten ligand molecules. Electrostatic interactions with positively-charged groups surrounding the hydrophobic area are also involved in binding.