Charles Eadsforth - Academia.edu (original) (raw)

Papers by Charles Eadsforth

Environmental toxicology and chemistry / SETAC, Jan 3, 2015

Surfactants are a commercially important group of chemicals widely used on a global scale. Despit... more Surfactants are a commercially important group of chemicals widely used on a global scale. Despite high removal efficiencies during wastewater treatment, their high consumption volumes mean that a certain fraction will always enter aquatic ecosystems, with marine environments being the ultimate sites of deposition. Consequently, surfactants have been detected within marine waters and sediments. However, aquatic environmental studies have mostly focused on the freshwater environment, whereas marine studies are considerably underrepresented by comparison. The present review aims to provide a summary of current marine environmental fate (monitoring, biodegradation, and bioconcentration) and effects data of five key surfactant groups; linear alkylbenzene sulfonates (LAS), alcohol ethoxysulphates (AES), alkyl sulphates (AS), alcohol ethoxylates (AE) and ditallow dimethyl ammonium chloride (DTDMAC). Monitoring data are currently limited, especially for AES and AS. Biodegradation was shown...

Tenside Surfactants Detergents, 2013

Xenobiotica, 1988

1. Dose-excretion studies with cypermethrin (as a 1:1 cis/trans mixture) and alphacypermethrin (o... more 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.

Journal of Environmental Monitoring, 2010

To investigate the potential sources of fatty alcohols arriving at a WWTP and entering the receiv... more To investigate the potential sources of fatty alcohols arriving at a WWTP and entering the receiving waters, a study was conducted at Treborth North Wales using compound specific stable isotope mass spectrometry (¹³C and ²H). Samples were collected from soils, marine sediments, detergents used in the catchment and in the WWTP. Total fatty alcohol concentrations decreased in the liquid phases through the treatment works with the majority of the compounds accumulating in the sludge (biosolids). Natural plant based detergents have δ¹³C values between -26 and -32‰ while petroleum-based detergents occupy a range between -25 and -30‰. The corresponding δ²H values are -250‰ for natural sourced materials and -50‰ for oil-based detergents which enable these two sources to be separated. The influent to the WWTP contained fatty alcohols which originated mainly from faecal sources and natural surfactants (∼75%) with a smaller amount potentially derived from petroleum-based surfactants (∼25%). The effluents from the WWTP contained mainly short chain compounds with a chain length less than C¹⁶. Their δ²H stable isotope signature was different to the other potential sources examined and suggests bacterial synthesis during the treatment processes. The sludge had relatively high concentrations of fatty alcohols as would be expected from their low water solubility. The stable isotopic signatures were consistent with a mixture of faecal and detergent sources. The sludge in this area is routinely spread on agricultural land as a fertiliser and may find its way back into the sea via land runoff. On the basis of the mean discharge rates and the mean C₁₂ concentration in the effluent, this WWTP would contribute ∼300 g day⁻¹ to the receiving waters. The marine sediment samples had short chain fatty alcohols that are typical of marine production and with stable isotope values that indicate exclusive marine production for the C₁₄ potentially mixed with terrestrial sources for the C₁₆ and C₁₈ compounds. Therefore, the fatty alcohols in the marine sediments are not the same as those that were discharged in the liquid effluent and these fatty alcohols were not the ones that entered the works through the influent but were synthesised or recycled within the works.

International Journal of Radiation Biology, 1976

The reaction of the radical anion -(SCN)2-, produced during pulse radilysis of aqueous KCNS solut... more 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.

International Journal of Radiation Biology, 1977

The reactions of hydrated electrons produced during pulse radiolysis habe been used to investigat... more 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.

Ecotoxicology and Environmental Safety, May 31, 2006

Recent improvements in methodology for the determination of alcohol ethoxylates (AE) in effluents... more 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.

Environmental Toxicology and Chemistry, 2016

The amphiphilic nature of surfactants drives the formation of micelles at the critical micelle co... more The amphiphilic nature of surfactants drives the formation of micelles at the critical micelle concentration (CMC). Solid-phase microextraction (SPME) fibres were used in the present study to measure CMC values of twelve 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 fibres and the concentration in water is observed. The CMC values determined with SPME fibres 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 fibre-water sorption isotherms gave information about the sorption mechanism to polyacrylate-coated SPME fibres. A limitation of the SPME method is that CMC for very hydrophobic cationic surfactants cannot be determined when the cation exchange capacity of the SPME fibres 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. This article is protected by copyright. All rights reserved.

Drug Metabolism and Disposition

IARC scientific publications

A novel immunochemical approach has been developed to monitor human exposures to ethylene oxide (... more A novel immunochemical approach has been developed to monitor human exposures to ethylene oxide (EO). The method exploits the interaction of EO with the amino function of the N-terminal valine residue of the alpha-chain of human haemoglobin (Hb). Antibodies were raised against the adducted valine in the form of the N-terminal tryptic heptapeptide and have been used to develop a sensitive radioimmunoassay (RIA) for the adducted heptapeptide. This method has been fully validated against a gas chromatography-mass spectrometry (GC-MS) method and has been applied to the monitoring of EO exposure in a group of sterilization workers.

Environmental Sciences Europe, 2013

ABSTRACT Surfactants are widely used across the globe both in industrial and consumer products; t... more ABSTRACT Surfactants are widely used across the globe both in industrial and consumer products; their biodegradation characteristics are therefore of high importance. Upon entering a wastewater treatment plant (WWTP), the majority of surfactants are aerobically mineralized to CO2 and H2O. However, a small fraction is inevitably left non-degraded and adheres to the remaining sludge. This sludge is usually further treated in anaerobic digester tanks. Assessment of existing methods for determining anaerobic biodegradability has led to the development of a new test method, which is in principle based on the method DIN 38414 part 8. This new test, named the anaerobic biodegradation under sludge digester conditions test (abbreviated to AnBUSDiC test) allows for a quantification of the degradation of surfactants under conditions encountered in the anaerobic digester tank of municipal WWTPs. The AnBUSDiC test has several advantages over existing methods. The main advantage is that it is particularly suitable for surfactants, because the two-step design minimizes possible unspecific digester gas formation caused by the surface activity of the test substances, therefore avoiding false positive results. Results In order to further standardize the AnBUSDiC test and gain regulatory acceptance, a ring test was organized involving seven laboratories, and five model surfactants from different surfactant classes (anionic, non-ionic (branched and linear) and amphoteric) plus a positive control, glucose. The AnBUSDiC test produced reliable repeatable results between laboratories; however, some additional modifications were suggested. It was identified that the original test method did not identify a clear endpoint from which a biodegradation value should be taken. It was proposed that a new more concise endpoint be defined in combination with the AnBUSDiC test to allow better comparability between test results. Conclusions The inclusion of a second addition of test substance is a major step forward in the elimination of the variability produced by non-specific gas production. With the exception of one anomalous result for linear alkylbenzene sulfonates, for which an explanation can be provided, the AnBUSDiC method appears to provide overall robust and interpretable results. Keywords: Surfactants; Anaerobic biodegradation; Environmental fate; Digester tank simulation test; Ring test

Pesticide Science, 1993

In a dietary toxicity study, laying hens received a diet containing the rodenticide flocoumafen a... more In a dietary toxicity study, laying hens received a diet containing the rodenticide flocoumafen at concentrations of 1.5, 5, 10 and 50 mg kg-' for five consecutive days. The LC,, at termination following a 28-day observation period was 16.4 mg kg-'.

Tenside Surfactants Detergents, 2014

ABSTRACT The aim of this study was to test whether the HPLC method for determining the n-octanol/... more ABSTRACT The aim of this study was to test whether the HPLC method for determining the n-octanol/water partition coefficient (log Pow) data of chemicals could be applied to alcohol ethoxylates (nonionic surfactants). In order to carry out this evaluation, the range of the standard calibration line first had to be extended from 0 – 6 (OECD 117) to 0 – 9. Experimental studies confirmed that the components of alcohol ethoxylates were eluted from the HPLC column in order of their predicted hydrophobicity. The HPLC method has proved to be particularly advantageous for the determination of log Pow values for alcohol ethoxylate products as it can generate data for highly hydrophobic material (log Pow > 6) and has sufficient resolving power to separate individual alcohol components from their ethoxylated moieties. This adapted HPLC method could be used to generate data for REACH submissions.

Environmental Toxicology and Chemistry, 2015

As a result of the stringent data requirements of the Registration, Evaluation, Authorisation, an... more As a result of the stringent data requirements of the Registration, Evaluation, Authorisation, and Restriction of Chemicals (REACH) regulation, a vast amount of ecotoxicological data has become available through the dissemination portal of the European Chemicals Agency (ECHA). As of April 2014, the database contained 12 439 unique substances from 47 909 dossiers. This vast database could be used to refine existing, or to create new, non-testing methods, such as quantitative structure-activity relationships (QSARs). Acute fish toxicity data were mined from the ECHA database using the eChemPortal; after filtering for single organic substances, 1159 experimental data points remained, representing 564 compounds. To evaluate the quality and accessibility of this data, the authors used the data to refine and improve an existing QSAR. The reliability of the data submitted to the ECHA database, as well as the effectiveness of the Klimisch scoring system, were assessed by comparing the refined QSAR with established QSAR benchmarks. The model developed meets all Organisation for Economic Co-operation and Development principles, has strong internal (leave-one-out internally cross-validated correlation coefficient [Q(2) LOO ] = 0.91) and external (external coefficient of determination (predicted vs experimental [test set])) validation statistics, and can provide reliable fish median lethal concentration (LC50) predictions for non-polar narcotics. Although some issues with dossier misinformation were discovered, it was found that the ECHA dissemination portal is a valuable and reliable data source. When queried using the eChemPortal, chemical dossiers containing reliable data could be found quickly. The ECHA dissemination portal holds great potential for future QSAR development and improvement, such as updating QSARs within the Ecological Structure-Activity Relationships (ECOSAR) program. Environ Toxicol Chem 2014;9999:1-10. © 2014 SETAC.

Xenobiotica, 1986

o-Fluoroaniline is rapidly metabolized and excreted in rats, rabbits and marmosets. Following a s... more 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.

Xenobiotica, 1985

[1-14C]Butyl glycidyl ether administered orally to male rats and rabbits (20 mg/kg) is rapidly ab... more [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.

SAR and QSAR in Environmental Research, 2014

To comply with the REACH (Registration, Evaluation, Authorisation and restriction of Chemicals) r... more 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.

Pure and Applied Chemistry, 2000

Pesticide Science, 1995

ABSTRACT The long-term fate of the acaricide, fenbutatin oxide, in soil has been investigated. Re... more ABSTRACT The long-term fate of the acaricide, fenbutatin oxide, in soil has been investigated. Residues of the compound and its two principal metabolites have been determined in soil samples obtained from citrus orchards in Italy and Spain where the product had been applied commercially over a period of 6–10 years.The average fenbutatin oxide content in the upper 0–15 cm soil layer ranged from ⩽ 1 mg kg−1 to 5 mg kg−1 in sites receiving single and double applications per year. The residues were located primarily (> 95%) in the top 0–30 cm layer and there was virtually no movement of the compound through the soil to lower depths. Below 0.5 m depths, the sites contained average concentrations of ⩽ 0.01 mg kg−1, the limit of determination. No significant build-up of residues was observed and the data indicate an approximate half-life in soil of just less than one year.Residues of the two metabolites, dihydroxy-bis(2-methyl-2-phenylpropyl)stan-nane and 2-methyl-2-phenylpropyl stannonic acid, were on average 11% and 16% of the fenbutatin oxide concentration, respectively. As with fenbutatin oxide, there was no significant movement through the soil to lower levels.