Andrew M. Fogarty

Silver nanoparticles in the environment: Sources, detection and ecotoxicology

The environmental impact of silver nanoparticles (AgNP) has become a topic of interest recently, this is due to the fact that AgNPs have been included in numerous consumer products including textiles, medical products, domestic appliances, food containers, cosmetics, paints and nano-functionalised plastics. The production, use and disposal of these AgNP containing products are potential routes for environmental exposure. These concerns have led to a number of studies investigating the release of particles from nano-functionalised products, the detection of the particles in the aquatic environment and the potential environmental toxicology of these AgNPs to aquatic organisms. The overall aim of this review is to examine methods for the capture and detection of AgNPs, potential toxicity and transmission routes in the aquatic environment.

Accelerated solvent-based extraction and enrichment of selected plasticisers and 4-nonylphenol, and extraction of tin from organotin sources in sediments, sludges and leachate soils.

Enrichment techniques have become an important feature in the trace analysis of oestrogen mimicking chemicals in the environment. Recent developments such as accelerated solvent extraction (ASE) have improved extraction recoveries in a wide variety of solid matrices including sediments, sludges and leachate soils. Such samples taken from the Irish Midlands Shannon Catchment region during the winter of 2004/5 and suspected to contain certain xenooestrogens or hormonally active agents were extracted using this technique, which was then coupled with high performance liquid chromatography (HPLC) for quantification purposes. ASE was thus employed to both isolate and pre-concentrate targeted analytes using the minimum amount of solvent hence making extractions more conservational. Two simple, yet extremely sensitive liquid chromatographic methods were developed based on UV detection; one for phthalates and one for alkylphenols, with recoveries reaching up to 92.0%. Acid digestion was used for the extraction of the tin and organotin compounds with analysis by polarography. In river sediment, levels of up to 24.4 mg kg(-1) phthalate, 1.14 mg kg(-1) 4-nonylphenol and 118 mg kg(-1) tin were found. In leachate sediments, values up to 49.8 mg kg(-1) phthalate, 1.57 mg kg(-1) 4-nonylphenol, and 36.0 mg kg(-1) tin were determined. In sludge, values up to 174 mg kg(-1) phthalate and 22.8 mg kg(-1) 4-nonylphenol were quantified. The highest value of tin (118 mg kg(-1)) was found present in an area of high leisure craft activity. Typical sediment levels of tin at other river locations ranged between 1.20 and 37.5 mg kg(-1).

An investigation into possible sources of phthalate contamination in the environmental analytical laboratory

A study of common laboratory equipment and components was performed in order to identify sources of contamination of phthalates prior to testing environmental samples for such compounds. A screening study revealed significant leaching from laboratory consumables, such as plastic syringes, pipette tips released maximum leachings of 0.36 µg cm−2 diethylhexyl phthalate (DEHP) and 0.86 µg cm−2 diisononyl phthalate (DINP), plastic filter holders produced maximum leachings of 2.49 µg cm−2 dibutyl phthalate (DBP) from polytetrafluoroethylene (PTFE); specifically 0.61 µg cm−2 DBP from regenerated cellulose and 5.85 µg cm−2 dimethyl phthalate (DMP) from cellulose acetate and Parafilm® leached levels up to 0.50 µg cm−2 DEHP. In addition, a high-temperature bake-out process was found necessary to eliminate quite high levels of two phthalates present in a commercial bulking agent for pressurized liquid extraction.

Investigation of the estrogenic risk to feral male brown trout (Salmo trutta) in the Shannon International River Basin District of Ireland.

The estrogenic potential of sewage treatment effluents and their receiving waters in the Shannon International River Basin District (SIRBD) of Ireland was investigated. An integrated approach, combining biological and chemical methods, was conducted to assess 11 rivers adjacent to sewage treatment plants (STPs) and their possible interference with the endocrine system of feral brown trout (Salmo trutta). Hepatosomatic index, gonadosomatic index, condition factor, histological (intersexuality) and endocrine (vitellogenin induction) parameters were assessed in a sample size of 10 at each location. The estrogenic burden was determined using an in vitro recombinant yeast assay containing the human estrogen receptor (YES assay). In addition, endocrine disrupting chemicals (EDCs) were quantitatively identified through a selection of pre-concentration techniques combined with chromatographic analysis at or near the selected locations. Chemical analysis of representative site samples identified phthalates and an alkylphenol in water and sediments in μg/L and mg/kg concentrations, respectively. There were no significant difference in somatic indices or the condition factor between upstream control and downstream test sites, and there was no evidence of reproductive alterations or the presence of intersex in studied male brown trout. However, raised vitellogenin (vtg) levels were detected in the blood plasma samples of male brown trout at 8 of the 11 sites. Significant levels were reported at 3 of the positive sites (p ≤ 0.05). In one particular location, vtg induction was observed in 100% of the male brown trout sampled downstream. These findings were supported by the YES assay, where estrogenic activity was detected in the same upstream and downstream sites giving 17β-estradiol equivalency factor (EEF) values of up to 2.67 ng/L. This study represents an integrated assessment approach, confirming the presence of estrogens in rivers of the SIRBD of Ireland, thus suggesting a cause-effect relationship to prolonged EDC-exposure in fish.

Isocratic LC methods for the trace analysis of phthalates and 4-nonylphenol in varying types of landfill and adjacent run-offs

To determine the levels of known endocrine disrupting chemicals such as phthalates and alkylphenols in environmental samples such as leachate water and sediment, suitable isocratic high performance liquid chromatographic (HPLC) methods utilising a narrow bore column were developed. The study was an analytical challenge in terms of developing a method, which would be sensitive enough to detect trace levels of these compounds, while still retaining the advantages of being suitable for relatively inexpensive instrumentation and featuring reasonable throughput. Generally speaking, when the internal diameter of the HPLC column is decreased by a factor of two, the signal of a sample component increases by a factor of four, the square of the change in diameter. However, combining a narrower bore column along with the isocratic method enabled us to see 20-fold increases in peak signal. The detection of these compounds was further improved by using pre-concentrating techniques known as solid-phase extraction (SPE) and accelerated solvent extraction (ASE). Limits of detection in the ng L−1 range were reached for target analytes. Maximum values (µg L−1) of 7.05 dibutyl phthalate (DBP), 7.37 diethylhexyl phthalate (DEHP), 5.56 diisononyl phthalate (DINP), 1.19 diisodecyl phthalate (DIDP) and 6.16 4-nonylphenol (NP) were found in sampled leachates, whilst maximum values (mg kg−1) of 42.3 DBP, 49.8 DEHP, 36.2 DINP, 20.0 DIDP and 1.14 NP were found in sediments. Concentrated leachate contained up to 226 µg L−1 DEHP. The highest levels of NP were found to leach from an unlined landfill, with concentrations of 10.6 µg L−1. The levels, which were quantified in the Irish midlands, are clearly linked to anthropogenic activity and were comparable to levels found in other pan-European studies.

Analysis of bio-obtainable endocrine disrupting metals in river water and sediment, sewage influent/effluent, sludge, leachate, and concentrated leachate, in the Irish Midlands Shannon Catchment.

The application of an acid digestion and subsequent solid-phase extraction (SPE) procedure were implemented as preliminary treatments prior to quantifying the levels of potentially endocrine disrupting metals (EDMs) in a variety of solid and liquid matrices. These included (solid) river sediment, leachate sediment and sewage sludge and also (liquid) river water, landfill leachate, concentrated leachate, sewage influent, and sewage effluent, sampled in the Irish Midlands. The total concentrations of cobalt (Co), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and manganese (Mn), after extraction and preconcentration, were determined by atomic absorption spectroscopy (AAS). Mercury (Hg) in sediment and sludge was determined using cold-vapour atomic fluorescence spectroscopy (AFS). For sewage sludge maximum values (mg/kgdw) of 4700 Ni, 1642 Mn, 100.0 Cd, 3400 Zn, 36.70 Co, 750.0 Pb, 485.8 Cr, and 1003 Cu were determined whilst in leachate sediment, maximum values (mg/kgdw) of 32.10 Ni, 815.0 Mn, 32.78 Cd, 230.3 Zn, 26.73 Co, 3525 Pb, 124.9 Cr, and 50.13 Cu were found. Over several months, the data showed elevated levels in sewage influents, effluents, and sludges compared to a battery of adjacent river water samples and corresponding sediments. There was a definite trend for target values for sediments to be exceeded, while intervention values were only exceeded for cadmium. Overall the pattern in terms of concentration was sewage > leachate > river matrices. A nonparametric assessment of the effect of sewage treatment method on median metal levels in sludge revealed statistically significant differences at the 95% level of confidence for Co, Cr, and Hg and at the 90% level of confidence for Cd.

Review of Catheter-Associated Urinary Tract Infections and In Vitro Urinary Tract Models

Catheter-associated urinary tract infections (CAUTIs) are one of the most common nosocomial infections and can lead to numerous medical complications from the mild catheter encrustation and bladder stones to the severe septicaemia, endotoxic shock, and pyelonephritis. Catheters are one of the most commonly used medical devices in the world and can be characterised as either indwelling (ID) or intermittent catheters (IC). The primary challenges in the use of IDs are biofilm formation and encrustation. ICs are increasingly seen as a solution to the complications caused by IDs as ICs pose no risk of biofilm formation due to their short time in the body and a lower risk of bladder stone formation. Research on IDs has focused on the use of antimicrobial and antibiofilm compounds, while research on ICs has focused on preventing bacteria entering the urinary tract or coming into contact with the catheter. There is an urgent need for in vitro urinary tract models to facilitate faster research and development for CAUTI prevention. There are currently three urinary tract models that test IDs; however, there is only a single very limited model for testing ICs. There is currently no standardised urinary tract model to test the efficacies of ICs.

A comparison of the efficacy of pulsed UV light and pulsed plasma gas-discharge systems for the novel inactivation of Cryptosporidium spp. and other clinically relevant microorganisms in drinking water

This frontier study investigated the timely development of pulsed ultraviolet light (PUV) and pulsed-plasma gas-discharge (PPGD) technologies for the destruction of harmful Cryptosporidium oocysts and other problematical microorganisms in water. This constitutes the first study to report on the use of these pulsed power electrotechnologies (PPET) for the destruction of chlorine resistant Cryptosporidium oocysts, which have caused waterborne illness outbreaks worldwide. By accumulating energy over relatively long time periods, and by dissipating this energy in ultrashort pulses, the energy remains constant thus offering a radically new approach to energy delivery that have been shown to be orders of magnitude more efficient compared to using conventional decontamination approaches. Critical inter-related factors affecting the effective and repeatable decontamination performance of PUV and PPGD were identified during this study. The PUV approach proved superior to the PPGD system for treating similar artificially spiked samples in water, which is a positive finding considering the fact that commensurate toxicological investigations carried out in this study revealed that PPGD-treated water produced unwanted toxic end-points. This innovative, technology-driven, project generated critical data that will narrow the gap between the underpinning science/engineering and operational use in future scaled-up water treatment plant studies. It will add considerably to critical data facilitating microbiological predictive modeling and will also impact positively on public health by safeguarding water quality and supplies.