Exploiting monitoring data in environmental exposure modelling and risk assessment of pharmaceuticals.

In order to establish the environmental impact of an active pharmaceutical ingredient (API), good information on the level of exposure in surface waters is needed. Exposure concentrations are typically estimated using information on the usage of an API as well as removal rates in the patient, the wastewater system and in surface waters. These input data are often highly variable and difficult to obtain, so model estimates often do not agree with measurements made in the field. In this paper we present an approach which uses inverse modelling to estimate overall removal rates of pharmaceuticals at the catchment scale using a hydrological model as well as prescription and monitoring data for a few representative sites for a country or region. These overall removal rates are then used to model exposure across the broader landscape. Evaluation of this approach for APIs in surface waters across England and Wales showed good agreement between modelled exposure distributions and available monitoring data. The use of the approach, alongside estimates of predicted no-effect concentrations for the 12 study compounds, to assess risk of the APIs across the UK landscape, indicated that, for most of the compounds, risks to aquatic life were low. However, ibuprofen was predicted to pose an unacceptable risk in 49.5% of the river reaches studied. For diclofenac, predicted exposure concentrations were also compared to the Environmental Quality Standard previously proposed by the European Commission and 4.5% of river reaches were predicted to exceed this concentration. While the current study focused on pharmaceuticals, the approach could also be valuable in assessing the risks of other 'down the drain' chemicals and could help inform our understanding of the important dissipation processes for pharmaceuticals in the pathway from the patient to ecological receptors.

Prevalence of sulfonamide resistance genes in bacterial isolates from manured agricultural soils and pig slurry in the United Kingdom.

The prevalences of three sulfonamide resistance genes, sul1, sul2, and sul3 and sulfachloropyridazine (SCP) resistance were determined in bacteria isolated from manured agricultural clay soils and slurry samples in the United Kingdom over a 2-year period. Slurry from tylosin-fed pigs amended with SCP and oxytetracycline was used for manuring. Isolates positive for sul genes were further screened for the presence of class 1 and 2 integrons. Phenotypic resistance to SCP was significantly higher in isolates from pig slurry and postapplication soil than in those from preapplication soil. Of 531 isolates, 23% carried sul1, 18% sul2, and 9% sul3 only. Two percent of isolates contained all three sul genes. Class 1 and class 2 integrons were identified in 5% and 11.7%, respectively, of sul-positive isolates. In previous reports, sul1 was linked to class 1 integrons, but in this study only 8% of sul1-positive isolates carried the intI1 gene. Sulfonamide-resistant pathogens, including Shigella flexneri, Aerococcus spp., and Acinetobacter baumannii, were identified in slurry-amended soil and soil leachate, suggesting a potential environmental reservoir. Sulfonamide resistance in Psychrobacter, Enterococcus, and Bacillus spp. is reported for the first time, and this study also provides the first description of the genotypes sul1, sul2, and sul3 outside the Enterobacteriaceae and in the soil environment.

Manufacture and use of nanomaterials: current status in the UK and global trends.

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.

Veterinary medicines in the environment.

The impact of veterinary medicines on the environment will depend on a number of factors including physicochemical properties, amount used and method of administration, treatment type and dose, animal husbandry practices, manure storage and handling practices, metabolism within the animal, and degradation rates in manure and slurry. Once released to the environment, other factors such as soil type, climate, and ecotoxicity also determine the environmental impact of the compound. The importance of individual routes into the environment for different types of veterinary medicines varies according to the type of treatment and livestock category. Treatments used in aquaculture have a high potential to reach the aquatic environment. The main routes of entry to the terrestrial environment are from the use of veterinary medicines in intensively reared livestock, via the application of slurry and manure to land, and by the use of veterinary medicines in pasture-reared animals where pharmaceutical residues are excreted directly into the environment. Veterinary medicines applied to land via spreading of slurry may also enter the aquatic environment indirectly via surface runoff or leaching to groundwater. It is likely that topical treatments have greater potential to be released to the environment than treatments administered orally or by injection. Inputs from the manufacturing process, companion animal treatments, and disposal are likely to be minimal in comparison. Monitoring studies demonstrate that veterinary medicines do enter the environment, with sheep dip chemicals, antibiotics, sealice treatments, and anthelmintics being measured in soils, groundwater, surface waters, sediment, or biota. Maximum concentrations vary across chemical classes, with very high concentrations being reported for the sheep dip chemicals. The degree to which veterinary medicines may adsorb to particulates varies widely. Partition coefficients (K(d)) range from low (0.61 L kg(-1)) to high (6000 L kg(-1)). The variation in partitioning for many of the compounds in different soils was significant (up to a factor of 30), but these differences could be not be explained by normalization to the organic carbon content of the soils. Thus, to arrive at a realistic assessment of the availability of veterinary medicines for transport through the soil and uptake into soil organisms, the K(oc) (which is used in many of the exposure models) may not be an appropriate measure. Transport of particle-associated substances from soil to surface waters has also been demonstrated. Veterinary medicines can persist in soils for days to years, and half-lives are influenced by a range of factors including temperature, pH, and the presence of manure. The persistence of major groups of veterinary medicines in soil, manure, slurry, and water varies across and within classes. Ecotoxicity data were available for a wide range of veterinary medicines. The acute and chronic effects of avermectins and sheep dip chemicals on aquatic organisms are well documented, and these substances are known to be toxic to many organisms at low concentrations (ng L(-1) to microg L(-1)). Concerns have also been raised about the possibility of indirect effects of these substances on predatory species (e.g., birds and bats). Data for other groups indicate that toxicity values are generally in the mg L(-1) range. For the antibiotics, toxicity is greater for certain species of algae and marine bacteria. Generally, toxicity values for antibacterial agents were significantly higher than reported environmental concentrations. However, because of a lack of appropriate toxicity data, it is difficult to assess the environmental significance of these observations with regard to subtle long-term effects.

Survey of four marine antifoulant constituents (copper, zinc, diuron and Irgarol 1051) in two UK estuaries.

A field survey of antifoulant concentrations was undertaken in two UK estuaries (Hamble and Orwell) in 1998 and 1999. The two locations offered variations in physical aspects (Orwell estuary being significantly larger than the Hamble) as well as differences in boat densities (Hamble having almost twice as many vessels moored in the estuary and marinas). Samples were analysed for copper, zinc, diuron and Irgarol 1051, and were collected in summer and winter in order to identify potential seasonal variations in concentrations. The effect that different marina types (e.g. locked marina, one located in a natural inlet and pontooned ones in the open estuary) had on antifoulant concentrations were also investigated. Concentrations of the organic booster biocides, diuron and Irgarol 1051 in the marinas and estuaries were mainly influenced by leaching from antifoulant paints applied to the hulls of leisure craft, and so levels reflected the number of vessels present in the water. As a consequence significantly higher concentrations were found in marinas (up to ca. 900 ng l(-1) for diuron and 240 ng l(-1) for Irgarol 1051) compared with estuaries (up to ca. 400 ng l(-1) for diuron and 100 ng l(-1) for Irgarol 1051) and in summer compared with winter. Sediment concentrations of Irgarol 1051 and diuron were rarely detectable other than in the marinas where high concentrations were detected near slipways assumed to be derived from washed off paint chips. Dissolved concentration profiles for copper and zinc in the estuaries and marinas were different from those for the organic booster biocides partly because other sources of these metals contributed to estuarine and marina loads. In particular, riverine loads and inputs from sacrificial anodes attached to leisure craft, exhibited a major influence of estuarine levels of zinc. Consequently, only in the Hamble estuary for copper was there a clear distinction between summer (typically 3-4 microg l(-1)) and winter dissolved values (typically 1-2 microg l(-1)) that could be largely attributable to the leaching of antifoulant paints. Sediment concentrations for both metals were similar for both estuaries, with little variation between winter and summer values (Zn ranging from 28 to 614 mg kg(-1) and Cu from 6 to 1016 mg kg(-1)) as with the organic booster biocides highest levels were measured at the base of slipways in marinas.

Partitioning of marine antifoulants in the marine environment.

The partitioning behaviour of the organic biocides, Irgarol 1051 and diuron and two inorganic biocides (copper and zinc) was investigated using six sediments of differing physico-chemical properties collected from unimpacted sites along the south coast of England. The kinetics of sorption and equilibrium partitioning between the sediments and seawater were investigated over a period of 20 days. Resulting organic carbon/water partition coefficients (log Koc) were related to suspended sediment concentration and ranged from 2.28 to 5.20 for diuron; and from 2.41 to 4.89 for Irgarol 1051. Sediment/water partition coefficients (log Kp) for copper and zinc varied from 2.46 to 5.08 l/kg and from 2.49 to 4.97 l/kg, respectively. Kinetic data indicated that there were significant interactions between the dissolved and particulate phases at the start of the experiments, just after mixing. This is thought to be a result of redistribution of organic carbon between the two phases.