Milled cereal straw accelerates earthworm (Lumbricus terrestris) growth more than selected organic amendments.

Earthworms benefit agriculture by providing several ecosystem services. Therefore, strategies to increase earthworm abundance and activity in agricultural soils should be identified, and encouraged. Lumbricus terrestris earthworms primarily feed on organic inputs to soils but it is not known which organic amendments are the most effective for increasing earthworm populations. We conducted earthworm surveys in the field and carried out experiments in single-earthworm microcosms to determine the optimum food source for increasing earthworm biomass using a selection of crop residues and organic wastes available to agriculture. We found that although farmyard manure increased earthworm populations more than cereal straw in the field, straw increased earthworm biomass more than manures when milled and applied to microcosms. Earthworm growth rates were positively correlated with the calorific value of the amendment and straw had a much higher calorific value than farmyard manure, greenwaste compost, or anaerobic digestate. Reducing the particle size of straw by milling to <3 mm made the energy in the straw more accessible to earthworms. The benefits and barriers to applying milled straw to arable soils in the field are discussed.

Unveiling the diversification dynamics of Australasian predaceous diving beetles in the Cenozoic.

During the Cenozoic, Australia experienced major climatic shifts that have had dramatic ecological consequences for the modern biota. Mesic tropical ecosystems were progressively restricted to the coasts and replaced by arid-adapted floral and faunal communities. Whilst the role of aridification has been investigated in a wide range of terrestrial lineages, the response of freshwater clades remains poorly investigated. To gain insights into the diversification processes underlying a freshwater radiation, we studied the evolutionary history of the Australasian predaceous diving beetles of the tribe Hydroporini (147 described species). We used an integrative approach including the latest methods in phylogenetics, divergence time estimation, ancestral character state reconstruction, and likelihood-based methods of diversification rate estimation. Phylogenies and dating analyses were reconstructed with molecular data from seven genes (mitochondrial and nuclear) for 117 species (plus 12 outgroups). Robust and well-resolved phylogenies indicate a late Oligocene origin of Australasian Hydroporini. Biogeographic analyses suggest an origin in the East Coast region of Australia, and a dynamic biogeographic scenario implying dispersal events. The group successfully colonized the tropical coastal regions carved by a rampant desertification, and also colonized groundwater ecosystems in Central Australia. Diversification rate analyses suggest that the ongoing aridification of Australia initiated in the Miocene contributed to a major wave of extinctions since the late Pliocene probably attributable to an increasing aridity, range contractions and seasonally disruptions resulting from Quaternary climatic changes. When comparing subterranean and epigean genera, our results show that contrasting mechanisms drove their diversification and therefore current diversity pattern. The Australasian Hydroporini radiation reflects a combination of processes that promoted both diversification, resulting from new ecological opportunities driven by initial aridification, and a subsequent loss of mesic adapted diversity due to increasing aridity.

Notes on the Australian Anacaenini (Coleoptera: Hydrophilidae): description of male of Phelea breviceps Hansen and unravelling the identity of Crenitis neogallica Gentili.

The holotype and additional specimens of the Tasmanian endemic Phelea breviceps Hansen, 1999, and the holotype of Crenitis neogallica Gentili, 1996 were examined in order to explore their generic and tribal placement. The morphology of Phelea is illustrated in detail, its male genitalia are described for the first time, and it is confirmed as a member of Anacaenini, sharing numerous characters with Crenitis Bedel, 1881 and the New Zealand endemic Horelophus walkeri Orchymont, 1913. Crenitis neogallica is removed from Anacaenini and transferred to the rygmodine genus Pseudohydrobius Blackburn, 1898 (as Pseudohydrobius neogallicus (Gentili, 1996) comb. nov.) and its holotype is illustrated. The genus Crenitis is hence removed from the Australian fauna.

An outlook on larval morphology of Copelatinae diving beetles with phylogenetic considerations (Coleoptera: Adephaga, Dytiscidae).

The larvae of 12 species of Copelatinae, Copelatus alternatus Sharp, 1882, C. caelatipennis princeps Young, 1963, C. glyphicus (Say, 1823), C. japonicus Sharp, 1884, C. masculinus Rgimbart, 1899, C. nakamurai Guorguiev, 1970, C. oblitus Sharp, 1882, C. parallelus Zimmermann, 1920, C. tenebrosus Rgimbart, 1880, Exocelina australiae (Clark, 1863), E. ferruginea (Sharp, 1882), and Liopterus haemorrhoidalis (Fabricius, 1787) are described or redescribed, including for the first time a detailed chaetotaxy analysis of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. A provisional parsimony analysis based on larval characteristics of 13 copelatine species was conducted using the program TNT, which reinforces the monophyletic origin of the Copelatinae. Copelatinae larvae stand out from the remaining Dytiscidae based on several synapomorphies, including the unusual shorter length of the mesothoracic legs. Legs and urogomphi morphology suggest that Copelatinae larvae studied evolved a creeping way of life. The provisional phylogenetic analysis presented in this study provides some arguments for the validity of the taxonomic status of the genera Liopterus Dejean, 1833 and Exocelina Broun, 1886.

Applying skills and knowledge: Principle Of Nursing Practice F.

This is the seventh article in a nine-part series describing the Principles of Nursing Practice developed by the Royal College of Nursing (RCN) in collaboration with patient and service organisations, the Department of Health, the Nursing and Midwifery Council, nurses and other healthcare professionals. The article discusses Principle F, the application of skills and knowledge to person-centred nursing care.

Principles of nursing practice: development and implementation.

This article, the first in a nine-part series, describes the development of the recent Principles of Nursing Practice initiative. It provides an overview of the Principles, the objectives that informed them and the challenges experienced in their development.

Intermediate to long term results of stemless metaphyseal reverse shoulder arthroplasty: A five to nine year follow-up.

BACKGROUND: Shoulder arthroplasty incidence is increasing as is the volume of revision surgeries. Revision surgery is easier if humeral bone stock is preserved with minimal bone defects and osteolysis. This has led to an increased focus on the development of various short stemmed and stemless implants which provides stable fixation whilst preserving humeral bone stock. PURPOSE: To review the medium to long term clinical and radiological outcomes, complications and survival rates of a stemless reverse shoulder prosthesis. PATIENTS AND METHOD: Patients with a minimum follow-up of 60 months following a reverse stemless shoulder arthroplasty were deemed eligible. Clinical and radiological data on twenty-one patients operated between 2009 and 2014 were recorded prospectively. Survivorship and patient recorded symptoms with the end point of revision surgery were recorded. RESULTS: Mean follow-up of 78 months (60-114 months). Mean range of active elevation was 136° (80-170°). Mean range of active abduction and active external rotation was 122° (70-170°) and 47° (10-75°) respectively. Mean Oxford score improved from 12 pre-operatively to 44 at final follow up (p < 0.0001). Mean Constant Murley Score improved from 18 to 72 (p < 0.0001). Mean ADLEIR score of 13 pre-operatively increased to 32 post-operatively (p < 0.0001). Notching was seen in 23.5% of cases and no radiolucent areas were observed around the glenoid component. There were two cases of post traumatic peri-prosthetic fractures that were managed conservatively and one case of deep-seated infection that required a washout. The survivorship at the most recent follow-up was 100%. CONCLUSION: The advantages of bone preservation with the stemless metaphyseal prosthesis combined with encouraging medium to long term clinical and radiological results are very promising, particularly with the improved post-operative patient satisfaction scores. This is the first study that reports the results with a minimum of 5 year follow-up and has the longest mean follow-up period. CLINICAL RELEVANCE: The reverse stemless shoulder prosthesis is an effective and reliable option for elective shoulder arthroplasty.

Root water potential integrates discrete soil physical properties to influence ABA signalling during partial rootzone drying.

To investigate the influence of different growing substrates (two mineral, two organic) on root xylem ABA concentration ([ABA](root)) and the contribution of the drying root system to total sap flow during partial rootzone drying (PRD), sunflower (Helianthus annuus L.) shoots were grafted onto the root systems of two plants grown in separate pots. Sap flow through each hypocotyl was measured below the graft union when one pot ('wet') was watered and other ('dry') was not. Each substrate gave unique relationships between dry pot matric potential (Psi(soil)), volumetric water content ((v)) or penetrometer resistance (Q) and either the fraction of photoperiod sap flow from roots in drying soil or [ABA](root). However, decreased relative sap flow, and increased [ABA](root), from roots in drying soil varied with root water potential (Psi(root)) more similarly across a range of substrates. The gradient between Psi(soil) and Psi(root) was greater in substrates with high sand or peat proportions, which may have contributed to a more sensitive response of [ABA](root) to Psi(soil) in these substrates. Whole plant transpiration was most closely correlated with the mean Psi(soil) of both pots, and then with detached leaf xylem ABA concentration. Although Psi(root) best predicted decreased relative sap flow, and increased [ABA](root), from roots in drying soil across a range of substrates, the inaccessibility of this variable in field studies requires a better understanding of how measurable soil variables (Psi(soil), (v), Q) affect Psi(root).

The "minute diving beetles" of southern Australia - taxonomic revision of Gibbidessus Watts, 1978, with description of six new species (Coleoptera, Dytiscidae, Bidessini).

Morphology and mitochondrial DNA sequence data are used to reassess the taxonomy of Australian diving beetles previously assigned to the genera Uvarus Guignot, 1939 and Gibbidessus Watts, 1978. Gibbidessus was described as a monotypic genus for Gibbidessus chipi Watts, 1978. The genus is significantly extended here. Based on molecular systematic evidence, Uvarus pictipes (Lea, 1899) is transferred to Gibbidessus. Gibbidessus chipi and Gibbidessus pictipes comb. nov. are redescribed, and six new species are described: Gibbiddessus atomus sp. nov. (SW Australia, Northcliffe area) [the smallest epigean diving beetle in Australia], G. davidi sp. nov. (SW Australia), G. drikdrikensis sp. nov. (Victoria), G. kangarooensis sp. nov. (SA Kangaroo Island), G. pederzanii sp. nov. (SW Australia, Nannup area), and G. rottnestensis sp. nov. (SW Australia). Species are delineated using characters such as male genital structure and beetle size, shape and colour pattern. Mitochondrial Cox1 data for 27 individuals, representing five species, were generated, and revealed clusters congruent with the morphological evidence. Gibbidessus occur in southern Australia, with the centre of diversification in the isolated peat- and wetlands of SW Australia. All species occur in very shallow water of seasonal, exposed or half-shaded wetlands and flooded meadows.

Dealing with a hairy beast-larval morphology and chaetotaxy of the Australian endemic diving beetle genus Spencerhydrus (Coleoptera, Dytiscidae, Cybistrini).

In this contribution, the larval morphology of Spencerhydrus Sharp, 1882 was studied, an Australian endemic genus in the diving beetle tribe Cybistrini. All instars of the only two species included in the genus (S. latecinctus Sharp, 1882 and S. pulchellus Sharp, 1882) are described and illustrated with the exception of the third instar of S. latecinctus. Detailed morphometric and primary chaetotaxic analyses were performed to discover useful characters for generic diagnosis and species distinction. Spencerhydrus can be distinguished from other Cybistrini genera by the medial projection of frontoclypeus slightly indented apically, with lamellae clypeales directed forward in a characteristic V-shaped pattern, the median process of prementum strongly developed, the presence of a single ventral sclerite on prothorax, the presence of basoventral spinulae on claws, and the reduced sclerotization of the abdominal segment VII which covers only the anterior half. Larvae of the two species of Spencerhydrus can readily be distinguished by the shape of the median process of prementum, which is visibly broader in S. pulchellus than in S. latecinctus.

Meeting report: risk assessment of tamiflu use under pandemic conditions.

On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps, the consensus was that oseltamivir ethylester-phosphate (OE-P) and oseltamivir carboxylate (OC) were unlikely to pose an ecotoxicologic hazard to freshwater organisms. OC in river water might hasten the generation of OC-resistance in wildfowl, but this possibility seems less likely than the potential disruption that could be posed by OC and other pharmaceuticals to the operation of sewage treatment plants. The work-group members agreed on the following research priorities: a) available data on the ecotoxicology of OE-P and OC should be published; b) risk should be assessed for OC-contaminated river water generating OC-resistant viruses in wildfowl; c) sewage treatment plant functioning due to microbial inhibition by neuraminidase inhibitors and other antimicrobials used during a pandemic should be investigated; and d) realistic worst-case exposure scenarios should be developed. Additional modeling would be useful to identify localized areas within river catchments that might be prone to high pharmaceutical concentrations in sewage treatment plant effluent. Ongoing seasonal use of Tamiflu in Japan offers opportunities for researchers to assess how much OC enters and persists in the aquatic environment.

Stakeholder involvement in systematic reviews: a scoping review.

BACKGROUND: There is increasing recognition that it is good practice to involve stakeholders (meaning patients, the public, health professionals and others) in systematic reviews, but limited evidence about how best to do this. We aimed to document the evidence-base relating to stakeholder involvement in systematic reviews and to use this evidence to describe how stakeholders have been involved in systematic reviews. METHODS: We carried out a scoping review, following a published protocol. We searched multiple electronic databases (2010-2016), using a stepwise searching approach, supplemented with hand searching. Two authors independently screened and discussed the first 500 abstracts and, after clarifying selection criteria, screened a further 500. Agreement on screening decisions was 97%, so screening was done by one reviewer only. Pre-planned data extraction was completed, and the comprehensiveness of the description of methods of involvement judged. Additional data extraction was completed for papers judged to have most comprehensive descriptions. Three stakeholder representatives were co-authors for this systematic review. RESULTS: We included 291 papers in which stakeholders were involved in a systematic review. Thirty percent involved patients and/or carers. Thirty-two percent were from the USA, 26% from the UK and 10% from Canada. Ten percent (32 reviews) were judged to provide a comprehensive description of methods of involving stakeholders. Sixty-nine percent (22/32) personally invited people to be involved; 22% (7/32) advertised opportunities to the general population. Eighty-one percent (26/32) had between 1 and 20 face-to-face meetings, with 83% of these holding ≤ 4 meetings. Meetings lasted 1 h to ½ day. Nineteen percent (6/32) used a Delphi method, most often involving three electronic rounds. Details of ethical approval were reported by 10/32. Expenses were reported to be paid to people involved in 8/32 systematic reviews. DISCUSSION/CONCLUSION: We identified a relatively large number (291) of papers reporting stakeholder involvement in systematic reviews, but the quality of reporting was generally very poor. Information from a subset of papers judged to provide the best descriptions of stakeholder involvement in systematic reviews provide examples of different ways in which stakeholders have been involved in systematic reviews. These examples arguably currently provide the best available information to inform and guide decisions around the planning of stakeholder involvement within future systematic reviews. This evidence has been used to develop online learning resources. SYSTEMATIC REVIEW REGISTRATION: The protocol for this systematic review was published on 21 April 2017. Publication reference: Pollock A, Campbell P, Struthers C, Synnot A, Nunn J, Hill S, Goodare H, Watts C, Morley R: Stakeholder involvement in systematic reviews: a protocol for a systematic review of methods, outcomes and effects. Research Involvement and Engagement 2017, 3:9. https://doi.org/10.1186/s40900-017-0060-4 .

Review of Australian Scirtes Illiger, Ora Clark and Exochomoscirtes Pic Coleoptera: Scirtidae) including descriptions of new species, new groups and a multi-gene molecular phylogeny of Australian and non-Australian species.

The phylogenetic relationships of 26 Australian species of Scirtes Illiger, Ora Clark and Exochomoscirtes Pic (Scirtidae) were investigated using adult morphology, particularly male and female genitalia, larval morphology and molecular data from the mitochondrial cytochrome c oxidase subunit I (COI) gene and the nuclear genes elongation factor 1-alpha (EF1- a) and topoisomerase I (TOP1). Four species of Scirtes and one of Ora from Europe, Southeast Asia and Japan were included. The genus Scirtes is shown to be paraphyletic with respect to the genera Ora and Exochomoscirtes. Australian Scirtes were shown to belong to four species groups: Scirtes elegans group (Yoshitomi 2009); S. helmsi group (Watts 2004); S. japonicus group (Nyholm 2002); and S. haemisphaericus group (Yoshitomi 2005). The prehensor and bursal sclerite of 15 species are illustrated as well as habitus illustrations of S. zwicki sp. nov. and S. albamaculatus Watts. Three new species from Australia are described: Scirtes lynnae, S. zwicki and S. serratus spp. nov. Scirtes nehouensis Ruta & Yoshitomi 2010 is synonymised with S. emmaae Watts 2004. Scirtes pygmaeus Watts, 2004 is synonymised with S. pinjarraensis Watts, 2006. Scirtes rutai nom. nov. is proposed as a replacement name for S. beccus Ruta, Kialka & Yoshitomi, 2014 from Sabah as it is preoccupied by S. beccus Watts, 2004 from Australia.

Stakeholder involvement in systematic reviews: a protocol for a systematic review of methods, outcomes and effects.

PLAIN ENGLISH SUMMARY: Researchers are expected to actively involve stakeholders (including patients, the public, health professionals, and others) in their research. Although researchers increasingly recognise that this is good practice, there is limited practical guidance about how to involve stakeholders. Systematic reviews are a research method in which international literature is brought together, using carefully designed and rigorous methods to answer a specified question about healthcare. We want to investigate how researchers have involved stakeholders in systematic reviews, and how involvement has potentially affected the quality and impact of reviews. We plan to bring this information together by searching and reviewing the literature for reports of stakeholder involvement in systematic reviews. This paper describes in detail the methods that we plan to use to do this. After carrying out comprehensive searches for literature, we will: 1. Provide an overview of identified reports, describing key information such as types of stakeholders involved, and how. 2. Pick out reports of involvement which include detailed descriptions of how researchers involved people in a systematic review and summarise the methods they used. We will consider who was involved, how people were recruited, and how the involvement was organised and managed. 3. Bring together any reports which have explored the effect, or impact, of involving stakeholders in a systematic review. We will assess the quality of these reports, and summarise their findings. Once completed, our review will be used to produce training resources aimed at helping researchers to improve ways of involving stakeholders in systematic reviews. ABSTRACT: Background There is an expectation for stakeholders (including patients, the public, health professionals, and others) to be involved in research. Researchers are increasingly recognising that it is good practice to involve stakeholders in systematic reviews. There is currently a lack of evidence about (A) how to do this and (B) the effects, or impact, of such involvement. We aim to create a map of the evidence relating to stakeholder involvement in systematic reviews, and use this evidence to address the two points above. Methods We will complete a mixed-method synthesis of the evidence, first completing a scoping review to create a broad map of evidence relating to stakeholder involvement in systematic reviews, and secondly completing two contingent syntheses. We will use a stepwise approach to searching; the initial step will include comprehensive searches of electronic databases, including CENTRAL, AMED, Embase, Medline, Cinahl and other databases, supplemented with pre-defined hand-searching and contacting authors. Two reviewers will undertake each review task (i.e., screening, data extraction) using standard systematic review processes. For the scoping review, we will include any paper, regardless of publication status or study design, which investigates, reports or discusses involvement in a systematic review. Included papers will be summarised within structured tables. Criteria for judging the focus and comprehensiveness of the description of methods of involvement will be applied, informing which papers are included within the two contingent syntheses. Synthesis A will detail the methods that have been used to involve stakeholders in systematic reviews. Papers from the scoping review that are judged to provide an adequate description of methods or approaches will be included. Details of the methods of involvement will be extracted from included papers using pre-defined headings, presented in tables and described narratively. Synthesis B will include studies that explore the effect of stakeholder involvement on the quality, relevance or impact of a systematic review, as identified from the scoping review. Study quality will be appraised, data extracted and synthesised within tables. Discussion This review should help researchers select, improve and evaluate methods of involving stakeholders in systematic reviews. Review findings will contribute to Cochrane training resources.

Chronic aquatic environmental risks from exposure to human pharmaceuticals.

This paper reviews current information on the chronic aquatic toxicity of human pharmaceuticals and how it should be measured. Chronic toxicity tests with Cyanobacteria are likely to be sensitive surrogates for both algae and other unicellular organisms, although possibly not for higher plants. In contrast, there is little evidence of a general need to perform chronic aquatic invertebrate tests for all human pharmaceuticals, although further acute-to-chronic ratio data are required for the main therapeutic classes and modes of action of pharmaceuticals before this issue can be fully resolved. Chronic fish tests may be necessary for some substances, but it is likely that these can be focused more accurately through use of information in mammalian toxicity datasets. For some substances and modes of action, life-cycle or partial life-cycle fish tests may be more relevant than reliance on early life-stage (ELS) tests, because the ELS test is unlikely to respond adequately to all pharmaceutical modes of action. Biomarkers may be useful in focusing research and testing efforts by identifying active substances and receptors of interest in aquatic species, and they may also be useful in field surveys for helping to establish possible cause and effect relationships. QSARs have been used by several authors to predict acute toxic effects, but predictions of chronic effects are currently hampered by the paucity of available chronic data to build predictive models. There seems to be no obvious reason why mixtures of pharmaceuticals in the environment should be treated in a different way to mixtures of other potentially hazardous substances. If mixture toxicity is considered to be an important environmental issue then all substances should be considered within an appropriate risk assessment framework.

Description of a new Tiporus Watts, 1985 from northern Queensland, Australia (Coleoptera: Dytiscidae, Hydroporinae).

Tiporus queenslandicus sp. n. is described from NE Queensland. The new species is similar to T. undecimmaculatus (Clark, 1862) and T. giuliani (Watts, 1978) from the Northern Territory and north-western Australia but well characterized by its larger size, more elongate habitus, and form of median lobe and parameres. Tiporus queenslandicus sp. n. is a lotic species being collected from rest pools of intermittent creeks and rivers with a sandy bottom. Important species-defining characters (habitus, median lobe, paramere, protibia of male) are illustrated. Together with T. queenslandicus sp. n. the genus comprises now 13 species.

Evolution of subterranean diving beetles (Coleoptera: Dytiscidae: Hydroporini, Bidessini) in the arid zone of Australia.

Calcrete aquifers in arid inland Australia have recently been found to contain the world's most diverse assemblage of subterranean diving beetles (Coleoptera: Dytiscidae). In this study we test whether the adaptive shift hypothesis (ASH) or the climatic relict hypothesis (CRH) is the most likely mode of evolution for the Australian subterranean diving beetles by using a phylogeny based on two sequenced fragments of mitochondrial genes (CO1 and 16S-tRNA-ND1) and linearized using a relaxed molecular clock method. Most individual calcrete aquifers contain an assemblage of diving beetle species of distantly related lineages and/or a single pair of sister species that significantly differ in size and morphology. Evolutionary transitions from surface to subterranean life took place in a relatively small time frame between nine and four million years ago. Most of the variation in divergence times of the sympatric sister species is explained by the variation in latitude of the localities, which correlates with the onset of aridity from the north to the south and with an aridity maximum in the Early Pliocene (five mya). We conclude that individual calcrete aquifers were colonized by several distantly related diving beetle lineages. Several lines of evidence from molecular clock analyses support the CRH, indicating that all evolutionary transitions took place during the Late Miocene and Early Pliocene as a result of aridification.

Quantitative structure-activity relationships for predicting potential ecological hazard of organic chemicals for use in regulatory risk assessments.

The use of quantitative structure-activity relationships (QSARs) for deriving the predicted no-effect concentration of discrete organic chemicals for the purposes of conducting a regulatory risk assessment in Europe and the United States is described. In the United States, under the Toxic Substances Control Act (TSCA), the TSCA Interagency Testing Committee and the U.S. Environmental Protection Agency (U.S. EPA) use SARs to estimate the hazards of existing and new chemicals. Within the Existing Substances Regulation in Europe, QSARs may be used for data evaluation, test strategy indications, and the identification and filling of data gaps. To illustrate where and when QSARs may be useful and when their use is more problematic, an example, methyl tertiary-butyl ether (MTBE), is given and the predicted and experimental data are compared. Improvements needed for new QSARs and tools for developing and using QSARs are discussed.

Evaluation of probabilistic risk assessment of pesticides in the UK: chlorpyrifos use on top fruit.

The use of probabilistic risk assessment (PRA) for examining chemical impacts has become an important area of debate within the European Union. This paper describes a case study on probabilistic techniques to assess pesticide risks in the UK aquatic environment. The main aim of this paper is to demonstrate both the potential strengths and weaknesses of PRA for assessing pesticides when compared with the conventional deterministic approach, and to examine whether PRA is useful within the European regulatory context. The organophosphate insecticide, chlorpyrifos, was selected as a model compound and toxicity exposure ratios calculated using Monte Carlo analysis and different distributions of spray drift and toxicity values following application to top fruit. Chlorpyrifos is highly toxic to arthropods but less toxic to fishes. Species sensitivity followed a log-normal distribution when fitted to all toxicity data. Toxicity data quantity had little influence on species sensitivity distribution model parameters when n was greater than 10 species. Below this, estimates were less accurate and precise, possibly because of the inclusion of data from many different sources. Estimates of chlorpyrifos exposure derived from the standard spray drift model differed substantially from measurements of chlorpyrifos in European surface waters. When a distribution based on measured concentrations was used in a PRA, the risk of acute fish mortality was low, and the risk of acute arthropod mortality was lower than in other scenarios, although not negligible. If PRA is used to assess pesticides, risk managers need further guidance on how to conduct a PRA and what constitutes 'unacceptable risk' under EC Directive 91/414/EEC, as judgement is required when simple trigger values are no longer used.