Parametric estimation of P(X >Y) for normal distributions in the context of probabilistic environmental risk assessment.
Jacobs, R. ; Bekker, A.A. ; Voet, H. van der; Braak, C.J.F. ter - \ 2015
PeerJ 3 (2015). - ISSN 2167-8359
species sensitivity distributions - stress-strength model - confidence-intervals - reliability - less - inference
Estimating the risk, P(X > Y), in probabilistic environmental risk assessment of nanoparticles is a problem when confronted by potentially small risks and small sample sizes of the exposure concentration X and/or the effect concentration Y. This is illustrated in the motivating case study of aquatic risk assessment of nano-Ag. A non-parametric estimator based on data alone is not sufficient as it is limited by sample size. In this paper, we investigate the maximum gain possible when making strong parametric assumptions as opposed to making no parametric assumptions at all. We compare maximum likelihood and Bayesian estimators with the non-parametric estimator and study the influence of sample size and risk on the (interval) estimators via simulation. We found that the parametric estimators enable us to estimate and bound the risk for smaller sample sizes and small risks. Also, the Bayesian estimator outperforms the maximum likelihood estimators in terms of coverage and interval lengths and is, therefore, preferred in our motivating case study.
Acute tier-1 and tier-2 effect assessment approaches in the EFSA Aquatic Guidance Diocument: are they sufficiently protective for insecticides? : Are they sufficiently protective for insecticides?
Wijngaarden, R.P.A. van; Maltby, L. ; Brock, T.C.M. - \ 2015
Pest Management Science 71 (2015)8. - ISSN 1526-498X - p. 1059 - 1067.
species sensitivity distributions - pyrethroid insecticide - lambda-cyhalothrin - chronic toxicity - daphnia-magna - chironomus-riparius - gamma-cyhalothrin - risk-assessment - joint toxicity - chlorpyrifos
BACKGROUND The objective of this paper is to evaluate whether the acute tier-1 and tier-2 methods as proposed by the Aquatic Guidance Document recently published by the European Food Safety Authority (EFSA) are appropriate for deriving regulatory acceptable concentrations (RACs) for insecticides. The tier-1 and tier-2 RACs were compared with RACs based on threshold concentrations from micro/mesocosm studies (ETO-RAC). A lower-tier RAC was considered as sufficiently protective, if less than the corresponding ETO-RAC. RESULTS ETO-RACs were calculated for repeated (n =¿13) and/or single pulsed applications (n =¿17) of 26 insecticides to micro/mesocosms, giving a maximum of 30 insecticide¿×¿application combinations (i.e. cases) for comparison. Acute tier-1 RACs (for 24 insecticides) were lower than the corresponding ETO-RACs in 27 out of 29 cases, while tier-2 Geom-RACs (for 23 insecticides) were lower in 24 out of 26 cases. The tier-2 SSD-RAC (for 21 insecticides) using HC5/3 was lower than the ETO-RAC in 23 out of 27 cases, whereas the tier-2 SSD-RAC using HC5/6 was protective in 25 out of 27 cases. CONCLUSION The tier-1 and tier-2 approaches proposed by EFSA for acute effect assessment are sufficiently protective for the majority of insecticides evaluated. Further evaluation may be needed for insecticides with more novel chemistries (neonicotinoids, biopesticides) and compounds that show delayed effects (insect growth regulators).
Effect of pesticides used in banana and pineapple plantations on aquatic ecosystems in Costa Rica
Diepens, N.J. ; Pfennig, S. ; Brink, P.J. van den; Gunnarsson, J.S. ; Ruepert, C. ; Castillo, L. - \ 2014
Journal of Environmental Biology 35 (2014)sp.issue. - ISSN 0254-8704 - p. 73 - 84.
species sensitivity distributions - fresh-water invertebrates - acetylcholinesterase activity - gambusia-affinis - chlorpyrifos - fish - ecotoxicology - toxicity - environment - parathion
Current knowledge on fate and effect of agricultural pesticides comes is mainly from temperate ecosystems. More studies are needed in tropical systems in order to assess contamination risks to nontarget endemic tropical species from the extensive use of pesticides e.g. in banana and pineapple plantations. In this study, acute laboratory toxicity tests with organophosphate pesticides ethoprophos and chlorpyrifos were conducted on two Costa Rican species, cladoceran Daphnia ambigua and fish Parachromis dovii. Tests showed that chlorpyrifos was more toxic than ethoprophos to D. ambigua and P. dovii and that D. ambigua was also more sensitive than P. dovii to both pesticides. Additionally, bioassays were performed by exposing D. magna and P. dovii to contaminated water collected from the field. Chemical analyses of field water revealed that fungicides were generally the most frequent pesticide group found, followed by insecticides/nematicides and herbicides. The bioassays and values obtained from the literature confirmed that D. magna was more sensitive to pesticide contamination than P. dovii and that D. ambigua was more sensitive than D. magna, suggesting that the native cladoceran is a more suitable test species than its temperate counterpart. Species sensitivity distributions showed no significant difference in sensitivity between tropical and temperate fish and the arthropod species exposed to chlorpyrifos in this study. Choline esterase activity (ChE) was measured in P. dovii in laboratory tests in order to assess the applicability of this biomarker. ChE inhibition in P. dovii was observed in the laboratory at levels below the LC10 of both ethoprophos and chlorpyrifos, confirming that ChE is an efficient biomarker of exposure. Both indigenous Costa Rican species used in this study were found to be suitable standard tropical test species. Further studies are needed to investigate how protective the safe environmental concentrations, derived from LC50 of native tropical species, are for protecting tropical aquatic natural communities
Ethoprophos fate on soil-water interface and effects on non-target terrestrial and aquatic biota under Mediterranean crop-based scenarios
Leitao, S. ; Moreira-Santos, M. ; Brink, P.J. van den; Ribeiro, R. ; Cerejeira, J. ; Sousa, J.P. - \ 2014
Ecotoxicology and Environmental Safety 103 (2014). - ISSN 0147-6513 - p. 36 - 44.
species sensitivity distributions - fungicide azoxystrobin - folsomia-candida - sandy soil - pesticides - toxicity - invertebrates - earthworms - bentazone - transport
The present study aimed to assess the environmental fate of the insecticide and nematicide ethoprophos in the soil-water interface following the pesticide application in simulated maize and potato crops under Mediterranean agricultural conditions, particularly of irrigation. Focus was given to the soil-water transfer pathways (leaching and runoff), to the pesticide transport in soil between pesticide application (crop row) and non-application areas (between crop rows), as well as to toxic effects of the various matrices on terrestrial and aquatic biota. A semi-field methodology mimicking a "worst-case" ethoprophos application (twice the recommended dosage for maize and potato crops: 100% concentration v/v) in agricultural field situations was used, in order to mimic a possible misuse by the farmer under realistic conditions. A rainfall was simulated under a slope of 20° for both crop-based scenarios. Soil and water samples were collected for the analysis of pesticide residues. Ecotoxicity of soil and aquatic samples was assessed by performing lethal and sublethal bioassays with organisms from different trophic levels: the collembolan Folsomia candida, the earthworm Eisenia andrei and the cladoceran Daphnia magna. Although the majority of ethoprophos sorbed to the soil application area, pesticide concentrations were detected in all water matrices illustrating pesticide transfer pathways of water contamination between environmental compartments. Leaching to groundwater proved to be an important transfer pathway of ethoprophos under both crop-based scenarios, as it resulted in high pesticide concentration in leachates from Maize (130µgL(-1)) and Potato (630µgL(-1)) crop scenarios, respectively. Ethoprophos application at the Potato crop scenario caused more toxic effects on terrestrial and aquatic biota than at the Maize scenario at the recommended dosage and lower concentrations. In both crop-based scenarios, ethoprophos moved with the irrigation water flow to the soil between the crop rows where no pesticide was applied, causing toxic effects on terrestrial organisms. The two simulated agricultural crop-based scenarios had the merit to illustrate the importance of transfer pathways of pesticides from soil to groundwater through leaching and from crop rows to the surrounding soil areas in a soil-water interface environment, which is representative for irrigated agricultural crops under Mediterranean conditions.
Sediment toxicity testing of organic chemicals in the context of prospective risk assessment: A review
Diepens, N.J. ; Arts, G.H.P. ; Brock, T.C.M. ; Smidt, H. ; Brink, P.J. van den; Heuvel-Greve, M.J. van den; Koelmans, A.A. - \ 2014
Critical Reviews in Environmental Science and Technology 44 (2014)3. - ISSN 1064-3389 - p. 255 - 302.
species sensitivity distributions - amphipod corophium-volutator - midge chironomus-riparius - fresh-water sediments - polycyclic aromatic-hydrocarbon - field-collected sediment - aquatic food webs - quality guidelines - benthic invertebrates - whole-sediment
Sediment toxicity tests play an important role in prospective risk assessment for organic chemicals. This review describes sediment toxicity tests for microorganisms, macrophytes, benthic invertebrates and benthic communities. Current approaches in sediment toxicity testing are fragmentary and diverse. This hampers the translation of single species test results between freshwater, estuarine and marine ecosystems and to the population and community levels. A more representative selection of species and endpoints as well as a unification of dose metrics and exposure assessment methodologies across groups of test species, constitutes a first step towards a balanced strategy for sediment toxicity testing of single organic compounds in the context of prospective risk assessment.
Use of chemicals and biological products in Asian aquacultire and their potential environmental risks: a critical review
Rico, A. ; Satapornvanit, K. ; Haque, M.M. ; Min, J. ; Nguyen, P.T. ; Telfer, T. ; Brink, P.J. van den - \ 2012
Reviews in Aquaculture 4 (2012)2. - ISSN 1753-5123 - p. 75 - 93.
species sensitivity distributions - fresh-water - macrobrachium-rosenbergii - veterinary antibiotics - aquatic environment - malachite green - mangrove areas - shrimp ponds - toxicity - fish
Over the past few decades, Asian aquaculture production has intensified rapidly through the adoption of technological advances, and the use of a wide array of chemical and biological products to control sediment and water quality and to treat and prevent disease outbreaks. The use of chemicals in aquaculture farms has raised environmental concerns owing to their potential impacts on downstream aquatic ecosystems. Currently little is known about the environmental fate and effects of the chemicals used in Asian aquaculture. Consequently, we reviewed recent information on the use of chemical and biological products in the most important Asian aquaculture producing countries and briefly summarize their main potential environmental impacts. We provide an overview of the main factors controlling the use of these chemicals and describe the international risk assessment guidelines available for aquaculture chemicals. Finally, data gaps and research needs for their implementation in Asian countries are discussed. Our review aims to form a basis for developing environmental risk assessment studies of the chemicals used in Asian aquaculture.
Variability in the dynamics of mortality and immobility responses of freshwater arthropods exposed to chlorpyrifos
Rubach, M.N. ; Crum, S.J.H. ; Brink, P.J. van den - \ 2011
Archives of Environmental Contamination and Toxicology 60 (2011)4. - ISSN 0090-4341 - p. 708 - 721.
species sensitivity distributions - marmorkrebs marbled crayfish - acute toxicity - pulsed exposure - life stages - time - chemicals
The species sensitivity distribution (SSD) concept is an important probabilistic tool for environmental risk assessment (ERA) and accounts for differences in species sensitivity to different chemicals. The SSD model assumes that the sensitivity of the species included is randomly distributed. If this assumption is violated, indicator values, such as the 50% hazardous concentration, can potentially change dramatically. Fundamental research, however, has discovered and described specific mechanisms and factors influencing toxicity and sensitivity for several model species and chemical combinations. Further knowledge on how these mechanisms and factors relate to toxicologic standard end points would be beneficial for ERA. For instance, little is known about how the processes of toxicity relate to the dynamics of standard toxicity end points and how these may vary across species. In this article, we discuss the relevance of immobilization and mortality as end points for effects of the organophosphate insecticide chlorpyrifos on 14 freshwater arthropods in the context of ERA. For this, we compared the differences in response dynamics during 96h of exposure with the two end points across species using dose response models and SSDs. The investigated freshwater arthropods vary less in their immobility than in their mortality response. However, differences in observed immobility and mortality were surprisingly large for some species even after 96h of exposure. As expected immobility was consistently the more sensitive end point and less variable across the tested species and may therefore be considered as the relevant end point for population of SSDs and ERA, although an immobile animal may still potentially recover. This is even more relevant because an immobile animal is unlikely to survive for long periods under field conditions. This and other such considerations relevant to the decision-making process for a particular end point are discussed.
Fungidice Risk Assessment for Aquatic Ecosystems: Importance of Interspecific Variation, Toxic Mode of Action, and Exposure Regime
Maltby, L. ; Brock, T.C.M. ; Brink, P.J. van den - \ 2009
Environmental Science and Technology 43 (2009)19. - ISSN 0013-936X - p. 7556 - 7563.
species sensitivity distributions - soil bacterial - pentachlorophenol - responses - impact - chlorothalonil - decomposition - carbendazim - communities - pesticides
The risk assessment of fungicides in Europe uses information from ecotoxicity studies performed on vertebrates, invertebrates, and primary producers, but not nontarget fungi. But which toxicity data should be used to assess risk and how important are modes of action and exposure regimes? A data set was compiled comprising acute single-species toxicity data for 42 fungicides, semifield data for 12 fungicides, and covering seven toxic modes of action and different exposure regimes. Most fungicides were general biocides and data from all taxonomic groups were used to construct species sensitivity distributions (SSDs) and assess risk. The derived lower-limit HC5 values and HC1 values were always protective of adverse ecological effects in semifield studies and HC5 values were protective for at least 3 of the fungicides. Expanding the analysis to include insecticides and herbicides, the following threshold values, derived from SSDs based on the most sensitive taxonomic group, are proposed to protect against adverse ecological effects from pesticide exposure: (i) the HC5 can be used for short-term exposures; (ii) the HC5 divided by 1.5 can be used for medium-term exposures; (iii) either the HC1 or the HC5 divided by 3 can be used for long-term exposures.
Effects of the pyrethroid insecticide gamma-cyhalothrin on aquatic invertebrates in laboratory and outdoor microcosm tests
Wijngaarden, R.P.A. van; Barber, I. ; Brock, T.C.M. - \ 2009
Ecotoxicology 18 (2009)2. - ISSN 0963-9292 - p. 211 - 224.
species sensitivity distributions - active ingredient chlorpyrifos - fresh-water microcosms - lambda-cyhalothrin - experimental ditches - community - responses - toxicity - single - field
The sensitivity of a range of freshwater lentic invertebrates to gamma-cyhalothrin (GCH), a single enantiomer of the synthetic pyrethroid lambda-cyhalothrin, was assessed in single species laboratory tests and an outdoor multi-species ecosystem test. The most sensitive species in the laboratory single species tests with GCH was Chaoborus obscuripes (96 h EC50: 3.8 ng/l). The species sensitivity distribution curve, based on the laboratory 96 h EC50 acute toxicity data for eight species, gave a median HC5 value for GCH of 2.12 ng/l. The NOECcommunity derived from the multi-species ecosystem test was 5 ng/l, and the insects Chaoborus sp. and Caenis sp. were identified as the most sensitive species. The results indicate that the median HC5, based on eight species selected to include those known to be sensitive to pyrethroids, provided a good estimation of the NOECcommunity for GCH. Furthermore, the results for GCH indicated that the endpoints typically used in higher-tier risk assessments for pesticides in Europe (HC5 and NOECcommunity) were consistent with expectations when compared to the equivalent endpoints for the racemate LCH
Effects of pesticides on soil invertebrates in model ecosystem and field studies: a review and comparison with laboratory toxicity data
Jänsch, S. ; Frampton, G.K. ; Römbke, J. ; Brink, P.J. van den; Scott-Fordsmand, J.J. - \ 2006
Environmental Toxicology and Chemistry 25 (2006)9. - ISSN 0730-7268 - p. 2490 - 2501.
species sensitivity distributions - earthworms - chemicals - tests - collembola - lumbricidae - oligochaeta - sublethal
A systematic review was carried out to investigate the extent to which higher-tier (terrestrial model ecosystem [TME] and field) data regarding pesticide effects can be compared with laboratory toxicity data for soil invertebrates. Data in the public domain yielded 970 toxicity endpoint data sets, representing 71 pesticides and 42 soil invertebrate species or groups. For most pesticides, the most frequent effect class was for no observed effects, although relatively high numbers of pronounced and persistent effects occurred when Lumbricidae and Enchytraeidae were exposed to fungicides and when Lumbricidae, Collembola, and Arachnida were exposed to insecticides. No effects of fungicides on Arachnida, Formicidae, or Nematoda or of herbicides on Lumbricidae, Formicidae, or Nematoda were observed in any studies. For most pesticides, higher-tier no-observed-effect concentration or lowest-observed-effect concentration values cannot be determined because of a lack of information at low pesticide concentrations. Ten pesticides had sufficient laboratory data to enable the observed higher-tier effects to be compared with 5% hazardous concentrations (HC5) estimated from acute toxicity laboratory data (atrazine, carbendazim, chlorpyrifos, diazinon, dimethoate, ¿-hexachlorocyclohexane, lambda-cyhalothrin, parathion, pentachlorophenol, and propoxur). In eight cases, higher-tier effects concentrations were within or below the 90% confidence interval of the HC5. Good agreement exists between the results of TME and field tests for carbendazim, but insufficient information is available for a comparison between TME and field studies for other pesticides. Availability and characteristics (e.g., taxonomic composition and heterogeneity) of the higher-tier effects data are discussed in terms of possible developments in risk assessment procedures.
Using the expert model PERPEST to translate measured and predicted pesticide exposure dat into ecological risks
Brink, P.J. van den; Brown, C.D. ; Dubus, I.G. - \ 2006
Ecological Modelling 191 (2006)1. - ISSN 0304-3800 - p. 106 - 117.
species sensitivity distributions - systems - atrazine - soil
An important topic in the registration of pesticides and the interpretation of monitoring data is the estimation of the consequences of a certain concentration of a pesticide for the ecology of aquatic ecosystems. Solving these problems requires predictions of the expected response of the ecosystem to chemical stress. Up until now, a dominant approach to come up with such a prediction is the use of simulation models or safety factors. The disadvantage of the use of safety factors is a crude method that does not provide any insight into the concentration-response relationships at the ecosystem level. On the other hand, simulation models also have serious drawbacks like that they are often very complex, lack transparency, their implementation is expensive and there may be a compilation of errors, due to uncertainties in parameters and processes. In this paper, we present the expert model prediction of the ecological risks of pesticides (PERPEST) that overcomes these problems. It predicts the effects of a given concentration of a pesticide based on the outcome of already performed experiments using experimental ecosystems. This has the great advantage that the outcome is more realistic. The paper especially discusses how this model can be used to translate measured and predicted concentrations of pesticides into ecological risks, by taking data on measured and predicted concentrations of atrazine as an example. It is argued that this model can be of great use to evaluate the outcome of chemical monitoring programmes (e.g. performed in the light of the Water Framework Directive) and can even be used to evaluate the effects of mixtures. (c) 2005 Elsevier B.V. All rights reserved.