Risk assessment pesticides

Thompson, H.M. and Mans, C. (2007). The relevance of sublethal effects in honey bee testing for pesticide risk assessment. Pest Management Science 63, 1058-1061. 

Balderacchi M, Trevisan M (2010) Comments on pesticide risk assessment by the revision of Directive EU 91/414. Environ Sci Pollut Res 17(3) 523-528... 

In considering pesticide residues, it was clearly shown that crops from organic production systems contain no or significantly lower levels of pesticide residues than crops from conventional systems (Baker et al., 2002). However, while some scientists are concerned about the potential health impacts from such residues (Porter et al., 1999 Benbrook, 2002), pesticide legislators maintain that current pesticide risk assessments and pesticide registration procedures are adequate and that residues below the current legal limits can not have a negative health impact in humans (e.g. PSD, 2006). 

EPA released the first case study of cumulative risks from 24 OPs in food for scientific review in mid-2000. Public comments were solicited and several scientific panel (SAP) meetings were held on various aspects of EPA s quantitative methods. In December 2001 a preliminary OP-CRA (cumulative risk assessment) was released, this time encompassing 30 OPs, additional foods, more residue data and all major routes of exposure. Public comments were solicited again and another series of SAP meetings were held. The revised final OP-CRA was issued in June 2002 after more than 20 SAP meetings and four rounds of public comment (US Environmental Protection Agency, 2002). It is the most sophisticated and data-rich pesticide risk assessment ever carried out. 

EFSA (2008) Conclusion regarding the peer review of the pesticide risk assessment of the active substance etofenprox. EFSA Scientific Report 213. European Food Safety Authority, Parma, pp 1-131 http //www.efsa.europa.eu/en/scdocs/scdoc/213r.htm... 

Winter CK. 1992. Dietary pesticide risk assessment. Rev Environ Contam Toxicol 127 23-67... 

The techniques used to establish the risks posed by pesticides are dynamic and evolving. The passage of the FQPA in 1996 paved the way for the development of sophisticated computational models for assessing pesticide exposure, and future refinement of such models is anticipated. Such advancements in pesticide risk assessment techniques should be applicable to the risk assessment of other chemicals in foods and in the environment. 

FIGURE 1.2 Examples of differing degrees of conservatism in assumptions used in pesticide risk assessments. 

The Pellston workshop in February 2002, which produced this book, aimed to develop guidance and increased consensus on the use of uncertainty analysis methods in ecological risk assessment. The workshop focused on pesticides, and used case studies on pesticides, because of the urgent need created by the rapid move to using probabilistic methods in pesticide risk assessment. However, it was anticipated that the conclusions would also be highly relevant to other stressors, especially other contaminants. 

For pesticide risk assessments, it may often be necessary to assess impacts of the same pesticide used in different crops, in different seasons, in different geographic regions, and on different species and ecosystems. This will require the use of multiple scenarios and possibly multiple assessment endpoints. 

From the standpoint of practical regulatory assessment, it would be desirable to reach a consensus on the selection of methods for routine use for pesticide risk assessments while recognizing that there may be scientific reasons for preferring alternative methods in particnlar cases. Such a consensus does not yet exist. Further case studies are required, covering a range of contrasting pesticides and scenarios, to evaluate the available methods more fully. While a consensus is lacking, it is important that reports on probabilistic assessments clearly explain how their methods work and why they were selected. 

The workshop recognized the importance of dealing with model uncertainty but did not evaluate the alternative approaches in detail. Further work is required to identify instances of model nncertainty for pesticide risk assessment and to develop guidance on how to deal with it. Some possible approaches are briefly discussed below. 

An approach that is sometimes helpful, particularly for recent pesticide risk assessments, is to use the parameter values that result in best fit (in the sense of LS), comparing the fitted cdf to the cdf of the empirical distribution. In some cases, such as when fitting a log-normal distribution, formulae from linear regression can be used after transformations are applied to linearize the cdf. In other cases, the residual SS is minimized using numerical optimization, i.e., one uses nonlinear regression. This approach seems reasonable for point estimation. However, the statistical assumptions that would often be invoked to justify LS regression will not be met in this application. Therefore the use of any additional regression results (beyond the point estimates) is questionable. If there is a need to provide standard errors or confidence intervals for the estimates, bootstrap procedures are recommended. 

In conclusion, we believe that error propagation methods like Monte Carlo, Bayesian Monte Carlo, and Ist-order error analysis should be promoted and extensively used in pesticide risk assessments implemented in both the United States and Europe. 

In some cases, the workshop produced a near consensus on how to resolve the issue, but further work is required to conhrm and implement the conclusion. In most cases, however, the workshop has identihed a range of possible solutions and further work is required to evaluate them. Uncertainty analysis in pesticide risk assessment is highly encouraged however, uncertainty analysis should be used and interpreted with caution. The methods used should be justified and described in detail in every assessment. 

The workshop did not reach firm conclusions on which methods of uncertainty analysis are suitable for use in pesticide risk assessment, or when they should be used. 

The ability to use probabilistic approaches to assess dietary pesticide exposure has also changed much of the emphasis of pesticide risk assessment practices from assessing long-term (chronic) exposure to short-term (acute) exposure. Deterministic approaches worked well with chronic assessments since the day-to-day variability in food consumption patterns and the variability of pesticide residue levels tended to average out over the course of a 70-year exposure period. Deterministic approaches have also often been used in the assessment of acute dietary risk by assuming an upper percentile level of food consumption and the maximum detected or allowable level of residue. The point estimate determined in this manner is then compared with the RfD to determine the acceptability of exposure under the specified conditions. 

Durkin, Patrick R. 2003, March 1. Glyphosate—Human Health and Ecological Risk Assessment FinalReport. Syracuse Environmental Research Associates, Inc. USDA Forest Service Forest Health Protection, http //www.fs.fed.us/foresthealth/pesticide/risk assessments/04ao3 glyphosate.pdf... 

Elmegaard N, Jagers op Akkerhuis GAJM. 2000. Safety factors in pesticide risk assessment differences in species sensitivity and acute-chronic relations. NERI Technical. No. 325. Silkeborg (Denmark) National Environmental Research Institute, Department of Terrestrial Ecology, 60 p. 

Cumulative risk assessments evaluate the health risk for aggregate exposures accumulated over time and for multiple contaminants or stressors. In some contexts (e.g. USEPA pesticide risk assessments), cumulative refers specifically to combined exposures to chemicals that share a common mechanism of toxicity (see http // www.epa.gov/oppsrrdl/cumulative/). Populations may be defined by their location relative to sources, their activities and customs, and their susceptibility to exposures. In this context, populations can include different ethnic groups, different communities, or different age groups. Cumulative risk is a very important concept in understanding environmental health risks to children in different settings, particularly in underdeveloped countries where children may be facing multiple stressors. 

Studies for pesticide risk assessment focus on the situation in a water body near the field edge, with the peak of exposure soon after application due to drift, runoff, or drainage. In most cases, endpoints are related to the initial concentration of the test item (which can encompass multiple applications). In contrast to this, the focus of EQS derivation is mostly on protection against effects of long-term exposure. 

For pesticide risk assessment, recovery is taken into account to derive an NOEAEC (no-observed ecologically adverse effect concentration). A maximum of 8 weeks is often taken as an acceptable recovery period, but the life cycle of the affected species should also be taken into consideration (SANCO 2002). 

Microcosm and mesocosm studies can be directly designed for the purpose of EQS derivation (e.g., the exposure scenario, communities to be monitored, etc.). Guidance for design and conduction of microcosm and mesocosm studies can be found in the references given for pesticide risk assessment, but OECD has recently published a guideline for a lentic field test that is not focused on pesticides alone (OECD 2006b). 

Pesticides - Toxicology. 2. Pesticides - Risk assessment. I. Frankhn,... 

See a/so Delaney Clause Federal Insecticide, Fungicide, and Rodenticide Act, US Food and Drug Administration, US Food, Drug, and Cosmetic Act, US Pesticides Risk Assessment, Human Health Toxic Torts. 

Lepper P. Use of higher-tier studies conducted in the context of pesticide risk assessment for quality standard setting. Poster presented at the SETAC Europe 16th Annual Meeting 7-11 May 2006, The Hague, The Netherlands. 

Society of Environmental Toxicology and Chemistry (SETAC). (November 1994). Aquatic Dialogue Group Pesticide Risk Assessment Mitigation - Final Report. Society of Environmental Toxicology and Chemistry (SETAC). 

Pesticides—Environmental aspects—Congresses. 2. Pesticides—Risk assessment—Congresses. 3. Ecological risk assessment—Simulation methods. I. Thorbek, Pernille. 

Pesticide Risk Assessment Peer Review Unit (EFSA)... 

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