When is it Legitimate to Downplay Individual Differences?

Crocker, D.R.; Langton, Steve

doi:10.1002/etc.4456

Cited by 4 publications

(15 citation statements)

References 7 publications

(20 reference statements)

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“…The EFSA guideline (European Food Safety Authority 2009, Appendix A) outlines more than 500 different species/crop scenarios for assessment depending on the timing of the pesticide application. Therefore, neither our study (2017) nor the letter of Crocker and Langton (2019) is dealing with "avian risk assessment" in general. Thus, the overall statement by Crocker and Langton (2019) that "pooling data between individuals will lead to less protective (avian) risk assessments" falls short and trivializes the issue to a black and white position.…”

Section: Potential For Misleading and Unprotective Risk Assessmentmentioning

confidence: 97%

“…Therefore, neither our study (2017) nor the letter of Crocker and Langton (2019) is dealing with "avian risk assessment" in general. Thus, the overall statement by Crocker and Langton (2019) that "pooling data between individuals will lead to less protective (avian) risk assessments" falls short and trivializes the issue to a black and white position. We agree fully with Crocker and Langton (2019) that a critical look at the data is necessary to avoid the possibility that the PT values used will lead to unprotective risk assessments.…”

Section: Potential For Misleading and Unprotective Risk Assessmentmentioning

confidence: 97%

“…Clearly, the best dataset for such a purpose would consist of a large enough sample size of radiotagged animals (usually~20 is considered sufficient) that are each tracked over 21 d. Since this is practically impossible for logistical and cost reasons, our idea is to expand the available radiotracking data with Monte Carlo simulations. It is unclear why Crocker and Langton (2019) call that incorrect because they also use these methods in their letter. The specifics of the approach to check, and account for, inter-/intraindividual variability and finally pooling data are, however, arguable and probably need to be re-evaluated case by case.…”

Section: Statistically Not Validmentioning

confidence: 99%

“…The specifics of the approach to check, and account for, inter-/intraindividual variability and finally pooling data are, however, arguable and probably need to be re-evaluated case by case. For instance, Crocker and Langton (2019) advocate averaging the repeated session PT value for each individual and calculating the 90th percentile over these averages. However, using this dataset, some individuals would then be represented by 3 repeated tracking sessions and others by 6 repeated tracking sessions, which could lead to "bias toward" individuals that are tracked more often, but as shown by our proposals it is an example of how to consider variability.…”

Section: Statistically Not Validmentioning

confidence: 99%

“…The protection goal in the EFSA guideline (European Food Safety Authority 2009) for long-term risk assessment on birds is the population level rather than the individual bird. Thus, the focus is not on the individual worst-case bird, as apparently advocated by Crocker and Langton (2019). Furthermore, the current manner of using radiotracking data from field studies for regulatory decision-making in the European Union limits the acceptable data to the so-called consumers, that is, those birds that were actually using the target crop during their tracking session.…”

Section: Potential For Misleading and Unprotective Risk Assessmentmentioning

confidence: 99%

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When is it Legitimate to Downplay Individual Differences?

Crocker¹,

Langton²

2019

Enviro Toxic and Chemistry

Self Cite

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Section: Potential For Misleading and Unprotective Risk Assessmentmentioning

confidence: 97%

Section: Potential For Misleading and Unprotective Risk Assessmentmentioning

confidence: 97%

Section: Statistically Not Validmentioning

confidence: 99%

Section: Statistically Not Validmentioning

confidence: 99%

Section: Potential For Misleading and Unprotective Risk Assessmentmentioning

confidence: 99%

See 3 more Smart Citations

When is it Legitimate to Downplay Individual Differences?

Crocker¹,

Langton²

2019

Enviro Toxic and Chemistry

Self Cite

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Response to David R. Crocker and Steven D. Langton “When is it Legitimate to Downplay Individual Differences?”

Ludwigs

Ebeling

Fredricks

et al. 2019

Enviro Toxic and Chemistry

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In their letter, Crocker and Langton (2019) critically discuss the approach of 21-d Monte Carlo PT (portion of diet from a pesticidetreated area) simulations proposed in Ludwigs et al. (2017). The aim of this method is to assess realistic 21-d PT values by including daily variability in habitat use for individual animals. Crocker and Langton (2019) believe that the method described by Ludwigs et al. ( 2017) is 1) unsuited to most radiotracking datasets; 2) statistically not valid; and 3) could lead to misleading and unprotective risk assessment. In our letter, we want to respond to the comments and concern raised by Crocker and Langton (2019). We still believe that use of the 90th percentile value for many PT datasets, irrespective of data quantity and quality, does not provide a good representation of exposure over the regulatory default time window of 21 d. Therefore, intra-individual variability of daily PT values, if available, should be taken into account. Our 2017 publication used one dataset as an example of how this could potentially be achieved. Of course, some datasets might be unsuitable for such an approach, and depending on the available data and potentially new data, the statistical approach and pooling of data might need to be adapted as well. However, if these points are addressed appropriately in the future, the method would in our opinion not lead to misleading and unprotective risk assessments. A follow-up publication using different datasets for other species is in preparation, to further demonstrate the benefits and constraints of our proposal.

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Assessing the Portion of Diet Taken by Birds and Mammals from a Pesticide‐Treated Area—Proposal for a Joint Way Forward

Ludwigs¹,

Ebeling

Haaf³

et al. 2022

Enviro Toxic and Chemistry

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An environmental risk assessment for birds and mammals is an important part of any application package for potential registration of pesticides in Europe. A realistic estimation of the exposure of a certain species to the pesticide under field conditions is a refinement factor in long-term higher-tier risk assessments. Although guidance on how to collect specific exposure data is provided, there is not yet a harmonized view on how to use and assess existing and newly recorded field data. Exposure is defined as the portion of diet taken from a pesticide-treated crop field over time (the PT factor), and it is set equal to the time a (tracked) individual is active (= foraging) in the crop of concern at the crop growth stage relevant to the pesticide application being assessed. While the PT factor is set to 1 in a first tier, it can be refined in higher tiers. Differences in the methodologies influencing the robustness of a data set and intraindividual variance in PT data are currently not considered. Our study, based on data recording in accordance with the European Food Safety Authority's recommendations, shows this variance for different species in different crops for both breeding and nonbreeding periods, with tracking sessions showing both interindividual as well as intraindividual variation across several days. We discuss PT data quality and how it can be used, considering intraindividual variance in a manner that is protective and conforms to current European guidance. The present study intends to support the planned revision of the current European guidance on how to conduct environmental bird and mammal risk assessments, and its further purpose is to open constructive discussions about how and which kind of PT data can be used.

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When is it Legitimate to Downplay Individual Differences?

Cited by 4 publications

References 7 publications

When is it Legitimate to Downplay Individual Differences?

When is it Legitimate to Downplay Individual Differences?

Response to David R. Crocker and Steven D. Langton “When is it Legitimate to Downplay Individual Differences?”

Assessing the Portion of Diet Taken by Birds and Mammals from a Pesticide‐Treated Area—Proposal for a Joint Way Forward

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