Correspondence/Rebuttal pubs.acs.org/est
Response to Comment on “Aquatic Exposure Predictions of Insecticide Field Concentrations Using a Multimedia Mass Balance Model”
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made on earlier studies1−3 that the FOCUS model is neither protective nor predictive for insecticide and fungicide field concentrations. As mentioned several times in our studies,1−3 protectiveness is not a general modeling criterion itself, it is only important because of the underlying principle in the environmental risk assessment for pesticides.5 Moreover, we used the correlation between predicted and measured waterphase concentrations (excluding PECsed in this analysis) only for the comparison of the predictiveness of the two models and not in order to judge the predictive capability of each model for real world data. The latter yet seems to be low for both models.1 We also fully agree with the final conclusion of Kehrein and Reichenberger that a model should be as simple as possible, but as complex as needed; it should, however, first and foremost be protective given its utilization for the environmental risk assessment of highly biologically active chemicals such as pesticides. We have shown in three1−3 different studies that the FOCUS modeling approach is neither protective nor predictive for fungicide or insecticide field concentrations, which means that the requirements of the environmental risk assessment are not at all fulfilled.
e acknowledge the interest in the topic and the scientific exchange as such, but we doubt that the rationale for this and former comments by Reichenberger et al. is pure scientific interest. We strongly criticize in our publications in ES&T1−3 the FOCUS models, and wonder why we repeatedly receive comments from individuals working for private companies (e.g., www.knoellconsult.com, Footways S.A.S., France) that generate parts of their revenues by applying exactly these FOCUS models. Most importantly, we are surprised at the extent to which the comments ignore the facts reported in our papers. We have, for example, not adapted the Small Region Model (SRM) model in any way as claimed by Kehrein and Reichenberger, we just used the input parameters relevant within the FOCUS scenarios to feed the SRM model. Without the use of these scenario-specific environmental parameters the model indeed yields predicted environmental concentrations (PEC) in the range of g/L, as argued by Kehrein and Reichenberger. Specifically, Kehrein and Reichenberger raised three major points of criticism on our study. First, they claim that the PECs reported in our study contain serious flaws. The arguments provided for this statement are not valid: Kehrein and Reichenberger for example claim that transfer coefficients were not provided in our study. Actually they were not changed in our SRM modeling using the FOCUS scenario input data because these transfer coefficients are calculated in FOCUS, in contrast to the SRM approach, for example according to the amount of daily rainfall. They can yet only be regarded as an approximation in our calculations. The same is true for the use of the Ganzelmeier drift values, for which Kehrein and Reichenberger claim that they cannot be used for an approximation of the amount of applied substance that does not reach the soil surface. As mentioned in our study, we used the Ganzelmeier drift values to account for the fact that pesticides are mainly applied via spray application. It is true that we used the areic mean values for the fraction of application rate as claimed by the Kehrein and Reichenberger but as mentioned before, this was only used as an approximation as it is also regularly done in FOCUS step 1 and step 2.4 In our study we used the SRM model with the edge-of-field and water body scenarios of the FOCUS modeling approach, which is necessary to make the predictions comparable to the FOCUS modeling results. In addition, the FOCUS scenarios were developed because they are relevant for European agriculture.4 Here, it seems that Kehrein and Reichenberger used the SRM model with the default scenario conditions with much bigger compartments sizes and thus differing dilution factors, which explains the entirely unrealistic modeling results they received. The second point deals with the predictive capability of both models. We fully agree with the comment of Reichenberger © 2016 American Chemical Society
Anja Knab̈ el* Sebastian Stehle Ralf Schulz
Institute for Environmental Science, University Koblenz-Landau, Fortstraße 7, Landau 76829, Germany
Martin Scheringer
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Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Knäbel, A.; Scheringer, M.; Stehle, S.; Schulz, R. Aquatic Exposure Predictions of Insecticide Field Concentrations Using a Multimedia Mass-Balance Model. Environ. Sci. Technol. 2016, 50, 3721−3728. (2) Knäbel, A.; Meyer, K.; Rapp, J.; Schulz, R. Fungicide Field Concentrations Exceed FOCUS Surface Water Predictions: Urgent Need of Model Improvement. Environ. Sci. Technol. 2014, 48, 455− 463. (3) Knäbel, A.; Stehle, S.; Schäfer, R. B.; Schulz, R. Regulatory FOCUS Surface Water Models Fail to Predict Insecticide Concentrations in the Field.
Published: November 7, 2016 13171
DOI: 10.1021/acs.est.6b04973 Environ. Sci. Technol. 2016, 50, 13171−13172
Environmental Science & Technology
Correspondence/Rebuttal
(4) FOCUS. FOCUS surface water scenarios in the EU evaluation process under 91/414/EEC. Report of the FOCUS working group on surface water scenarios, EC Document Reference SANCO/4802/ 2001- rev.2, 2001. (5) EFSA. Guidance on tiered risk assessment for plant protection products for aquatic organisms in edge-of-field surface waters. EFSA J. 2013, 11, 3290.10.2903/j.efsa.2013.3290
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DOI: 10.1021/acs.est.6b04973 Environ. Sci. Technol. 2016, 50, 13171−13172
