Winds of change, developing a non-target plant bioassay employing field-based pesticide drift exposure: A case study with atrazine

Brain, Richard A.; Goodwin, Greg; Abi‐Akar, Farah; Lee, Brian; Rodgers, Carol; Flatt, Brian; Lynn, Abby; Kruger, Greg R.; Perkins, Daniel M.

doi:10.1016/j.scitotenv.2019.04.411

Cited by 29 publications

(57 citation statements)

References 18 publications

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“…Tier-I EPA Refined: Assumptions include low boom (20" boom height), fine to medium/coarse DSD, 90th centile windspeed dataset 3. Tier-I EPA Refined: Assumptions include low boom (20" boom height), fine to medium/coarse DSD, 50th centile windspeed dataset Results of this modeling (Figure 15) confirm that the Tier-1 USEPA Default model (USEPA 2016) overestimated deposition by 20-to 70fold when compared to the measured values also shown in the figure obtained from the field measurements from Brain et al (2019). For example, at 100 ft (30 m) from the boom, the AgDRIFT® default value for deposition was 70 times greater than the measured value (see SI Section 4, SI Table S4-1 for other values).…”

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 55%

“…Off-field, plants are exposed to airborne drift moving laterally away from the spray swath in a path that is determined by speed and direction of the prevailing wind and receive a fraction of the applied rate that depends on the rate of sedimentation of the droplets. This phenomenon is illustrated in Figure 12, has been characterized and quantified in multiple field studies (Brain et al 2019(Brain et al , 2017De Jong and Udo De Haes 2001;Marrs and Frost 1997;Plant 1991a, 1991b;Marrs et al 1989), and is illustrated in a video available for public viewing 7 To better evaluate predicted versus actual spray drift deposition for atrazine the standard AgDRIFT® model (version 2.1.1, USEPA 2020d) was used to generate predicted spray drift deposition using EPA default assumptions as well as refined assumptions (see SI Section 4 for details of the analysis). The AgDRIFT scenarios evaluated were based on a rate of application of 2.24 kg/ha (2 lb.…”

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 92%

“…This issue has recently been addressed in a study designed to measure real-world drift of herbicide resulting from field-scale application of atrazine in order to assess in-situ, off-field non-target plant exposure and responses (Brain et al 2019). The study combined physical deposition collectors for residue analysis with a field-based bioassay that characterized off-field effects using vegetative vigor of sensitive standard non-target terrestrial plants (cucumber and lettuce) following downwind drift exposure from in-field atrazine application of 2.24 kg a.i./ha (2 lb.…”

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 99%

“…TerrPlant, 4 EPAs screening model for estimating exposure of non-target plants via drift of spray relies on endpoints derived under the presumption of direct overhead application. The fundamental issue with this approach is that it presumes nontarget plants are exposed analogous to in-field target weeds (i.e., via a direct overhead spray), which is not the case (Brain et al 2019(Brain et al , 2017. The guideline assays for assessing effects of pesticides on vegetative vigor 5 and seedling emergence 6 studies are designed to simulate a worst-case exposure by effectively saturating the foliage from a direct overhead track-sprayer, analogous to an in-field weed exposed to the maximum rate spray application.…”

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 99%

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Assessment of risks to listed species from the use of atrazine in the USA: a perspective

Smith

Armbrust

Brain

et al. 2021

Journal of Toxicology and Environmental Health, Part B

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Atrazine is a triazine herbicide used predominantly on corn, sorghum, and sugarcane in the US. Its use potentially overlaps with the ranges of listed (threatened and endangered) species. In response to registration review in the context of the Endangered Species Act, we evaluated potential direct and indirect impacts of atrazine on listed species and designated critical habitats. Atrazine has been widely studied, extensive environmental monitoring and toxicity data sets are available, and the spatial and temporal uses on major crops are well characterized. Ranges of listed species are less well-defined, resulting in overly conservative designations of "May Effect". Preferences for habitat and food sources serve to limit exposure among many listed animal species and animals are relatively insensitive. Atrazine does not bioaccumulate, further diminishing exposures among consumers and predators. Because of incomplete exposure pathways, many species can be eliminated from consideration for direct effects. It is toxic to plants, but even sensitive plants tolerate episodic exposures, such as those occurring in flowing waters. Empirical data from long-term monitoring programs and realistic field data on off-target deposition of drift indicate that many other listed species can be removed from consideration because exposures are below conservative toxicity thresholds for direct and indirect effects. Combined with recent mitigation actions by the registrant, this review serves to refine and focus forthcoming listed species assessment efforts for atrazine. Abbreviations: a.i. = Active ingredient (of a pesticide product). AEMP = Atrazine Ecological Monitoring Program. AIMS = Avian Incident Monitoring SystemArach. = Arachnid (spiders and mites). AUC = Area Under the Curve. BE = Biological Evaluation (of potential effects on listed species). BO = Biological Opinion (conclusion of the consultation between USEPA and the Services with respect to potential effects in listed species). CASM = Comprehensive Aquatic System Model. CDL = Crop Data LayerCN = field Curve Number. CRP = Conservation Reserve Program (lands). CTA = Conditioned Taste Avoidance. DAC = Diaminochlorotriazine (a metabolite of atrazine, also known by the acronym DACT). DER = Data Evaluation Record. EC25 = Concentration causing a specified effect in 25% of the tested organisms. EC50 = Concentration causing a specified effect in 50% of the tested organisms. EC50 RGR = Concentration causing a 50% reduction in relative growth rate. ECOS = Environmental Conservation Online System. EDD = Estimated Daily Dose. EEC = Expected Environmental Concentration. EFED = Environmental Fate and Effects Division (of the USEPA). EFSA = European Food Safety Agency. EIIS = Ecological Incident Information System. ERA = Environmental Risk Assessment. ESA = Endangered Species Act. ESU = Evolutionarily Significant UnitsFAR = Field Application RateFIFRA = Federal Insecticide, Fungicide, and Rodenticide Act. FOIA = Freedom of Information Act (request). GSD = Genus Sensitivity Distribution. HC...

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Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 55%

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 92%

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 99%

Section: Spray Drift and Volatilization/redepositionmentioning

confidence: 99%

See 2 more Smart Citations

Assessment of risks to listed species from the use of atrazine in the USA: a perspective

Smith

Armbrust

Brain

et al. 2021

Journal of Toxicology and Environmental Health, Part B

Self Cite

View full text Add to dashboard Cite

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“…Applications were made at 6:00 AM on the day of application and then the samplers moved into the treated areas 30 min after the application. Previous studies reported that this time interval was sufficient to allow for small droplets to settle upon the treated surface (Brain et al 2019;Munjanja et al 2020;Prueger et al 2017). Wind speed at application was <2 km h -1 .…”

Section: Herbicide Applicationmentioning

confidence: 98%

Dicamba emissions under field conditions as affected by surface condition

Mueller

Steckel

2020

Weed Technol

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The evolution and widespread distribution of glyphosate-resistant broadleaf weed species catalyzed the introduction of dicamba-resistant crops that allow this herbicide to be applied POST to soybean and cotton. Applications of dicamba that are most cited for off-target movement have occurred in June and July in many states when weeds are often in high densities and at least 10-cm or greater at the time of application. For registration purposes, most field studies examining pesticide emissions are conducted using bare ground or very small plants. Research was conducted in Knoxville, TN in the summer of 2017, 2018, and 2019 to examine the effect of application surface (tilled soil, dead plants, green plants) on dicamba emissions under field conditions. Dicamba emissions after application were affected by the treated surface in all years, with the order from least to most emissions being dead plants < tilled soil < green plant material. In fact, dicamba emissions were > 300% when applied to green plants compared to other surfaces. These findings suggest that dicamba applications made to bare ground will likely underestimate what may occur under normal field use conditions when POST applications are made and the crop canopy or weed groundcocver is nearly 100% green material. A potential change to enhance the accuracy of current environmental simulation models would be to increase the theoretical findings to allow for the effect of green plant material on dicamba emissions under field conditions.

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A Field Study Method as a Potential Higher Tier Option to Refine Herbicide Risk Assessment for Nontarget Terrestrial Plants

Isemer

Mihan

Peeters³

et al. 2020

Integr Envir Assess & Manag

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During herbicide spray application, nontarget terrestrial plants (NTTPs) growing in the off‐field area need to be protected from unacceptable effects of herbicide drift. The risk of such unintended effects is assessed in order to establish whether a particular use can be approved, possibly in combination with mitigation measures. In Europe, the risk of herbicide treatment to NTTPs is assessed on the basis of tier 2 studies done under controlled conditions in greenhouses. Following the concept of a tiered testing approach, higher tier field studies under more realistic conditions could be used to refine the risk assessment. No current guideline for conducting higher tier NTTP field studies is available. We developed an NTTP higher tier field study method done on an experimental plant community established by sowing of a seed mixture. The setup was optimized in 3 pilot field studies and subsequently used for a definitive study testing effects of the herbicide iofensulfuron‐sodium. Results show that the method can be regarded as a suitable higher tier option for assessing effects of herbicides on NTTPs. Growth of species from the soil seed bank cannot be avoided and has to be carefully considered when evaluating results. Adaptations of the study design may be necessary when testing different herbicides. Community‐level endpoints were at the same level as single‐species endpoints. Results of the field study were compared to standard greenhouse study results for the same herbicide. No observed effect rates (NOERs) in the field were about a factor of 10 higher and show that the current tier 2 risk assessment for NTTPs can be regarded as protective in this case. Whether the present field study design and the assessed endpoints can be used in higher tier risk assessment of NTTPs depends on selection of the specific protection goal and requires further discussion. Integr Environ Assess Manag 2020;16:691–705. © 2020 Bayer AG. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)

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Winds of change, developing a non-target plant bioassay employing field-based pesticide drift exposure: A case study with atrazine

Cited by 29 publications

References 18 publications

Assessment of risks to listed species from the use of atrazine in the USA: a perspective

Assessment of risks to listed species from the use of atrazine in the USA: a perspective

Dicamba emissions under field conditions as affected by surface condition

A Field Study Method as a Potential Higher Tier Option to Refine Herbicide Risk Assessment for Nontarget Terrestrial Plants

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