Integrating Exposure and Effect Distributions with the Ecotoxicity Risk Calculator: Case Studies with Crop Protection Products
Risk curves describe the relationship between cumulative probability and magnitude of effect and thus express far more information than risk quotients. However, their adoption has remained limited in ecological risk assessment. Therefore, we developed the Ecotoxicity Risk Calculator (ERC) to simplify the derivation of risk curves, which can be used to inform risk management decisions. Case studies are presented with crop protection products, highlighting the utility of the ERC at incorporating various data sources, including surface water modeling estimates, monitoring observations, and species sensitivity distributions. Integr Environ Assess Manag 2021;17:321–330. © 2020 Syngenta Crop Protection, LLC. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
A field spray drift study to determine the downwind effects of isoxaflutole herbicide to nontarget plants
Spray drift buffers are often required on herbicide labels to prevent potential drift effects to nontarget plants. Buffers are typically derived by determining the distance at which predicted exposure from spray drift equals the ecotoxicology threshold for sensitive plant species determined in greenhouse tests. Field studies performed under realistic conditions have demonstrated, however, that this approach is far more conservative than necessary. In 2016, the US Environmental Protection Agency estimated that isoxaflutole (IFT), a herbicide used to control grass and broadleaf weeds, could adversely affect downwind nontarget dicot plants at distances of ≥304m from the edge of the treated field due to spray drift. This prediction implies that a buffer of at least 304m is required to protect nontarget plants. To refine the predicted buffer distance for IFT, we conducted a field study in which sensitive nontarget plants (lettuce and navy bean, two to four leaf stage) were placed at various distances downwind from previously harvested soybean fields sprayed with Balance® Flexx Herbicide. The test plants
were then transported to a greenhouse for grow out following the standard vegetative vigor test protocol. There were three trials. One had vegetation in the downwind deposition area (i.e., test plants placed in mowed grass; typical exposure scenario) and two had bare ground deposition areas (worst‐case exposure scenario). For both plant species in bare ground deposition areas, effects on shoot height and weight were observed at 1.52m but not at downwind distances of ≥9.14m from the edge of the treated area. No effects were observed at any distance for plants placed in the vegetated deposition area. The field study demonstrated that a buffer of 9.14m protects nontarget terrestrial plants exposed to IFT via spray drift even under worst‐case conditions. Integr Environ Assess Manag 2021;00:1–13. © 2021 Bayer. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
How Protective to the Environment is the Pesticide Risk Assessment and Registration Process in the United States?
The media, public, and other stakeholders are generally unaware of the degree of protection provided to the environment by the current pesticide registration process in the United States. Each pesticide product must meet extensive fate and toxicological data requirements (typically 100+ studies) to be considered by the U.S. Environmental Protection Agency (EPA). The EPA uses that information to conduct ecological, human health, and benefits assessments and make decisions on whether to register pesticides and, if so, under what conditions. The assessments rely on conservative assumptions, models, and inputs to consistently err on the side of caution throughout the pesticide registration process. The rigorous compliance requirements specified in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and Endangered Species Act (ESA) are designed to preclude unacceptable adverse effects. However, this reality seldom, if ever, makes headlines. Pesticides are not causing the dire widespread apocalyptic effects often portrayed by some media outlets. Rather, pesticides have been doing what they were intentionally designed to do, controlling pests and increasing yields, within the stringent limitations of registered labels. The continually evolving pesticide registration process was originally predicated on the unintended adverse effects neither anticipated nor considered over 50 years ago, due to insufficient regulation and oversight at the time. However, the contemporary regulatory paradigm in the U.S. is data rich and analysis intensive by design, and perhaps understandably, biased towards ensuring environmental protection when registering pesticides.
Improving Environmental Risk Assessments of Chemicals: Steps Towards Evidence-Based EcotoxicologyView Publication Details ⇨
Advancing soil ecological risk assessments for petroleum hydrocarbon contaminated soils in Canada: Persistence, organic carbon normalization and relevance of species assemblages
Sediment toxicity studies and ecological risk assessments on organic contaminantsroutinely apply organic carbon normalization to toxicity data; however, no studies examine its potential for use in soils with petroleum hydrocarbon (PHC) contamination. Limited studies in soil ecotoxicology assess the influence of species assemblages used in species sensitivity distribution construction on the resulting guideline designated to of soil dwelling organisms. Canadian regulations utilize more conservative approaches to deriving guidelines with soil ecotoxicology data compared to the rest of the world, so we investigated the impact of these on soil invertebrates in a variety of field soils. In addition to toxicity, the persistence of a medium PHC mixture was also assessed in the field soils to determine the duration of toxic effects. We found organic matter influenced PHC toxicity to soil invertebrates, but persistence was influenced more by soil cation exchange capacity. Incorporating organic carbon normalization into species sensitivity distribution curves provided a higher level of protection to soil dwelling receptors in low organic matter soils as well as reduce the variability of PHC soil toxicity data. Soil remediation guidelines derived for protection of soil dwelling organisms using a diverse species assemblage provided similar levels of protection as guidelines developed with test species specific for remote, forested land uses in Canada. We conclude that: (i) Canadian hazard concentration values for PHC contamination of soils should be revisited as they may not be protective and (ii) that soil PHC guidelines for protection of soil dwelling organisms should be expressed as carbon normalized values.View Publication Details ⇨
Lead exposure through consumption of small game harvested using lead-based ammunition and the corresponding health risks to First Nations in Alberta, Canada
The harvesting of game birds, such as grouse, with small arms using lead ammunition continues to be common practice in Alberta, Canada. Grouse are routinely consumed as a subsistence traditional food by First Nations in Alberta and the use of lead ammunition increases the potential lead exposure through the consumption of residual bullet or shot fragments in the edible portion of the meat. After removal of visible shot and ammunition fragments, similar to how the samples would be prepared for consumption, impacted and non-impacted grouse breast meat samples were analyzed to characterize the lead content. Using publicly available consumption rates, the potential lead exposures from consumption of both impacted and non-impacted grouse breast meat were estimated and the corresponding health risks were predicted. Comparison of the predicted health risks revealed a significantly higher risk (p< 0.05) for the consumption of ammunition-impacted meat.View Publication Details ⇨
Whole fish vs. fish fillet—The risk implications for First Nation subsistence consumers
Consumption advisories associated with mercury concentrations are typically based on consumption of fish fillets; however, many First Nation community members consume more than just the fish fillet because of both preference and availability. Food frequency questionnaires were completed by 106 community members to identify which parts of the fish were typically and preferentially consumed. The results of the questionnaires showed that, depending on the species of fish, between 20% and 100% of the respondents ate more than just the fish fillet. Two northern Alberta First Nations harvested 73 piscivorous fish as part of separate studies investigating fish quality. Fillets and whole fish from two species, northern pike (Esox lucius) and walleye (also known as pickerel; Sander vitreus), were analyzed for mercury concentrations. Measured mercury concentrations in whole fish were significantly lower than in fillets (p < 0.05 in all cases). This paper investigates the implications of fish consumption advisories for First Nation communities where many subsistence consumers eat more than just the fish fillet. Consideration of traditional consumption practices may result in a more accurate assessment of exposure for the development of fish consumption guidelines.View Publication Details ⇨
Cadmium Tissue Concentrations in Kidney, Liver and Muscle in Moose (Alces alces) From First Nations Communities in Northern Alberta
The consumption of traditional foods, including moose, is vitally important to Canada’s indigenous communities for dietary, social, and cultural reasons. Cadmium is a key contaminant of concern in moose as it accumulates primarily the organs, with the kidney accumulating more than the liver. The objectives of this study were to identify relationships between cadmium concentrations in the kidney, liver and muscle tissue of moose, and to estimate benchmark consumption quantities that are associated with minimal health risk for three First Nation communities: the Chipewyan Prairie Déné First Nation, the Swan River First Nation and Cold Lake First Nations. Moose quality studies were conducted with the Chipewyan Prairie Déné First Nation in 2012, the Swan River First Nation in 2014 and the Cold Lake First Nations in 2016, all located in Alberta, Canada. The measured cadmium tissue concentrations from these studies were found to be comparable to those reported in the 2016 Alberta First Nations Food, Nutrition and Environment Study, and other North American studies. The results of our study suggest that linear relationships exist between cadmium concentrations in kidney and liver tissue, which can be used as a tool to predict organ concentrations in moose from northern Alberta. First Nations communities can use this information to predict cadmium tissue concentrations in both kidney and liver in the absence of actual, measured cadmium concentrations. Benchmark consumption quantities that are associated with minimal risk were estimated for the different tissue types.View Publication Details ⇨
Deriving a water quality guideline for protection of aquatic communities exposed to triclosan in the canadian environment
Triclosan is an antibacterial and antifungal chemical used in a variety of consumer products, including soaps, detergents, moisturizers, and cosmetics. Aquatic ecosystems may be exposed to triclosan following the release of remaining residues in wastewater effluents and biosolids. In December 2017, Environment and Climate Change Canada (ECCC) released a federal environmental quality guideline (FEQG) report that contained a federal water quality guideline (FWQG) for triclosan. This guideline will be used as an adjunct to the risk assessment and risk management of priority chemicals identified under the Government of Canada’s Chemicals Management Plan (CMP). The FWQG value for triclosan (0.47 μg/L) was derived by ECCC using a hazardous concentration for 5% of species (HC5) from a species sensitivity distribution (SSD). We recalculated the FWQG after performing an independent analysis and evaluation of the available aquatic toxicity data for triclosan and compared our results with the ECCC FWQG value. Our independent analysis of the available aquatic toxicity data entailed conducting a literature search of all available and relevant studies, evaluating the quality and reliability of all studies considered using thorough and consistent study evaluation criteria, and thereby generating a data set of high‐quality toxicity values. The selected data set includes 22 species spanning 5 taxonomic groups. An SSD was developed using this data set following the ECCC approaches. The HC5 from the SSD derived based on our validated data set is 0.76 μg/L. This HC5 value is slightly greater (i.e., less sensitive) than the value presented in ECCC’s final FWQG. Integr Environ Assess Manag 2018;00:000–000. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).View Publication Details ⇨