united states forest los padres national forest 406 south...

United States Department of Agriculture

Forest Service

Los Padres National Forest Monterey Ranger District

406 South Mildred King City, CA 93930 831-385-5434 831-385-1189 TDD 831-385-0628 FAX

File Code: 1920 Date: March 27, 2014

Subject: Ecological Risk Assessment Strategic Community Fuelbreak Improvement Project

To: Project File Prepared By: Jeff Kwasny

Section 1 – Introduction Proposed Action: Apply with low-volume applicator Triclopyr butoxyethyl ester (BEE) [Garlon® 4 Ultra or an equivalent formulation] mixed with modified seed oil at a 50:50 ratio on the basal cut stump/stubble (collar to cut) of brush removed during construction and maintenance of fuelbreaks to retard resprouting. Land managers frequently make decisions regarding the use of herbicides on National Forest System lands. These decisions must be based not only on effectiveness of these tools, but also on an understanding of the risks associated with their use. For herbicides used by the Forest Service in its management activities, Human Health and Ecological Risk Assessments (HERA) are prepared. In these documents, the process of risk assessment is used to quantitatively evaluate the probability (i.e. risk) that an herbicide use might pose harm to humans or other species in the environment. It is the same assessment process used for regulation of allowable residues of pesticides in food, as well as safety evaluations of medicines, cosmetics, and other chemicals. The Forest Service incorporates relevant information from the HERA into environmental assessment documents prepared for herbicide projects, and are used to guide decision-making and to disclose to the public potential environmental effects. This risk assessment process will follow a four-step process: Hazard Identification, Exposure Assessment, Dose-Response Assessment and Risk Characterization. The outcome will be to ensure that people and the environment are protected from adverse effects that may be associated with the proposed pesticide use. Risk assessment is a process designed to answer questions about how toxic a chemical is, what exposure results from its various uses, what the probability that use will cause harm is, and how to characterize the risk. These are the basic steps recommended by the National Research Council of the National Academy of Sciences (NRC 1983) for conducting and organizing risk assessments. Toxicity is an inherent property of all substances; all chemical substances can produce adverse health effects at some level of exposure. Risk of adverse health effects is a function of toxicity and exposure. Exposure to a substance determines the dose and the substance’s toxicity determines the potency of the dose. Therefore, determining both toxicity and exposure is necessary in assessing the risk in using chemicals. Hazard is best defined as the potential of a substance to cause harm, whereas risk is the probability of adverse effect under specified conditions of exposure.

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Hazard Identification

This step involves the review and evaluation of a pesticide’s toxic properties – the extent and type of adverse effects. Information provided is a summarization of key research to identify any potential health problems that the selected herbicides can cause.

Exposure Assessment

This step estimates the potential magnitude, duration, and timing of dose that non-target organisms might receive as a result of their exposure to the compound. Several highly conservative scenarios have been developed within the SERA (2011) risk assessments and are used as a benchmark herein. Three general types of exposure scenarios are considered, accidental, acute non-accidental, and longer term. Exposure assessments for birds and mammals are summarized in tables 3 & 5. The highest exposures are associated with consumption of contaminated grasses, and the lowest exposures are associated with the consumption of contaminated water. The exposure assessment for mammals is somewhat more detailed to encompass more diverse body weights. For terrestrial plants, three exposure scenarios are considered quantitatively: direct spray, spray drift, and runoff. Exposures to aquatic organisms are not displayed here because none of the treatment sites are within a ¼ mile of surface water. A standard set of exposure assessments are contained in the SERA (2011) and project specific exposure assessments from the EXCEL worksheet, Strategic Community Fuelbreak Improvement Project 2014 (available in the project file) are displayed herein. Dose-Response Assessment

This assessment considers the effects (in terms of magnitude and/or incidence) that occur or are predicted to occur at a given dose level. State and Federal guidelines require that laboratory animals receive doses sufficient to produce toxic effects. These tests often use doses which are much higher than those to which people might be exposed. The highest dose in a study which does not result in an observable effect (that is, the dose below the dose at which an effect was seen) is called the “no-observable-effect level” (NOEL). This NOEL is often the basis for calculating allowable human exposure. To compensate inevitable uncertainties in the risk assessment process, various uncertainty factors may have been applied to the NOEL to determine the allowable exposure level. For example, the allowable human exposure may be set a hundredfold lower than the NOEL.

Risk characterization

The risk characterization integrates data from hazard identification, dose response and exposure assessment to develop a qualitative or quantitative estimate of the likelihood that any of the hazards associated with the proposed use of pesticides will occur based on plausible levels of exposure.

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References Used

The information presented here to display potential ecological risks associated with the application of triclopyr is found in: Triclopyr –Human Health and Ecological Risk Assessment Final Report prepared for the USDA Forest Service by Syracuse Environmental Research Associates, Inc. (SERA 2011), and is incorporated into this assessment by reference. Section 2 – Hazard Identification

Triclopyr is a growth-regulating herbicide for the control of woody and broadleaf perennial plants. It has a half-life in the soil of 30 to 90 days, and degrades to carbon dioxide and organic matter through microbial action. Triclopyr has a moderate to low solubility in water and normally binds to clay and organic matter, so it’s potential to contaminate ground water is slight. The commercial formulation of triclopyr BEE is the formulation proposed for this project due to its effectiveness in controlling woody plants (Dow AgroSciences 2009, Kwasny 2013).

Application Methods

Apply solution with a low-volume applicator such as backpack sprayer with hand-held wand, spray bottle, or wick (wipe-on) applicator. These methods allow close-up direct application to the exposed cut stump preventing drift or droplets from drifting onto non-target plants and soil. Treatment will focus on the cambium or sapwood (xylem) inside the bark around the entire circumference. If the bark has been ripped off the stump/stubble, then treat around the ripped area as well as the top of the stump/stubble. The application method modeled in the SERA risk assessment and the project specific EXCEL worksheets (Strategic Community Fuelbreak Improvement Project – Excel worksheets - Human Health and Ecological Risk Assessment 2013) are for foliar application. Primary difference between foliar and cut-stump applications is that cut-stump applications would decrease the risk or become very improbable of certain foliar application scenarios such as contaminating nearby grasses, broadleaf foliage or fruit. Hazards Associated with Triclopyr

Laboratory mammalian species are often used as “surrogates” for wildlife species. The use of a few species of experimental mammalian species as surrogates for a large number of diverse wildlife species is an uncertain process; nonetheless there does not appear to be any systematic differences among mammalian species, when comparable toxicity values are expressed in mg/kg/day. While the available data is limited, this apparent consistency among species diminishes concern with the use of data based on a limited subset of species to characterize risk for terrestrial mammals in general. Mammals Several standard toxicity studies in experimental mammals were conducted and submitted to the Environmental Protection Agency (EPA) as part of the registration process for triclopyr. In addition, toxicity studies involving the exposure of mammals to triclopyr were conducted and are published in the available literature. All of these studies, which are used in the human health risk

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assessment to identify the potential toxic hazards associated with exposures to triclopyr, can also be used to identify potential toxic effects in wildlife mammalian species. In experimental mammals exposed to triclopyr, the kidney appears to be the primary target tissue. In the absence of data on most wildlife species, it seems reasonable to assume that the kidney will also be the primary target organ in mammalian wildlife. An assessment of the potential toxic hazards associated with the exposures of wildlife mammalian species to triclopyr is based on the same studies on experimental mammals that are used in the human health risk assessment. Studies regarding histopathology and clinical chemistry data on triclopyr suggest that the liver and kidney are the primary target organs. Like any chemical, triclopyr at sufficiently high exposure levels can cause toxic effects, including death. Nonetheless, triclopyr has a low order of acute lethal potency. Although triclopyr causes developmental effects only at doses that cause maternal toxicity, reproductive effects are obviously an endpoint of concern to both human health and ecological risk assessments and the quantitative risk assessment for mammalian wildlife is based on the same data as used in the human health risk assessment. Allometric relationships, which are used extensively in the exposure assessment for triclopyr, are sometimes apparent for sensitivity among species. In the biological sciences, allometry is the study of the relationship of body size or mass to various anatomical, physiological, or pharmacological parameters. Both the NOAELs and LOAELs suggest that these values decrease with increasing body weight—i.e., larger animals are more sensitive than small animals (Serra, 2009). Maximum Tolerated Dose (MTD) is an estimate of a dose that may represent a threshold for a response. To examine this possibility, typical body weights for mice, rats, and dogs are taken from U.S. EPA/ORD (1988), which provides representative average body weights for mice, rats, and dogs in both subchronic and chronic studies. These body weights along with the geometric means of the NOAELs and LOAELs were fit into the general allometric equations. Birds For birds, the most relevant data for this risk assessment are the standard dietary and bird reproduction studies required for registration as well as the acute oral LD50 studies. Toxicity data, available only on a few avian species, do not indicate substantial or systematic differences in species sensitivities to triclopyr. As in experimental mammals, triclopyr has been tested for reproductive effects in birds. The NOAEL of 126 mg a.e./kg bw in quail is used as the NOAEL for acute exposures in all birds. The reproductive NOAEL of 7.5 mg/kg bw/day is applied to all species of birds to assess the consequences of longer-term exposures to triclopyr. Information on the toxicity of triclopyr to birds is summarized in (SERA, 2011, Appendix 3). In avian toxicity studies, the acute LD50 values for gavage administration of triclopyr range from 529 to 1698 mg a.e./kg . As also summarized in SERA there are several acute dietary studies that have been conducted with triclopyr acid, triclopyr TEA, and triclopyr BEE (Garlon 4).

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Based on the studies in mallards and quail, U.S. EPA/OPP (1998) classifies triclopyr acid as being practically non-toxic to slightly toxic to birds and triclopyr TEA and triclopyr BEE (Garlon 4) as practically non-toxic to birds. Although passerines may be more sensitive than the standard test species, the classification scheme used by U.S. EPA/OPP results in a designation of slightly toxic based on the dietary LC50 of 1383 ppm a.e. Again from SERA 2011, are two field studies, Boren et al. (1993) and Schulz et al. (1992), which involve triclopyr applications in the range of application rates that may be used in Forest Service programs. Neither study indicates that the triclopyr applications caused adverse effects in birds. TCP The SERA risk assessment relies on the EPA review of the toxicity of TCP. Neither the data in the EPA review nor the data found in the open literature permits an assessment of species sensitivity to TCP for mammals. Consequently, the NOAELs of 25 mg/kg bw for acute exposures and 12 mg/kg bw for longer-term exposures are used to characterize risks to all mammalian receptors with exposures to TCP. Relatively little information is available on the toxicity of TCP to birds. No chronic toxicity studies are available and thus no dose-response assessment for chronic effects in birds can be proposed. The acute gavage LD50 for TCP in bobwhite quail is >2000 mg/kg bw (Campbell et al. 1990). Based on this index of toxicity, TCP would be regarded as less toxic than triclopyr acid, triclopyr TEA or triclopyr BEE. Terrestrial Invertebrates The honey bee is the standard test organism for assessing the potential effects of pesticides on terrestrial invertebrates. Acute contact toxicity studies in honey bees are available on triclopyr acid and triclopyr TEA (U.S. EPA/OPP 1998a). In both bioassays, the LD50 values were greater than 100 μg/bee. Based on these results, U.S. EPA/OPP (1998) classifies triclopyr as practically non-toxic to bees. U.S. EPA/OPP (2009) summarizes a more recent study on the toxicity of triclopyr BEE to honey bees in which the contact LD50 is reported as >72 μg/bee. One chronic bioassay is available in earthworms (Hayward 2000). In this study, earthworms were exposed to Garlon 4 at concentrations of about 1.4 ppm a.e. or 6.9 ppm a.e. for a total of 56 days – i.e., a 28 day exposure for adults followed by a 28 day exposure for juveniles. No adverse effects were noted on reproduction or growth at either concentration. These results are consistent with the study by Potter et al. (1990) which assayed for the impact of triclopyr (Garlon 3A) to earthworms and other invertebrates at an application rate of 0.56 kg a.i./ha (≈0.36 lb 7 a.e./acre) to turf plots. There was no significant reduction in mixed earthworm populations, mites, springtails, or ants in turf and soil core samples.

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Terrestrial Plants Triclopyr is absorbed by foliage and translocated to roots. Triclopyr and other pyridinecarboxylic acid herbicides, such as picloram, mimic indole auxin plant growth hormones and cause uncontrolled growth in plants. At sufficiently high levels of exposure, the abnormal growth is so severe that vital functions cannot be maintained and the plant dies. Pine, an important group of nontarget plant species, tends to be tolerant to triclopyr exposures after fall dormancy but more sensitive to triclopyr during the spring and summer (Radosevich et al. 1977). The sunflower (a dicot) is the most sensitive species for both TEA (EC25 = 0.005 lb a.e./acre) and triclopyr BEE (EC25 = 10 g a.i./ha) (≈0.0064 lb a.e./acre). For both triclopyr TEA and BEE, the monocots, like wheat and oats, are much more tolerant with EC25 values in excess of about 0.3 lb a.e./acre. The study by Newmaster et al. (1999) suggests that some bryophytes and lichens may be sensitive to long-term effects after triclopyr exposure. The EC50 for a decrease in relative abundance 6 months after application is about 1 kg/ha or 0.89 lbs/acre (Newmaster et al. 1999, Figure 3, p. 1105). Also, changes in relative abundance were apparent at 6 weeks after application (Newmaster et al. 1999, Figure 7, p. 1108). The statistical analyses provided by Newmaster et al. (1999) involve the use of a non-threshold polynomial model. While this may be a reasonable method for quantifying effects among the two herbicides studied (glyphosate and triclopyr), this may be less appropriate for risk assessment. Nonetheless, this study does appear to present a plausible basis for concern that exposure to substantial triclopyr drift may have long- term impacts on bryophyte and lichen communities. Terrestrial Microorganisms Several diverse studies are available on the toxicity of triclopyr to terrestrial microorganisms. None of these studies suggests that triclopyr is likely to have an impact on soil microorganisms. Hallbom and Bergman (1979) noted no effect of triclopyr on nitrogen fixation of lichen at 100 ppm; however, the reporting units are not clear. Section 3 – Exposure Assessment As part of a series of Human Health and Ecological Risk Assessments prepared for the USDA/Forest Service between 1998 and now, Syracuse Environmental Research Associates (SERA) developed EXCEL worksheets as an internal tool for calculating exposures used in ecological risk assessments. Because of the need to encompass many different types of exposure as well as the need to express the uncertainties in the assessment, those worksheets involve numerous scenarios that encompass a wide range of field conditions. Calculations are based on research and modeling referenced in the Triclopyr Human Health and Ecological Risk Assessments Final Report, prepared for the USDA Forest Service by Syracuse Environmental Research Associates, Inc. (SERA 2011).

SERA have not developed a specific EXCEL worksheet for applying triclopyr on cut-stumps. For this assessment, we selected the worksheet developed for foliar application of triclopyr with a back-pack sprayer. Primary difference is foliar versus cut-stump application, therefore

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potential exposure estimates will be significantly lower than estimates provided in this risk assessment.

Exposure assessments for mammals and birds are summarized in Tables 4&5. The highest exposures are associated with the consumption of contaminated grasses, and the lowest exposures are associated with the consumption of contaminated water. This is a common pattern for pesticides applied to vegetation. Terrestrial Vertebrates For dermal exposure, the units of measure usually are expressed in mg of agent per cm² of surface area of the organism and abbreviated as mg/cm². In estimating dose, however, a distinction is made between the exposure dose and the absorbed dose. The exposure dose is the amount of material on the organism (i.e., the product of the residue level in mg/cm² and the amount of surface area exposed), which can be expressed either as mg/organism or mg/kg body weight. The absorbed dose is the proportion of the exposure dose that is actually taken in or absorbed by the animal. For terrestrial applications of triclopyr, mammals and birds might be exposed to any applied pesticide from direct spray, the ingestion of contaminated media (e.g., vegetation, prey species, or water), grooming activities, or indirect contact with contaminated vegetation. In the exposure assessments for the ecological risk assessment, estimates of oral exposure to mammals and birds are expressed in the same units as the available toxicity data. As in the human health risk assessment, these units are usually expressed as mg of agent per kg of body weight and abbreviated as mg/kg for terrestrial animals. Unless otherwise specified, all exposure estimates for triclopyr are expressed as mg a.e. (acid equivalents). Because of the relationship of body weight to surface area as well as to the consumption of food and water, small animals will generally receive a higher dose, in terms of mg/kg body weight, relative to large animals, for a given type of exposure. Thus, most Forest Service risk assessments focus on the small mammal. Complication with triclopyr is that larger mammals appear to be substantially more sensitive than smaller mammals to triclopyr (i.e., evidence adverse effects at lower doses). In order to more fully consider the offsetting factors of exposure and sensitivity in large and small mammals, the exposure assessment for mammals is elaborated to consider five nontarget mammals: small (20 g) and medium (400 g) sized omnivores, a 5 kg canid, a 70 kg herbivore, and a 70 kg carnivore. No remarkable differences in sensitivities among birds are apparent. Consequently, only four standard avian receptors are considered: a 10 g passerine, a 640 g predatory bird, a 2.4 kg piscivorous bird, and a 4 kg herbivorous bird. Triclopyr BEE hydrolyzes to triclopyr acid and 2-butoxyethanol. 3,5,6-Trichloro-2-pyridinol (TCP) is the major metabolite of triclopyr in both mammals and in the environment. 2-butonxyethanol completely degrades to CO2 very rapidly in the environment, thus the uncertainty associated with the toxicity of 2-butoxyethanol has relatively little impact on this risk assessment. This is not the case for TCP however. Because triclopyr and TCP persist in the environment much longer, they are included in this risk assessment.

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No toxicity data are available on terrestrial phase amphibians. Consequently, exposure assessments for these terrestrial vertebrates are not developed. Direct Spray The unintentional direct spray of wildlife during broadcast applications of a pesticide is a credible exposure scenario. In a scenario involving exposure to direct spray, the amount of pesticide absorbed depends on the application rate, the surface area of the organism, and the rate of absorption. Dermal Contact with Contaminated Vegetation The only approach for estimating the potential significance of dermal contact with contaminated vegetation is to assume a relationship between the application rate and dislodgeable foliar residue. Unlike the human health risk assessment, in which estimates of transfer rates are available, there are no transfer rates available for wildlife species. Wildlife species are more likely than humans to spend long periods of time in contact with contaminated vegetation. It is reasonable to assume that for prolonged exposures, equilibrium may be reached between pesticide levels on the skin, rates of dermal absorption, and pesticide levels on contaminated vegetation. Since data regarding the kinetics of this process are not available, a quantitative assessment for this exposure scenario cannot be made in the ecological risk assessment. For triclopyr, as well as most other herbicides and insecticides applied in broadcast applications, the failure to quantify exposures associated with dermal contact adds relatively little uncertainty to the risk assessment, because the dominant route of exposure will be the consumption of contaminated vegetation. Ingestion of Contaminated Vegetation or Prey In cut-stump applications, with the use of a low-volume sprayer or wick applicator, it is unlikely that there will be much overspray to contaminate food items consumed by mammals and birds. Exposure assessments for the consumption of contaminated vegetation have been developed for mammals and birds. Both acute and chronic exposure scenarios for mammals and birds have been developed for the consumption of contaminated vegetation and are summarized in Tables 3&5. Fruit and short grass are the food items that comprise the commodities with the lowest residue rates (fruit) and the highest residue rates (short grass). These food items are not necessarily intended to be interpreted literally; instead, they are intended to encompass the range of triclopyr and TCP concentrations in food items likely to be consumed by a variety of mammals and birds. For both the acute and chronic exposure scenarios, the assumption is made that 100% of the diet is contaminated. This may not be a realistic assumption for some acute exposures and will probably be a rare event in chronic exposures—i.e., animals may move in and out of the treated areas.

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The estimated food consumption rates by various species of mammals and birds are based on field metabolic rates (kcal/day), which, in turn, are based on the adaptation of estimates from Nagy (1987) by the U.S. EPA/OPP in 1993. These allometric relationships account for much of the variability in food consumption among mammals and birds. There is, however, residual variability, which is remarkably constant among different groups of organism (Nagy 1987, Table 3). As discussed further by Nagy (2005), the estimates from the allometric relationships may differ from actual field metabolic rates by about ±70%. Consequently, in all worksheets involving the use of the allometric equations for field metabolic rates, the lower bound is taken as 30% of the estimate and the upper bound is taken as 170% of the estimate. Along with the exposure scenarios for the consumption of contaminated vegetation, similar sets of exposure scenarios are provided for the consumption of small mammals by either a predatory mammal or a predatory bird as well as the consumption of contaminated insects by a small mammal, a 400 g mammal, and a small bird. Terrestrial Invertebrates Honeybees are used as a surrogate for other terrestrial insects, and honeybee exposure levels associated with broadcast applications are modeled as a simple physical process based on the application rate and surface area of the bee. The amount of a pesticide deposited on a bee during or shortly after application depends on how close the bee is to the application site as well as foliar interception of the spray prior to deposition on the bee. The available toxicity data on terrestrial invertebrates do not support the derivation of separate toxicity values for different groups of terrestrial insects. Thus, the honeybee is used as a surrogate for other insect species. Ingestion of contaminated Vegetation or Prey Like terrestrial mammals and birds, terrestrial invertebrates may be exposed to triclopyr through the consumption of contaminated vegetation or contaminated prey. An estimate of food consumption is necessary to calculate a dose level for a foraging herbivorous insect. Insect food consumption varies greatly, depending on the caloric requirements in a given life stage or activity of the insect and the caloric value of the food to be consumed. The derivation of consumption values for specific species, life stages, activities, and food items is beyond the scope of the current analysis. Details concerning estimated exposure levels for the consumption of contaminated vegetation by herbivorous insects are provided in Tables 7-11. Terrestrial Plants Generally, the primary hazard to nontarget terrestrial plants associated with this project is unintended direct deposition. Unintended direct spray will result in an exposure level equivalent to the application rate. It is plausible that some nontarget plants immediately adjacent to the application spot could be sprayed directly. Off-site drift is more or less a physical process that depends primarily on droplet size and meteorological conditions rather than specific properties of

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the compound being sprayed. Due to the viscosity of the solution, design criteria, and basal application, off-site drift is not considered in this assessment. Triclopyr BEE is adsorbed by clay particles and organic matter particles in the soil. Maximum soil penetration is 24 inches, and this only occurs in sandy soils, cool temperatures, and heavy rainfall. In relatively arid locations, the maximum penetration is estimated at 4-8 inches (SERA 2011). Exposures to terrestrial plants associated with runoff from the treated site to adjacent untreated sites are summarized in Table 14 for foliar spraying. Section 4 – Dose-Response Assessment The purpose of the dose-response assessment is to describe the degree or severity of risk as a function of dose. In ecological risk assessment, the focus is on a population or community rather than an individual. Thus, the use of uncertainty factors is less common and the general methods for dose-response assessment are less conservative. For the most part, the toxicity values are either experimental NOAELs (mg/kg bw) or NOAECs (mg/L). A minor exception to the use of NOAELs involves the use of an indeterminate LD50 for honeybees. Honeybees are not sensitive to triclopyr, and the use of an indeterminate LD50 for honeybees has no impact on the characterization of risk. The dose-response assessments for triclopyr BEE in terrestrial animals are relatively standard and uncomplicated, except for mammals. The available toxicity data on triclopyr indicate that larger mammals are substantially more sensitive than smaller mammals, and this relationship can be characterized quantatively. Mammals Typically, the dose-response assessment for mammalian wildlife adopts a reference dose (RfDs), similar to human health risk assessments. An RfD is basically defined as a level of exposure that will not result in any observable adverse effects in an individual (NOAELs). NOAELs are based on studies in rats. This risk assessment relies on the EPA review of the toxicity of TCP. Neither the data in the EPA review nor the data found in the open literature permits an assessment of species sensitivity to TCP for mammals. Consequently, the NOAELs of 25 mg/kg bw for acute exposures and 12 mg/kg bw for longer-term exposures are used to characterize risks to all mammalian receptors with exposures to TCP. Birds The toxicity data, available only on a few avian species, do not indicate substantial or systematic differences in species sensitivities to triclopyr. The lowest acute NOAEL for signs of toxicity is 126 mg a.e./kg bw/day in Northern bobwhite quail after gavage exposure to triclopyr BEE (Campbell and Lynn 1991). The Holmes et al. (1994) study suggests that zebra finches (small passerines) may be somewhat more sensitive than game birds or waterfowl. Thus, the NOAEL of 126 mg a.e./kg bw in quail is used as a NOAEL for acute exposures in all birds. This is an admittedly conservative approach because gavage dosing – i.e., the route of the 126 mg a.e./kg bw/day dose – typically leads to severe effects than equivalent dietary dosing.

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The NOAEL in bobwhites is supported by the longer-term NOAEL of 9.7 mg a.e./kg bw in zebra finches reported by Holmes et al. (1994). The reproductive NOAEL of 7.5 mg/kg bw/day is applied to all species of birds to assess the consequences of longer-term exposures to triclopyr. Relatively little information is available on the toxicity of TCP to birds. No chronic toxicity studies are available and thus no dose-response assessment for chronic effects in birds can be proposed. A single dose gavage study in quail reports an NOAEL of 125 mg/kg bw (Campbell et al. 1990) but an acute 5-day dietary study reports a LOAEL based on decreased body weight grain and food consumption of about 116 mg/kg bw/day (Long et al. 1990). The LOAEL of 116 mg/kg bw/day will be used directly and the interpretation of the resulting HQs is discussed in the risk characterization Terrestrial Invertebrates Most ecological risk assessments conducted by the U.S. EPA/OPP use the honeybee as a surrogate for other terrestrial insects. U.S. EPA/OPP (2009, Table 4-3, p. 76) uses an indefinite LD50 of >72 μg a.e./bee for the honeybee. Typical body weights for worker bees range from 81 to 151 mg (Winston 1987, p. 54). Taking 116 mg as an average body weight, a dose of 72 μg/bee corresponds to about 620 mg/kg bw. A dose-response assessment of the toxicity of TCP to terrestrial invertebrates cannot be proposed due to the lack of pertinent data. Terrestrial Plants For triclopyr BEE formulations, as for most herbicides, there are adequate data from which to derive toxicity values for sensitive and tolerant species of terrestrial plants. The available studies include assays for both foliar spray, which are used to assess effects associated with direct spray, wind erosion, or drift, as well as seedling emergence assays, which are used to assess soil exposures associated with herbicide runoff to an untreated field. The lowest NOAEC is 0.0028 lb a.e./acre in sunflowers, which is used to characterize risks to sensitive species of terrestrial plants. Monocots are much more tolerant to both types of formulations. The highest reported NOAEC is about 2 lb a.e./acre (2.242 kg/ha) in oats and is used to assess risks to tolerant species of terrestrial plants. A dose-response assessment of the phytotoxicity of TCP is not provided because no data is available on the toxicity of TCP to terrestrial plants. Overview Overviews of the toxicity values for terrestrial organisms are given in Table 1 for triclopyr BEE, and Table 2 for TCP. In the summary tables, doses or exposures to triclopyr BEE are expressed in units of mg a.e./kg bw or lb a.e./acre for plants. All toxicity values for TCP are expressed as mg/kg bw (i.e., mg TCP/kg bw) or mg/L (i.e., mg TCP/L).

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Table: 1: Triclopyr BEE, Toxicity Values for Terrestrial Organisms Group/Duration Endpoint Toxicity Value¹ Organism

Terrestrial Animals Acute Small Mammals² Estimated acute NOAEL 440 mg/kg bw Medium (400g) Mammals Acute NOAEL 100 mg/kg bw Canines² Estimated acute NOAEL 20 mg/kg bw Large Herbivorous Mammals² Estimated acute NOAEL 8 mg/kg bw Birds Gavage NOAEL 126 mg/kg bw Honey Bee (oral) Indefinite LD50 620 mg/kg bw Herbivorous Insect Indefinite LD50 620 mg/kg bw Longer Term³ Small (20g) Mammals² Estimated chronic NOAEL 22 mg/kg bw Medium (400g) Mammals Chronic NOAEL 5 mg/kg bw Canines² Estimated chronic NOAEL 1 mg/kg bw Large Herbivorous Mammals² Estimated chronic NOAEL 0.4 mg/kg bw Bird Reproductive NOAEL 7.5 mg/kg bw

Terrestrial Plants Soil Sensitive Seedling emergence NOAEC 0.022 lb/acre Tolerant Seedling emergence NOAEC 2.0 lb/acre Foliar Sensitive Foliar spray NOAEC 0.0028 lb/acre Tolerant Foliar spray NOAEC 2.0 lb/acre

¹ All toxicity values for triclopyr BEE expressed as mg a.e./kg bw for animals and lb a.e./acre for plants ² Acute and chronic toxicity values based on allometric relationships ³ Note that the longer-term toxicity values are based on triclopyr acid, and not triclopyr BEE as triclopyr BEE will breakdown in the environment to triclopyr acid in a relatively short period of time Table 2: Trichloro-2-pyridinol (TCP), Toxicity Values for Terrestrial Organisms Group/Duration Endpoint Toxicity Value Organism

Terrestrial Animals Acute Non-canine Mammals Acute NOAEL 25 mg/kg bw Canine Mammals Acute NOAEL 25 mg/kg bw Birds Acute LOAEL 116 Honey Bee (oral) No data N/A Longer-term Small Mammal Chronic NOAEL 12 mg/kg bw Large Mammal Chronic NOAEL 12 mg/kg bw Bird No data N/A

Terrestrial Plants Soil Sensitive No data N/A Tolerant No data N/A Foliar Sensitive No data N/A Tolerant No data N/A

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Section 5 – Risk Characterization Overview Conceptually, risk characterization is simply the process of comparing the exposure assessment to the dose-response assessment. In the human health risk assessment, the defined effect level is almost always the reference dose (RfD), and the ratio of the exposure to the reference dose is referred to as the hazard quotient (HQ). In the ecological risk assessments, the defined effect level may be an NOEC or a risk level. The risk level, in turn, may be a lethal dose (e.g., LD50 or some other response level such as an LD25) or a dose causing some risk of a non- lethal effect (e.g., an LD50 or LD25). For aquatic organisms and for some terrestrial organisms for which exposure is characterized by a concentration rather than a dose, the defined risk levels may be expressed as a lethal concentration (LC50 or some other response level) or a sub lethal concentration that leads to some effect (e.g., an EC50). In general, the Forest Service prefers to use NOAEL or NOEC values in risk characterizations. This risk assessment highlights (pink) those scenarios that represent a high risk and as a result, design criteria and/or mitigation measures are developed to reduce the chances of those scenarios from happening. The application of any effective herbicide is likely to alter vegetation, the secondary effects of which may include changes to food availability and quality of habitat for both terrestrial and aquatic organisms. These secondary effects are likely to vary over time and vary among different species of mammals. Mammals Contaminated Vegetation A summary of Hazard Quotients for the mammals are displayed in Table 4. The risk characterization for mammals identifies HQs >1 at the upper bound of estimated exposure scenarios associated with the consumption of contaminated vegetation. As with other similar tables given in this risk assessment, these HQs apply to foliar spraying (versus our proposal for cut-stump application) with the unit application rate of 0.5 lb a.e./acre. The high HQs for mammals consuming contaminated vegetation suggest that triclopyr applications may cause adverse effects in mammalian wildlife populations. By treating the cut-stump and basal area of the target plants, practically eliminates the likelihood of large mammals consuming contaminated vegetation. In other words, the quantitative risk characterization must be tempered by actual proposed application method of basal/cut-stump treatments versus foliar spray treatments used in the SERA 2011 worksheets. TCP In SERA (2011), the only TCP exposure scenarios for mammals that highlight a level of concern involve the consumption of contaminated vegetation with a foliar application at the rate of 1 lb a.e./acre. By treating the cut-stump and basal area of the target plants, practically eliminates the likelihood of large mammals consuming contaminated vegetation. The quantitative risk characterization must be tempered by actual proposed application rate and method of basal/cut-stump treatments versus foliar spray treatments used in the SERA worksheets.

13

As with triclopyr, the relationship of the NOAEL to the LOAEL suggests that HQs of about 4 could be associated with adverse effects which could range from subclinical changes in blood chemistry to birth defects. The upper bound HQs would mostly likely reflect extreme exposures which might occur only rarely (Table 13). Birds The risk characterization for birds is essentially identical to that for mammals except for differences in the impact of body size on apparent risk. For birds, there is no clear indication of systematic differences in sensitivity with body size. Thus, smaller birds have somewhat higher HQs than larger birds, because smaller birds will consume more food per unit body weight than will larger birds. As with mammals, the upper bound HQs (Table 6) for exposure scenarios associated with the consumption of contaminated vegetation are substantial at an application rate of 0.5 lb a.e./acre and will increase linearly with the application rate. Based on the HQs, adverse effects in birds could be anticipated. TCP Because no chronic data are available on the toxicity of TCP to birds, risks associated with chronic exposure to TCP residues cannot be characterized quantitatively. For acute exposures, risks are characterized based on a LOAEL of 116 mg/kg bw rather than a NOAEL. The LOAEL of 116 mg/kg bw is based only on decreases in body weight gain and food consumption in which no overt signs of toxicity were observed (Long et al. 1990) and the toxicological significance of this LOAEL is questionable. Terrestrial Invertebrates The quantitative risk characterization for terrestrial invertebrates is limited by the available toxicity data. The toxicity value used to develop HQs is an indeterminate LD50 of >620 mg a.e./kg bw. This dose is used to develop HQs for direct spray and the consumption of contaminated vegetation. All HQs are below the level of concern at the unit application rate of 0.5 lb a.e./acre (Table 12). While HQs are not typically derived for soil invertebrates, there is little indication that concentrations of triclopyr in soil are likely to adversely affect soil invertebrates. The peak concentrations of triclopyr that are likely to occur in the upper 12 inches of soil following applications of triclopyr are about 0.24 ppm a.e. following an application of 1 lb a.e./acre. Proposed concentrations could exceed this at the base of target plants; at the maximum application rate of 9 lb a.e./acre, the maximum expected concentrations would be about 2.2 ppm a.e. This maximum concentration is a factor of about 3 below the chronic NOAEC for earthworms in the study by (Hayward 2000).

14

Terrestrial Plants Quantitative risk characterizations for terrestrial plants are given for several types of exposures: runoff (Table 14), direct spray and drift (Table 15), and exposures to contaminated soils via wind erosion (Table 16). As with all effective herbicides, a direct spray of triclopyr will adversely affect most plants. Tolerant species of plants, such as grasses, however, might not be killed or even adversely affected. For sensitive plant species, drift will be an issue, and the hazards associated with drift will vary with the application method; being greatest for aerial application lesser for backpack foliar application, and least for cut-stump application. Drift estimates used in the current risk assessment are generic, while actual drift during a field application could vary substantially based on site-specific conditions, i.e. viscosity, droplet size, wind, application method, etc. Terrestrial Microorganisms The potential for substantial effects on soil microorganisms appears to be low. Laboratory bioassays conducted in artificial growth media suggest a very high degree of variability in the response of soil bacteria and fungi to triclopyr with NOAELs of up to 1000 ppm in some species and growth inhibition at concentrations as low as 0.1 ppm in other species. If the laboratory bioassays were used to characterize risks to terrestrial microorganisms, transient inhibition in the growth of some bacteria or fungi might be expected. This inhibition could result in a shift in the population structure of microbial soil communities, but substantial impacts on soil, including gross changes in capacity of soil to support vegetation, do not seem plausible. This assessment is consistent with the field experience involving the use of triclopyr to manage vegetation. Amphibians Acute risks to amphibians following applications of triclopyr BEE would reach a level of concern at an application rate of about 3 lbs a.e./acre, based on potential peak exposures to triclopyr BEE. A formal quantitative risk characterization for longer-term exposures of amphibians to triclopyr BEE is not developed because of the lack of adequate chronic toxicity studies on amphibians. Risks associated with the potential impact of TCP on amphibians are not assessed because of the lack of data on the toxicity of TCP to amphibians. Reptiles and Amphibians (Terrestrial Phase) The toxicity of triclopyr or TCP to reptiles or terrestrial phase amphibians is not addressed in the available literature. Information about the toxicity of triclopyr to terrestrial phase amphibians is not available the open literature or in the studies submitted to the U.S. EPA. More specifically, toxicity data involving the exposure of terrestrial phase amphibians to triclopyr are not included in either the recent EPA ecological risk assessment on triclopyr (U.S. EPA/OPP 2009a) or in the database on amphibian and reptile toxicity data maintained by the Canadian National Wildlife Research Centre (Pauli et al. 2000).

15

Aquatic Organisms Exposures to aquatic organisms are not displayed because none of the treatment sites are within a ¼ mile of surface water.

16

Table 3. Summary of Exposure Assessments for the Mammals G01a

Application Rate: 0.5 lb a.e./acre

Scenario Receptor mg/kg/day or mg/kg/event

Central Lower Upper

Accidental Acute Exposures Direct Spray first-order absorption Small mammal (20g) 8.69E-01 3.44E-01 2.14E+00

100% absorption Small mammal (20g) 1.21E+01 6.06E+00 2.42E+01 Contaminated Water

Spill Small mammal (20g) 3.99E-01 6.65E-02 1.39E+00 Spill Larger Mammal (400g) 2.96E-01 4.93E-02 1.03+00 Spill Canid (5 kg) 2.30E-01 3.83E-02 7.98E-01 Spill Large Mammal (70g) 1.76E-01 2.94E-02 6.13E-01

Consumption of contaminated Fish Spill Large Mammalian Carnivore (70

kg) 6.69E-02 1.12E-03 1.32E+00

Spill Canid (5 kg) 9.63E-02 1.61E-03 1.90E+00

Non-Accidental Acute Exposures Contaminated Fruit [Lowest Residue Rates]

Small mammal (20g) 7.94E+00 1.09E+00 2.89E+01 Larger Mammal (400g) 1.81E+00 2.49E-01 6.61E+00 Large Mammal (70g) 1.03E+00 1.42E-01 3.76E+00

Contaminated Broadleaf Foliage Small mammal (20g) 3.81E+01 3.81E+00 1.94E+02 Larger Mammal (400g) 8.70E+00 8.70E-01 4.44E+01 Large Mammal (70g) 4.96E+00 4.96E-01 2.53E+01

Contaminated Tall Grass Small mammal (20g) 3.05E+01 3.05E+00 1.58E+02 Larger Mammal (400g) 6.96E+00 6.96E-01 3.62E+01 Large Mammal (70g) 3.96E+00 3.96E-01 2.06E+01

Contaminated Short Grass [Highest Residue Rate] Small mammal (20g) 7.20E+01 7.62E+00 3.45E+02 Larger Mammal (400g) 1.64E+01 1.74E+00 7.89E+01 Large Mammal 9.36E+00 9.91E-01 4.49E+01

Contaminated Water Small mammal (20g) 2.93E-05 1.10E-08 2.20E-03 Larger Mammal (400g) 2.17E-05 8.14E-09 1.63E-03 Canid (5 kg) 1.69E-05 6.32E-09 1.26E-03 Large Mammal (70g) 1.29E-05 4.85E-09 9.71E-04 Contaminated Insects Small mammal (20g) 9.63E+00 9.63E-01 4.91E+01 Larger Mammal (400g) 2.20E+00 2.20E-01 1.12E+01 Consumption of small mammal (after direct spray) by predator Canid (5 kg) 1.36E+00 4.07E-01 2.31E+00 Consumption of contaminated Fish Large Mammalian Carnivore (70

kg) 4.91E-06 1.84E-10 2.09E-03

Canid (5 kg) 7.07E-06 2.65E-10 3.00E-03

Chronic/Longer Term Exposures Contaminated Fruit [Lowest Residue Rates]

Small mammal (20g) 3.09E+00 2.81E-01 1.95E+01 Larger Mammal (400g) 7.05E-01 6.43E-02 4.44E+00

17

Large Mammal (70g) 4.02E-01 3.66E-02 2.53E+00 Contaminated Broadleaf Foliage

Small mammal (20g) 2.50E+00 6.72E-02 4.60E+01 Larger Mammal (400g) 5.72E-01 1.53E-02 1.05E+01 Large Mammal (70g) 3.26E-01 8.74E-03 5.98E+00

Contaminated Tall Grass Small mammal (20g) 2.00E+00 5.37E-02 3.75E+01 Larger Mammal (400g) 4.57E-01 1.23E-02 8.56E+00 Large Mammal 2.61E-01 6.99E-03 4.87E+00

Contaminated Short Grass [Highest Residue Rate] Small mammal (20g) 4.73E+00 1.34E-01 8.18E+01 Larger Mammal (400g) 1.08E+00 3.07E-02 1.87E+01 Large Mammal (70g) 6.15E-01 1.75E-02 1.06E+01

Contaminated Water Small mammal (20g) 1.46E-07 1.46E-12 5.12E-06 Larger Mammal (400g) 1.08E-07 1.08E-12 3.80E-06 Canid (5 kg) 8.43E-08 8.43E-13 2.95E-06 Large Mammal (70g) 6.47E-08 6.47E-13 2.27E-06 Consumption of contaminated Fish Large Mammalian Carnivore (70

kg) 2.46E-08 2.46E-14 4.87E-06

Canid (5 kg) 3.53E-08 3.53E-14 7.01E-06

18

Table 4. Summary of Hazard Quotients (Toxicity) for the Mammals G01V6Mam


Scenario Receptor Hazard Quotients

Central Lower Upper

Accidental Acute Exposures Direct Spray

first-order absorption Small mammal (20g) 2E-03 8E-04 5E-03 100% absorption Small mammal (20g) 3E-02 1E-02 6E-02

Contaminated Water Spill Small mammal (20g) 9E-04 2E-04 3E-03 Spill Larger Mammal (400g) 3E-03 5E-04 1E-02 Spill Canid (5 kg) 1E-02 2E-03 4E-02 Spill Large Mammal (70g) 2E-02 4E-03 8E-02

Consumption of contaminated Fish Spill Large Mammalian Carnivore (70

kg) 8E-03 1E-04 0.2

Spill Canid (5 kg) 5E-03 8E-05 9E-02

Non-Accidental Acute Exposures Contaminated Fruit [Lowest Residue Rates]

Small mammal (20g) 2E-02 2E-03 7E-02 Larger Mammal (400g) 2E-02 2E-03 7E-02 Large Mammal (70g) 0.1 2E-02 0.5

Contaminated Broadleaf Foliage Small mammal (20g) 9E-02 9E-03 0.4 Larger Mammal (400g) 9E-02 9E-03 0.4 Large Mammal (70g) 0.6 6E-02 3

Contaminated Tall Grass Small mammal (20g) 7E-02 7E-03 0.4 Larger Mammal (400g) 7E-02 7E-03 0.4 Large Mammal (70g) 0.5 5E-02 3

Contaminated Short Grass [Highest Residue Rate] Small mammal (20g) 0.2 2E-02 0.8 Larger Mammal (400g) 0.2 2E-02 0.8 Large Mammal 1.2 0.1 6

Contaminated Water Small mammal (20g) 7E-08 2E-11 5E-06 Larger Mammal (400g) 2E-07 8E-11 2E-05 Canid (5 kg) 8E-07 3E-10 6E-05 Large Mammal (70g) 2E-06 6E-10 1E-04 Contaminated Insects Small mammal (20g) 2E-02 2E-03 0.1 Larger Mammal (400g) 2E-02 2E-03 0.1 Consumption of small mammal (after direct spray) by predator Canid (5 kg) 7E-02 2E-02 0.1 Consumption of contaminated Fish Large Mammalian Carnivore (70

kg) 6E-07 2E-11 3E-04

Canid (5 kg) 4E-07 1E-11 2E-04

Chronic/Longer Term Exposures Contaminated Fruit [Lowest Residue Rates]

Small mammal (20g) 0.1 1E-02 0.9 Larger Mammal (400g) 0.1 1E-02 0.9

19

Large Mammal (70g) 1.0 9E-02 6 Contaminated Broadleaf Foliage

Small mammal (20g) 0.1 3E-03 2 Larger Mammal (400g) 0.1 3E-03 2 Large Mammal (70g) 0.8 2E-02 15

Contaminated Tall Grass Small mammal (20g) 9E-02 2E-03 1.7 Larger Mammal (400g) 9E-02 2E-03 1.7 Large Mammal 0.7 2E-02 12

Contaminated Short Grass [Highest Residue Rate] Small mammal (20g) 0.2 6E-03 4 Larger Mammal (400g) 0.2 6E-03 4 Large Mammal (70g) 1.5 4E-02 27

Contaminated Water Small mammal (20g) 7E-09 7E-14 2E-07 Larger Mammal (400g) 2E-08 2E-13 8E-07 Canid (5 kg) 8E-08 8E-13 3E-06 Large Mammal (70g) 2E-07 2E-12 6E-06 Consumption of contaminated Fish Large Mammalian Carnivore (70

kg) 6E-08 6E-14 1E-05

Canid (5 kg) 4E-08 4E-14 7E-06

20

Table 5. Summary of Exposure Assessments for the Birds G01b


Scenario Receptor mg/kg/day or mg/kg/event

Central Lower Upper

Accidental Acute Exposures Contaminated Water

Spill Small bird (10g) 7.35E-01 1.22E-01 2.55E+00 Spill Large Bird (4 kg) 1.02E-01 1.70E-02 3.53E-01

Consumption of contaminated Fish Spill Fish-eating bird (2.4 kg) 1.12E-01 1.86E-03 2.20E+00

Non-Accidental Acute Exposures Contaminated Fruit [Lowest Residue Rates] Small bird (10g) 1.74E+01 2.38E+00 6.33E+01

Large Bird (4 kg) 1.98E+00 2.71E-01 7.20E+00 Contaminated Broadleaf Foliage

Small bird (10g) 9.42E+01 9.42E+00 4.81E+02 Large Bird (4 kg) 1.07E+01 1.07E+00 5.47E+01

Contaminated Tall Grass Small bird (10g) 7.54E+01 7.54E+00 3.92E+02 Large Bird (4 kg) 8.57E+00 8.57E-01 4.45E+01

Contaminated Short Grass [Highest Residue Rate]

Small bird (10g) 1.78E+02 1.88E+01 8.54E+02

Large Bird (4 kg) 2.02E+01 2.14E+00 9.72E+01 Contaminated Water

Small bird (10g) 5.39E-05 2.02E-08 4.05E-03 Large Bird (4 kg) 7.47E-06 2.80E-09 5.60E-04

Contaminated Insects Small bird (10g) 2.19E+01 2.19E+00 1.12E+02 Consumption of small mammal (after direct spray) by predator Carnivorous bird (640 g) 1.61E+00 4.84E-01 2.74E+00 Consumption of contaminated Fish

Fish-eating bird (2.4 kg) 8.21E-06 3.08E-10 3.49E-03

Chronic/Longer Term Exposures Contaminated Fruit (Lowest Residue Rate)

Small bird (10g) 6.76E+00 6.16E-01 4.26E+01 Large Bird (4 kg) 7.69E-01 7.01E-02 4.84E+00

Contaminated Broadleaf Foliage Small bird (10g) 6.19E+00 1.66E-01 1.14E+02 Large Bird (4 kg) 7.04E-01 1.89E-02 1.29E+01

Contaminated Tall Grass

Small bird (10g) 4.95E+00 1.33E-01 9.27E+01

Large Bird (4 kg) 5.64E-01 1.51E-02 1.05E+01 Contaminated Vegetation (Short Grass - Highest Residue Rate)

Small bird (10g) 1.17E+01 3.32E-01 2.02E+02 Large Bird (4 kg) 1.33E+00 3.78E-02 2.30E+01

Contaminated Water Small bird (10g) 2.70E-07 2.70E-12 9.44E-06 Large Bird (4 kg) 3.73E-08 3.73E-13 1.31E-06

Consumption of contaminated Fish Fish-eating bird (2.4 kg) 4.10E-08 4.10E-14 8.14E-06

21

Table 6. Summary of Hazard Quotients (Toxicity) for the Birds G01V6Brd


Scenario Receptor Hazard Quotients

Central Lower Upper

Accidental Acute Exposures Contaminated Water

Spill Small bird (10g) 6E-03 1E-03 2E-02 Spill Large Bird (4 kg) 8E-04 1E-04 3E-03

Consumption of contaminated Fish Spill Fish-eating bird (2.4 kg) 9E-04 1E-05 2E-02

Non-Accidental Acute Exposures Contaminated Fruit [Lowest Residue Rates] Small bird (10g) 0.1 2E-02 0.5

Large Bird (4 kg) 2E-02 2E-03 6E-02 Contaminated Broadleaf Foliage

Small bird (10g) 0.7 7E-02 4 Large Bird (4 kg) 9E-02 9E-03 0.4

Contaminated Tall Grass Small bird (10g) 0.6 6E-02 3 Large Bird (4 kg) 7E-02 7E-03 0.4

Contaminated Short Grass [Highest Residue Rate]

Small bird (10g) 1.4 0.1 7

Large Bird (4 kg) 0.2 2E-02 0.8 Contaminated Water

Small bird (10g) 4E-07 2E-10 3E-05 Large Bird (4 kg) 6E-08 2E-11 4E-06

Contaminated Insects Small bird (10g) 0.2 2E-02 0.9 Consumption of small mammal (after direct spray) by predator Carnivorous bird (640 g) 1E-02 4E-03 2E-02 Consumption of contaminated Fish

Fish-eating bird (2.4 kg) 7E-08 2E-12 3E-05


Small bird (10g) 0.9 8E-02 6 Large Bird (4 kg) 0.1 9E-03 0.6

Contaminated Broadleaf Foliage Small bird (10g) 0.8 2E-02 15 Large Bird (4 kg) 9E-02 3E-03 1.7

Contaminated Tall Grass

Small bird (10g) 0.7 2E-02 12

Large Bird (4 kg) 8E-02 2E-03 1.4 Contaminated Vegetation (Short Grass - Highest Residue Rate)

Small bird (10g) 1.6 4E-02 27 Large Bird (4 kg) 0.2 5E-03 3

Contaminated Water Small bird (10g) 4E-08 4E-13 1E-06 Large Bird (4 kg) 5E-09 5E-14 2E-07

Consumption of contaminated Fish Fish-eating bird (2.4 kg) 5E-09 5E-15 1E-06

22

Table 7. Consumption of Fruit by a Herbaceous Insect, Acute exposure G07a Short Title Fruit Receptor Herbivorous Insect Duration Acute Material consumed Fruit

Parameter/Assumption Code / Range

Equation/ Value Units

Commodity Concentration on vegetation

Conc Central 3.5 mg/kg food Lower 1.6 Upper 7.5

Receptor Amount consumed per day per unit body weight

Amnt Central 1.3 kg food/kg BW per day

Lower 0.6 Upper 2.2

Estimate Dose Dose Conc × Amnt

Central 4.55 mg/kg bw Lower 0.96

Upper 16.5

23

Table 8. Consumption of Broadleaf/Small Insects by a Herbivorous Insect, Acute exposure G07b Short Title Broadleaf Vegetation

Receptor Herbivorous Insect Duration Acute Material consumed Broadleaf/Small Insects

Parameter/Assumption Code / Range Equation/ Value Units

Commodity Concentration on vegetation Conc

Central 22.5 mg/kg food Lower 7.5 Upper 67.5



Lower 0.6 Upper 2.2



Upper 148.5

24

Table 9. Consumption of Short grass by a Herbivorous Insect, Acute exposure G07c Short Title Short Grass Receptor Herbivorous Insect

Duration Acute Material consumed Short grass

Parameter/Assumption Code / Range Equation/ Value Units

Commodity Concentration on vegetation Conc

Central 42.5 mg/kg food Lower 15 Upper 120



Lower 0.6 Upper 2.2


Central 55.25 mg/kg bw Lower 9

Upper 264

25

Table 10. Consumption of Tall Grass by a Herbivorous Insect, Acute exposure G07d Short Title Tall Grass Receptor Herbivorous Insect Duration Acute Material consumed Tall Grass

Parameter/Assumption Code / Range

Equation/ Value Units

Commodity Concentration on vegetation

Conc Central 18 mg/kg food Lower 6 Upper 55



Lower 0.6 Upper 2.2



Upper 121

26

Table 11 Summary of Exposure Assessment for the Herbivorous or Predatory Insects G08a

Application Rate: 0.5

lb a.e./acre

Food Item Receptor mg/kg/day or mg/kg/event

Central Lower Upper Acute Exposures Fruit/Large Insects Insect 4.55 0.96 16.5 Broadleaf/Small Insects

Insect 2.93E+01 4.50E+00 1.49E+02

Short Grass Insect 5.53E+01 9.00E+00 2.64E+02 Long Grass Insect 23.4 3.6 121

Table 12.

Summary of Hazard Quotients (Toxicity) for the Herbivorous or Predatory Insects Application Rate:

0.5 lb a.e./acre G08b

Food Item Receptor Hazard Quotients Toxicity

Value Central Lower Upper Acute Exposures Fruit/Large Insects Insect 7E-03 2E-03 3E-02 620 <LD50

Broadleaf/Small Insects

Insect 5E-02 7E-03 0.2 620 <LD50

Short Grass Insect 9E-02 1E-02 0.4 620 <LD50 Long Grass Insect 4E-02 6E-03 0.2 620 <LD50

27

Table 13: TCP: Selected HQs for Mammals @ 1 lb. a.e./acre* Non-Accidental Acute Exposures

Contaminated Fruit (Lowest Residue Rate) Small mammal (20g) 0.2 2E-02 0.7 Larger Mammal (400g) 4E-

6E-03 0.2

Large Mammal (70g) 2E-

3E-03 9E-02 Contaminated Vegetation (Short Grass - Highest Residue Rate)

Small mammal (20g) 1.6 0.2 8

Larger Mammal (400g) 0.4 4E-02 1.8 Large Mammal (70g) 0.2 2E-02 1.0


Small mammal (20g) 0.3 3E-02 1.3 Larger Mammal (400g) 7E-

8E-03 0.3

Large Mammal (70g) 4E-

4E-03 0.2 Contaminated Vegetation (Short Grass - Highest Residue Rate)

*Exposures are for 1 lb. a.e./acre. Exposure rates for 0.5 lb. a.e./acre has not been generated

Small mammal (20g) 0.9 4E-02 10 Larger Mammal (400g) 0.2 9E-03 2

28

Table 14. Summary of Exposure Assessment and Risk Characterization for Terrestrial Plants from Runoff G04

Short Title Runoff to terrestrial plants Receptor Terrestrial vegetation Duration Acute User-Specified Gleams-

Driver File None

Parameter/Assumption Code / Range Value Units Reference Worksheet Application

Rate ApRtWB 0.5 lb/acre Worksheeet A01 Offsite Application Rates Inputs Run ID: Risk Assessment

Application Rate Used in Run: ApRtRun 1 lb/acre

Functional Off-site Application Rate

ApRtOffsite Central 0.0006 lb/acre

Lower 0.0000002 Upper 0.046 Calculated Values

Normalized Off-site Functional Application Rate

NormApRtOffsite ApRtOffsite / ApRtRun Central 0.0006 Unitless Eq

Lower 0.0000002

Eq Upper 0.046

Eq

Off-site Application Rate at Workbook Application Rate

ApRtWB ApRtWB x NormApRtOffsite

Central 0.0003 lb/acre Eq Lower 0.0000001

Eq

Upper 0.023

Eq Toxicity Values (seedling emergence) in units of lbs/acre Sensitive Tolerant Endpoint NOEC NOEC 0.02 2 Section 4.3.2.5. Hazard Quotients

Central 2E-02 2E-04

Lower 5E-06 5E-08

Upper 1.2 1E-02

29

Table 15. Summary of Exposure Assessment and Risk Characterization for Sensitive and Tolerant Terrestrial Plants from Drift After Backpack Directed Foliar Application. G05

Short Title Drift to terrestrial plants

PlntDrift2

Receptor Terrestrial vegetation

Duration Acute

Parameter/ Assumption Code / Range

Equation/ Value Units Reference/

Designation

Application Rate ApRt 0.5 lb/acre Worksheet A01 Toxicity Values(Post-

emergence in lb/ac) Sensitive species NOEC 0.0028 lb/acre Section 4.3.2.5.

Tolerant species NOEC 2 lb/acre Section 4.3.2.5.

Proportion of Drift at distances downwind in feet [0 feet = direct spray] Prop

Direct Spray feet 1 unitless Worksheet A04 25 feet 0.00832

50 feet 0.00433 100 feet 0.00241 300 feet 0.000941 500 feet 0.000579 900 feet 0.000312

Estimates of functional offsite application rate OfApRt =ApRt x Prop

0

0.5 lb/acre Eq 25

0.00416 Eq

50

0.002165 Eq 100

0.001205 Eq

300

0.0004705 Eq 500

0.0002895 Eq

900

0.000156 Eq Hazard Quotients

(Sensitive Species) HQSens = ApRt / ToxValSens 0

179

25

1.5

50

0.8

100

0.4

300

0.2

500

0.1

900

6E-02

Hazard Quotients (Tolerant Species) HQTol

= ApRt / ToxValTol

0

0.3

25

2E-03

50

1E-03

30

100

6E-04 300

2E-04

500

1E-04 900

8E-05

31

Table 16. Summary of Exposure Assessment and Risk Characterization for Sensitive and Tolerant Terrestrial Plants from Wind Erosion at the Specified Application Rate.

Short Title Wind erosion, terrestrial plants

PlntWind2

Receptor Terrestrial vegetation

Duration Acute

Parameter/Assumption Code / Range Equation/ Value Units Reference/ Designation

Application Rate ApRt 0.5 lb/acre Worksheet A01 Toxicity Values (Post-

emergence in lb/ac) Sensitive species NOEC 0.0028 lb/acre Section 4.3.2.5.

Tolerant species NOEC 2 lb/acre Section 4.3.2.5.

Soil losses due to wind ersion Loss_TonHa

Central 5 Tons per hectare per year

Scenario parameter

Lower 1 Scenario parameter

Upper 10 Scenario parameter

Conversion for tons/ha to grams per cm2 Conv1 0.01

Soil losses in grams/square centimeter Loss_GrCm

Central 0.05 g/cm2 per year

Eq

Lower 0.01 Eq

Upper 0.1 Eq Soil Density Dens 2 g/cm2

Soil losses in cm/day Loss_CmDay = Loss_GrCm /(Dens * 365) Central 6.84932E-05 cm per

day Eq

Lower 1.36986E-05 Eq Upper 0.000136986 Eq Depth of incorporation Depth 1 cm Scenario parameter Proportion of

contaminated soil lost per day

PropLost

Central 6.84932E-05 unitless Lower 1.36986E-05 Upper 0.000136986 Estimates of

functional offsite application rate OfsiteApRt =ApRt x PropLost

Central 3.42466E-05 lb/acre Eq

Lower 6.84932E-06 Eq

Upper 6.84932E-05 Eq Hazard Quotients

(Sensitive Species) HISens = OffsiteApRt / ToxValSens

Central 1E-02

Lower 2E-03

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Upper 2E-02

Hazard Quotients (Tolerant Species) HITol

= OffsiteApRt / ToxValTol

Central 2E-05

Lower 3E-06

Upper 3E-05

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REFERENCES

Boran, et al. 1993. Boren JC; Lochmiller RL; Leslie DM; Engle DM. Long-term effects of woody vegetation management on seasonal body condition of northern bobwhites. Journal of Range Management 46:520-523. Campbell et al. 1990. Campbell S; Hoxter KA; Jaber M. 3,5,6-Trichloro-2-pyridinol: an acute oral toxicity study with the northern bobwhite. Dow AgroSciences, unpublished report. Wildlife International Ltd. Project no.: 103-347. 27 December 1990. IN: SERA 2011. Campbell and Lynn. 1991. Campbell S; Lynn S. Triclopyr BEE: An Acute Oral Toxicity Study With the Northern Bobwhite: Unpublished study prepared by Dow Chemical Co. IN: SERA 2011. Hallbom and Berman. 1979. Hallbom L; Bergman B. Influence of Certain Herbicides and a Forest Fertilizer on the Nitrogen Fixation by the Lichen Peltigera praetextata. Oecologia. 40: 19-27. Hayward JC. 2000. The effects of Garlon 4 on reproduction and growth in the earthworm Eisenia fetida. Dow AgroSciences, unpublished report. CEMAS Report No. CEMR-1325, 14 December 2000. IN: SERA 2011. Long et al. 1990. Long RD; Hoxter KA; Jaber M. 3,5,6-Trichloro-2-pyridinol: a dietary LC50

study with the mallard. Dow AgroSciences, unpublished report. IN: SERA 2011. Nagy KA. 1987. Field metabolic rate and food requirement scaling in mammals and birds. Ecological Monographs. 57: 111-128. Nagy KA. 2005. Field metabolic rate and body size. Journal of Experimental Biology. 208: 1621-1625. Newmaster et al. 1999. Newmaster SG; Bell FW; Vitt DH. The effects of glyphosate and triclopyr common bryophytes and lichens in northwestern Ontario. Canadian Journal of Forest Research. 29 (7): 1101-1111. NRC (National Research Council). 1983. Risk Assessment in the Federal Government: managing the process. Washington, D.C: National Academy Press; 176 p. IN: SERA 2011. Pauli et al. 2000. Pauli BD; Perrault JA; Money SL; A Database of Reptile and Amphibian Toxicology Literature. National Wildlife Research Centre 2000, Canadian Wildlife Service, Environmental Conservation Branch, Technical Report Series Number 357. Available at: http://dsp-psd.communication.gc.ca/Collection/CW69-5-357E.pdf.

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Potter, et al. 1990. Potter DA; Buxton MC; Redmond CT; Patterson CG; Powell AJ. Toxicity of Pesticides to Earthworms (Oligochaeta: Lumbricidae) and Effect on Thatch Degredation in Kentucky Bluegrass Turf. Journal of Economic Entomology. 83: 2362-2369. Radosevish et al. 1977. Radosevish SR; Graves WL; Agamalian HA. Response of two Adenostoma Species to Several Herbicides. Weed Science. 25: 188-192. SERA (Syracuse Environmental Research Associates, Inc.). 2009. Dinotefuran – Human Health and Ecological Risk Assessment, Final Report. SERA TR-052-18-03b. Report dated April 24, 2009. SERA (Syracuse Environmental Research Associates, Inc.). 2011. Triclopyr – Human Health and Ecological Risk Assessment, Final Report. SERA TR-052-25-03a, report dated May 24, 2011. Schulz, et al. 1992. Schulz CA; Leslie DM; Lochmiller RL; Engle DM. Autumn and winter bird populations in herbicide-treated cross timbers in Oklahoma. The American Midland Naturalist 127 (2): 215-223. U.S. EPA/ORD (U.S. Environmental Protection Agency/Office of Research and Development). 1988. Recommendations for and Documentation of Biological Values for use in Risk Assessment. U.S. EPA, Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Cincinnati, OH. U.S. EPA 600/6-87/008. U.S. EPA/OPP (U.S. Environmental Protection Agency/Office of Pesticide Programs). 1993. U.S. EPA/OPP (U.S. Environmental Protection Agency/Office of Pesticide Programs). 1998. Reregistration Eligibility Decision (RED): Triclopyr. U.S. EPA/OPP (U.S. Environmental Protection Agency/Office of Pesticide Programs). 2009. Risks of Triclopyr Use to Federally Threatened California Red Legged Frog (Rana aurora draytonii). Available at: http://www.epa.gov/espp/litstatus/effects/redleg-frog/.

Winston ML. 1987. The Biology of the Honeybee. Harvard University Press, Cambridge, MA. ISBN 0-674-07409-2 280pp.

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ACRONYMS, ABBREVIATIONS, AND SYMBOLS

a.e. acid equivalent a.i. active ingredient BEE butoxyethyl ester cm centimeter ECx concentration causing X% inhibition of a process EC25 concentration causing 25% inhibition of a process EC50 concentration causing 50% inhibition of a process kg kilogram L liter lb pound LC50 lethal concentration, 50% kill LD50 lethal dose, 50% kill LOAEL lowest-observed-adverse-effect level LOC mg milligram mg/kg/day milligrams of agent per kilogram of body weight per day NOAEL no-observed-adverse-effect level NOEC no-observed-effect concentration NOEL no-observed-effect level OPP Office of Pesticide Programs RED re-registration eligibility decision RfD reference dose SERA Syracuse Environmental Research Associates TCP 3,5,6-trichloro-2-pyridinol TEA triethylamine U.S. EPA U.S. Environmental Protection Agency µg In the metric system, a microgram is a unit of mass equal to one millionth (1×10−6) of a gram, or one thousandth (1×10−3) of a milligram. The unit symbol is µg according to the International System of Units.

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