We recently developed the Terrestrial Endangered Species Assessment (TERESA) models for efficiently determining threatened and endangered (i.e., listed) species potentially at risk from exposure to a pesticide in the United States. The TERESA models are used following a screening-level assessment and co-occurrence analysis but prior to highly refined and probabilistic assessments. For each listed species, the TERESA models determine potential exposure and risk for up to 30 agricultural and non-agricultural use patterns and 4 application scenarios/use pattern. For listed wildlife species (e.g., TERESABird, TERESAMammal), the models estimate exposure dose by adjusting estimated dietary and drinking water concentrations by a conservative estimate of proximity of the species range or critical habitat to the use pattern footprint of interest. For listed terrestrial plant species (i.e., TERESAPlant), exposure is estimated by adjusting application rate by proximity distance. A proximity-adjusted approach is also used to estimate potential exposure to receptor groups upon which each listed species depends for food, habitat, pollination services, etc. The previous versions of the TERESA models relied on the US EPA’s TerrPlant model to assess direct effects to listed terrestrial plant species and effects to plants as a source of food and habitat in the wildlife and terrestrial invertebrate TERESA models. The Agency recently replaced the TerrPlant model with the Plant Assessment Tool (PAT). The PAT employs mechanistic representations of fate (e.g., degradation) and transport to model runoff and spray drift exposure to plants in terrestrial and wetland environments. The PAT represents a considerable refinement over TerrPlant but is a far more complex model, requiring many additional inputs, and depends on the outputs of other models (PRZM and VVWM). To ensure that the TERESA models remain current for pesticide endangered species assessments, we replaced the TerrPlant component in the TERESA models with the PAT. As in previous versions, risk quotients for direct and indirect risk are calculated for each combination of listed species, use pattern, and application scenario included in a TERESA-PAT simulation. Using a representative pesticide as a case study, we demonstrate that the TERESA-PAT models are effective and efficient in screening out listed terrestrial species and use patterns that are clearly not at risk and identifying those in need of further refinement.

Incorporating the US EPA’s PAT assessment tool into the TERESA modeling suite for determining pesticide risks to threatened and endangered species in the United States

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