Affordable Access

Publisher Website

A Refined Ecological Risk Assessment for California Red-legged Frog, Delta Smelt and California Tiger Salamander Exposed to Malathion in California.

  • Clemow, Yvonne H1
  • Manning, Gillian E1
  • Breton, Roger L1
  • Winchell, Michael F2
  • Padilla, Lauren2
  • Rodney, Sara I1
  • Hanzas, John P2
  • Estes, Tammara L3
  • Budreski, Katherine2
  • Toth, Brent N2
  • Hill, Katie L1
  • Priest, Colleen D4
  • Teed, R Scott1
  • Knopper, Loren D5
  • Moore, Dwayne R J4
  • Stone, Christopher T2
  • Whatling, Paul6
  • 1 Intrinsik Corp., 1125 Colonel By Drive, Carleton University Campus, CTTC - Suite 3600, Ottawa, ON, K1S 5R1, Canada. , (Canada)
  • 2 Stone Environmental Inc., 535 Stone Cutters Way, Montpelier, VT, 05602, USA.
  • 3 Department of Environmental Science, Louisiana State University, 1271 Energy, Coast and Environment Building, Baton Rouge, LA, 70803, USA.
  • 4 Intrinsik Environmental Sciences Inc. (US), 41 Campus Drive, Suite 202, New Gloucester, ME, 04260, USA.
  • 5 Stantec Consulting Ltd., 200-835 Paramount Drive, Stoney Creek, ON, L8J 0B4, Canada. , (Canada)
  • 6 FMC Corporation, 1600 Wilson Boulevard, Suite 700 Arlington, VA 22209.
Published Article
Integrated Environmental Assessment and Management
Wiley (John Wiley & Sons)
Publication Date
Oct 31, 2017
DOI: 10.1002/ieam.2002
PMID: 29087623


The California red-legged frog (CRLF), delta smelt (DS), and the California tiger salamander (CTS) are three species listed under the United States Federal Endangered Species Act (ESA), all of which inhabit aquatic ecosystems in California. The US Environmental Protection Agency (USEPA) has conducted deterministic screening-level risk assessments for these species potentially exposed to malathion, an organophosphorus insecticide and acaricide. Results from our screening-level analyses identified potential risk of direct effects to DS as well as indirect effects to all three species via reduction in prey. Accordingly, for those species and scenarios in which risk was identified at the screening-level, we conducted a refined probabilistic risk assessment for CRLF, DS, and CTS. The refined ERA was conducted using best available data and approaches, as recommended by the 2013 National Research Council (NRC) report Assessing Risks to Endangered and Threatened Species from Pesticides. Refined aquatic exposure models including the Pesticide Root Zone Model (PRZM), the Vegetative Filter Strip Modeling System (VFSMOD), the Variable Volume Water Model (VVWM), the Exposure Analysis Modeling System (EXAMS), and the Soil and Water Assessment Tool (SWAT) were used to generate estimated exposure concentrations (EECs) for malathion based on worst-case scenarios in California. Refined effects analyses involved developing concentration-response curves for fish and species sensitivity distributions (SSDs) for fish and aquatic invertebrates. Quantitative risk curves, field and mesocosm studies, surface water monitoring data, and incident reports were considered in a weight-of-evidence approach. Currently labeled uses of malathion are not expected to result in direct effects to CRLF, DS or CTS, or indirect effects due to effects on fish and invertebrate prey. This article is protected by copyright. All rights reserved.

Report this publication


Seen <100 times