Ecotoxicity of boric acid in standard laboratory tests with plants and soil organisms.
To verify the continuous sensitivity of ecotoxicological tests (mainly the test organisms), reference substances with known toxicity are regularly tested. Ideally, this substance(s) would lack specificity in its mode action, be bioavailable and readily attainable with cost-effective means of chemical characterization. Boric acid has satisfied these criteria, but has most recently been characterized as a substance of very high concern, due to reproductive effects in humans, thus limiting its recommendation as an ideal reference toxicant. However, there is probably no other chemical for which ecotoxicity in soil has been so intensively studied; an extensive literature review yielded lethal (including avoidance) and sublethal data for 38 taxa. The ecotoxicity data were evaluated using species sensitivity distributions, collectively across all taxa, and separately according to species type, endpoints, soil type and duration. The lack of specificity in the mode of action yielded broad toxicity among soil taxa and soil types, and provided a collective approach to assessing species sensitivity, while taking into consideration differences in test methodologies and exposure durations. Toxicity was species-specific with Folsomia candida and enchytraied species demonstrating the most sensitivity; among plants, the following trend occurred: dicotyledonous (more sensitive) ≫ monocotyledonous ≫ gymnosperm species. Sensitivity was also time and endpoint specific, with endpoints such as lethality and avoidance being less sensitive than reproduction effects. Furthermore, given the breadth of data and toxicity demonstrated by boric acid, lessons learned from its evaluation are discussed to recommend the properties required by an ideal reference substance for the soil compartment.
Environment and Climate Change Canada, Biological Assessment and Standardization Section, 335 River Road, Ottawa, ON, K1A 0H3, Canada. Juliska.Princz@canada.ca.
Juliska
J
Princz
ECT Oekotoxikologie GmbH, Böttgerstraße 2-14, D-65439, Flörsheim, Germany.|Institute for Ecology, Evolution and Diversity, Goethe University, Siesmayerstraße 70, D-60323, Frankfurt am Main, Germany.
Leonie
L
Becker
ECT Oekotoxikologie GmbH, Böttgerstraße 2-14, D-65439, Flörsheim, Germany.
Adam
A
Scheffczyk
Aquaterra Environmental Consulting Inc., Orton, ON, L0N 1N0, Canada.
Gladys
G
Stephenson
Environment and Climate Change Canada, Biological Assessment and Standardization Section, 335 River Road, Ottawa, ON, K1A 0H3, Canada.
Rick
R
Scroggins
ECT Oekotoxikologie GmbH, Böttgerstraße 2-14, D-65439, Flörsheim, Germany.
Thomas
T
Moser
ECT Oekotoxikologie GmbH, Böttgerstraße 2-14, D-65439, Flörsheim, Germany.
Jörg
J
Römbke
D000818:Animals; D001181:Arthropods / Q000187:drug effects; D001888:Boric Acids / Q000633:toxicity*; D054750:Ecotoxicology; D010944:Plants / Q000187:drug effects*; D012987:Soil; D012989:Soil Pollutants / Q000633:toxicity*; D018675:Toxicity Tests
D001888:Boric Acids; D012987:Soil; D012989:Soil Pollutants; C032688:boric acid
Boric acid; Invertebrates; Reference substance; SSD; Soil; Toxicity