Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

used surfactant/adjuvant mixed with, or found in pesticide formulations. We reasoned if the data
support adverse effects from this one of more than 4,000 substances, then other unidentified inert
ingredients could also be toxic and may pose a significant risk to salmonids and their habitat.
We selected NP polyethoxylates and NP because of their widespread use in pesticide
formulations and abundance of information regarding environmental concentrations and adverse
effects to salmonids and their prey. The data indicated that these surfactants can kill outright,
disrupt endocrine systems, particularly reproductive physiology, and bioaccumulate in benthic
invertebrates from expected concentrations in the environment (Arsenault, Fairchild et al. 2004;
Madsen, Skovbolling et al. 2004; Jardine, MacLatchy et al. 2005; Luo, Ban et al. 2005;
McCormick, O'Dea et al. 2005; Segner 2005; Hutchinson, Ankley et al. 2006; Lerner, Bjornsson
et al. 2007; Lerner, Bjornsson et al. 2007). Importantly, we found studies that linked Atlantic
salmon population crashes in Canada to use of NP in insecticide formulations. However, the
BEs did not provide any information as to the prevalence of this material in formulations of the
three OP insecticides that pertain to this consultation. We did receive confirmation from the
technical registrant of methomyl that no methomyl containing formulation they make contains
NP. Significant uncertainty surrounds the number and type of compounds, as well as the toxicity
of these other materials used in pesticide formulations. As a result, we must caveat our
conclusions regarding population-level responses with the uncertainty that the actual risk posed
to listed salmonids and their habitat is likely greater when all ingredients are taken into account.
H. Exposure to other pesticides present in the action area can act in combination with
carbaryl, carbofuran, and methomyl to increase effects to salmonids and their habitat.
The available toxicity and exposure data support the hypothesis. Other carbamates and OPs
found in the action area likely result in additive or synergistic effects to exposed salmonids and
aquatic invertebrates. The magnitude of effects will depend on the duration and concentrations
of exposure.
I. Exposure to elevated temperatures can enhance the toxicity of the stressors of the action.
We found no consistent correlation with elevated temperature and toxicity of the three N-methyl
carbamates. However, salmonids are coldwater species, and exposure to elevated temperatures
increases physiological stress, thus making them more susceptible to other stressors.
Additionally, other AChE inhibitors such as OPs are more toxic to salmonids and aquatic
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