Table 2.

Estimated EC₃₀ values (with large sample 95% CIs) and relative potencies for each of the 11 pyrethroids.

Chemical	EC30 estimate (nM)	95% CI	Relative potencya
β-Cyfluthrin	1,046		645–1,447		0.61
Bifenthrin
Cypermethrin
Deltamethrin	635		438–832		1.00
Esfenvalerate	1,301		793–1,809		0.49
Fenpropathrin	2,047		819–3,274		0.31
λ-Cyhalothrin	1,101		765–1,437		0.58
Permethrin
Resmethrin
S-Bioallethrin	932		389–1,475		0.68
Tefluthrin	1,891		1,317–2,464		0.34
Mixture	1,568		1,279–1,857		0.41
aRelative potencies for the effects of 11 pyrethroids on Na+ influx based on deltamethrin (EC30 = 635 nM) as the index chemical. Relative potency was calculated as the ratio of the EC30 for deltamethrin over the EC30 for each chemical. The EC30 values and 95% CIs were determined from the four to seven measurements presented in Figure 1.