es5b02069_si_001.pdf (504.02 kB)
Does the Choice of NOEC or EC10 Affect the Hazardous Concentration for 5% of the Species?
journal contribution
posted on 2015-08-04, 00:00 authored by Yuichi Iwasaki, Kensuke Kotani, Shosaku Kashiwada, Shigeki MasunagaWe
evaluated if the choice of no observed effect concentration
(NOEC) or a 10% effect concentration (EC10) affects the hazardous
concentrations for 5% of the species (HC5s) estimated from species
sensitivity distributions (SSDs). By reviewing available literature
reporting NOECs and reanalyzing original toxicity data to estimate
EC10s, we developed two SSDs for five chemicals (zinc, lead, nonylphenol,
3,4-dichlorobenzenamine, and lindane) based separately on 9–19
EC10s and NOECs. On average, point estimates of HC5s based on EC10s
were 1.2 (range of 0.6–1.9) times higher than those based on
NOECs. However, both EC10-based and NOEC-based HC5s estimated for
five substances were on the same order of magnitude, and their 95%
confidence intervals overlapped considerably. Thus, although EC10
was chosen as a representative of ECx in this study,
our results suggest that the choice of ECx (e.g.,
EC5, EC10, or EC20) or NOEC does not largely affect the resulting
HC5s. Therefore, use of NOECs would be acceptable particularly in
regulatory contexts, although the NOEC has important shortcomings
and should be used with caution.