EPA's Vessel General Permit and Small Vessel General

A later study by the same workers reported declines in female body weights at 0.1, 1.0, and 10.0
μg/L and reduction of male GSI at 0.01 – 10 ug/L (Chikae et al., 2004b – after Carlisle et al
2009). Interpretation of the ecological implications of such data in the light of conflicting results
reported by the same research group leads us to exclude this study from consideration when
evaluating EPAs post permit DEHP estimates.
NMFS concludes that DEHP contributions from vessels are not expected to tip the balance
between neutral and harmful levels in waters where our species occur because the bulk of the
response thresholds reviewed in Carlisle et al (2009) occurred at concentrations orders of
magnitude greater than ambient water concentrations modeled by EPA and conflicting data from
the same research group were reported for those responses observed at or near EPAs modeled
concentrations.
Nonylphenol and Octylphenol Ethoxylates
EPAs Report to Congress describes the environmental fate and transport of nonylphenol and
octylphenol ethoxylates in vessel discharges (USEPA 2010b), yet the BE does not acknowledge
this discharge constituent class. These substances are often collectively referred to as
nonylphenols and represent two distinct subsets of the broader family of alkylphenols that are
commonly used in many products such as liquid detergents and soaps. Longer chain
nonylphenol and octylphenol ethoxylates degrade to shorter chained ethoxylates under aerobic
conditions. In general, the shorter the chain, the more hydrophobic, persistent, and toxic the
substance becomes. 4-Nonylphenol (NP) is a shorter-chain nonylphenol that has been found in
surface water and is toxic to aquatic life. NP is formed from the longer chain nonylphenol and
octylphenol ethoxylates as they break down. In general, the hydrophobicity, persistence, and
toxicity of the substance all increase as the ethoxylate chain becomes shorter. NP accumulates in
sediment, occurring at concentrations several orders of magnitude greater in sediment than in
water. The short-chained isomers may be quite persistent once they are buried in the sediment,
and bottom-feeding fish can be significantly exposed to these persistent and toxic compounds
(USEPA 2010b).
EPA’s Report to Congress indicated that there were no analytical results which could be directly
compared with EPA's 1.7 ug/L marine acute benchmark for the degradate, NP. The Services
note that Toxic Equivalency Factors are available for adjusting for NPE mixtures. An alternative
to a Toxic Equivalency analysis would be to estimate NP degradate loading equivalents based on
moles NP producing substances in vessel discharges.
Toxicity data indicate that some listed species are greater than the proposed correction factor of
two more sensitive to these substances than standard test species (e.g., LC50s 13 for atlantic
sturgeon is 50 ug/L, shortnose sturgeon and spotfin chub LC50s were reported at 80 ug/L
(Dwyer et al 2005), Fathead minnow LC50s averaged 290 ug/L and sheepshead minnow
averages 460 ug/L in EPAs ECOTOX database). NP is a common adjuvant used in pesticides
13 LC50 refers to lethal concentration, 50% or the amount of a toxin required to kill half the members of a tested population after
a specified test duration.
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