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15 July 2010 

Darrin Polhemus

Deputy Director

Division of Water Quality

State Water Resources Control Board

1001 I Street

Sacramento, CA 95814

Re: Effects on Water Quality of Alkylphenol Ethoxylate Surfactants (APEOs)

Dear Darrin:

In response to your June 24 request for information on APEOs, we first direct you to the 

letter you will have received from Rainer Hoenicke at SFEI. We have been in contact

with Rainer and his staff and would like to acknowledge and reference their excellent 

summary on this topic, which they have kindly shared with SCCWRP staff.

Much of the data presented in SFEI’s summary letter is consistent with what exists from

work in Southern California. We also agree with their assessment that very little has 

been added to the literature to help with interpretation of environmental APEO 

concentrations since 2008. Lastly, we concur with SFEI’s recommendation for a search 

for “safer” alternatives due to the combination of APEOs high usage and apparent

persistence in receiving waters. In the remainder of this letter, we provide additional 

data, information, and our own interpretation and perspective on the potential for impacts 

due to this class of emerging contaminant. 

Presently, we know that residues of APEOs, which include breakdown products known 

as 4-nonylphenol (4-NP) and 4-octylphenol, occur in treated wastewater effluent. 

Concentrations of 4-NP in final effluent from POTWs utilizing advanced primary and full 

secondary treatment processes were ~1-2 ug/L. This compound was, however, not 

frequently detected at > 1 ng/L in receiving seawater, ostensibly due to the high degree of 

instantaneous mixing at the marine outfall locations (SCCWRP unpublished data). We 

also know that APEO residues can accumulate in marine sediments, sometimes to parts 

per million levels (3200 ng/g for 4-nonylphenol and 3900 ng/g for nonylphenol 

ethoxylates) in the Southern California Bight (Schlenk et al. 2005). More recent work at 

these same outfall locations show concentrations to be an order of magnitude lower (< 10 

to 380 ng/g). In contrast, very little to no APEO concentration data exist for other 
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permitted discharges (e.g. stormwater runoff) or in water bodies receiving these 

discharges. 

In contrast to the tissues from Morro Bay as reported by SFEI, concentrations of 4-NP in 

livers of hornyhead turbot (Pleuronichthys verticalis) collected near large POTW marine 

outfalls were similar to sediment levels (25 to 290 ng/g)(SCCWRP unpublished data). 

These findings are consistent with most other studies and provide very strong evidence 

that APEOs do not biomagnify like so-called persistent organic pollutants (e.g. DDE, 

PCBs and PBDEs) do. As SFEI points out, the primary concern with APEOs in aquatic 

systems is its endocrine disrupting potential. 

In the same study, several measures of chemical exposure and biological response at the 

tissue and individual level for P. verticalis were determined for > 600 individuals (Bay et 

al. 2008). There was no clear outfall effect in blood plasma levels of reproductive 

hormones (estradiol, testosterone) or egg proteins (vitellogenin) in male fish. Moreover, 

the incidence of fish intersex was virtually non-existent -- 1 of 373 males examined 

exhibited ova-testis, one of the expected histological indicators associated with endocrine 

disruption. The sole molecular response where a possible outfall effect was observed was 

for the thyroid hormone thyroxine. Lastly, the local population trends for P. verticalis

based on trawl surveys at these outfalls have not shown any indication of steady or 

continuous decline. The results of this study coupled with the apparent absence of 

obvious effects on the biology in other California receiving waters suggests that we 

cannot attribute effects that are likely to be associated with APEOs at their current 

environmental levels directly to this class of contaminants. Due to the lack of targeted 

studies on APEOs, however, we do not have a good idea of sediment threshold levels that 

would be protective of aquatic marine or freshwater life, nor do we know at this time the 

role of and/or potential for APEOs to modulate other modes of toxicity. This lack of 

information is in part due to the complexity of APEO formulations and the resulting 

absence of an economical, robust analytical methodology to characterize a broad suite of 

APEO residue compounds.

RECOMMENDATIONS

 Refine and/or develop improved measurement methods for APEOs and their 

residues

 Continue to monitor APEOs and their residues in regional and pilot scale surveys, 

including upcoming stormwater monitoring projects

 Initiate and carry out targeted studies to determine sediment levels where 

expected effects to sentinel organisms (e.g. fish) start to occur

 Share aquatic fate and toxicological information with agencies (e.g. DTSC) 

responsible for screening and/or approving the use of high volume chemicals
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References

Bay S et al. 2008. Effects of emerging contaminants on Southern California flatfish: 

synthesis and next steps. Abstract for the Society of Environmental Toxicology and 

Chemistry National Meeting, Tampa, FL. 

Schlenk D et al. 2005. In vivo bioassay buided fractionation of marine sediment extracts 

from the Southern California Bight, USA, for estrogenic activity. Environ Toxicol Chem 

24:2820-2826.

Sincerely yours,

Keith Maruya

Principal Scientist

Southern California Coastal Water Research Project

3535 Harbor Boulevard Suite 110

Costa Mesa, CA 92626

cc: Stephen Weisberg

Steven Bay

Rainer Hoenicke, SFEI