September 4, 1997

Two independent environmental monitoring studies, one in Canada and the other in the U.S., have reported results that show "real world" levels of alkylphenol ethoxylate (APE) biodegradation intermediates to be in the low part per billion or lower range for river and lake water samples and in the low part per million or lower range for sediment samples. These results confirm that APEs are effectively removed in sewage treatment and that APE intermediates are biodegradable.

The Canadian study (D.T. Bennie and others, The Science of the Total Environment, vol. 193, pages 263-275, 1997) measured levels of nonylphenol (NP), NP monoethoxylate (NP1E), NP diethoxylate (NP2E), and octylphenol (OP) in 35 water samples from the Great Lakes (excluding Lake Michigan) and the upper St. Lawrence River. Measurable quantities of NP and OP were found in only 24% of the samples, with maximum values of 0.92 and 0.084 micrograms per liter (parts per billion, ppb). NP1E and NP2E were detected in 58% and 32% of the samples, at maximum levels of 7.8 and 10 ppb. The highest levels detected are below levels reported to produce short-term (acute) toxic effects in fish or other aquatic species. The authors suggest that additional research be done to review the potential for any long-term effects of these materials.

In this same study, nine sediment samples were collected from heavily industrialized sites. All sediments had measurable levels of NP (range = 0.17 - 72 parts per million, ppm, dry weight), 8 of 9 sediments had measurable levels of OP (range = <0.01 - 1.8 ppm), and 6 of 9 had measurable levels of NP1E (<0.015 - 38 ppm) and NP2E (<0.015 - 6.0 ppm). The significance of these findings was not assessed by the authors of the study due to the lack of data on the toxicity and availability of these biodegradation intermediates to sediment organisms, but the highest values indicate that sewage treatment at the nearby discharge points is inadequate.

The U.S. study (J.A. Field & R.L. Reed, Environ. Sci. Technol., vol. 30, pages 3544 - 3550, 1996) used a new analytical method to detect an additional class of APE biodegradation intermediates, NP and octylphenol ether carboxylates (NPECs and OPECs). Samples were collected from the lower Fox River in Wisconsin, which receives treated waste water from 15 paper manufacturing plants as well as six municipal sewage treatment plants. Samples also were collected from eight rivers in the Eastern U.S. which had been previously sampled for APE biodegradation intermediates (C.G. Naylor and others, Journal of the American Oil Chemists Society, vol. 69, pages 695 - 703, 1992).

No OPECs were detected at any site. The highest levels of NPECs were found in the Fox River (13.5 ppb total NPECs). NPECs were detected in only 4 of 8 of the Eastern U.S. rivers, with total NPEC levels (where detected) ranging from 1.4 - 6.3 ppb. These levels are also below those reported to cause short- or long-term toxicity in aquatic organisms.