Ethoxylates

Nonylphenol (NPE) and Octylphenol Ethoxylates (OPEs)

From a class known as non-ionic surfactants, there is a group of ethoxylates known as 4-alkylphenol ethoxylates (APE) that fall under the category of EDC. They are widely being used and their demand is increasing by 2% per year as is shown in numerous studies from the USA (Licea et al, 2005). Furthermore, from understanding the chemistry of APEs we see that the most common surfactants from the APE class are nonylphenol (NPE) and octylphenol ethoxylates (OPEs). NPEs however account for 80% of APEs and OPEs for the remainder (Chen et al, 2005; Guenther et al, 2002).

Ethoxylate Uses

These non-ionic surfactants have many applications in the production of industrial and household products, playing roles as lubricant oil addictives and phosphate antioxidants for rubber and plastics (Licea et al, 2005). They are also involved in sewage treatment plants. For instance, NPEs are used for subsequent treatment at sewage treatment plants; a biodegradation process of NPEs takes place during the different steps of the treatment, resulting to biorefractory metabolites being formed (Yang et al, 2006). The formation of these metabolites are persistent and toxic in the environment and after their release into the aquatic environment, they end up accumulating in aquatic organisms (Guenther et al, 2002). Different bodies of water, such as rivers, lake estuaries and coastal waters have all been shown to contain these alkylphenols (APs) (Chen et al, 2005). Aquatic organisms, such lobsters are affected by concentrations of APs; at high concentrations APs are toxic to the crustacean family and contribute to lobster mortality and at lower concentrations, APs have endocrine disrupting effects (Biggers et al, 2004). In addition, APs act as surfactants and can therefore also contaminate surface water and sediments. For example, sediment samples from the Pear River Delta which is adjacent to the Northern South China Sea, were found to be contaminated with NPs and octylphenols (OPs). (Licea et al, 2005).

Human Ethoxylate Exposure

Moreover, in order to determine the amount of exposure of APs in humans, a German team conducted a study in which the levels of NPs in 39 foods and beverages purchased from German supermarkets were measured. These included fruits and vegetables, dairy products, fish and meat, bread, pasta, beer, coffee, and chocolates (Guenther et al, 2002). The results revealed that the concentrations of NPs in several different foods were within the range of 0.1-19.4 ?g/kg. However, the highest concentrations of NPs were detected in apples, tomatoes and in fatty foods like fish and meat. It is estimated that the average daily intake of NPs via food for an adult is approximately 7.5 ?g/day. What concentrations are needed to cause toxicity is still unknown (Yang et al, 2006).

References:

Licea AF., Marquez-Rocha F., Ponce E., Vazquez-Duhalt., and Viana MT. 2005. Nonylphenol, an integrated vision of a pollutant. Applied Ecology and Environmental Research. 4(1):1-25.

Guenther K., Heinke V., Kleist E., Prast H., Raecker T., and Thiele B. 2002. Endocrine Disrupting Nonylphenols Are Ubiquitous in Food. Environ Sci Technol. 36(8):1676-1680.

Chen A., and Rogan WJ. 2005. Health risks and benefits of bis (4-chlorophenyl)-1,1,1-trichloroethane (DDT). The Lancet. 366:763-773.

Biggers W., and Laufer H. 2004. Identification of Juvenile Hormone-Active Alkylphenols in the Lobster Homarus americanus and in Marine Sediments. Biological Bulletin. 206(1):13-24.

Yang M, Park MS, and Lee HS. 2006. Endocrine Disrupting Chemicals: Human Exposure and Health Risks. J. Environmental Science and Health Part C. 24: 183-224.