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Alkylphenolic compounds
This site includes a lot of information on alkylphenols, including the full text of a report I wrote on their oestrogenic affects in 1994, which was published by Friends of the Earth in 1995. This page is the introduction, whilst the alkylphenols in depth page covers some issues in more depth.
Uses
Alkylphenols such as nonylphenol and octylphenol are mainly used to make alkylphenol ethoxylate (APE) surfactants (detergents), though alkylphenols themselves can be used as plasticisers in plastics, and the derivatives alkylphenol phosphites can be used as UV stabilisers in plastics.
In Europe alkylphenol ethoxylates are used in:
- Industrial detergents, such as those used for wool washing and metal finishing.
- Some industrial processes, such as emulsion polymerisation
- The spermicidal lubricant nonoxynol-9.
- Various laboratory detergents, including Triton X-100.
- In some pesticide formulations.
Outside Europe alkylphenol ethoxylates are also used in many domestic products; for example in the USA they are in many liquid clothes detergents. In Europe these products contain the slightly more expensive, but much safer, alcohol ethoxylates.
Hormone disrupting effects
Alkylphenols were first found to be oestrogenic (oestrogen-mimicking) in the 1930s (Dodds and Lawson, 1938), and more evidence was published in 1978 (Mueller and Kim, 1978). However, it was only in 1991 that publication of the effects of nonylphenol on cultured human breast cells led to health concerns (Soto et al., 1991). This and more recent research has shown that the growth of these cells is increased by alkylphenols at concentrations 1000 to 10000 times higher than the oestradiol levels required to produce the same growth. Oestrogenic effects have also been shown on rainbow trout hepatocytes, chicken embryo fibroblasts and a mouse oestrogen receptor (Jobling and Sumpter, 1993; White et al., 1994). Oestrogenic effects are present at tissue concentrations of 0.1 µM for octylphenol and 1 µM for nonylphenol (Soto et al., 1995). A recombinant yeast screen using the human oestrogen receptor has shown similar results (Routledge and Sumpter, 1996).
Recent research is showing oestrogenic effects of nonylphenol at ever lower concentrations. Levels of 0.05 micro-g per litre were enough to increase the number of eggs produced by minnows, as well as increasing vitellogenin levels (ENDS, 1999b). This research also suggested that nonylphenol was leading to an increase in natural oestrogen levels.
Fate in the Environment
APEs do not break down effectively in sewage treatment plants or in the environment. They tend to loose some of their ethoxylate groups quite easily, which prevents them acting as detergents - this is called 'primary biodegradability'. This leaves alkylphenols, alkylphenols with one or two ethoxylate groups and alkylphenoxy carboxylic acids (APEC) , which persist for longer. Alkylphenols accumulate where there is inadequate oxygen, e.g. in sediments, whilst APEC persist in rivers and effluents, for example analysis of sewage effluents found that these compounds accounted for 63% of total alkylphenolic metabolites (Di Corcia et al., 1998).
In spite of how important APEC are in the environment, they are often not tested for in the environment, so only a partial measurement of contamination is made. Any water analyses for pollution must measure all APE metabolites, including the alkylphenoxy carboxylic acids - if they don't then they're meaningless.
Alkylphenolic compounds are concentrated by organisms such as fish and birds, leading to contamination in their internal organs between ten and several thousand times greater than in the surrounding environment.
Another source of nonylphenol ethoxylate contamination to the environment in the UK is the ICI plant at Wilton, Teesside.
Much of the key research on the fate and levels of alkylphenolic compounds in the environment has been done be Dr Marijan Ahel who has been quoted as saying "In 1990, industry said a phase-out was not possible. Now after ten years they admit it is possible and we have not sacrificed anything from our daily lives". He also said that companies had spent "several million dollars" repeating his work: "the science is the same - it is only the emphasis that is different" "What happens in sensitive environments they don't show. Something that stays in the river just several days is great enough to have an effect." (ENDS, 1999b).
Human exposure routes
Alkylphenols as air pollution
Surprising new US research has revealed that nonylphenol is present as an air pollutant in the New York and New Jersey urban atmosphere, apparently due to vapourisation from the Hudson River (Dachs et al., 1999). The authors state:
"the high concentrations found in the coastal atmosphere of the New York-New Jersey Bight (2.2 - 70 ng/m3) suggests that the NPs occurrence in the atmosphere may be an important human and ecosystem health issue in urban, industrial, and coastal-impacted areas receiving treated sewage effluents"
Alkylphenols in water pipe treatments
Research by the UK Government's Drinking Water Inspectorate has shown that various products for drinking water pipes leach alkylphenols and phthalates into the drinking water. One epoxy resin leached 1,400 micro-g of dibutyl phthalate per square metre into water in the first hour after curing; a cement coating leached 12,000 micro-g per square metre of nonylphenol ethoxylate immediately after curing, with continued high leaching for 3 days (ENDS, 1999c).
Other exposure routes
Human exposure to these chemicals may also be occurring by the following routes:
- Absorption through skin from shampoos, cosmetics, spermicidal lubricants and domestic and industrial detergents.
- Contaminated drinking water, extracted from polluted rivers.
- Inhalation and ingestion from pesticide sprays.
- Contamination of food from fields spread with sewage sludge containing alkylphenols.
Contamination of the body
Nonylphenol and bisphenol a have both been detected in human umbilical cords at up to 2 parts per trillion wet weight for nonylphenol and 1.6.ppt for bisphenol a (ENDS, 1999b).
Regulatory action
European
Many individual EU member states and other European countries have already brought in controls on alkylphenols, for example Switzerland has already banned the use of all alkylphenol ethoxylates, and the UK has had a voluntary agreement against the use of alkylphenols in domestic cleaning products since 1976.
However, trans-national controls also exist, through the OSPAR agreement on marine pollution of the North East Atlantic, which includes an agreement to phase out the use of nonylphenol ethoxylates as cleaning agents by 2000 (ENDS, 1995).
Alkylphenols are also being assessed by the complex European Union Existing Substances process. A draft risk management document has now been produced by the UK, which proposes a range of bans on alkylphenol use, including industrial and institutional cleaning, textiles, leather, pulp and paper, metal working, cosmetics and agricultural sectors (ENDS, 1999a). It also proposes limits on discharges from NPE production, emulsion polymerisation, phenol/formaldehyde production and plastic stabiliser industries.
This regulatory pressure is forcing many companies to phase out APEs, for example ten major manufacturers of polyacrylamide emulsions have agreed to phase out APE use in Europe by the end of 2001 (ENDS, 1998).
USA
It is now becoming likely that the US will take some sort of regulatory action against alkylphenols, though there is heavy chemical industry lobbying against controls, e.g. The 'Alkylphenol Ethoxylates Research Council' (ENDS, 1999b).
The Washington Toxics Coalition has produced a report on alkylphenol use in the USA, "Troubling Bubbles: The Case for Replacing Alkylphenol Ethoxylate (APE) Surfactants". More information is available on their web site.