'Alkylphenols are a family of organic compounds obtained by the alkylation of phenols. The term is usually reserved for commercially important propylphenol, butylphenol, amylphenol, heptylphenol, octylphenol ethoxylates (OPEs), nonylphenol ethoxylates (NPEs), dodecylphenol and related "long chain alkylphenols" '(LCAPs)'. 1
What are they used for?
Alkylphenols have been in use in industry for nearly 50 years. Initial use was in detergents and as additives to fuel. Importantly they are a component in phenolic resins. Alkylphenol compouds are also used in the manufacture of thermoplastic elastomers, antioxidants and fire retardants.
Further downstream in other compounds they can be found in adhesives, paints and coatings and high performance rubber products..
Another alkylphenol derivative, alkylphenol phosphite, can be used as a UV stabiliser in plastics.
UK has had a voluntary agreement against the use of octyphenols in domestic cleaning products since 1976.
Alkylphenols in the environment
Though considerably reduced in volume, octyphenols are still found in the environment, particularly in water where they are easily soluble.
'OPEs are known to be very toxic to wildlife, particularly aquatic organisms. There is also concern that they mimic the behaviour of animal hormones, that they are an "endocrine disruptor". OPEs break down relatively easily into Octylphenols (OPs), which are more harmful and can be very persistent in the environment. This persistence means that they can be transported far from the point of original release of OPEs. OPs are accumulated and concentrated by aquatic organisms and birds. It is therefore possible that the presence of OPEs and hence OPs in the environment poses a long-term threat to wildlife on both a local and global scale.' 2
Human exposure to alkylphenols and alkylphenol ethoxylates may come through contaminated foods such as fish and drinking water. Indoor air and to a lesser extent, outdoor air may contain levels of octyphenol.
‘Human health effects from 4-tert-octylphenol or the corresponding octylphenol ethoxylates at low environmental doses or at biomonitored levels from low environmental exposures are unknown. Several alkylphenols, including octylphenol, have demonstrated estrogenic effects particularly when injected at high doses in animals. These high dose parenteral effects of octylphenol have included altered sex hormone levels and hypothalamic-pituitary suppression, impaired steroidogenesis, altered estrus cycles and reproductive outcomes, altered neonatal sexual development, testicular atrophy, and impaired spermatogenesis ‘ 4
In a study examining the effects of 4-NP in human breast tumor cells (MCF-7 cells) in vitro, changes in gene expression were observed in several genes involved in cell proliferation, DNA transcription and cell signaling — all systems that are disrupted in tumor formation (Oh, 2009). 3
Regulation in the EU and USA
The production and use of nonylphenol and nonyphenol ethoxylates is prohibited in the European Union due to its effects on health and the environment. In Europe, due to environmental concerns, they also have been replaced by more expensive alcohol ethoxylates, which are less problematic for the environment due to their ability to degrade more quickly than nonylphenols. The European Union has also included NP on the list of priority hazardous substances for surface water in the Water Framework Directive. They are now implementing a drastic reduction policy of NP's in surface waterways. The Environmental quality standard for NP was proposed to be 0.3 ug/l.
In the USA, the EPA set criteria which recommends that nonylphenol concentration should not exceed 6.6 ug/l in fresh water and 1.7 ug/l in saltwater. In order to do so, the EPA is supporting and encouraging a voluntary phase-out of nonylphenol in industrial laundry detergents. Similarly, the EPA is documenting proposals for a "significant new use" rule, which would require companies to contact the EPA if they decided to add nonylphenol to any new cleaning and detergent products. They also plan to do more risk assessments to ascertain the effects of nonylphenol on human health and the environment. 1
2 Scottish Environment Protection Agency, (SEPA)
3 Breast Cancer Fund
4 Centers for Disease Control and Prevention, (CDC)