Summary of alkylphenols report
- Alkylphenol ethoxylate surfactants are
usually made from a branched-chain nonylphenol or octylphenol,
reacted with ethylene oxide. They are used in a variety of industrial
processes, including wool washing, but are no longer in domestic
detergents in the UK. Alkylphenols are also used by some industries.
- Alkylphenol ethoxylates are biodegraded
by removal of ethoxy groups, producing less biodegradable products:
alkylphenol mono- and di-ethoxylates, alkylphenoxy acetic and
alkylphenoxypolyethoxy acetic acids, and alkylphenols. These
metabolites frequently persist through sewage treatment and in
rivers. Anaerobic conditions generally lead to the accumulation
- Rivers in Switzerland have been found
to contain concentrations of tens of µg/1 of a wide range
of alkylphenolic metabolites. Low levels have also been found
in drinking water in the USA, with a total concentration of alkylphenolic
compounds of almost 1 µg/1. There is little UK data on
concentrations in the environment, but a recent modelling study
concluded that 83 % of UK nonylphenol ethoxylate production enters
the environment, with 37 % entering the aquatic environment.
- Metabolites of alkylphenol ethoxylates
accumulate in organisms, with bioconcentration factors varying
from ten to several thousand, depending on species, metabolite
- The metabolites of alkylphenol ethoxylates
are generally more toxic than the original compounds. Alkylphenol
ethoxylates have LC50s above about 1.5 mg/1, whereas nonylphenol
LC50s are generally around 0.1 mg/1.
- Alkylphenols were first found to be oestrogenic
(oestrogen-mimicking) in the 1930s, but more recent research
has highlighted the implications of these effects. The growth
of cultured human breast cancer cells is affected by nonylphenol
at concentrations as low as 1 µM (220 µg/1), or concentrations
of octylphenol as low as 0.1 µM (20 µg/1). Oestrogenic
effects have also been shown on rainbow trout hepatocytes, chicken
embryo fibroblasts and a mouse oestrogen receptor.
- Studies on UK rivers receiving sewage
effluent have shown that an oestrogenic pollutant is present,
as male rainbow trout placed in these rivers produce a female
egg yolk protein.
- By comparing environmental concentrations,
bioconcentration factors and in vitro oestrogenic effect levels,
this report concludes that current environmental levels of alkylphenolic
compounds are probably high enough to be affecting the hormonal
control systems of some organisms. It is also possible that human
health could be being affected.
- Some progress has been made in phasing
out alkylphenols and alkylphenol ethoxylates, but many industries
are still using them.
This page was last
updated in October 1999
to the hormone disrupting chemicals home page