Some chemicals implicated so far
This page outlines some of the chemicals that have been implicated
as hormone disrupters. Note that due to the large quantity of research
now being published, and the plethora of chemicals implicated in
some way, it is not possible for to list every chemical. In addition,
it is not always possible to keep all the specific chemical pages
totally up to date.The chemicals are divided into three groups,
'Industrial Chemicals', 'Natural Hormones', and 'Pesticides'.
Industrial
Chemicals
Phthalates
This group of chemicals are very widely used as plasticisers in
plastics such as PVC, but some of them are also testicular toxins
and can disrupt hormones.
Alkylphenols
Alkylphenols and their derivatives have a variety of uses, including
as industrial detergents and, outside Europe, as domestic detergents
. They have been shown to be oestrogenic in many systems.
Bisphenol A
An ingredient of lacquers that are used in dental treatment, and
to coat metal containers such as food cans. It has been shown to
leach from these cans into vegetables, and it is oestrogenic to
human breast cancer cell cultures.
Polychlorinated biphenyls (PCBs) and Dioxins
Dioxins are often produced during incineration, and also by some
industrial processes, such as the production of chlorinated hydrocarbons
and paper production. PCBs were used in electrical equipment such
as transformers, but were banned some years ago. However, a large
quantity of PCBs is still present in transformers and capacitors.
Brominated flame retardants
Brominated flame retardants are a group of chemicals that are used
in plastics and textiles to give flame retardant properties. Many
of them are persistent and bioaccumulative, and several are hormone
disrupters.
Parabens
A group of chemicals used as preservatives in cosmetics, and in
some antibacterial toothpastes. Several chemicals in the group are
oestrogen mimics.
Butylated hydroxyanisole
Butylated hydroxyanisole (BHA) is a food antioxidant. It is slightly
oestrogenic to breast cancer cells, binds rainbow trout oestrogen
receptor and stimulates transcriptional activity of the human oestrogen
receptor (Jobling et al., 1995).
Natural
Hormones
Phytoestrogens
Phytoestrogens are natural hormones present in many plants, and
in particularly high levels in soya.
Pollution by female hormones
Research in the UK has found that sewage effluents, and in some
cases rivers, were oestrogenic, causing the production of the egg
yolk protein in male trout. These hormones are naturally excreted,
in a conjugated form, in the urine of women; bacteria in the sewage
works then re-activate the hormones (Panter et al., 1999). The research
also detected estradiol, from the contraceptive pill, in some cases,
but the natural oestrogens were always more important.
Pesticides
A large number of pesticides have been identified as possible or
definite endocrine disrupters, many of the pesticides implicated
are described below.
DDT
The insecticide DDT has been banned in the developed world for
many years, though is in widespread use in the developing world.
Various DDT metabolites have endocrine effects, including blocking
the action of male hormones.
Lindane
Lindane is a pesticide which is under a great deal of regulatory
pressure around the world. On July 13th 2000 an EU regulatory committee
voted to ban agricultural uses of Lindane in Europe - though it
can still be used in some other products, such as ant killer. It
is a persistent pollutant, and is found in human breast milk. The
estrogenic properties of lindane have been demonstrated in several
systems, including the production of egg yolk protein and egg shell
protein in liver cells from Atlantic salmon. Lindane has also been
shown to damage human spermatozoa at concentrations as low as those
found in female genital tract secretions.
Vinclozolin
Vinclozolin is a fungicide and is a proven endocrine disrupter,
causing anti-androgenic ('anti-maleness') effects. Exposure of male
rats in the womb and shortly after birth to low doses of vinclozolin
leads a range of sex organ changes, including retained nipples,
reduced ejaculated sperm numbers and reduced ventral prostate weight
. Young male rats exposed to vinclozolin showed delayed puberty.
These anti-androgenic effects are due to two of its metabolites
(breakdown products), which are able to bind the androgen receptor
(including the human androgen receptor), blocking its activity.
Carbendazim
Carbendazim is a fungicide. It disrupts the production of sperm
and damages testicular development in adult rats, probably partly
through disrupting the assembling of cells in tissues which is the
same way as carbendazim works as a
fungicide. In addition, carbendazim is also a teratogen damaging
development of mammals in the womb. Experiments have shown that
exposure of developing rats in the womb leads to deformities such
as lack of eyes and hydrocephalus ("water on the brain").
Benomyl
Benomyl
is a fungicide, that is metabolized into carbendazim, see above.
Procymidone
Procymidone
is an anti-androgen, with anti-maleness properties similar to vinclozolin.
It is able to block androgen binding to the human androgen receptor,
and male offspring of rats exposed to procymidone during pregnancy
and early lactation showed a range of reproductive deformities,
such as permanent nipples and malformed penises.
Chlorpyrifos
Chlorpyrifos is a organophosphate insecticide, and has been listed
as a potential endocrine disrupter by the German Federal Environment
Agency, who report that it is linked to male and female genital
deformities. Chlorpyrifos is a neurotoxin, and exposure to low concentrations
can affect brain development in rats. Chlorpyrifos has also been
shown to affect the thyroid system in ewes, reducing blood thyroxine
concentrations.
Deltamethrin
Deltamethrin is a pyrethroid insecticide and has been listed as
a potential endocrine disrupter by the German Federal Environment
Agency, who report that it can affect sperm and the placenta. Research
has shown that chronic exposure of adult rats to deltamethrin causes
the death of some testicular cells.
Dimethoate
Dimethoate is an organophosphate insecticide and has been listed
as a potential endocrine disrupter by the German Federal Environment
Agency. Dimethoate caused testicular damage, damage to sperm production
and reduction in testosterone levels when fed to adult male rats.
Dimethoate also resulted in decreased thyroxine concentrations in
ewes, and affected thyroid metabolism in mice.
Carbofuran
Carbofuran is a carbamate insecticide and has been listed as a
potential endocrine disrupter by the German Federal Environment
Agency. Carbofuran caused sperm and reproductive system damage when
fed to either adult male rats or to developing male rats exposed
in the womb. Damage to sperm production was also seen when adult
rabbits were exposed to carbofuran. Carbofuran has also been shown
to affect the thyroid system in ewes, resulting in increased thyroxine
concentrations.
Amitraz
The insecticide Amitraz has been shown to disrupt oestrus in rats,
due to amitraz binding the a-noradrenergic receptors and blocking
the action of norepinephrine.
Trichlorfon
The organophosphate insecticide Trichlorfon has been listed as
a potential endocrine disrupter by the German Federal Environment
Agency, who report that it can cause mammary tumours and affect
sperm and egg production.A cluster of Down's syndrome children in
Hungary was associated with consumption of fish from a local fish
farm after the fish had become excessively contaminated by trichlorfon.
A degradation product of trichlorfon, dichlorvos, has been shown
to damage immune system function in humans; trichlorfon itself damages
immune function in Carp.
Penconazole
The fungicide Penconazole has been listed as a potential endocrine
disrupter by the German Federal Environment Agency, who report that
it can affect thyroid, prostate and testes weight.
Prochloraz
The conazole fungicide Prochloraz has been listed as a potential
endocrine disrupter by the German Federal Environment Agency, who
report that it can affect pituitary weight.
Propiconazole
The conazole fungicide Propiconazole has been listed as a potential
endocrine disrupter by the German Federal Environment Agency, who
report that it can affects steroid metabolism.
Tridemorph
The morpholine fungicide Tridemorph has been listed as a potential
endocrine disrupter by the German Federal Environment Agency, who
report that it is linked to cystic ovaries. Tridemorph is a potent
inhibitor of the human sterol isomerase enzyme, which is part of
the cholesterol biosynthesis pathway.
Epoxyconazole
Epoxyconazole is a fungicide that has been listed as a confirmed
endocrine disrupter by the German Federal Environment Agency, who
report that it can have effects on sex hormone balance and cause
ovarian tumors.
Metiram
The dithiocarbamate pesticide Metiram has been listed as a confirmed
endocrine disrupter by the German Federal Environment Agency, who
report that it can reduce levels of thyroid hormones.
Oxydemeton-methyl
Oxydemeton-methyl has been listed as a potential endocrine disrupter
by the German Federal Environment Agency, who report that it can
affect egg production and testis and ovary size.
Atrazine
The herbicide atrazine has been shown to affect reproductive system
development in rats. Mothers were dosed with atrazine and their
offspring showed a delay in vaginal opening in the females and a
higher incidence of prostate inflammation in the males. Atrazine
has also been shown to affect hormone metabolism in women, which
may have possible implications for breast cancer - see DDT for more
details.
Linuron
Linuron is a urea-based herbicide which has been shown to have
a weak affinity for the androgen receptor. A multi-generation study
with rats dosed with Linuron led to a range of male reproductive
tissue problems in offspring, including testicular malformations
and reduced size of androgen-dependant tissues.
Other pyrethroids
Research using the MCF-7 human breast carcinoma cells line has
found that the pyrethroid insecticides sumithrin, fenvalerate are
oestrogens, permethrin is a weak estrogen and d-trans allethrin
may be an anti-estrogen.
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