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Pesticides
Friends of the Earth has recently launched a new 'Real Food' campaign, which includes a campaign for zero pesticide residues - more details on the Real Food web site.
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. More details...
Lindane
Lindane is an organochlorine pesticide which is under a great deal of regulatory pressure around the world. On the 13th July 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 [26]. It is a persistent pollutant, and is found in human breast milk [27]. The oestrogenic properties of lindane have been demonstrated in several systems, including the production of vitellogenin (egg yolk protein) and zona radiata (egg shell protein) in primary hepatocyctes (liver cells) from Atlantic salmon (Salmo salar L.) [28]. Lindane has also been shown to damage human spermatozoa at concentrations as low as those found in female genital tract secretions [29].
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 [1]. Young male rats exposed to vinclozolin showed delayed puberty [2]. 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 [3, 4].
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 [5, 6]. 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") [7].
Benomyl
Benomyl is a fungicide, that is metbolised 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 [8].
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 [14]. Chlorpyrifos is a neurotoxin, and exposure to low concentrations can affect brain development in rats [9,10]. Chlorpyrifos has also been shown to affect the thyroid system in ewes, reducing blood thyroxine concentrations [18].
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 [14]. Research has shown that chronic exposure of adult rats to deltamethrin causes the death of some testicular cells [11].
Dimethoate
Dimethoate is an organophosphate insecticide and has been listed as a potential endocrine disrupter by the German Federal Environment Agency [14]. Dimethoate caused testicular damage, damage to sperm production and reduction in testosterone levels when fed to adult male rats [12]. Dimethoate also resulted in decreased thyroxine concentrations in ewes [18], and affected thyroid metabolism in mice [13].
Carbofuran
Carbofuran is a carbamate insecticide and has been listed as a potential endocrine disrupter by the German Federal Environment Agency [14]. Carbofuran caused sperm and reproductive system damage when fed to either adult male rats or to developing male rats exposed in the womb [15,16]. Damage to sperm production was also seen when adult rabbits were exposed to carbofuran [17]. Carbofuran has also been shown to affect the thyroid system in ewes, resulting in increased thyroxine concentrations [18].
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 [19].
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 [14].
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 [20]. A degradation
product of trichlorfon, dichlorvos, has been shown to damage
immune system function in humans; trichlorfon itself damages
immune function in Carp [21].
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 [14].
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 [14].
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 [14].
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 [14]. Tridemorph is a potent inhibitor of the human sterol isomerase enzyme, which is part of the cholesterol biosynthesis pathway [22].
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 tumours [14].
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 [14].
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 [14].
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 [23]. 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 [24].
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 oestrogen and d-trans allethrin may be an anti-oestrogen [25].