FOE Briefing: Endocrine Disrupting Pesticides

Endocrine Disrupting Pesticides

Briefing

Endocrine Disrupting Pesticides

Introduction

Endocrine disrupting chemicals (EDCs) are found in a variety of products, such as pesticides, wood preservatives, paints and plastics as well as occurring naturally, in some plants. These chemicals interfere with the working of the hormone system in mammals, birds, amphibians and fish. Their potential health effects include reproductive disorders, cancer and impaired development. In January 1998, the Environment Agency1 launched a consultation exercise urging companies to take precautionary measures to protect the environment from endocrine disrupting chemicals. In 1999, the Federal Environment Agency2 in Germany published a list of pesticides they considered to be confirmed or potential endocrine disrupters, some of these are described below.

How Endocrine Disrupting chemicals work

The endocrine system is vital to the functioning of plants and animals, controlling growth, maintenance and reproduction. It comprises a complex system of chemical messages (hormones) that trigger particular organs to produce a response, e.g. produce sperm, cause cells to multiply and cause cells to differentiate and develop new functions. This chemical message system is based on very low concentrations of hormones. Thus, powerful messages can be sent around the body of plants and animals with tiny amounts of hormones. In vertebrates the hormones are carried in the blood supply. The endocrine system is particularly active during the development of the foetus and reproductive systems later in life.

Endocrine disrupting chemicals (EDCs) fool target cells into behaving differently. They act in several ways, including:
.    as a false hormone binding to hormone receptors in the cell which then respond as if the natural hormone is present (e.g.oestrogen mimics).

.    as a hormone blocker (antagonistic effect)preventing the natural hormone from producing the natural response in the same way that a vehicle parked across an entrance prevents other vehicles from getting in.

.    by interfering with the synthesis of natural hormones

.    by interfering with the removal of hormones from circulation

Endocrine disruption is therefore extremely complex and studies of how it occurs are hampered by the lack of a full understanding of how natural hormones are produced and work. However, there is a growing body of evidence that a large number of chemicals are involved and that the effects could be conserable on both humans and their environment.

In humans, several health problems (listed below)which may be linked to EDCs have been recorded3.
.    decline in sperm count in many countries4
.    increase of 55% of incidence of testicular cancer (1979 - 1991) in England & Wales5
.    increase in prostrate cancer6
.    increase in breast cancer in women e.g.annual increase of one per cent in the USA since the 1940s.7

In wildlife, the following are examples of effects which have been linked to EDCs:

.    masculinisation of female dog whelks (a type of shell fish)
.    eggs found in testes of roach in many rivers in the UK..    low egg viability, enlarged ovaries and reduced penis size in Florida alligators
.    egg shell thinning and female-female paring in birds
Further details of these can be found in the Environment Agency report8. Endocrine disruption in wildlife has already been shown to threaten populations of species.

The research necessary to confirm which chemicals can be classed as EDCs and how they interfere with hormones is still being carried out. However, the Environment Agency has stated that there should be action to reduce further environmental exposure whilst this research is progressing. The list of chemicals proven to be EDCs is likely to grow as more research is carried out and so is the list of products affected. The evidence against the pesticides vinclozolin and carbendazim is very strong. Residues of both of these have been regularly found on fruit and vegetables since 1995(see below).

EDCs in the environment come from a wide range of sources, including some natural ones. Pesticide residues on food are just one of the ways in which humans are exposed to these chemicals and the cumulative effects are unknown. Some of the chemicals under scrutiny, and their sources, are listed below.

Endocrine Disrupting Chemicals

Many different chemicals have been found to be potential EDCs including the following:
Organochlorine compounds
These include dioxins which are produced as by-products of other chemicals (e.g. production of PVC), and burning certain materials in incinerators. PCBs, now banned, also fall in this category.

Industrial Chemicals
Chemicals used in industrial detergents,paints/varnishes, plastics and pesticides such as Alkylphenols and alkyl phenol ethoxylates.

Other synthetic chemicals
For example, Bisphenol A (BPA) is used in plastic manufacture (including plastic bottles) as a stabiliser, and in linings of steel tinplate food cans and water pipes. Phthalates are plasticisers (making plastic more flexible) used in PVC and in a range of products including toys, inks, paints and adhesives.

Phytoestrogens
These are naturally occuring in plant materials,including soya. Humans are usually able to break these down rapidly but there are concerns about the use of soya based infant foods which are not a natural part of our diet9.

Pesticides
Several widely used pesticides are known or potential EDCs including atrazine, benomyl,carbendazim, carbufuran, chlorpyrifos, dimethoate,DDT, lindane, vinclozolin and synthetic pyrethroids such as deltamethrin. Further details about three of these are given below.

Pesticide Residues Safety Levels

The thresholds for pesticide residues are agreed internationally by the Codex Alimentarius Commission (CAC). CAC is a joint body of the Food and Agriculture Organisation of the UN and the World Health Organisation (WHO). The CAC standards are set to protect consumer health and facilitate trade and are used by the World Trade Organisation to regulate trade. For pesticides CAC has agreed Maximum Residue Levels (MRL) for many but not all foods. MRLs are based on theAcceptable Daily Intake (ADI) agreed by the WHO with a considerable safety margin. However, safety assessments by the WHO do not take into account possible endocrine disrupting properties of pesticides. Many products currently licensed have not been screened as EDCs. Many MRLs may well be too high to exclude hormone disruption as a possible effect of being exposed to residues in food.

The pesticide approval process (The Control of Pesticides Regulations 1986, the Plant Protection Products Regulations 1995 and The Food and Environment Protection Act 1985) may require endocrine disruption to be screened before new products enter the market in the future. Older pesticides are currently being reviewed at present but this does not include a review of endocrine disruption. The Pesticide Safety Directorate(PSD)monitors the standard tests for reproductive function and carcinogenicity which may indicate endocrine disruption. However, pesticide formulations with possible EDCs as active ingredients are still being given PSD and Health & Safety Executive (HSE)approval. There is also a major review of pesticide safety data taking place in preparation for the harmonization of pesticide regulations and approvals within the EU.

Endocrine Disrupting Pesticides

Pesticides which have been shown to affect hormone systems are frequently used in UK agriculture.Residues of these products are often found by routine sampling carried out by MAFF. These surveys have also found endocrine disrupting pesticides in imported products .

Vinclozolin
Usage
This is registered as a fungicide for use on oilseed rape, apples, peas and beans. It is not widely used onapples or oilseed, but was used on a quarter of peas and beans in 199510.
Residues
Since 1995, it has been detected on imported celery,grapes, kiwi fruit, lettuce, pears, sweet peppers and tomatoes, as well as on UK lettuce, strawberries and pears. In the 1998 surveys by MAFF and the UK Industry (published in 1999) 11, no residues were found on UK lettuces (it is not approved for such use in the UK) although illegal use of other fungicides was found. However Vinclozolin was detected in some samples of tomatoes (also a non-approved use) and kiwi fruit.
Toxicity
Vinclozolin is a proven endocrine disrupter, causing anti-androgenic ('anti-maleness') effects. It does this by binding to the natural male hormone receptors.Studies on rats found that exposure of male rats in the womb and shortly after birth to low doses of vinclozolin lead to a range of sex organ changes12. Young male rats exposed to vinclozolin showed delayed puberty13.
Carbendazim
Usage
This is the most commonly used fungicide in the UK.
It is registered for use as a fungicide on Brussels sprouts, blackcurrants, gooseberries, beans, lettuce,black berries, loganberries, raspberries, tomatoes,oilseed rape, cucumbers, pepper, strawberries,celery, onions, cherries, plums, apples, barley, wheat,winter rye, mushrooms, stored fruit, cabbages and potatoes.
Residues
Since 1995 it has been detected on UK apples, UK and imported celery, grapes, marmalade, UK and imported pears, apricots, bananas, imported cucumbers, mixed dried fruit, retail and 'pick your own' gooseberries, peaches, imported and 'pick your own' strawberries, imported tomato products,clementines and UK green beans. In the 1998 MAFF & industry surveys, residues were detected in several samples of UK and imported apples, as well as in some samples of tomatoes, grapes,lemons, lettuce and mango.
Carbendazim has also been detected in processed products such as fruit based infant food, canned fruit, fruit squash and fruit juice.
Toxicity
Carbendazim disrupts the production of sperm and damages testicular development in adult rats. In addition, carbendazim is a teratogen _ damaging development of mammals in the womb. Rats developing in the womb and exposed to Carbendazim, have been found to lead to deformities such as lack of eyes and hydrocephalus (“water on the brain”)14.

Lindane
Usage
Lindane is still approved for use on food and fodder crops in the UK, including apples and in grain stores.Recent pesticide usage surveys show that over 41 tones of lindane have been applied to farm crops over one year15. Following a recent safety review,MAFF announced that its approval as a seed dressing was withdrawn because of risk of exposure to workers.
Residues
Residues of lindane commonly occur in chocolate. In the 1998 survey by the UK food industry, all samples of chocolate and cocoa butter contained lindane. Although these were below the MRL, this is no guarantee of safety (see above). The likely source of this lindane is its use on the cocoa crop. In 1998 lindane residues were also found in milk, infant formula milk and cheese.
Toxicity
The Austrian Ministry of Agriculture16 carried out a review of the toxicity of lindane for the EC and pointed to serious gaps in the data on health effects.The review concludes that lindane should be“suspended from the market”. One of its main concerns is the possible link between lindane and cancer.

Friends of the Earth Position

Friends of the Earth wants to see an immediate review of all pesticides for potential endocrine disrupting properties. This review should apply to all UK approved products as well as pesticides found on imported produce but not approved for use here.

Any products where there is evidence of endocrine disruption should be suspended until that review has been carried out. If the review reveals potential effects the product should be withdrawn from the market.
Food imports containing pesticides where evidence of endocrine disruption exist should not be allowed to enter the food chain.
All new products should be screened and none approved if endocrine disruption is shown.

Consumers should be informed by retailers what pesticides have been used on fresh produce and what residues have been detected in all food to allow them to make an informed choice as to whether to purchase or not.
Epidemiological studies of endocrine disruption should be increased so that the full extent of the problem can be assessed. In the mean time the precautionary principle should be applied to minimise exposure of vulnerable groups.
The Government should greatly increase investment in research in non chemical pest control in agriculture and greatly increase research and development and conversion support for organic farming.
FOE would like to see 30% of agricultural land to be under organic management by 2010. This targetshould be under pinned by legislation.
FOE also wants to see a pesticides tax, the revenue from which would be used to support organic conversion and pesticide reduction programmes in the UK.

Summary

Exposure to endocrine disrupting pesticide residues in food poses a significant health risk to humans. The long-term consequences of such exposure are difficult to assess but the current state of scientific information suggests that a highly precautionary approach is needed to avoid serious health problems in the future.
Written by Pete Riley, Sandra Bell and Michael Warhurst

The Real Food Campaign
Friends of the Earth
26-28, Underwood Street
London
N1 7JQ
E-mail - info@foe.co.uk
Website - www.foe.co.uk