Testing laboratories will obtain the active ingredient from the manufacturer and may use that ingredient in diluted form mixed with water which will often be pure and of neutral pH value.
This does not in any way reflect the conditions in which the pesticides will be used.
Commercial formulations may contain a variety of co-formulants in order
to enhance the action and prolong the activity of the active ingredient.
Many of those ingredients are extremely toxic.
Additional risk comes from the water used on the farm in order to
deliver the formulation to the target organism.
That water may be acidic or alkali and it may contain fluorine and or
chlorine in addition to any other pesticide residues which may be
present either in the water or as the remains of earlier spraying
activities.
Many of the co-formulants in commercially available products have levels
set for maximum occupational exposures and warnings are common that
"inhalation of the solvent may be at least, or more, important than that
of the active ingredient."
Laboratory conditions can never mimic conditions found in the field.
Early insecticides could be extremely dangerous to man and many were
used as poisons in murder or suicide attempts. These chemicals included
compounds of arsenic, fluorine, copper, mercury and zinc but they were
mostly poisons of ingestion with indefinite active life.
A variety of oils, such as creosote, and soap emulsions were used to
block the respiratory systems of the insects.
Recently liquid detergents were nominated for use as insecticides
in glasshouses but the application was withdrawn for lack of safety
data. Many pesticide poisoned victims find themselves reacting to such
products which are regarded as perfectly safe by the majority of the
population. What ingredients in detergents can produce such effects?
Naphthalene, paradichlorobenzene and methyl bromide gave off vapours
which had insecticidal properties and so were useful in fumigation
systems.
Contact poisons such as nicotine based products and others of plant
origin such as derris and the pyrethrum and pyrethrins were also widely
used but they broke down rapidly in light. These compounds were
stabilised to ensure prolonged activity by the addition of other
compounds which, though not toxic in themselves, had a synergistic
effect and greatly increased the toxicity of the formulation.
William Rae in his book "Pesticides" wrote of pyrethroids.
"Experimental investigations with animals provided evidence in the
early nineteenth century, prior to mass indoor application, that
pyrethroids are neurotoxic. They are membrane poisons which are known
among other functions, to disturb the nervous conduction not only of
insects and other invertebrates, but also of vertebrates and,
therefore humans. Because of their deficient specificity, high
effectiveness, irreversibility and accumulation of their effects as
well as their persistence in the environment, many investigators
predicted that the mass use of pyrethroids in the environment of
humans would lead to chronic health impairment. Results of clinical
investigations suggest that the predictions have become a reality..
..."
Benzene and the related products such as toluene, xylene and naptha are
all hydrocarbons derived from oil and coal tar.
Benzene combines with chlorine in certain conditions to form the
organochlorine insecticides such as benzene hexachloride (BHC or
Gammexane), hexachlorocyclobenzene (HCH), DDT, toxaphene, dieldrin,
and Gamma BHC known as lindane.
Recently reports suggest that those who work with solvents for just
one hour a day for 10 years will be more likely to develop Parkinson's
disease and that the onset of the disease will be earlier in life.
Substances which contain solvents include petrol, plastics, rubber,
cleaning fluids, glue, paint, perfumes and pesticides and it is
interesting that those poisoned by pesticides often find themselves
sensitised to all these products.
Even more potent insecticides were to be discovered with the advent of orghanophosporus chemistry and the arrival of parathion, schradan and systox. Some of these new chemicals were found to be systemic in action and they were absorbed into the sap of plants and translocated making the entire plant toxic to insects for weeks.
The plants also became toxic to animals and this resulted in the introduction of the time intervals between treatment and harvest.
The systemic action of OP compounds in plants is mirrored by the action
of these compounds in both man and animal.
The property was utilised to full effect in the warble fly eradication
programme which was initiated in order to protect the hides used by the
leather industry from the destructive activity of the grub which formed
large holes in the skin of the cattle. Despite the known dangers from
the residues in the meat and the potential harm caused to the animal
the compulsory eradication programme employed four OP compounds,
crufomate, famphur, fenthion and phosmet.
These oily chemicals were poured along the backs of the cows but because
of the systemic nature of the chemical the effect was the same as if it
had been injected directly into the blood stream.
Effectively this made the entire animal toxic to insects which then
died within the living animal.
Farmers were warned not to treat the animals at certain times of the
year because the grubs would be close to the spine of the animal and
could cause serious ill effects if they died and caused infection in
that position.
Some organophosphorus compounds were discovered to induce delayed
neurological problems in man. A test was devised to determine which OP
compounds were capable of causing this delayed damage. The test
involved poisoning chickens with the OPs and determining if they
suffered with similar problems. The test became known as the "Hen Test"
but it has been widely criticised as a standard for safety because
some chemicals which have passed the hen tst have later been found to
induce the damage in humans. This may not be surprising when we realise
that the hens are given the antidotes to the poison both before
poisoning them and several times after the poison was administered. In
some cases despite the use of antidotes many of the hens died and yet
the chemical has still been cleared as safe to use on food crops.
This test remains as the foundation for regulatory opinion on the safety
of organophosphate pesticides.
Warnings were issued that farmers should not use organochlorine
insecticides in dairies and cowsheds because the dust or droplets
containing the chemical could be inhaled with resultant contamination
of milk.
OPs are also excreted in the milk but it was not until well
into the eradication programme that milk withdrawal times were
introduced after treatment in order to reduce OP residues in milk.
Some insecticides are known to effect some species more than others.
Thiophosphate was apparently safe for chickens but kills ducks.
Dieldrin killed wild birds and aldrin has killed sheep.
An American farmer treated cows with diluted Tetra-ethyl pyrophosphate
(TEPP) and killed all his cows within an hour.
Some OP pesticides can be altered by the action of sunlight or the metabolic processes within the body of animals or humans and these breakdown products may be far more toxic than the original compound.
It is known that some chemicals can mimic the action of hormones.
This was shown with dramatic effect when a laboratory involved in the
study of breast cancer discovered that the cells were growing when
they should not have been. Their experiments were ruined and it was
not until they realised that chemicals found in the plastic of the
dishes they used were triggering the growth that the work was able to
continue.
This brought concerns about chemicals with hormonal actions which are
being released into rivers via the sewage disposal system and which
were shown to change the sex of fish.
Hormones are easily disrupted as actions are controlled not by the
amount of hormone present but by the balance between them within the
body. Most depend on the presence of naturally occurring phosphorus
compounds without which the hormone receptors are unable to operate.
Hormone imbalances are involved in thyroid disorders, osteoporosis and
in diabetes to name but a few and some of these disturbances in
hormone levels can have far reaching and unexpected effects.
Worryingly test animals have been bred which can be more or less susceptible to chemically induced hormone disruption. It is to be hoped that such animals are not used by the testing laboratories to indicate a false view of the safety of hormone disrupting pesticides.
Some chemicals used as pesticides are also found in pharmaceuticals
and many of the companies have interests in both sciences.
DES (diethylstilbestrol) was a synthetic oestrogen regarded, like
Tamoxifen which is used to control breast cancer, as a wonder drug.
DES was used to prevent miscarriages and premature births in an
experiment on some 5 million women and doctors wanted to use it
routinely in all pregnancies.
It was prescribed for menopausal symptoms, acne, prostate cancer,
gonorrhea and even as a growth regulator to slow girls who were
growing too tall as well as its use as the "morning after pill".
It was also used as a food additive on farms.....
Then rat studies began to show abnormalities.
Rare vaginal cancers began appearing in teenage children born to the
women who were given the drug which reportedly often also failed to
halt the miscarriages it was prescribed to prevent.
Later it was suspected of causing fertility and immune system problems
and testicular cancer in male children born to mothers given the
treatment. Daughters of treated women were reported to show permanent
changes in the T and natural killer cells of the immune system and yet
they did not show greater vulnerability to infection.
The claim was that the delayed long-term effects that did not show
until later in life were previously unrecognized medical phenomena.
Hormone disrupting chemicals may therefore have extremely serious long-term effects.
Benzenes are common ingredients in pesticides.
Cholesterol is formed from benzene by processes which depend on natural
compounds based on phosphorus.
Steroid hormones are formed from Cholesterol and again this process
depends upon phosphorus.
It is easy to see how an organophosphate pesticide may disrupt the
hormone system in ways that are difficult to detect.
Despite claims that all these chemicals are properly tested before
being allowed on the market it is clear that large numbers of people
are poisoned by them every year. Ironically a former UK safety
regulator wrote a published article in which he accused poisoned
individuals as suffering from mass hysteria. At the same time he
blamed them for the environmental damage caused by chemicals to which
farmers had turned to avoid suffering the ill effects of exposure to
organophosphorus based pesticides.
He did not seem to realise that he was admitting that the regulators
had allowed yet another group of environmentally hazardous chemicals
to be used by farmers.
An indication of poor regulatory work is also found in the story of Roundup toxicity as it is said that the formulation is many times more toxic than the active ingredient. An apparent admission that the product has not been properly tested is found in a Government issued book advising doctors how to treat poisoned individuals.
"It is believed that this surfactant (polyoxyethyleneamine) was responsible for some of the features observed in cases of severe poisoning due to glyphosate containing products...The new surfactants are expected to be less toxic than polyoxyethyleneamine but there is inadequate human experience to verify this."
In effect this means that they released the product as safe but people were made seriously ill, so they assumed it was a co-formulant problem and changed the surfactant in the hope that the product would be safer. Now they are waiting to see if more sick people will show that they were wrong in their assumption.
Rarely are pesticides fully tested in the form in which they are
sold but in almost every case they are tested as individual chemicals.
There appears to be no concern shown over the cumulative or synergistic
effects on individuals or groups of individuals frequently exposed to
combinations of two or more chemicals with different modes of action.
Because they may well act on different systems within the body their
combined action may not simply be additive but their effects may be
multiplied many times.
Recently the UK regulators issued requests to the manufacturers for
information on the products already licensed for use. That request was
for the declaration of ingredients which may be mutagenic, carcinogenic
or toxic to reproduction. The request was made in the year 2000 but the
law regarding these substances should have been enacted in March 1999.
The substances about which there is concern are the hydrocarbon
co-formulants of which benzene is the substance of most concern with
naphthalene also specifically mentioned.
In July 1999, months after the regulations should have been in force, the
regulators wrote in respect to ingredients listed in an OP formulation
commonly added to grain in the store after harvest that :
Naphtha - is a general name for a range of heavy aromatic carbons,
some of which are commonly used in pesticide formulations. Sources of
naphtha may contain one or more alkyl benzenes. The toxicity of naphtha
can be influenced substantially by the presence or absence of benzene.
Light aromatics - This is a general chemical class describing
distillation fractions from petroleum products. It is a very broad group
of compounds with varying toxicity profiles. Again they are commonly
used in pesticide formulations.
Alkyl phenol ethoxylates - These are approved in pesticide
formulations to help disperse non water soluble active ingredients in
water. They also have industrial use as detergents. Alkyl phenols can be
found in a wide range of compounds. Because of the variety of compounds
from which an ethoxylate may be derived, the toxicity of ethoxylates
will differ very markedly.
Sulfotep and TEPP - A search of our database shows that
sulfotep and TEPP are not active substances or co-formulants in
any approved pesticide formulation in the UK. It is however known
that they can occur as an impurity in low levels of some pesticides.
The toxicity of any impurity would be accounted for in the overall
toxicity testing we require for registration purposes.
It is not known how the regulators can account for the toxicity of an
unknown ingredient but it is clear that "Commercial Confidentiality" is
being employed to good effect by the manufacturers and the regulators
in order to prevent the many victims of poisoning discovering the true
list of ingredients.
Apparently simple changes can protect the OP molecule from attack by
water and render the entire formulation much more dangerous to the
exposed individual.
Given that alkyl benzenes are listed as ingredients in the formulation and that the same regulatory body wrote to the manufacturers stating that "It is not possible for PSD to identify with certainty whether substances such as these are present in approved pesticide products or in adjuvants." it would seem that we should all be concerned.
Later the regulators attempted to explain away their lack of information
with the comment that :
"I can assure you that PSD does maintain full details of product
formulations including co-formulants. There were two reasons for asking
in this letter for approval holders to check their own products against
the list of substances in the 16th Amendment to the Marketing and Use
Directive. The first was due to the sheer numbers involved. PSD has
approved 4,000 products and there are over 700 substances listed in
the 16th amendment. The second problem was the detailed terminology for
the petroleum extracts, examples are given in the letter. The records
that the PSD hold may not match these descriptions exactly and PSD
needed to confirm with approval holders via the EC or CAS reference
number, that any petroleum extracts were correctly identified."
Recently the Pesticide Safety Directorate in the UK reported that many of the co-formulants such as benzenes and other solvents are to be limited due to their toxic potential, including the ability to cause cancers. It is also reported that some 50% of currently available pesticides are to be withdrawn from the market by the year 2003 and that this is because the manufacturers were unable to provide the required safety data.
This indicates that the regulators do not know exactly what chemicals are in the products which they licence as safe for us to eat.
Dated 16/9/2000 Updated 1/8/2001