A number of chemical coformulants are added to pesticide formulations. They include carriers, solvents, surfactants, dispersants, spreading products, adhesives, absorption-improving products, antioxidants, bactericides, colouring products, fillers and perfume. In 1997, around 69% of pesticides sold in Denmark consisted of coformulants, corresponding to about 10,000 tonnes. Part of the quantity of coformulants is water. Coformulants are also called inert ingredients (Danish Environmental Protection Agency 1998a). The coformulants comprise a motley collection of chemicals, some of which are more acutely toxic than the active ingredients, e.g. organic solvents (information from the Danish Working Environment Authority). Isophoron is a commonly used solvent in a number of products, and the total quantity used is large. The substance has recently been classified as Carcinogenic Cat3. Some of the substances feature in DEPA’s list of undesirable compounds. The coformulants have been in focus because they include organic solvents and because it was found in 1997 that they included alkylphenols and alkylphenolethoxylates, which, in experimental studies, show hormonal effects on mammals. These coformulants are now being phased out, which means that many products are being reformulated, using substitute coformulants whose known properties are deemed to be less harmful.

Coformulants (or additives) in pesticides are not in themselves subject to authorisation. The various substances are subject to the regulation as described for chemicals in the Act on Chemical Substances and Products. For pesticides there are therefore no actual requirements concerning analyses of the individual ingredients. However, the authorities must know the precise composition of the products, so that all the ingredients can be identified. DEPA can also demand so-called data sheets for the individual coformulants. These data sheets contain brief information about the substances’ physical, chemical and toxicological properties, where these have been determined. When assessing coformulants, DEPA also consults the list of dangerous substances, which gives the classification of a number of chemicals (including some pesticides).

The toxicological properties of coformulants can also to some extent be seen from the tests required on the formulated product. These tests include tests for acute toxicity with oral intake, intake through the skin and inhalation, skin and eye irritation and, in some cases, ecotoxicological tests on aquatic organisms, bees, worms, microflora, etc. If a coformulant has a serious long-term effect and is included in the product in a sufficiently high concentration, the product is classified accordingly and has to undergo an exposure and risk analysis, even if the active ingredient does not have serious effects. DEPA can withdraw authorisation of a product simply on grounds of a coformulant. In addition, a coformulant must be declared on the label if it occurs in a concentration of 0.2% or more in the case of very toxic and toxic substances and 5% or more in the case of harmful or caustic substances.

7.2 Proportionality: the chemical impact in agriculture

Definition of proportionality

Here, proportionality should be understood to mean a proportional assessment of the harmful effects of pesticides on the environment and health compared with other chemicals used in agriculture or unintentionally added to the cultivated soil. It lies outside the scope of the sub-committee’s mandate to examine the use of chemicals in other sectors of society and to compare these environmental impacts with the environmental impact resulting from the chemicals used in agriculture. In addition, the pesticides have been assessed against naturally occurring toxins, and the use of naturally occurring substances as pesticides has also been assessed. The assessment thus covers:

	chemical substances in agriculture
	chemical substances in food products

In the assessment, the sub-committee has assessed the current size of the environmental load and its development, together with its regulation, and – lastly – the size of the load in relation to the occurrence and effects of the pesticides.

7.2.1 Chemical substances in agriculture

Like the rest of society, conventional farmers are dependent on chemical substances. The extensive use of fertilisers leads to loss of nitrogen and phosphorus to the aquatic environment and loss of ammonia to uncultivated land and forests. The use of chemical products has become more widespread in the agricultural sectors in step with the increasing demands concerning productivity. Such aids as fertiliser, ground chalk and pesticides are used in the production of crops, wood pulp, ornamental greenery, etc. Various waste products are used as fertilisers, some of which can contain xenobiotic substances. Pharmaceuticals, growth promoters and disinfectants are used in animal husbandry. Finally, pollutants are transported in the air. They derive, e.g., from the combustion of oil, coal, straw and waste, and traffic. The herbicidal substance DNOC can be formed from air-pollution components during atmospheric, chemical reactions, see section 4.5. Ozone is formed in a complicated interaction between oxygen, combustion products and the sunlight. Ozone can cause considerable damage to crops (Fenger 1995).

Cultivated land receives heavy metals from fertilisers, ground chalk, sludge and other waste products and from manure. It also receives heavy metals from the atmosphere. Both in Denmark and internationally, pollution with heavy metals – particularly cadmium, lead and mercury – has been considerably reduced. There are thus strict requirements concerning the content of heavy metals in fertilisers, chalk, sludge and other waste products. Cadmium is particularly problematical because both manmade and natural dispersal of cadmium is diffuse and because most cadmium compounds are relatively mobile in the environment. Cadmium is absorbed by plants parallel with phosphorus and thus makes cereal crops a major source of people’s intake of cadmium. People’s intake of lead, cadmium and mercury is generally high. Lead is not absorbed by plants but lands on their surfaces in the form of small particles from the atmosphere. However, national and long-range transboundary air pollution with heavy metals has been considerably reduced in the last 15 years. Better treatment of flue gas and a ban on lead in petrol have reduced air pollution. Since 1978, the deposition of cadmium has been reduced by 66%, and atmospheric emissions of lead have fallen by more than 75%. The use of copper and zinc as growth promoters in pig production means that the content of these metals is rising on soil regularly fertilised with pig manure from herds in which these growth promoters are used. Both metals affect the soil’s microorganisms and, in high concentrations, can inhibit plant growth.

The metals are not a serious problem in cultivated land today. However, this does not apply to really contaminated land, e.g. former industrial sites. Even so, taken together, the different sources can cause an increase in the soil’s content of heavy metals. The environmental authorities are therefore taking targeted action to reduce the use of heavy metals – particularly cadmium, lead and mercury – in society. Seen in proportion to the impact of pesticides, heavy metals are a bigger health problem than pesticides, but are not a big environmental problem. With the environment policy pursued, the problem is being reduced at source, both nationally and internationally. Owing to the continuing although diminishing supply, the load from heavy metals must be monitored on a long-term basis.

A very large number of chemical substances are used in society. Some of them end up in wastewater sludge and are thereby conveyed to land under cultivation. In 1997, the Danish Environmental Protection Agency introduced limit values for significant and representative, xenobiotic organic substances in sludge. It took this action to protect the environment and to promote the phasing-out of these substances from their cycles in society. There are now limit values for a number of tar substances (PAHs), the surfactants LAS, nonylphenols and the plasticiser DEHP. At the same time, both ecotoxicological and human toxicological soil quality criteria have been set for a wide range of substances that can occur as contaminants in soil or waste products. A number of studies are in progress to determine whether these protection levels are adequate.

Xenobiotic substances can also be present in low concentrations as contaminants in animal feed. The substances in question are banned pesticides, such as DDT and toxaphen, and industrial contaminants, such as PCB. These substances can be supplied to plants during their growth period as atmospheric deposition as a consequence of long-range transfrontier atmospheric pollution, together with combustion products, such as PAHs and dioxins. The cleaning products used by farmers for cleaning stables contain LAS and nonylphenol compounds. Small amounts of plasticisers, e.g. DEHP, are released from hoses, tanks, paint and plastic objects. The total supply means that manure also contains xenobiotic substances, which reach soil under cultivation by this pathway. Lastly, there is a direct supply of contaminants from the atmosphere to plant surfaces and the soil. The contaminants in question are PAHs, PCB, dioxins, chlorinated phenols and benzenes, together with a number of other, persistent organic contaminants. With frequent application of sludge on the same area, the total quantity of xenobiotic substances can be of the same order of magnitude as the pesticide load.

Most of the xenobiotic organic substances that are supplied to cultivated land are degradable, but as a rule over a very long period of time. The presence of xenobiotic substances is undesirable, so for precautionary reasons, consumption and dispersal are limited as much as possible or, in the case of persistent organic substances, for example, a ban is introduced. The exposure of the agricultural sector to xenobiotic substances is low compared with other sectors. Compared with the effect of pesticides, the direct effect of xenobiotic substances on cultivated soil and thus on crops is small. However, relatively little is known about potential, indirect pollution by xenobiotic substances, for example via air or through accidental loss, spillage or discharge to water. There may therefore be grounds for concern since the long-term effects of even small concentrations are not known. The aim of environment policy in this area is a reduction at source, both nationally and internationally, but in view of the continuing supply, the load from xenobiotic substances must be monitored on a long-term basis.

The formation of tropospheric ozone is closely linked with nitrogen oxide pollution from traffic, industry and energy production. Tropospheric ozone must not be confused with the ozone in the stratosphere, which is beneficial because it provides protection against UV radiation. Ozone is formed by the action of sunlight on nitrogen oxides and organic compounds – especially hydrocarbons. Ozone is a constituent of smog and affects the eyes, throat and lungs. It is particularly harmful to asthmatics. Ozone has a harmful effect on vegetation when it penetrates the plant cells. The damage occurs especially when the concentration of ozone in the air is over 40 ppb. The most serious effect of ozone, both ecologically and economically, is the effect on plant growth and seeding.

Seen in relation to pesticides, ozone is an example of a component of air pollution that is formed from emissions from traffic, energy production and industry and that causes considerable losses to the agricultural sector in the form of reduced yields. Work is going on within both the EU and UN-ECE FN-ECE to reduce the formation of ozone.

In animal husbandry, regular use is made of a number of veterinary drugs. Besides drugs for treatment of diseases, large quantities of prophylactic drugs are used, including the so-called growth promoters. Growth promoters are usually antibiotics but can also be salts of copper or zinc. Owing to the suspicion that use of certain pharmaceuticals can lead to the development of resistant bacteria, attention has recently focused on farmers’ use of antibiotics. The substances can also be spread in the environment with manure. Since the substances in question can be both biologically active in low concentrations, persistent and mobile in soil, the possibility cannot be excluded that some of the veterinary pharmaceuticals can constitute a risk to the environment in line with many other xenobiotic substances. Studies have been initiated under the Danish Environmental Research Programme to throw light on these questions. It will be some years before the final results can be expected, but preliminary studies indicate that particularly the broad-spectrum antibiotics have serious effects on microorganisms, whereas the effects on soil arthropods are relatively limited. Seen in relation to pesticides, veterinary pharmaceuticals and growth promoters constitute a potential risk of development of resistance in microorganisms, making treatment of infections in domestic animals and humans difficult. As far as the effects in the environment are concerned, veterinary pharmaceuticals and growth promoters probably constitute less of a risk than pesticides. However, there is a lack of studies of these matters - particularly of the risk of pollution of the groundwater.

7.2.2 Chemical substances in food products

Besides pesticide residues, food products contain a large number of contaminants and chemical substances, partly anthropogenous and partly of natural origin. In the Government’s report on food safety, these food components are systematically reviewed (Danish Government 1998). There follows a comparative analysis of the health consequences of pesticide residues in food products.

Many factors affect food safety. They include:

	naturally occurring toxic substances, e.g. algal toxins in mussels
	residues from medical treatment of animals, e.g., antibiotics
	contaminants from the environment, e.g. dioxins
	pesticide residues, e.g. from weed control
	additives and aromatics added intentionally to improve, for example, colour, taste and shelf-life
	migration from packaging
	chemical compounds formed during preparation, e.g. fried food mutagens.

Table 7.1 lists the health effects of the different contaminants of food products. The cause of health effects is shown, together with an assessment of the risk to humans given as the number of deaths or cases of poisoning per year or a safety margin between the actual exposure and NOAEL. The table shows that residues of the (individual) present pesticides have a large safety margin of 1000. They are thus less dangerous than the old, persistent chlorinated pesticides, which have a safety margin of 10-500, depending on the individual substance. The heavy metals lead, cadmium and mercury are far more dangerous to humans that pesticide residues, having a safety margin of only 2-10. It is at the same time thought that toxic constituents in food plants, such as glycoalkaloids in potatoes and tomatoes, lectins in dried beans, prussic acid glycosides in apricot kernels, bamboo shoots and flax seed, together with phenylhydrazines in mushrooms, constitute a greater risk than pesticide residues. There is growing interest in these toxic substances because their content in food plants can be inadvertently increased by genetic modification. Special attention is being paid to this in the risk analysis of genetically modified plants. Lastly, there is nitrate, which is deemed to be a bigger problem in drinking water than pesticide residues in the current concentrations.

Table 7.1
Health effects from different contaminants in food products. For each type of contaminant, the figure shows the number of deaths, cases of poisoning or other effect that can be expected per year or the safety margin between the actual level and the level at which it begins to become possible to observe the effects (Danish Government 1998). The individual pesticide, which has a margin of more than 1000, is thus less dangerous than any of the metals lead, cadmium and mercury, which have a low margin of 2-10. Question marks indicate that there is too little knowledge on which to base an assessment.

(*): Nitrate can be converted into nitrite, which can cause acute poisoning in infants and can contribute to the formation of carcinogenic nitrosamines. It is not possible to set a margin.

7.3 Natural substances

All plants contain varying concentrations of toxic substances to protect themselves against attack by viruses, microorganisms and herbivores, particularly insects. However, through evolution, the different species of microorganisms and animals have specialised in living from plants that are otherwise poisonous to other organisms. Common examples of such poisonous plants are deadly nightshade, spring groundsel and cow parsnip. The last two of these are imported, non-indigenous species that are not regulated by natural enemies that tolerate the plants’ constituents. Humans eat only a few plant species – normally less than 100. Although some crop plants contain substances that have a toxic effect on certain other groups of organisms, most of them have very little toxic effect on humans, who have deliberately selected the crops that are acceptable and edible. Humans also use poisonous plants, such as the coffee plant and the tobacco plant. The tobacco plant, in particular, and its special uses present a considerable risk of cancer in humans. In connection with the introduction of so-called "Novel Food" products, including products made from genetically modified plants, the authorities are carrying out a risk analysis in line with the analysis of pesticides with a view to protecting the consumers.

Unlike pesticides, natural toxins are mainly inside the plant and only exhibit their toxic effect when other organisms approach the plant, touch it or eat it. Pesticides, on the other hand, are normally spread over large areas with the aim of eliminating pests with at least 90% effect on the whole area. All organisms within the area are thereby exposed to and hit by the pesticide or later eat parts of plants containing pesticide residues.

A count of authorised plant protection products carried out in 1998 (Environmental Protection Agency1998b) shows that a total of 9 naturally occurring active ingredients have been authorised. Two others are at the application stage. As shown in table 7.2, six are extracted from plants, two from minerals and two from animals. Application has been made for use of a wide range of microbiological products as insecticides or fungicides.

Table 7.2
Naturally occurring substances authorised for use as pesticides, or at the application stage, in Denmark. See also table 9.1 concerning microbiological pesticides.

Apart from the mineral sulphur, these naturally occurring substances are relatively easily degradable, so their action time is short. They are currently used only on small areas of land, where, as in the case of synthetic active ingredients, the aim is to knock out more than 90% of the pests. In principle, there is thus no difference between these substances and synthetic pesticides, and the insecticides mentioned can be expected to have similar sideeffects on non-target organisms to those described in section 5.1.

The naturally occurring active ingredients shown in table 7.2 are much less toxic to mammals and degrade considerably faster than synthetic pesticides. An example is the insecticide pyrethrin I and II, which is extracted from the chrysanthemum flower. Pyrethrin is poisonous to insects and has a low potential for producing toxicity in humans. If injected directly into the blood, the substance has a highly toxic effect on mammals. The normally low toxicity is due to slow absorption through the skin or in the gastrointestinal tract in mammals. Pyrethrins are very unstable and break down almost instantaneously in sunlight. The effect of this mixture is increased in the spray product by adding a synergist, piperonylbutoxide. This substance is only slightly toxic in itself, but impedes the enzyme systems that break pyrethrins down, enabling them to act for a longer period of time in insects.

One of the main groups of modern synthetic pesticides is the so-called pyrethroids, which contain the same chemical, active group as pyrethrum, but in which the molecule has been made more stable by use of aromatic structures, halogenation or reaction with cyanide. This considerably increases the toxic effect on insects – 1000 times, for instance, for deltamethrin compared with naturally occurring pyrethrins. The increased stability of the molecules at the same time gives a risk of dispersal in the atmosphere and to surface water and ground water. The pyrethroid example illustrates the fact that synthetic pesticides usually contain chemical structures that are seldom found in nature. The physical and chemical properties of the molecule, and thus its toxicity, are thereby changed. This effect depends particularly on changes in the direction of lower degradability, greater persistence, changed solubility and increased penetration in membranes.

7.4 The sub-committee’s conclusions and recommendations

Conclusion concerning coformulants

Coformulants, which are added to pesticide formulations, are not covered by an authorisation scheme of the same scope as for active pesticide chemicals. Coformulants are a very broad and extensive group of substances, the composition of which can vary within the individual product or type of product. The coformulants are normally less harmful to the environment and health than the active ingredient, but often occur in large concentrations, and substances that are harmful to the environment and/or health can be used – e.g. substances that produce acute or chronic toxicity. Some of the substances can thus be more harmful to the environment or health than the active ingredient to which they are added. A few of the substances feature in DEPA’s list of undesirable substances.

Conclusion concerning natural substances compared with pesticides

All plants contain varying concentrations of toxic substances to protect themselves against attack by viruses, microorganisms and herbivores. Most herbivores eat only specific food plants. Humans thus eat only a limited number of plant species – less than 100 – that have been selected and used for many generations as components in human food. Therefore, even though crop plants contain substances that have a toxic effect on certain other groups of organisms, in most cases they produce very little toxicity in humans. Unlike pesticides, the toxic natural substances are inside the plant and only exhibit their toxic effect when other organisms approach it, touch it or eat it. Pesticides, on the other hand, are normally spread over larger areas of land, with the aim of knocking out pests – often with around 90% effect in the entire area. All organisms in the area in question are thus exposed to and hit by the pesticide or later eat plant parts containing pesticide residues. Synthetic pesticides usually contain chemical structures that are seldom found in nature. The physical and chemical properties of the molecule, and thus its toxicity, are thereby changed. This effect depends particularly on changes in the direction of lower degradability, greater persistence, changed solubility and increased penetration in membranes.

The following specific conclusions can be drawn:

The heavy metals cadmium, lead and mercury present a greater health problem than pesticides, but are not a serious problem environmentally. However, attention must be paid to a potential accumulation in cultivated soil of, in particular, cadmium, lead and copper.

Compared with the effect of pesticides, the direct effect of xenobiotic substances on cultivated soil and thus on crops is small. However, relatively little is known about potential, indirect pollution by xenobiotic substances, for example via air or through accidental loss, spillage or discharge to water. There may therefore be grounds for concern since the long-term effects of even small concentrations are not known. With the environment policy now pursued, efforts are being made, both nationally and internationally, to ensure a reduction at source, but owing to the continuing supply of such substances, the load must be monitored on a long-term basis.

Organic pollutants are not generally a problem in cultivated soil. With frequent application of sludge on the same area, the total quantity of xenobiotic substances can be of the same order of magnitude as the pesticide load.

The use of veterinary drugs and growth promoters involves a risk of the development of resistant microorganisms, and too little is as yet known about the possible effect of manure on cultivated land to assess veterinary drugs and growth promoters in relation to pesticides.

A number of naturally occurring substances are to a limited extent used as pesticides. The substances in question are relatively easily degradable, so their action time is short, but the sub-committee finds that there is in principle no difference between these substances and synthetic pesticides. The sub-committee concludes that, compared with natural substances, pesticides have a considerably greater potential for environmentally harmful effects because of the way they are used, their relatively low degradability and their chemically determined, intensified mode of action. With respect to human health, the sub-committee finds that some naturally occurring constituents of plants can present a risk and that, for example in connection with "Novel Food" products, they should be subjected to a risk analysis in line with pesticides.

The sub-committee’s recommendations concerning coformulants

The sub-committee recommends that the authorisation scheme be expanded so that the requirements concerning coformulants approach the requirements made concerning active ingredients. In this connection, all carcinogenic substances should be banned. However, coformulants are also used for other purposes than pesticide formulations. Therefore, the regulations on the use of these substances should be generally tightened for all applications.

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