Pesticide adjuvants

Attapulgite C10-12 pareth-3 Methyl canolate adjuvant, pesticides growing crops Dicetyldimonium chloride Dicocodimonium chloride Distearyidimonium chloride ... 

Florida, Illinois, Louisiana, Massachusetts, New Jersey, Pennsylvania, and Rhode Island (43). 1-Propanol is allowed as a flavoting substance and adjuvants according to 21 CFR 172.515 (48), and is exempted from the requirement of tolerance when used as a solvent or cosolvent iu pesticide formulations (49) (see Flavors AND spices Pesticides). 

Other U.S. regulatory clearances for sorbic acid allow its use as an antimicotic in the manufacture of food packaging materials (159), as a pesticide adjuvant when appHed to growing crops (160), and with methylceUulose and dimethylpolysiloxane as an antifoaming agent (161). 

The full extent of the toxicity of pesticides to aquatic life is not known. Although chronic toxicity testing is required for new substances, little is known about the long-term effects of older pesticides. Also, very little is known about the toxicity and occurrence of the products formed when pesticides break down (metabolites) or the many non-pesticidal additives (co-formulants and adjuvants) used in pesticide formulations. However, the future is looking brighter. New modelling techniques, EQS development, and the involvement of the NRA in the pesticide registration process, coupled with the development of newer, less persistent pesticides with lower dose rates, all should help to reduce the risk of pesticide pollution. 

The main purpose of pesticide formulation is to manufacture a product that has optimum biological efficiency, is convenient to use, and minimizes environmental impacts. The active ingredients are mixed with solvents, adjuvants (boosters), and fillers as necessary to achieve the desired formulation. The types of formulations include wettable powders, soluble concentrates, emulsion concentrates, oil-in-water emulsions, suspension concentrates, suspoemulsions, water-dispersible granules, dry granules, and controlled release, in which the active ingredient is released into the environment from a polymeric carrier, binder, absorbent, or encapsulant at a slow and effective rate. The formulation steps may generate air emissions, liquid effluents, and solid wastes. 

To solve this problem, modern pesticide formulations use a variety of additives (adjuvants) to improve the mass efficiency. Surfactants and polymeric rheology modifiers are used to reduce spray drift, surfactants are used to modify surface tension and reduce... 

Cross, B., Scher, H.B., Eds. "Pesticide Formulations" Chapter 13. Berger, P., et al. "Dynamic Surface Tensions of Spray Tank Adjuvants," ACS 1988, Washington, DC. 

Surfactants are often used in agrochemical formulations as adjuvants, e.g. as wetting agents to improve the physico-chemical characteristics of the solution and to increase the uptake of active ingredients (e.g. pesticides) [6-8]. The surfactants can be included in pesticide products and/or added to the tank mix prior to use however, they rarely exceed 1% of the total applied spray. Examples of typical surfactants used in agrochemical formulations are shown in Table 2.8.3 [9]. 

A possible source of groundwater contamination, which has up to now almost been neglected, is associated with the introduction of surfactants into soils as pesticide additives (Table 6.7.3). Non-ionic surfactants composed of alcohols and fatty acids are most widely recommended as adjuvants to facilitate and enhance the absorbing, emulsifying, dispersing, wetting and penetrating properties of pesticides. Other pesticide adjuvants are silicone-based surfactants,... 

Hildebrandt A, Lacorte S, Barcelo D (2007) Assessment of priority pesticides, degradation products, and pesticide adjuvants in groundwaters and top soils from agricultural areas of the Ebro river basin. Anal Bioanal Chem 387 1459-1468... 

The PAN Pesticide Database brings together a diverse array of information on pesticides from many different sources, providing human toxicity (chronic and acute), ecotoxicity and regulatory information for about 5400 pesticide active ingredients and their transformation products, as well as adjuvants and solvents used in pesticide products. ... 

Surfactant An adjuvant which improves the emulsifying, dispersing, spreading, and wetting properties of a pesticide. 

The transport phenomenon for any spray material released In the air Is foremost a function of the particle size and size distribution of the released spray. The particle density plays a minor role, the settling rate from Stokes law for example varies as the square root of the density. Further, the density differences between liquids commonly used for pesticides Is very little, varying only slightly from water at density of 1 gm/ml. Other formulation physical factors of surface tension, viscosity and viscoelasticity play significant roles In the atomization process. These are altered by the addition of petroleum and vegetable oil as solvents and carriers as well as a host of adjuvants In varying... 

C below the melting point. The nature and the size of the exposed surface of the deposit on the leaf surface can be modified by spray adjuvants such as wetting agents, thickeners or particulating agents. The deposited pesticide may also interact with the target surface, with leaf exudates or with the polymeric wax-like surface of cutin. It may also physically penetrate the surface of the leaf. 

Atmospheric Vapor. As emphasized elsewhere in this volume, most forest pesticides can be expected to volatilize. Even those with seemingly low vapor pressures (less than 10 6torr) are observed to vaporize from soil, leaves, and especially from aqueous solutions and suspensions (23-25) Consequently, a significant and perhaps major proportion of applied chemicals—pesticides, solvents, and adjuvants—can be expected to move eventually into the atmosphere. 

Pesticides are the "active" chemicals used by forest pest managers to contain and reduce tree loss from pest predation. They are usually marketed in formulations which also contain adjuvants. 

Field observations during aerial spray applications have demonstrated that anywhere from 15-75% of the pesticide mix admitted from the aircraft reaches the forest canopy (2). In some cases under unstable conditions, "on-target" deposit was less than 2% of the total emitted material. The portion of the spray deposit that does not land "on-target" (i.e. on conifer foliage) may be transported to aquatic and other non-target habitats. Overall, the amount of adjuvants in the mixes that deposits onto... 

Extensive testing of pesticides and their formulations is required before they are granted registration in Canada. However, no data is presently obtained on the chemical or biological effects of the final spray mix which contain more adjuvant. This is surprising as in some mixes, such as the Matacil 1.8D OSC, the final adjuvant content is greater than that of the pesticide. 

Bioaccumulation All classes of surfactant are active surface tension depressants. At the critical micelle concentration (CMC) abrupt changes occur in the characteristic properties of surfactants such that surface and interfacial tensions in an aqueous system are at their minimum while osmotic pressure and surface detergent properties are significantly increased. The CMC for most surfactants is reached around 0.01% (18, 19). These effects have an impact on the potential for bioaccumulation of the pesticide, and in the organisms monitored the presence of Dowanol and nonylphenol increased the accumulation of fenitrothion and aminocarb at least 20-300% respectively, over the accumulation obtained in their absence (20). In effect, these adjuvants... 

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