Skin irritation of plant protection products - Comparison of classification according to Directive 67/548/EEC and Regulation No. 1272/2008, respectively, in relation to conventional calculation method (additivity)

According to Directive 91/414/EC concerning the placing of plant protection products on the market MemberStates have to ensure that a plant protection product, when it is properly applied for the intended purpose, has noharmful effect on human health.For evaluation of the toxicity of preparations (containing active substance(s) and co-formulants) amongst otherssufficient information should be available on their irritation potential. These tests shall provide e.g. informationabout the potential of skin irritancy including the possible reversibility of the effects observed. The skin irritancy ofplant protection products must be determined according to Dir. 92/69/EEC, Method B4. Tests can only be omittedif foreseeable severe skin effects may be produced or if effects can be totally excluded. On the other hand,classification of preparations could be performed based on irritant properties of the components according to Dir.1999/45/EC and Reg. No. 1272/2008, respectively, under specific circumstances. For this purpose concentrations ofall classified irritant components have to be considered. In general, the approach of classifying mixtures as irritantor corrosive to the skin when data are available on the components, but not on the mixture as a whole, is based onthe theory of additivity. Thus every single corrosive or irritant component contributes to the overall irritant orcorrosive properties of the mixture in proportion to its potency and concentration.Directive 67/548/EEC: Substances and preparations are considered irritant if the mean value of all scores for eithererythema and eschar formation or oedema formation is 2 or more (in the case where the test has been carried outusing three animals, a mean value of 2 or more is observed calculated for each individual animal in at least twoanimals) from gradings at 24, 48 and 72 hours after patch removal.Directive 1999/45/EC: Individual concentration limits expressed as a weight/weight percentage, determining theclassification of the preparation:Classification of the substance Classification of preparationC; R35 C; R34 Xi; R38C; R35 10 % 5 % - < 10 % 1 % - < 5 %C; R34 10 % 5 % - < 10 %Xi; R38 20 %Regulation No. 1272/2008: The major criterion for the irritant category is that at least 2 of 3 tested animals have amean score of 2,3 - 4,0 for erythema/eschar or for oedema from gradings at 24, 48 and 72 hours after patchremoval.Generic concentration limits of ingredients classified for skin corrosive/irritant hazard (Category 1 or 2) that triggerclassification of the mixture as corrosive/irritant to skin:Sum of ingredients classified as: Concentration triggering classification of a mixture as:Skin Corrosive Cat. 1 Skin Irritant Cat. 2Skin Corrosive Cat. 1A, 1B, 1C 5 % 1 % - < 5 %Skin irritant Cat. 2 10 %(10 × Skin Corrosive Cat. 1A, 1B, 1C) + Skin irritant Cat. 2 10 %Co-formulants in plant protection products are added intentionally to the formulation in order to gain/improvecertain characteristics. These substances are used to achieve the maximum target effects ensuring the necessaryproperties for the application. Therefore, they can enhance exposure of pests and/or efficiency of the activeingredient.Comparison of skin irritation classification of pesticide preparations was performed using in vivo data andcalculation methods according to Dir. 1999/45/EC and Reg. No. 1272/2008. All plant protection products classifiedwith R38 and authorised in DE as well as all authorised plant protection products with known irritant ingredientswhere chosen for the evaluation.The results of the comparison show, that the conventional calculation method seems to be not sufficiently suitablefor an adequate assessment of irritant properties of complex pesticide preparations. For many plant protectionproducts the skin irritation hazard will be underestimated if the calculation method is applied. One possible reasonmight be the influence of ingredients, which are weak irritating with scores below the threshold of classification.Using the calculation method these compounds are not taken into account. Furthermore synergistic effects orinteractions between components are not considered, either.