The present application provides improved bioactive chemicals having increased bioactive activity and a method for manufacturing such materials. The improved chemical material is provided with an optimum particle size or a small set of optimal particle sizes within the bioactive chemical material in order to obtain increased activity of the active ingredient. The use of an optimum particle size enables a reduction in the amount of active ingredient required in the bioactive chemical for a specified biological effect. The formulation comprises a bioactive material in particulate form in which at least 50% of the particles by volume or mass are in the range 0.5M to 1.5M, where M is the most biologically active particle size class or mode, and the number of particulate size classes is at least 12 and preferably at least 20, such that the particulate distribution can be characterized efficiently and the mode be well defined. In an alternate formulation, at least 90% of the bioactive material particles by volume or mass are in the range 0.5M to 1.5M, and 50% of the particles by volume or mass are in the range 0.75M to 1.25M. Where two or more particle size classes are found to increase efficacy of the active ingredient, several fractions are be mixed together in optimum proportions.Linvention porte sur des produits chimiques bioactifs à bioactivité renforcée et sur leur procédé de fabrication. Les particules des produits présentent une taille ou un éventail réduit optimes de tailles de particules, renforçant lactivité de lingrédient actif. Cette optimisation de la taille permet de réduire la quantité requise du produit pour un effet biologique donné. 50 % au moins des particules (en volume ou en masse) ont entre 0,5 et 1,5 M, M étant la classe ou le mode de taille des particules les plus bioactives, et le nombre des classes de particules étant dau moins 12, et de préférence de 20, ce qui permet de caractériser efficacement la distribution des particules et de définir cor
