The authority said that chlorine dioxide, acidified sodium chlorite, trisodium phosphate and peroxyacids, which are already used on US poultry to kill off contaminates, posed no safety concerns. "Despite a long history of use, no published data exist to indicate that the four substances, within the proposed conditions of use, will lead to increased bacterial tolerance to these substances or to increased resistance to therapeutic antibiotics and other antimicrobial agents," EFSA's Panel on Biological Hazards (BIOHAZ) stated. However, the panel did flag up one possible concern regarding peroxyacids, claming that there was insufficient data made available to determine whether the substances could effectively kill or reduce bacteria on poultry. Use of these antimicrobial substances as a means of decontaminating poultry is currently not allowed within the European Union. The regulator said that further testing into whether there is any possibility that these types of substances can cause resistance to therapeutic antibiotics, would be required before allowing their use within the EU's poultry sector. Under current rulings, only drinking water is authorised for use on chicken carcasses in the EU. According to BIOHAZ, there has been some evidence that suggests a possible link between bacterial tolerance and the use other antimicrobial substances or biocides not included in its latest tests. Previous studies EFSA says it has published several opinions on the four antimicrobial agents - chlorine dioxide, acidified sodium chlorite, trisodium phosphate and peroxyacids - between 2005 and 2006 conducted by another of its panels. The research, which looked at their suitability and effectiveness at killing or reducing bacteria in food, was conducted by EFSA's Panel on additives, flavourings, processing aids and materials in contact with food (AFC). The panel concluded that on the basis of the information available at the time, no dangers were found in using the four substances on food.