Quaternary ammonium compounds (QACs) are surface-active substances containing a quaternary cationic nitrogen atom, substituted by alkyl chains of varying length. They are used as biocides, pesticides, disinfectants and additives for technical applications.
BAC is a mixture of alkylbenzyldimethylammonium chlorides of various even-numbered alkyl chain lengths (C8-C18). The greatest biocide activity is associated with the C12-C14 derivatives, which are the main components of the mixture.
DDAC is a mixture of alkyl-quaternary ammonium salts with typical alkyl chain lengths of C8, C10 and C12. C10 is the main component and makes more than 90 % of the mixture. In most cases the term DDAC is thus used for the Didecyldimethylammonium chloride congener.
DDAC used to be approved in the EU as a plant protection product (for ornamental plants). BAC has never been approved as active substance in plant protection products. Still, as both BAC and DDAC have pesticide properties they were until a few years ago contained in various products used for the treatment of various food-related crops in the field within the EU. Some of these products adulterated were even marketed as suitable for organic agriculture (e.g. grapefruit seed extract based products containing >20% BAC) without the QACs contained being declared.
BAC and DDAC are furthermore widely used as biocides for the cleaning/sanitation of surfaces in the areas of food, feed and medical production sectors as well as domestically. Personal care products such as hand sanitizers, wet wipes and eye-drops may also contain them.
Dairy Industry is probably the most important food-related field of DDAC and BAC use.
DDAC and BAC containing products are for example employed for the disinfection of all kind of surfaces milking equipment, milk storage tanks and ice-cream machines. BAC and DDAC are popular among dairy farmers, where they are used to disinfect udder and milking equipment with the goal of preventing mastitis and producing raw milk with low bacterial count, which is preferential both from the hygienic and economic point of view. Unlike many chlorine-containing products BAC and DDAC do not cause skin irritation.
Legal Aspects and Monitoring Programs: In October 2012 the Standing Committee on the Food Chain and Animal Health (SCoFCAH) endorsed Guidelines on measures to be taken as regards the presence of DDAC and BAC
in or on food and feed. These guidelines contained an agreed temporary enforcement level of 0.5 mg/kg for food and feed. It was further recommended that EU Member States carry out investigations on the possible causes of
BAC / DDAC contamination and a monitoring program was put in place to get an overview of the BAC and DDAC levels in food and feed of plant and animal origin.
Based on the monitoring data collected (summarized in an EFSA report a flat MRL level of 0.1 mg/kg was established in 2014 for both didecyldimethylammonium chloride and benzalkonium chloride in all food products (Reg. 1119/2014/EU). These MRLs apply to the chloride salts. A revision of these MRLs is planned to take place by 31 December 2019 and if necessary they will be amended modified based on newer residue data. Before the agreement on temporary MRLs (0.5 mg/kg) in 2012 and the implementation of specific MRLs in 2014 (0.1 mg/kg), the default MRL of 0.01 mg/kg laid down in Reg. 396/2005/EC used to apply.