.3. Evaluation of data
In order to follow trends in FA over time, results were compared with data from the Swedish part of the TRANSFAIR study (Becker, 1998) and analyses from two subsequent NFA surveys (Mattisson et al., 2009 and Wallin et al., 2009). To compare differences over time, mean values were used if the product was analysed from more than one producer; this was necessary as samples from 1995 to 97 were pooled in equal amounts prior to analysis.