sentence: This group included 397 women randomly selected for a previous study of the xenoestrogenic activities of serum PFAA extracts ( Bjerregaard-Olesen et al. 2016d ) , plus a random sample of 305 additional women.The blood samples were processed within 2 h after blood draw , and the serum was stored at − 80 ° C ( Mortensen et al. 2013 ) .