sentence: Studies of individual PFAA congeners suggest that PFAAs may interfere with the estrogen system in vitro ( Benninghoff et al. 2011 ; Henry and Fair 2013 ; Hu et al. 2003 ; Kang et al. 2016 ; Kjeldsen and Bonefeld-J ø rgensen 2013 ; Liu et al. 2007 ; Rosenmai et al. 2013 ; Sonthithai et al. 2016 ) , in fish ( Benninghoff et al. 2011 ; Fang et al. 2012 ) , and in humans ( Barrett et al. 2015 ; Itoh et al. 2016 ; Knox et al. 2011 ; Lopez-Espinosa et al. 2016 ) .