APs can affect a number of reproductive

parameters in fish, including gonadal development (Meier et al., 2007b), induction of plasma vitellogenin (Vtg) in male and juvenile fish GSI-IX (Jobling and Sumpter, 1993 and White et al., 1994), inhibition of spermatogenesis (Gimeno et al., 1998, Jobling and Sumpter, 1993, Miles-Richardson et al., 1999 and Weber et al., 2002), and oogenesis (Tanaka and Grizzle, 2002 and Weber et al., 2003). Tollefsen et al. (2007) and Tollefsen and Nilsen (2008) found that APs were able to bind to plasma sex steroid-binding proteins (rtSBP) in rainbow trout (Oncorhynchus mykiss). The highest affinity was seen for mono-substituted APs with 4–8 carbon chain length, but this was still 104–106 times lower than the affinity for the natural sex steroid 17β-estradiol (E2). The results suggested that endocrine disruption may occur after exposure to realistic concentrations of APs and a variety of other PW compounds. Tollefsen et al. (2006) further showed that chemicals in solid phase extracts of PW were able to displace E2 from the rtSBP and induce estrogenic effects. The bioactive chemicals were not identified. Tollefsen et al. (2011) demonstrated that complex mixtures

of oil-related compounds could modulate the endocrine physiology APO866 concentration of Atlantic cod. Fish were exposed to either diluted PW (0.5% and 0.1%), dispersed oil (0.2 mg L−1), or artificial PW water mixed with nine low to medium molecular weight APs and PAHs. The total sex-steroid binding capacity was up-regulated in the blood of female cod, indicating interference with blood steroid transport. Induction of plasma Vtg was not found, Glutamate dehydrogenase although the number of males and females with elevated Vtg was higher in certain exposure groups than in the control group. General health parameters such as gonadosomatic, hepatosomatic or fish condition index were not affected, which

suggests that the endocrine disrupting effect was too low to elicit clear physiological or growth effects. When exposing late larvae and juveniles of Atlantic cod to PW Meier et al. (2010) found that individuals exposed to 1% PW had significantly higher levels of Vtg and CYP1A in plasma and liver, respectively. No similar effects were seen at exposure to 0.1% and 0.01% PW. Serious reproductive disturbance was demonstrated by Meier et al. (2007b) in first-time spawning Atlantic cod that were force fed a paste containing C4–C7 APs. Total AP doses during 1 and 5 weeks were 0.02–80 mg kg−1 body weight. Treatment impaired oocyte development, reduced estrogen levels, and delayed spawning by 17–28 days in female fish.