6 Safe and Nutritious Aquaculture Produce
209
2.25 ng dioxin toxic equivalents (TEQ)/kg feed and 4.0 ng TEQ/kg fish. The EU has
recently revised dioxin limits and assigned new limits for the 12 dioxin-like (DL)
PCBs, such that combined values of 8 ng TEQ/kg for fish products and 7 ng/TEQ
for fish feeds have now been introduced (EC 2006a,b).
The polybrominated diphenyl ethers (PBDEs) have been used as flame retardants
in a wide variety of household furniture and electrical equipment since their introduction in the 1980s and global annual production currently exceeds 70 kt, with
around 75% produced in North America (Hites et al. 2004b). Numerous PBDE
congeners exist with different levels of bromination ranging from the tetra through
to the deca-brominated products. The less brominated congeners tend to be more
persistent in the environment and in 2004 the EU banned production of the tetra to
nona-brominated products in favour of the less persistent deca-brominated
congeners (Covaci et al. 2003; SACN/COT 2004). However, due to their lipophilic
and persistent characteristics the PBDEs are currently increasing in the environment
including fish products (FSA 2004; EFSA 2005).
As described above replacement of significant amounts of either FO or FM can
be achieved without loss of growth performance or affects on fish health (Kaushik
et al. 2004; Torstensen et al. 2005; Mourente et al. 2005). However, significant
inclusion of dietary VO results in reduction of the flesh content of n-3 HUFA
content, although this could potentially be offset by reduced levels of organic
contaminants, as vegetable oils generally contain lower levels of these pollutants
than most marine fish oils (SACN/COT 2004).
In the RAFOA II trial in salmon fed 100% FO, the flesh dioxin/furan content
was 0.58 and the DL-PCBs 1.18 ng TEQ/kg making a total of 1.76 ng TEQ/kg that
was well within existing and proposed EU limit values for dioxins and DL-PCBs
(EC, 2006a). By contrast, salmon produced on diets containing 75% VO had
reduced values of 0.21 and 0.42 ng TEQ/kg, for dioxins/furans and DL-PCBs,
respectively, compared to fish fed FO. The total of 0.63 TEQ/kg flesh for dioxin +
DL-PCBs represents a 64% reduction compared to fish fed FO (Fig. 6.6). The flesh
dioxin + DL-PCB concentration in fish fed 100% FO of 1.76 ng TEQ/kg is lower
than those reported by Lundebye et al. (2004) of 2.5 and by Bell et al. (2005) of
2.01 ng TEQ/kg. Indeed, all of these values are lower than those reported for
Scottish farmed salmon by Hites et al. (2004a) of ~3 ng TEQ/kg. The value of
0.63 ng TEQ/kg for dioxin + DL-PCBs in salmon fed 75% VO for the whole production cycle is slightly lower than that reported by Bell et al. (2005) for salmon
grown for the whole production cycle on diets containing 100% VO (0.68 ng TEQ/
kg) but higher than the value found by Berntssen et al. (2005) in fish from the
RAFOA II study conducted in Norway and fed 100% VO (0.30 ng TEQ/kg). The
differences found between these studies are due to different dioxin + DL-PCB concentrations in the oils used in the dietary formulations. In the two RAFOA studies
capelin oil was used whereas the study of Bell et al. (2005) used a mixture of capelin
and herring oils as the FO component. The concentration of dioxins and DL-PCBs
in capelin are generally lower than in herring, although there is considerable geographical and seasonal variation for both species (Lundebye-Haldorsen and Lie
1999; SCAN 2000). The dioxin + DL-PCB concentrations found in salmon flesh in
209
2.25 ng dioxin toxic equivalents (TEQ)/kg feed and 4.0 ng TEQ/kg fish. The EU has
recently revised dioxin limits and assigned new limits for the 12 dioxin-like (DL)
PCBs, such that combined values of 8 ng TEQ/kg for fish products and 7 ng/TEQ
for fish feeds have now been introduced (EC 2006a,b).
The polybrominated diphenyl ethers (PBDEs) have been used as flame retardants
in a wide variety of household furniture and electrical equipment since their introduction in the 1980s and global annual production currently exceeds 70 kt, with
around 75% produced in North America (Hites et al. 2004b). Numerous PBDE
congeners exist with different levels of bromination ranging from the tetra through
to the deca-brominated products. The less brominated congeners tend to be more
persistent in the environment and in 2004 the EU banned production of the tetra to
nona-brominated products in favour of the less persistent deca-brominated
congeners (Covaci et al. 2003; SACN/COT 2004). However, due to their lipophilic
and persistent characteristics the PBDEs are currently increasing in the environment
including fish products (FSA 2004; EFSA 2005).
As described above replacement of significant amounts of either FO or FM can
be achieved without loss of growth performance or affects on fish health (Kaushik
et al. 2004; Torstensen et al. 2005; Mourente et al. 2005). However, significant
inclusion of dietary VO results in reduction of the flesh content of n-3 HUFA
content, although this could potentially be offset by reduced levels of organic
contaminants, as vegetable oils generally contain lower levels of these pollutants
than most marine fish oils (SACN/COT 2004).
In the RAFOA II trial in salmon fed 100% FO, the flesh dioxin/furan content
was 0.58 and the DL-PCBs 1.18 ng TEQ/kg making a total of 1.76 ng TEQ/kg that
was well within existing and proposed EU limit values for dioxins and DL-PCBs
(EC, 2006a). By contrast, salmon produced on diets containing 75% VO had
reduced values of 0.21 and 0.42 ng TEQ/kg, for dioxins/furans and DL-PCBs,
respectively, compared to fish fed FO. The total of 0.63 TEQ/kg flesh for dioxin +
DL-PCBs represents a 64% reduction compared to fish fed FO (Fig. 6.6). The flesh
dioxin + DL-PCB concentration in fish fed 100% FO of 1.76 ng TEQ/kg is lower
than those reported by Lundebye et al. (2004) of 2.5 and by Bell et al. (2005) of
2.01 ng TEQ/kg. Indeed, all of these values are lower than those reported for
Scottish farmed salmon by Hites et al. (2004a) of ~3 ng TEQ/kg. The value of
0.63 ng TEQ/kg for dioxin + DL-PCBs in salmon fed 75% VO for the whole production cycle is slightly lower than that reported by Bell et al. (2005) for salmon
grown for the whole production cycle on diets containing 100% VO (0.68 ng TEQ/
kg) but higher than the value found by Berntssen et al. (2005) in fish from the
RAFOA II study conducted in Norway and fed 100% VO (0.30 ng TEQ/kg). The
differences found between these studies are due to different dioxin + DL-PCB concentrations in the oils used in the dietary formulations. In the two RAFOA studies
capelin oil was used whereas the study of Bell et al. (2005) used a mixture of capelin
and herring oils as the FO component. The concentration of dioxins and DL-PCBs
in capelin are generally lower than in herring, although there is considerable geographical and seasonal variation for both species (Lundebye-Haldorsen and Lie
1999; SCAN 2000). The dioxin + DL-PCB concentrations found in salmon flesh in