Mark Thorson wrote:
>
> "Pete C." wrote:
> >
> > Mark Thorson wrote:
> > >
> > > "Pete C." wrote:
> > > >
> > > > blake murphy wrote:
> > > > >
> > > > > what levels of added p.c.b.'s and toxic chemicals do you need before
> > > > > the farmed fish aren't 'quite right'?
> > > >
> > > > Ones that are quantified and significant. As an example, the difference
> > > > between 1 ppb and 3 ppb is "huge", "3X", "300%", but bloody irrelevent
> > > > in the real world.
> > >
> > > In this study, PCB levels in salmon ranged from
> > > 145-460 ppb. That's a huge amount!
> >
> > Again, incomplete data. Where is the data from the wild caught control
> > samples? Without that data no meaningful conclusion can be drawn as to
> > the alleged difference between wild caught and farmed product.
>
> But we know the numbers for farmed salmon, and
> the numbers ain't good!
>
> This study gives numbers comparing farmed vs. wild,
> and there's a huge difference, especially at the
> high end of the range.
>
> Environ Sci Technol. 2006 Sep 1;40(17):5347-54.
> PCBs, PCDD/Fs, and organochlorine pesticides in farmed
> Atlantic salmon from Maine, eastern Canada, and Norway,
> and wild salmon from Alaska.
> Shaw SD, Brenner D, Berger ML, Carpenter DO, Hong CS,
> Kannan K.
> Marine Environmental Research Institute, P.O. Box 1652,
> Blue Hill, Maine 04614, USA.
>
> Farmed Atlantic salmon (Salmo salar) from Maine and
> eastern Canada, wild Alaskan Chinook salmon (Oncorhynchus
> tshawytscha), and organically farmed Norwegian salmon
> samples were analyzed for the presence of polychlorinated
> biphenyls (PCBs), dioxin-like PCBs, polychlorinated
> dibenzo-p-dioxins (PCDDs), dibenzo-p-furans (PCDFs), and
> chlorinated pesticides. PCDD and PCDF congeners were not
> detected in > 80% of the samples analyzed. Total PCB
> concentrations (7.2-29.5 ng/g, wet weight, ww) in the
> farmed salmon were significantly higher than those in
> the wild Alaskan Chinook samples (3.9-8.1 ng/g, ww).
> Concentrations of PCBs, WHO PCB TEQs, and chlorinated
> pesticides varied significantly by region. PCB and WHO
> PCB TEQ concentrations in farmed salmon from eastern
> Canada were lower than those reported in samples
> collected two years earlier, possibly reflecting recent
> industry efforts to lower contaminant concentrations in
> feed. Organically farmed Norwegian salmon had the highest
> concentrations of PCBs (mean: 27 ng/g, ww) and WHO PCB
> TEQs (2.85 pg/g,ww); their TEQ values are in the higher
> range of those reported in farmed salmon from around the
> world. Removal of skin from salmon fillets resulted in
> highly variable reductions of lipids and contaminants,
> and in some skin-off samples, contaminant levels were
> higher, suggesting that skin removal does not protect
> the consumer from health risks associated with
> consumption of farmed salmon.


What I see from that data is that levels in both are quite variable, and
indeed some of the farmed samples had lower levels (7.2 ng/g) than some
of the wild samples (8.1 ng/g).

Showing just the high and low of a group of samples is misleading since
you don't know what the distribution is. Those extremes may represent
only one sample, and make it very easy to distort the data to fit an
agenda. The only mean value given was for the organic farmed Norwegian
samples.

It's entirely possible that most of the samples from both groups were in
the 7-8 ng/g range showing no difference between farmed and wild, or
most of the wild near 4 ng/g and most of the farmed near 29 ng/g showing
a huge difference.

Again, it's incomplete data and subject to presentation in a manner that
may be misleading. Either way we're talking about extremely low levels.