Honestly, this is a lot of new age health nonsense that repackages itself as Judeo-Christian. It fails to logical analysis.
I'll be honest. After all these years, I still don't understand exactly what "new age" means. The term seems to be so loosely applied.

But, I will emphatically say that this is not a strictly Christian topic. It is a human-health one. (The Christian part comes in, I believe, when we discuss dietary laws with regards to sin. It is not a sin to eat pork, but is it healthy? They are two entirely unrelated issues.)
I'd like to know what these 'toxins' pigs are eating that are being retained. Toxins are a fun word to throw around because they don't have to be backed by naming any real substance.
You'll have to do some research, but a pig's digestive system is such that whatever it eats (and in the wild this often means feces and decaying carcasses) becomes meat on its bones within four hours. A cow's more complex digestive system processes the grasses and grains for 24 hours before it becomes meat on the bones. It really boils down to whether you feel okay about eating a likeness of what was originally eaten by the animal. And if it doesn't bother you, then I think you have every right to eat whatever you want. Even scripture supports that (in other words, you do not sin by eating it).
But, is it healthy? No.
But let's look at the logic- pigs eat the same foods that humans eat.
Farm raised pigs today do eat grain, if they are not allowed to eat the feces of the other pigs (which they will.) But the wild pig (which is the subject of the old dietary laws) eats much more. eck!
Cows eat grass which is broken down by bacteria and they only aborb the fatty acids the bacteria produce. Is there some toxic substance we are feeding animals that we are worried about them retaining? If there are toxins, they come from the plants they are eating... and cows eat the same plants, which grow on the same earth that grows the vegetables humans, pigs and cows eat. I'm wondering where these mysterious "toxins" are coming from.
A very good book I would recommend reading is
Living Downstream by Sandra Steingraber. She provides impressive research and data linking many of the toxins we consume today (petroleum-based toxins from fertilizers and pesticides.) to the most common diseases we suffer today. She explains how these toxins survive up the food chain and into our diets. There are studies strongly indicating the exponential rise in hormone-based cancers in the 20th century are directly linked to these products being introduced into our world after WWII. But here, you would go beyond the dietary laws and seek mainly organic consumables.
Now on to salmon and other fish- I will bring up a real "toxin" and its called mercury. It is found throughout streams, lakes and other bodies of water because of air pollution. The federal government has recommendations for how much fish people eat because of mercury poisoning.
Salmon, and other cold-water fish, has one of the lowest amounts of heavy metals (the worst one is mercury). However, farm-raised salmon has more pollutants. This is particularly true of fish exported from China (raised on farms where little or no regulation occurs.) Tuna has one of the highest mercury counts, and yes, you are correct there are warnings, but I would not trust the federal government to act completely in the consumer's interest. It takes way too long to finally regulate or even legislate unhealthy consumables.
As for starch (white) - what do you think Asians have been eating for thousands of years? 1/3 of Asians smoke and are still in better health than most of the world- so I don't think their high starchy diet as anything to do with it.
There is a clear link between asians who eat a more americanized diet and who
smoke and a spike in heart disease and cancer. This alone clearly reveals how even in one generation, an entire ethnic group of people can be significantly ill-affected by poor diet and smoking.
Human beings have been living off a diet of occassional meat (fatty and lean), a good portion of vegetables and tons of grains like wheat and rice. This is what our bodies are designed for and what they are acustomed to. This idea that starch is bad and certain meats are wrong for us is nonsense. People will believe anything to avoid facing the truth about our diet- if you want to feel healthy, eat less.
I agree! Before WWII, and long before industrialization, the main diet for humans was mainly organic, unprocessed foods rich in whole grains, vegetables, and fewer meats (simply because they are harder to obtain and keep). But, the topic here is more about whether it is important or not to be careful about what you consume today and why.