Is Pacific Albacore tuna safe to eat?

Mercury, radiation and maybe other things that are not good are in tuna.

http://www.scientificamerican.com/article/canned-tuna-may-contain-excessive-mercury/

http://www.usatoday.com/story/news/nation/2014/04/28/fukushima-radiation-oregon-tuna/8436187/

This got me wondering how researchers determine what levels of mercury are safe and what levels of radiation are safe. Then I started thinking about how other foods that have pesticides, herbicides and other things on or in them can contribute to cancer and other illnesses. Maybe individually some things can be eaten without too much worry, but what if combining all of these foods in your diet can lead to illness later in life? Considering this, is the standard for safe levels of poison in your food correct?

Lead anyone?

http://www.inhabitots.com/85-of-kids-drinks-snacks-could-contain-high-levels-of-lead/

Mercury in rainwater?

http://www.wsn.org/water/citymercuryrain.html

Originally posted by Metal Brain
Maybe individually some things can be eaten without too much worry, but what if combining all of these foods in your diet can lead to illness later in life?

Cancer is caused by an interaction between the environment and genes. I believe that for someone with a lifespan of about 80, the chance of getting at least one cancer during their life is very high. The environmental side includes food as well as many other things in the environment.
Some specific things dramatically increase the risk of cancer (smoking for example), but you simply cannot avoid most of the ones that have much smaller effects.
Also, until you have determined what causes cancer, you cannot avoid it. If you avoid foods grown with insecticides, you may end up eating a food grown by a different method that has a different cancer causing agent. Given that the insecticides at the the concentrations on food are not known to cause cancer there is no rational reason to avoid them.
Similarly, you should avoid getting sunburnt, and consider using sunscreen when you need to go out in the sun for long periods. But at the same time, if you avoid the sun, you may suffer from vitamin D deficiency or other effects.