The evidence-based literature is mostly devoid of human trials using doses of such a high level to which you refer. The FDA (US) and Health Canada consider up to 3 gms of (EPA plus DHA) to be generally safe for most people . Of course, this implies that such may not be so for some very minor sectors within the population such as those on anti-coagulant treatment with blood thinners, those on defibrillators for a heart condition, and some others. The Amer. Heart Assoc. have indicated to health professionals that up to 2-4 gms (EPA plus DHA) may be used for blood triglyceride-lowering.