Kelp is an organic plant complexed carbon based Alkaline Mineral Rich food source and I use Norwegian kelp which comes from the coldest waters and is as safe as one may get!
And besides that, if you are supplying your body with the extra Calciums which it needs, then you have "NO" need to worry about any so called heavy metals from Kelp!
Most of the Heavy Metals propoganda against Kelp is just because some different Money people do not want you to learn about the real value of taking Kelp which is so much cheaper and does your body good , verses any Drug which they sell for many times the cost which most of the times just ends up making you Sicker in the end!
But "IF" you want to support the Drug industry, that is your choice!