Should I be concerned about the arsenic content in magnesium?

Well that is how they are paying for things. They make money off affiliate links for the companies of the products they test. So if you click on one of the products on their site, and purchase it, they get paid for that. That's not inherently a bad thing. They are obviously doing things for the right reason. The affiliate links are simply to help cover their costs. It's not like other sites, who's whole purpose is to get people to click affiliate links.

Also, the more contact they have with the supplement companies, and more they make them aware of issues like this, the more likely those supplement companies are going to make changes to fix those issues. That makes the whole industry safer, which is a win in my book.