I drink the wheat grass powder from Amazing Grass. I wrote the company about the mold issue. Mold is on the grass that people can grow. This stuff is tested and purified to the highest standards, so I was satisfied with their process. It's grown and picked in optomum envirmnent. I love that company.
About the chlorella. I'm sure it's safe to take. It's the number 1 supplement in Japan. More than any other vitamin. Like I said, I take a tiny dosage. Not enough to draw out any heavy metals.