The small scoop is around 2.2g, 40g a day is alot but Ive heard loads of people on them doses with no bad side effects from heavy metals. You can get youself tested for heavy metals, if you are worried this would be the best option. I never worry about heavy metals in kratom as i think its no more of a risk then the other foods that we eat but I only take low doses average 5g per day. I recommend joining this fb group as you will get alot of good replys https://www.facebook.com/groups/384