Smoke Pot, Get Lead Poisoning? (Germany/Europe)
http://www.webmd.com/news/20080409/s…lead-poisoning

Neuropsychological effects of formaldehyde use
http://www.unboundmedicine.com/medli…maldehyde_use_

Microbiological contaminants of marijuana
http://www.hempfood.com/IHA/iha01205.html

Paraquat and marijuana: epidemiologic risk assessment.
http://www.pubmedcentral.nih.gov/art…tool=pmcentrez