An analysis conducted on rolling papers showed that there was at least one heavy metal in 90% of the papers that were tested. And according to data, 8% of them contained at least one heavy metal in concentration levels above the allowable state limits for cannabis products. “There is a wide range of concentrations of metals contamination in these products from a relatively low level to grossly contaminated,” researchers noted. Although rolling paper manufacturers have to adhere to some regulations, including listing their ingredients, these are generally less monitored than other products within the tobacco and cannabis industry. Paper is made out of plants, which naturally absorb contaminants from the soil that they were planted in.