Chemestry
Commercial seeds are sometimes treated with toxic methylmercury (although the use of methylmercury has been banned in the US and the UK since the 1980s), which serves as a preservative and a cumulative neurotoxic poison that is considered useful by some to discourage recreational use of the seeds as an entheogen (hallucinogen). There is no legal requirement in the United States to disclose to buyers that seeds have been treated with a toxic heavy metal compound. According to the book Substances of Abuse, in addition to methylmercury, the seeds are claimed to be sometimes coated with a chemical that cannot be removed with washing that is designed to cause unpleasant physical symptoms such as nausea and abdominal pain. The book states that this chemical is also toxic.