The substance causing members to get sick from the exhibits was Methaqualone, the active ingredient of Mandrax, emitting toxic vapour causing members to get sick and feel nauseous.
“Commissioner, it is Methaqualone. So, the active ingredient of Mandrax is Methaqualone. But some people will tell you it is the Anthranilic acid that actually gives off the vapour that is so toxic. It is not a pleasant smell, Commissioner. ... The smell is what we are talking about here. So that is what makes you sick. It makes you nauseous. It can give you heart palpitations. ... They did get sick. And that is, it is true, you do get sick.”