Sometimes the toxicity has to be inferred from published information on related compounds, and such assessments should always be performed by experts. There are several organisations responsible for establishing the occupational exposure limits. They are also misused, despite the clear warnings in the front of the booklet. The US Government also has Permissible Exposures Limits set by the Dept. of Labor Occupational Safety and Health Administration, and Recommended Exposure Limits set by the US National Institute for Occupational Safety and Health. The Deutsche Forschungsgemeinschaff Maximum Concentrations in the Workplace are often also used.
All substances are poisons.
There is not one that is not a poison. 1.6 milligrams mouse Ricin is a toxin lectin and hemagglutinin isolated from the castor bean. Safety Officers and Laboratory Managers at educational institutions and companies are likely to have several guides, and a polite request should obtain a loan or copy of one, even if you aren't at that institution. There are several useful books. There are a lot of myths about the occupational use of contact lenses, many of which relate back to a Bethlehem Steel welder in Baltimore who, on the 26 July 1967, accidentally caused an arc flash that hit his hard contact lens.