The hobbyist or craftsperson should realize first that all fabric dyes are reactive chemicals whose long term toxicological or carcinogenic potential have not been well studied in most instances. Therefore, care must always be taken to avoid contaminations of working and living spaces and exposures to dyes by either accidental ingestion, skin absorption, or inhalation. Below are basic hygiene precautions to be observed with all dyes, then specific and relative hazards of the different chemical classes are detailed.