Hazards due to toxic chemicals

A very large number of compounds encountered in organic chemistry laboratories are poisonous, i.e. toxic . Indeed, nearly all substances are toxic to some extent and the adoption of safe and careful working procedures which prevent the entry of foreign substances into the body is therefore of paramount importance, and should become second nature to all laboratory workers. Toxic substances can enter the body by the following routes  

Ingestion (through the mouth). This is fortunately not common in laboratories, but can occur through the accidental contamination of food, drink or tobacco, and by misuse of mouth pipettes. It is strongly recommended that no one should ever eat, drink or smoke in a laboratory. The practice of storing bottles of milk or beer in laboratory refrigerators is to be strongly condemned. 

Workers should always wash their hands thoroughly on leaving a laboratory and before eating. All pipetting by mouth should be avoided since there are excellent rubber bulb and piston-type pipette fillers available commercially. 

In addition to the ingestion hazard associated with smoking, the vapours of many volatile compounds yield toxic products on pyrolysis when drawn through a lighted cigarette or pipe (e.g. carbon tetrachloride yields phosgene). 

Inhalation (into the lungs). This is a more common pathway for the absorption of toxic chemicals these may be in the form of gases, vapours, dusts or mists. All toxic powders, volatile liquids and gases should only be handled in efficient fume cupboards. The practice of sniffing the vapours of unknown compounds for identification purposes should be conducted with caution. 

---