Global consumption of organophosphorus flame retardants and plasticizers (OPs), of which some are reported to be toxic, is rapidly increasing. The levels, distribution and sources of 15 OPs were investigated in public and domestic buildings, sewage treatment plants (STPs), deposition and fish. In all sampled environments OPs were detected at relatively high levels (ppt-ppb) and public buildings tended to have higher levels than domestic buildings. OPs were poorly removed from wastewater, especially the chlorinated OPs tended to pass through the STPs without being removed or degraded. Of the total amount of OPs entering the STPs, 50% was emitted to the recipients via the effluent. Based on the findings of the studies, the total mass flow of OPs in Sweden was estimated. Finally, the exposure to OPs via inhalation was examined for five occupational groups in which aircraft technicians were significantly more exposed to OPs than other groups. This book is valuable for professionals in areas like environmental protection, environmental health and industrial hygiene. It may also be useful for manufacturers of OPs and for professionals in legislation and regulation of chemical substances.