The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals. 152. Inorganic chloramines

Abstract

Inorganic chloramines, i.e. monochloramine (NH2Cl), dichloramine (NHCl2) and trichloramine (NCl3), are formed when free1 chlorine reacts with nitrogen-containing substances present in e.g. chlorinated (disinfection) water sources. In the occupational setting, this may occur in swimming pool facilities (139) and in the food processing industry (63, 65, 76, 85). Inorganic chloramines may also be formed in industrial processes when liquid waste containing ammoniums ions is mixed with a sodium hypochlorite solution (100). Monochloramine, dichloramine and trichloramine are not known to be commercial products but monochloramine is generated in situ as needed to disinfect drinking water and waste water (68, 132). Monochloramine and dichloramine are water soluble of which the former is the dominating inorganic chloramine in the chlorinated water sources mentioned above. Trichloramine is immiscible with water, has a relatively high vapour pressure at room temperature and thus evaporates relatively fast into the air compartment (67). Trichloramine is therefore the dominating inorganic chloramine in the indoor air of swimming pools (20, 64). In the food processing industry, the fraction of trichloramine in air is considerably lower (63, 65, 76, 85). In recent years there has been an increased reporting of health problems such as irritation and pulmonary effects among staff in indoor chlorinated swimming pool facilities and in the food processing industry where chlorinated water is used. Chlorination of water gives rise to a number of disinfection by-products also in air, mainly inorganic chloramines (6, 83, 108, 138, 139). The aim of this document is to evaluate health effects associated with occupational exposure to inorganic chloramines, and if possible, to recommend health-based occupational exposure limits (OELs).