Inorganic chloramines: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting

Abstract

Inorganic chloramines are not commercially available, but monochloramine is produced in situ for disinfection or for use in chemical synthesis. Inorganic chloramines are also formed when free chlorine reacts with nitrogen containing substances, e.g. ammonia and urea, present in chlorinated water sources. Occupational exposure may, therefore, occur in e.g. swimming pool facilities and the food processing industry. Monochloramine is soluble and stable in water and the dominating inorganic chloramine in chlorinated water sources. No clinical effects were seen in healthy volunteers given monochloramine in drinking water during 4 or 12 weeks in doses of 0.043 or 0.034 mg/kg bw/day, respectively. Limited data indicate that monochloramine is weakly mutagenic in vitro but not genotoxic in vivo. One drinking water study indicated equivocal evidence of carcinogenicity in female rats but not in male rats and mice. No reproductive or developmental effects were shown in rodents in the few studies located. Dichloramine is soluble but unstable in water. In the only study located, mild histological effects in kidneys, thyroid and gastric cardia were observed in rats administered dichloramine in drinking water for 13 weeks. Trichloramine is immiscible with water and evaporates easily from water into air. Therefore, the primary exposure route of concern in the occupational setting is inhalation. Occupational exposure to trichloramine has been demonstrated in indoor swimming pool facilities and in the food processing industry where chlorinated water is used for disinfection. Exposure-response relationships between airborne levels and self-reported ocular and upper airway irritation have been shown in several studies. Exposure to trichloramine may aggravate asthma symptoms in individuals with existing asthma. The risk of developing asthma following long-term exposure to trichloramine cannot be evaluated at present. No data on genotoxic, carcinogenic, reproductive or developmental effects were located. The toxicological data for mono-and dichloramine are insufficient to recommend health-based occupational exposure limits (OELs). As regard trichloramine, the critical effect is judged to be irritation observed in several studies on pool workers, starting at approximately 0.4 mg/m 3 (stationary sampling). Based on these data, a health-based OEL of 0.1 mg/m 3 (8-h time-weighted average) is recommended. This corresponds to 0.2 mg/m 3 for stationary measurements in swimming pool facilities. No short-term exposure limit (STEL) is recommended.

Occupational Exposure to Trichloramine and Endotoxins

“…To date, there is no suitable reference value for personal trichloramine concentration. The NEG presented a recommendation for a health-based OEL for personal measurements at 100 μg/m 3 27 . Average trichloramine concentrations in air measured in both adventure and rehabilitation swimming pool facilities were lower than the NEG's recommendation.…”

“…In 2010, France presented a reference value of 300 μg/m 3 24 and in 2011, Germany and Switzerland adopted a reference value of 200 μg/m 3 25,26 . The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals (NEG) presented a recommendation for a health-based OEL value of 100 μg/m 3 for personal measurements and a corresponding value of 200 μg/m 3 valid for stationary sampling in swimming pool facilities 27 . In line with this, the Public Health Agency of Sweden (Folkhalsomyndigheten) has established a recommended reference value for stationary sampling of 200 μg/m 3 for visitors 28…”

Hypochlorous Acid: From Innate Immune Factor and Environmental Toxicant to Chemopreventive Agent Targeting Solar UV-Induced Skin Cancer

“…Chloramine formation involves the HOCl-dependent derivatization of primary and secondary biological amines as contained in small biochemicals (such as histamine and taurine) and macromolecules (proteins etc.) (62)(63)(64). Moreover, hydroxyl radical formation may occur downstream of either Fe(II)dependent Fenton chemistry, scenarios observable under conditions of MPO-facilitated heme degradation as a consequence of excess HOCl formation or pathological elevation of labile iron (65)(66)(67).…”

Update on irritant-induced occupational asthma

“…Working in a swimming pool may also involve chronic irritant exposures when concentrations of disinfection by-products are elevated, but studies remain inconclusive on their impact on IIA [9,23]. In a US study of 2359 adolescents, higher blood trihalomethanes concentrations, used to asses exposure to disinfection by-products, was associated with increased risk of asthma, but only among smokers and males [24].…”