Chloramines are formed by the reaction of chlorine and ammonia. Monodi-, and trichloramines may be formed depending on the ratio of chlorine to ammonia and the pH of the water. GVs were not recommended for di- and trichloramine because of inadequate data.

In a study in rats, monochloramine was administered in drinking water at dose levels of 0, 3, 5, or 9 mg/kg bw/day for 2 years. The NOAEL was the highest dose tested, 9 mg/kg bw/day. The decrease in body weight occurring at this level was not considered to be of toxicological significance but rather was attributed to the unpalatability of the drinking waten Applying an uncertainty factor of 100 to this NOAEL and allocating 100% of the resulting TDI to drinking water results in a GV of 3 mg/L. The 100% allocation to drinking water is justified since exposure to monochloramine from other sources is expected to be negligible. Most individuals will be able to taste monochloramine at the GV, especially if traces of the strong smelling di- and trichloramine are admixed with the mono compound. This constitutes a natural safety net for excessive exposure to monochloramine.

Chloramine generally produces by-products similar to those observed with chlorine but at lower concentrations. An exception to this is formation of cyanogen chloride (CNCL) (Bull and Kopfler 1991). CNCL is the main reaction by-product of monochloramine disinfection. CNCL is rapidly metabolized to cyanide in the body, and the GV was therefore based on the toxic effect of cyanide. In a 6-month study in pigs, clear effects in behavioral patterns and serum biochemistry were observed at 1.2 mg/kg bw/day. Using this dose as the LOAEL, an uncertainty factor of 100, and allocating 20% of the TDI to drinking water gives a GV of 0.07 mg/L for cyanide.

No additional uncertainty factor for use of an LOAEL was considered necessary, because there are indications that pigs are more sensitive to the effects of cyanide than other experimental animals. An allocation of 20% of the TDI to drinking water (rather than the default value of 10%) was made because exposure to cyanide from other sources is normally small.