Identification
of Tobacco-Specific Nitrosamines as
Disinfection Byproducts in Chloraminated Water
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Abstract
Tobacco-specific
nitrosamines (TSNAs) exist in environmental waters;
however, it is unknown whether TSNAs can be produced during water
disinfection. Here we report on the investigation and evidence of
TSNAs as a new class of disinfection byproducts (DBPs). Using five
common TSNAs, including (methylnitrosamino)-1-(3-pyridyl)-1-butanone
(NNK) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) as
the targets, we first developed a solid phase extraction (SPE) and
liquid chromatography-tandem mass spectrometry (LC-MS/MS) method capable
of rapidly determining these TSNAs at levels as low as 0.02 ng/L in
treated water. Using this highly sensitive method, we investigated
the occurrence and formation potential (FP) (precursor test conducted
in the presence of chloramines) of TSNAs in treated water from two
wastewater treatment plants (WWTPs) and seven drinking water treatment
plants (DWTPs). NNAL was detected in the FP samples, but not in the
samples before the FP test, confirming NNAL as a DBP. NNK was detected
in the treated wastewater before the FP test, but its concentration
increased significantly after chloramination in two of three tests.
Thus, NNK could be a DBP and/or a contaminant in wastewater. Moreover,
these TSNAs were detected in FP tests of wastewater-impacted DWTP
plant influents in 9 of 11 samples. However, TSNAs were not detected
at full-scale DWTPs, except for at one DWTP with high ammonia where
breakpoint chlorination was not achieved. The concentration of the
sum of five TSNAs (0.3 ng/L) was 100-fold lower than NDMA, suggesting
that TSNAs have a minor contribution to total nitrosamines in water.
We examined several factors in the treatment process and found that
chlorine or ozone may destroy TSNA precursors and granular activated
carbon (GAC) treatment may remove the precursors. Further research
is warranted into the efficiency of these processes at different DWTPs
using sources of varying water quality