Progressive Increase in Disinfection Byproducts and
Mutagenicity from Source to Tap to Swimming Pool and Spa Water: Impact
of Human Inputs
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Abstract
Pools and spas are enjoyed throughout the world for exercise and
relaxation. However, there are no previous studies on mutagenicity
of disinfected spa (hot tub) waters or comprehensive identification
of disinfection byproducts (DBPs) formed in spas. Using 28 water samples
from seven sites, we report the first integrated mutagenicity and
comprehensive analytical chemistry of spas treated with chlorine,
bromine, or ozone, along with pools treated with these same disinfectants.
Gas chromatography (GC) with high-resolution mass spectrometry, membrane-introduction
mass spectrometry, and GC-electron capture detection were used to
comprehensively identify and quantify DBPs and other contaminants.
Mutagenicity was assessed by the <i>Salmonella</i> mutagenicity
assay. More than 100 DBPs were identified, including a new class of
DBPs, bromoimidazoles. Organic extracts of brominated pool/spa waters
were 1.8× more mutagenic than chlorinated ones; spa waters were
1.7× more mutagenic than pools. Pool and spa samples were 2.4
and 4.1× more mutagenic, respectively, than corresponding tap
waters. The concentration of the sum of 21 DBPs measured quantitatively
increased from finished to tap to pool to spa; and mutagenic potency
increased from finished/tap to pools to spas. Mutagenic potencies
of samples from a chlorinated site correlated best with brominated
haloacetic acid concentrations (Br-HAAs) (<i>r</i> = 0.98)
and nitrogen-containing DBPs (N-DBPs) (<i>r</i> = 0.97)
and the least with Br-trihalomethanes (<i>r</i> = 0.29)
and Br–N-DBPs (<i>r</i> = 0.04). The mutagenic potencies
of samples from a brominated site correlated best (<i>r</i> = 0.82) with the concentrations of the nine HAAs, Br-HAAs, and Br-DBPs.
Human use increased significantly the DBP concentrations and mutagenic
potencies for most pools and spas. These data provide evidence that
human precursors can increase mutagenic potencies of pools and spas
and that this increase is associated with increased DBP concentrations
