Mutagenic Azo Dyes, Rather Than Flame Retardants, Are the Predominant Brominated Compounds in House Dust

Characterization of toxicological
profiles by use of traditional
targeted strategies might underestimate the risk of environmental
mixtures. Unbiased identification of prioritized compounds provides
a promising strategy for meeting regulatory needs. In this study,
untargeted screening of brominated compounds in house dust was conducted
using a data-independent precursor isolation and characteristic fragment
(DIPIC-Frag) approach, which used data-independent acquisition (DIA)
and a chemometric strategy to detect peaks and align precursor ions.
A total of 1008 brominated compound peaks were identified in 23 house
dust samples. Precursor ions and formulas were identified for 738
(73%) of the brominated compounds. A correlation matrix was used to
cluster brominated compounds; three large groups were found for the
140 high-abundance brominated compounds, and only 24 (17%) of these
compounds were previously known flame retardants. The predominant
class of unknown brominated compounds was predicted to consist of
nitrogen-containing compounds. Following further validation by authentic
standards, these compounds (56%) were determined to be novel brominated
azo dyes. The mutagenicity of one major component was investigated,
and mutagenicity was observed at environmentally relevant concentrations.
Results of this study demonstrated the existence of numerous unknown
brominated compounds in house dust, with mutagenic azo dyes unexpectedly
being identified as the predominant compounds.