Urban environmental justice communities are potentially
exposed
to multiple toxic metals, through contaminated air, soil, water, and
food. However, information on metals and their sources is lacking.
This study uses non-negative matrix factorization (NMF) in a community-based
participatory research study to identify potential sources and to
understand how these metals cluster in a population near an urban
oil drilling site. We recruited 203 Latinx, Black, and Asian residents
who lived within 1 km of an oil drilling site in south Los Angeles
and collected toenail clippings to assess exposure to arsenic (As),
cadmium (Cd), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb),
and antimony (Sb). Using NMF, we identified three clusters based on
concentrations in the participants’ toenails. As, Cd, Pb, and
Sb grouped together, indicative of an industrial source. A second
grouping was composed of Ni and Mn, which may be related to oil drilling.
We also identified a third source factor predominantly driven by Hg
and As, which may arise from dietary sources. Utilizing NMF, a dimension
reduction method, we identified a source factor high in Ni and Mn
in residents living in a neighborhood near an active oil drilling
site.