2 research outputs found
Expanded Target-Chemical Analysis Reveals Extensive Mixed-Organic-Contaminant Exposure in U.S. Streams
Surface water from
38 streams nationwide was assessed using 14
target-organic methods (719 compounds). Designed-bioactive anthropogenic
contaminants (biocides, pharmaceuticals) comprised 57% of 406 organics
detected at least once. The 10 most-frequently detected anthropogenic-organics
included eight pesticides (desulfinylfipronil, AMPA, chlorpyrifos,
dieldrin, metolachlor, atrazine, CIAT, glyphosate) and two pharmaceuticals
(caffeine, metformin) with detection frequencies ranging 66–84%
of all sites. Detected contaminant concentrations varied from less
than 1 ng L<sup>–1</sup> to greater than 10 μg L<sup>–1</sup>, with 77 and 278 having median detected concentrations
greater than 100 ng L<sup>–1</sup> and 10 ng L<sup>–1</sup>, respectively. Cumulative detections and concentrations ranged 4–161
compounds (median 70) and 8.5–102 847 ng L<sup>–1</sup>, respectively, and correlated significantly with wastewater discharge,
watershed development, and toxic release inventory metrics. Log<sub>10</sub> concentrations of widely monitored HHCB, triclosan, and
carbamazepine explained 71–82% of the variability in the total
number of compounds detected (linear regression; <i>p</i>-values: < 0.001–0.012), providing a statistical inference
tool for unmonitored contaminants. Due to multiple modes of action,
high bioactivity, biorecalcitrance, and direct environment application
(pesticides), designed-bioactive organics (median 41 per site at μg
L<sup>–1</sup> cumulative concentrations) in developed watersheds
present aquatic health concerns, given their acknowledged potential
for sublethal effects to sensitive species and lifecycle stages at
low ng L<sup>–1</sup>
Tapwater Exposures, Effects Potential, and Residential Risk Management in Northern Plains Nations
In the United States (US), private-supply tapwater (TW)
is rarely
monitored. This data gap undermines individual/community risk-management
decision-making, leading to an increased probability of unrecognized
contaminant exposures in rural and remote locations that rely on private
wells. We assessed point-of-use (POU) TW in three northern plains
Tribal Nations, where ongoing TW arsenic (As) interventions include
expansion of small community water systems and POU adsorptive-media
treatment for Strong Heart Water Study participants. Samples from
34 private-well and 22 public-supply sites were analyzed for 476 organics,
34 inorganics, and 3 in vitro bioactivities. 63 organics and 30 inorganics
were detected. Arsenic, uranium (U), and lead (Pb) were detected in
54%, 43%, and 20% of samples, respectively. Concentrations equivalent
to public-supply maximum contaminant level(s) (MCL) were exceeded
only in untreated private-well samples (As 47%, U 3%). Precautionary
health-based screening levels were exceeded frequently, due to inorganics
in private supplies and chlorine-based disinfection byproducts in
public supplies. The results indicate that simultaneous exposures
to co-occurring TW contaminants are common, warranting consideration
of expanded source, point-of-entry, or POU treatment(s). This study
illustrates the importance of increased monitoring of private-well
TW, employing a broad, environmentally informative analytical scope,
to reduce the risks of unrecognized contaminant exposures