Which chemical compounds did you find most often?
The most frequently detected compounds (those that were found in more
than half the streams samples) were: coprostanol (85.7%, a fecal steroid,
a natural part of human and animal waste), cholesterol (84.3%, a plant
and animal steroid also widely naturally occurring), N-N-diethyltoluamide
(74.1%, insect repellent), caffeine (70.6%, a stimulant), tri(2-chloroethyl)phosphate
(57.6%, a fire retardant), triclosan (57.6%, an antimicrobial disinfectant),
and 4-nonylphenol (50.6%, a nonionic detergent metabolite).
In broader terms, steroidal compounds were found in 89% of the streams
followed by nonprescription drugs (81%), an insect repellant (74%),
detergent metabolites (69%), disinfectants (66%), plasticizers (64%),
fire retardants (60%), antibiotics (48%), insecticides (45%), polycylic
aromatic hydrocarbons (44%), reproductive hormones (40%), other prescription
drugs (32%), antioxidants (29%), fragrances (27%) and a solvent (24%).