Table 1. Environmental water concentrations (in μg/L) reported for BTR, 5MeBTR and 5ClBTR.

Water compartment	BTR	5MeBTR	5ClBTR	References
Airport samplinga	126 000	820–17 000		[20,21]
WWTP influents	0.022–44	0.0065–4.9		[3,22,23,24,25]
WWTP effluents	0.01–100	0.002–1.538	0–0.0772	[10,12,15,17,19,22,23,24,25]
Surface water	0.011–5.44	0.02–2.4	0.002–1.5	[3,6,12,17,18,19,25,26,27,28,29,30,31]
Drinking water	0.00006–0.0794	0.01	0.00005–0.0698	[10,19]

^a airport groundwater sampling wells and perched water monitoring wells.