Table 1.

The concentrations and removal rates of painkillers in the environmental matrices.

Drug	Excretion and Metabolites	WWTP Removal Rate (%)	Wastewater Influent (ng/L)	Wastewater Effluent (ng/L)	Surface Water (ng/L)
diclofenac	5–10% unchanged, metabolites: glucuronide, sulfate conjugates [49]	9–60 [50] 57.9 [47]	up to 302 [50] 191,000 [47]	1300–3300 [51] Up to 5450 [50] 10,000 [52] 80,000 [47]	up to 490 [50] 1200 [48] 1410 [53]
ibuprofen	1% unchanged Metabolites: (+)-2-40-(2-Hydroxy-2-methylpropyl)-phenylpropionic acid (25%) and (+)-2-40-(2- carboxypropyl)-phenylpropionic acid (37%), conjugated ibuprofen (14%) [49]	78–100 [50] 94.8 [47]	5533 [50] 344,000 [47]	711 [50] 18,000 [47]	400 [50] 126 [53]
naproxen	<1 unchanged, metabolites: 6-o-Desmethyl naproxen (o1%), conjugates (66–92%) [49]	50–98 [50]	611,000 [50]	33,900 [50] 10,000 [52]	297 [53] 390 [48] 400 [50]
ketoprofen	Metabolites: Glucuronide conjugates [49]	15–100 [50]	5700 [50] 1000–10,000 [54]	1620 [50]	120 [48] 329 [50]
paracetamol	80% as conjugates, metabolites: Sulphate conjugate (30%), paracetamol cysteinate, mercapturate (5%) [49]	91–99 [50]	292,000 [50] 1000–10,000 [54]	1480 [50] 100,000 [52]	10,000 [48] 66 [50]
acetylsalicylic acid	Metabolites: Salicylic acid (10%), salicyluric acid (75%), salicylic phenolic (10%) and acyl (5%) glucuronides, gentisic acid (o1%) [49]	0 [50]	1000–10,000 [54]	1510 [50]	<50 [50]