Assessing the Discharge of Pharmaceuticals Along the Dutch Coast of the North Sea - Reviews of Environmental Contamination and Toxicology - page 11

Pharmaceutical concentrations in sewage-water effluents are generally higher
than in surface water. Fig. 3 shows that only 32 of the 102 pharmaceuticals in the
database have, in one or more sewage-water effluent samples, concentrations above
the LOD. Concentrations of pharmaceuticals in Dutch sewage-water effluents
varied from 11 ng L −1 (dimetridazol) to 10 µg L −1 (iomeprol). The highest median
concentrations in sewage-water effluents were observed for X-ray contrast media,
with median concentrations ranging from 190 to 3,100 ng L −1 . The pharmaceuticals
with the highest median concentration of each of the seven above-mentioned phar-
maceutical groups were anhydro-erytromycin (310 ng L −1 ), dimetridazol (12 ng L −1 ),
diclofenac (520 ng L −1 ), iomeprol (3.1 µg L −1 ), gemfibrozil (580 ng L −1 ), sotalol
(1.1 µg L −1 ), and carbamazepine (490 ng L −1 ).
Pharmaceutical concentrations in industrial wastewater effluents are generally
higher than in surface or sewage-water effluents. Most industrial wastewater samples
are collected from pharmaceutical industry facilities and hospitals. Fig. 4 shows that
only 54 of the 102 listed pharmaceuticals in the database have, in one or more industrial
wastewater effluent samples, concentrations above the LOD. Concentrations of phar-
maceuticals in Dutch industrial wastewater effluents varied from 11 ng L −1 (terbutalin)
to 1.1 mg L −1 (iohexol). The highest median concentrations in industrial wastewater
effluents were observed for the X-ray contrast media, with median concentrations rang-
ing from 540 ng L −1 to 665 µg L −1 . The pharmaceuticals with the highest median con-
centration of each of the seven pharmaceutical groups were: oxytetracyclin (68 µg L −1 ),
dimetridazol (11.3 µg L −1 ), paracetamol (21.4 µg L −1 ), iomeprol (665 µg L −1 ), gemfibro-
zil (3.73 µg L −1 ), sotalol (1.7 µg L −1 ), and ifosfamide (995 ng L −1 ).
The pharmaceuticals discharged to the DCZ are dominated by X-ray contrast
media ( n = 7), followed by antibiotics ( n = 6), analgesics/antipyretics/anti-inflam-
matory drugs ( n = 2), beta blockers ( n = 2), fibrates/lipid regulators ( n = 1), veteri-
nary antibiotics ( n = 1), and others ( n = 1).
Although the concentrations of many pharmaceuticals in sewage- and industrial-
water effluents are higher than those in surface water, the estimated loads of pharma-
ceuticals directly discharged to the DCZ are low compared to the riverine input to the
DCZ. This is a result of the huge difference in flow rates between surface waters and
sewage and industrial water entering the DCZ. The direct discharge loads of the top
20 pharmaceuticals are shown in Table 1. The highest pharmaceutical loads dis-
charged to the DCZ in sewage-water effluents and industrial water were calculated
for sotalol to be from 0.16 to 0.27 t yr −1 , with a median of 0.18 t yr −1 , and for diatri-
zoic acid to range from 0 to 0.327 t yr −1 , with a median of 0.067 t yr −1 . The direct
discharge of pharmaceuticals to the DCZ was calculated to be <5% of the corre-
sponding riverine discharge of pharmaceuticals.
The median loads of the top 20 pharmaceuticals entering the Netherlands by
rivers Rhine, Meuse, and Scheldt are presented in Table 1. The median loads vary
from 0.05 t yr −1 , for lincomycin, to 42.7 t yr −1 , for iopromide. The highest loads
result from X-ray contrast media, with values up to 42.7 t yr −1 (iopromide).
Barreveld et al. (2001) estimated the median load of carbamazepine entering the
Netherlands, near Lobith in 1997, to be 4.1 t yr −1 , with an average of 6.3 t yr −1 .
These values agree well with the loads calculated in this study for carbamazepine
(total of 7.5 t yr −1 ) in 2002.