Environmental Engineering Reference
In-Depth Information
Stockholm County Council (2005) carried out an environmental hazard assessment
of individual pharmaceuticals, based on three properties: persistence (P), bioaccu-
mulation (B), and toxicity (T). Each of these properties is assigned a value on a
0-3 scale. The sum of the values constitutes the Persistence/Bioaccumulation/
Toxicity (PBT) index. A PBT index of 0 indicates that the substance is readily bio-
degradable, does not bioaccumulate, and has low ecotoxicity. A PBT index of 9
indicates that the substance is not readily biodegradable, has a potential for bioaccu-
mulation, and has very high ecotoxicity. For example, the pharmaceuticals tamoxifen
(antiestrogen) and ethinylestradiol (sex hormone) each have a PBT index of 9.
Only 5 of the top 20 pharmaceuticals discharged to the DCZ (Table 2) are
classified by the Stockholm County Council (2005). The PBT indices for carbamazepine,
sulfamethaxazol, diclofenac, metoprolol, and ibuprofen are 4, 3, 7, 4, and 5, respec-
tively. Diclofenac has the highest PBT index. This pharmaceutical is very resistant
(not readily biodegradable), bioaccumulates, and is moderately toxic: lethal,
effective, and inhibitory concentrations (50% affected) ranged between 10 mg L
−1
and 100 mg L
−1
. Only three pharmaceuticals mentioned in this study have a PBT
index of 9: propanolol, norfloxacin, and tamoxifen.
Unfortunately, the X-ray-contrast-media agents, which are most ubiquitously
present in Dutch surface-, sewage-, and industrial water, are not classified by the
Stockholm County Council (2005). However, Steger-Hartman et al. (1998, 1999)
reported that environmental sublethal effects to organisms are unknown for X-ray
contrast media. Moreover, no toxic effects were observed in
Daphnia magna
, using
the chronic reproduction test, with concentrations up to 1 g L
−1
, or in bacteria (
Vibrio
fisheri, Pseudomonas putida
), algae (
Scenedesmus subspicatus
), crustaceans (
Daphnia
magna
), and fish (
Danio rerio, Leuciscus
), using short-term acute ecotoxicological
test systems containing up to 10 g L
−1
of iopromide. Although it is unlikely that X-ray
contrast media pose an immediate threat to the environment, their environmental
presence at relatively high concentrations, high persistence, and unknown sublethal
effects compel further environmental research and assessment.
4
Summary
This chapter assessed the annual median discharge of over 100 pharmaceuticals to
the DCZ. Calculations were based on pharmaceutical concentrations in surface-,
sewage-, and industrial water in the Netherlands.
In 2002, riverine discharge to the DCZ for individual pharmaceuticals varied
from 0 (concentration below LOD) to 27 t yr
−1
. However, in 2002 the annual
amount was less than 2 t for 75% of the studied pharmaceuticals. The highest loads
were calculated for X-ray contrast media, that is, values of 18-27 t yr
−1
for
iopromide.
The top 20 pharmaceuticals discharged by rivers to the DCZ are dominated by
X-ray contrast media (
n
= 7), followed by antibiotics (
n
= 6), analgesics/antipyret-
ics/anti-inflammatory drugs (
n
= 2), beta blockers (
n
= 2), fibrates/lipid regulators
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