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EC number: 215-235-6
CAS number: 1314-41-6
The PBT and vPvB criteria of Annex
XIII to the Regulation does not apply to inorganic substances.
The assessment approach for
Persistent, Bioaccumulative, and Toxic (PBT) substances was established
because of the possibility that some man-made chemicals may accumulate
in parts of the environment, and whereby such an accumulation may cause
unpredictable effects in the long term that may be very difficult to
These PBT criteria are not directly
applicable to metals as it neglects various processes affecting the
fate, bioavailability and toxicity of inorganic compounds.
(partitioning, speciation, complexation, competition with other ions,
adsorption, precipitation, dissolution etc.). A unit world model (UWM)
was proposed as an alternative to the PBT criteria and has the potential
to be used for the hazard assessment of both metal ions and organic
chemicals. The primary advantage of the UWM approach for hazard
assessment is that it goes beyond the individual consideration of
persistence, bioaccumulation, and inherent toxicity by integrating them
to give an overall expression of hazard in the form of a critical
loading. In doing so, it circumvents the problem of the inherently
inﬁnite persistence of metals and, potentially, provides a consistent
and more level playing ﬁeld for assessing these diverse substances
(Harvey et al., 2007). The UWM can also take into account the effect of
speciation and water properties (pH, hardness etc.) on bioavailability
8.1.1 Persistence assessment
Metals are obviously persistent in the
sense that they do not degrade to CO2, water, and other
elements of less environmental concern. As a consequence, it has been
argued that traditional persistence measures used for organic substances
do not equally apply to metals (Adams et al. 2000). While it is
recognized that metals are conserved, the form and availability of the
metal can change and the persistence of the bioavailable species is the
more appropriate hazard indicator for metals.
This potential transformation of metal
species to non-bioavailable forms through complexation, precipitation,
adsorption, and settling is recognized in Annex IV of Guidance to
Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging
of substances and mixtures. For soluble metal species, a rapid removal
definition based on laboratory, mesocosm, and/or field data tests has
been proposed. The term “Rapid removal” is a more accurate description
for metals in this respect, because, partitioning (e.g. by precipitation
and especially speciation processes) can lead to the non-available form
and the elimination of metals from the water column. However, caution is
advised given the possibility that 1) these processes do not necessarily
reduce bioavailability and/or 2) the reduction in bioavailability
afforded by these processes is not necessarily permanent. In accordance
with the principles of rapid removal used for organic substances rapid
removal can be defined for metals as a reduction of the soluble metal
species by > 70% in 28 days.
A preliminary assessment on the
removal of Pb from a water column based on the standard lake as defined
in EUSES model (suspended solids: 15 mg/L; depth: 3 m; settling rate:
2.5 m/d and residence time 40 days) and a constant partition coefficient
for Sb to suspended matter (log Kp = 5.47 l/kg) is shown in the Figure
in annex ( Total
and dissolved Pb removal from the water column using EUSES standard lake
parameters and a constant log Kp of 5.47 l/kg).
This assessment does not take into
account potential remobilisation due to e.g. resuspension or diffusion.
Based on a log Kp of 5.47 l/kg, it is predicted that 82% of the Pb added
to the water column (initial total Pb concentration of 0,1 mg/l) is
adsorbed on the suspended matter. Therefore, the initial partitioning of
Pb to suspended solids immediately satisfies the 70% removal
Similar results are obtained for
speciation model-calculated (using WHAM) distribution coefficients (Kp),
i.e. lead removal from the water column of a generalized lake based upon
the EUSES model lake exceeds 70% removal in 28 days. Sensitivity
calculations indicate 70% removal in 28 days can be achieved at water
column depths exceeding the EUSES lake value (3 m) by factors of 15 or
greater. Further sensitivity calculations also indicate that 70% removal
is still achieved within 28 days when the settling velocity is decreased
from 2.5 m/d to 0.24 m/d which is the low end of the POC range. Finally,
the potential for remobilization from anoxic and oxic sediments,
quantified by comparing water column lead concentrations resulting from
sediment feedback to the 70% removal concentration, is insignificant.
For conditions favoring remobilization, water column dissolved lead
concentrations at pseudo steady state were more than 100 times less than
the 70% removal concentration.
the criterion for persistence based on degradation is not applicable for
inorganic Pb. Under conditions of a standard EUSES lake and different
estimated partition coefficient for suspended matter, Pb meets the
criteria for rapid removal from the water column.
Bioaccumulation is the process whereby
aquatic organisms accumulate substances in their tissues from water and
diet. Bioaccumulation is of potential concern both because of the
possibility of chronic toxicity to the organisms accumulating substances
in their tissues and because of the possibility of toxicity to predators
eating those organisms. Some metal-specific considerations need to be
made on the concept of bioaccumulation. Due to their natural occurrence,
biota will naturally accumulate metals at least to some degree without
deleterious effect (ICMM, 2007). For most metals and inorganic metal
compounds the relationship between water concentration and BCF in
aquatic organisms is inverse, and bioconcentration data are therefore
often not reliable predictors of chronic toxicity or food chain
accumulation in the aquatic environment. Unlike organic substances,
which may be taken up by passive diffusion across cell walls, the uptake
and removal processes of essential elements are actively regulated in
order to maintain a reasonable constant internal concentration
(homeostatis). Also non-essential metals such as Pb are homeostatically
regulated to some extent and therefore also for non-essential metals, an
inverse relationship between the metal concentration and the external
concentration may be observed (Mc Geer et al., 2003).
According to the REACH guidance R7c
(2012) ‘the observed variability in bioaccumulation and bioconcentration
data due to speciation and especially homeostatic regulation can
therefore complicate the evaluation of data (Adams & Chapman, 2006). The
data may be used for assessments of secondary poisoning and human
dietary exposure. However, special guidance is required for
classification of metals and inorganic substances are currently outside
the scope of PBT assessments’.
Moreover, according to theREACH
guidance R11 on PBT assessment (2012) 'the PBT and vPvB criteria of
Annex XIII to the Regulation do not apply to inorganic substances but
shall apply to organo-metals'.
the ‘bioaccumulative’ criterion is not applicable to Pb.
A substance is considered
to fulfil the toxicity criteria (T) when the long-term no-observed
effect concentration (NOEC) / EC10for marine or freshwater
organisms is less than 10μg/L
or when it is classified as carcinogenic (category 1A or 1B), germ cell
mutagenic (category 1A or 1B), or toxic for reproduction (category 1A,
1B or 2) or there is evidence of chronic toxicity (STOT RE 1 or STOT RE
2) according to the CLP Regulation.
The long term NOEC/EC10for
are situated between 0.48μg
Pb/L (L. stagnalis, 7 days, reproduction; pH: 6.9, DOC: 3.96
mg/L; H: 87.0 mg/l CaCO3) and 1558.6μg
Pb/L (P. promelas, 7 days, dry weight; pH: 7.35, DOC: 6.95 mg/L;
H: 60 mg/l CaCO3). In total, 180 NOEC/EC10values
are available for 27 different freshwater species, of which 25 NOEC/EC10values
are lower than 10μg/L.
The normalised freshwater HC5,50%under worst-case conditions
(DOC 2.6 mg/L; pH 6.6) is 4.7μg
Pb/L. The PNECfreshwateris 2.4μg
long term NOEC/EC10for marine organisms are situated
Pb/L (M. trossulus, 48 hours, abnormalities) and 1409.6μg
Pb/L (M. galloprovincialis, 48 hours, mortality). In total, 59
NOEC/EC10values are available for 20 different marine
species, of which 4 NOEC/EC10values are lower than 10μg/L.
The normalised marine HC5,50%under worst-case conditions (DOC
1.2 mg/L; pH 8.1) is 6.5μg
Pb/L. The PNECmarineis 3.3μg
Pb fulfil the toxicity criteria based on the most sensitive NOEC, HC5-50and
PNEC values, which are below 10μg/L.
- The criterion for ‘persistence’ is
not applicable for inorganic Pb. Under conditions of a standard EUSES
lake and different estimated partition coefficient for suspended matter,
Pb meets the criteria for rapid removal from the water column (> 70% in
- The criterion for ‘bioaccumulation’
criterion is not applicable to inorganic substances such as Pb.
- Pb is considered to be toxic, since
the most sensitive NOECs, HC5-50 and PNEC values are lower than 10μg
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