UNECE Task Force on Persistent Organic Pollutants (POPs)
Lead Reviewer’s Track A
Summary of Expert Reviews of
PENTACHLOROPHENOL (PCP)
14 April, 2009
Table of Contents
I. Introduction................................................................................................................... 1
II. Method ......................................................................................................................... 1
III. Availability, reliability, completeness and relevance of information and references ............. 2
IV. POP Characteristics: ..................................................................................................... 2
A. Potential for long-range atmospheric transport:................................................................. 2
General Conclusion: ....................................................................................................... 2
Individual Comments: .................................................................................................... 2
Pentachlorophenol ...................................................................................................... 2
Pentachloroanisole...................................................................................................... 3
B. Toxicity and Ecotoxicity:............................................................................................................4
General Conclusion: ....................................................................................................... 4
Individual Comments: .................................................................................................... 4
Pentachlorophenol ...................................................................................................... 4
Pentachloroanisole...................................................................................................... 6
C. Persistence: .................................................................................................................................7
General Conclusion: ....................................................................................................... 7
Individual Comments: .................................................................................................... 7
Pentachlorophenol ...................................................................................................... 7
Pentachloroanisole...................................................................................................... 9
D. Bioaccumulation:........................................................................................................................9
General Conclusion: ....................................................................................................... 9
Individual Comments: .................................................................................................. 10
Pentachlorophenol .................................................................................................... 10
Pentachloroanisole.................................................................................................... 11
V. Monitoring or equivalent scientific information suggesting long-range transboundary
atmospheric transport.................................................................................................. 12
VI. Sufficiency of the information to suggest that the substance is likely to have significant
adverse human and/or environmental effects resulting from its long-range
transboundary atmospheric transport ............................................................................ 12
VII. Summary Comments ................................................................................................ 13
Summary Table of Comments ........................................................................................... 14
I. Introduction
There are five reviewers involved in the reviewing process for PCP. They based their
reviews on information included in the following documents:
1. Institute of Environmental Protection, Warsaw (May 2008): Pentachlorophenol,
Dossier prepared in support of a proposal of pentachlorophenol to be considered as
a candidate for inclusion in the Annex I to the Protocol to the 1979 Convention on
Long-Range Transboundary Air Pollution on Persistent Organic Pollutants (LRTAP
Protocol on POPs)
2. Ministry of VROM, the Netherlands (February 12, 2009): Addendum to the risk
profile of Pentachlorophenol
3. USWAG (June 16, 2008): Comments on Pentachlorophenol Revised Risk
Assessments: Notice of Availability and Solicitation on Risk Reduction Options —
Docket ID No. EPA-HQ-OPP-2004-0402
4. USWAG (April 6, 2005): Unique Operational Characteristics of Creosote,
Pentachlorophenol, and Chromated Copper Arsenate as Wood Pole and Cross-Arm
Preservatives
5. Pentachlorophenol Task Force (September 9, 2008): Letter to Executive Secretariat
on behalf of PCP manufacturer
6. Canadian Technical Comments on Pentachlorophenol Dossier (January 7, 2009)
7. US EPA (September 25, 2008): Reregistration Eligibility Decision (RED) for
Pentachlorophenol
Although some documents were not clearly identified as the references for some reviewers,
the contents of the reference material was referred in other cited documents. For example,
the USEPA RED were referred to and summarized in the Canadian Technical Comments
on the PCP Dossier (2008) and in the Addendum to the risk profile of Pentachlorophenol
(Ministry of VROM, 2009). The addendum updated information on each of the criteria and
summarized the comments from each of the listed references.
II. Method
All five reviewers independently used the provided scientific information evaluated against
the requirements outlined in Executive Body Decision 1998/2. This report summarizes the
conclusions from each reviewer. The primary conclusions are located at the end of this
report in Table 1, Summary of Comments.
In this summary report, the conclusions from each reviewer about both the
pentachlorophenol (PCP, parent compound) and pentachloroanisol (PCA, the primary
metabolite of PCP) are included. The discussion about the micro-contaminants (including
dioxins, furans, and hexachlorobenzene (HCB) is also included in the Table 1, Summary of
Comments.
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III.
Availability, reliability, completeness and relevance of information and references The overall quality of the dossier and the addendum prepared by Ministry of VROM (2009)
were good. The data are comprehensive and cover all areas relevant for the review. The
area with the largest data gaps was the environmental and biota levels of PCP and its
degradation products (e.g., PCA). It was mentioned that PCP and/or PCA had been
detected in humans and wildlife in industrial and remote regions, but concentrations were
not given. Therefore, as reviewer 2 indicated, available data do not allow to directly and
adequately characterize adverse human and/or environmental effects resulting from longrange transboundary atmospheric transport. The dossier highlights that more information
are needed to adequately characterize risks for the environment and the human health from
impurities contained in commercial PCP and from its metabolite pentachloroanisole.
IV.
POP Characteristics:
A. Potential for long-range atmospheric transport:
Criteria from Executive Body Decision 1998/2 on information to be submitted and the
procedure for adding substances to annexes I, II or III to the Protocol on Persistent
Organic Pollutants
“Evidence that the substance has a vapor pressure below 1,000 Pa and an atmospheric
half-life greater than two days. Alternatively, monitoring data showing that the substance is
found in remote regions.”
General Conclusion:
All five reviewers concluded for the parent compound, pentachlorophenol (PCP), the
criteria for potential for long range transboundary atmospheric transport are met.
Individual Comments:
Pentachlorophenol
Reviewer 1:
• Adequate evidence is provided in the dossier showing that the half-life for
pentachlorophenol is greater than 2 days and that the vapour pressure of all the congers is
below 1000 Pa. The information is sufficient in scope to strongly suggest that there is a
high potential for long range atmospheric transport.
Reviewer 2:
• According to the documents provided, PCP has a vapour pressure of 2 mPa at 20°C, and
0.0070-0.213 Pa at 25°C.
2
•
•
•
•
PCP has been detected associated with particulate matter in air. Experimental data proved
that PCP is lost by gravitational settling, and that vapour phase PCP is degraded by
photolysis and, to a lesser extent, by reaction with photochemically produced hydroxyl
radicals.
PCP can be photo-oxidized in the atmosphere, mainly through reaction with OH-radicals.
PCP half-life in atmosphere based on reaction with OH-radicals is 19.43 days as calculated
by the AOPW. Other studies available showed that PCP degradation rates may considerably
vary as a function of some environmental conditions (e.g. pH, temperature, oxygen supply,
redox potential, light, etc.) and span from a few hours to eight weeks.
Pilot calculations on PCP transport performed by EMEP, and data presented by Duchak et
al (2002), show that PCP is capable of being transported over considerable distances (15003000 Km).
PCP has been detected in some groups of population in Quebec as well as in the eggs of
birds of prey in sub-arctic areas. Observed PCP levels could be due to consumption of
foodstuffs contaminated by PCP itself and/or by its precursors. Therefore, these
information, although indicative of a likely long-range transport, cannot be considered
conclusive.
Reviewer 3:
• Pentachlorophenol meets the indicative value for long-range transport, which is illustrated
by modeling results in the dossier. The conclusion of the dossier is supported.
Reviewer 4:
• According to the documents provided, PCP has a vapor pressure of 2 mPa (20°C) or 0.007
– 0.213 Pa (25°C);
• Atmospheric half-life: <24 h, >5 d, 19.43 d (photodegradation half-life);
• PCP may be associated with particulate matter in the air and thus will be lost by
gravitational settling;
• EMEP calculations and OECD modeling show PCP to be transported over considerable
distances of several thousand kilometers;
• PCP has been detected in human and wildlife populations in remote regions such as the
North-American Arctic and Norwegian sub-Arctic.
Reviewer 5:
•
•
PCP is characterized by higher vapor pressure (2 mPa at 20 °C) than DDT (0,02 mPa at 20
°C ) or dioxins (5,8×10-2 mPa – 1,8×10-5 mPa ), therefore might not be so prone to
sorption on PM 2,5 µm or PM 10,0 µm and at the same time not so prone to transport
over long distances. However data of the transport distances of between 1500 and 3000 km
and the half life about 58 days allow us to conclude that PCP fulfills the indicative value for
the long range transport.
Additionally PCP has been detected in all environment parts: surface waters and sediments,
rainwater, drinking water, aquatic organisms, soils, food, human milk, adipose tissue and
urine. The level of PCP in the environment have declined rapidly over the last decade.
Pentachloroanisole
Reviewer 1:
• The presence of PCA in the arctic air may support the long-range transport of PCP and/or
its degradation products.
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Reviewer 2:
• As to pentachloroanisole (PCA), a metabolite of PCP, several studies reported that it is
subject to long range environmental transport and that it has a high bioaccumulation
potential, while evidence for biomagnification has not been produced.
Reviewer 3:
• Especially pentachloroanisole has been found in remote areas. It is not clear whether
pentachlorophenol was transported or it was pentachloroanisole. The dossier does not
discuss this item.
• However, pentachloroanisole has a low vapor pressure (0.0458 Pa, estimated with the
estimation program EPIWIN, which is also mentioned in the dossier) and a long estimated
atmospheric half-life (9.8 days).
• On basis of these data that are not presented in the dossier, pentachloroanisole is considered
to fulfill the indicative value for long range transport.
Reviewer 4:
• Pentachloroanisole (PCA) is an important metabolite of PCP. Its POPs characteristics have
been described in the PCP dossier (May 2008) but not really evaluated against the criteria.
There is indication that PCA fulfills some of the POPs criteria (e.g. bio-accumulation), but
with the data available it is not possible to review this degradation product.
Reviewer 5:
• Based on the data provided in the dossier can be conclude that PCA fulfills the indicate
values for the POP criteria.
B. Toxicity and Ecotoxicity:
Criteria from Executive Body Decision 1998/2 on information to be submitted and the
procedure for adding substances to annexes I, II or III to the Protocol on Persistent
Organic Pollutants
“Potential to adversely affect human health and/or the environment”.
General Conclusion:
All five reviewers concluded for the parent compound, pentachlorophenol (PCP), the
criteria for toxicity and ecotoxicity are met.
Individual Comments:
Pentachlorophenol
Reviewer 1:
• The toxicity data presented in the dossier, addendum, and Canadian technical comments for
pentachlorophenol are fairly extensive.
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•
All the information indicates pentachlorophenol is very toxic to aquatic organisms. For
human health, there is sufficient evidence to indicate that the parent pentachlorophenol may
pose health concerns through dermal, inhalation and oral routes.
•
The addendum did a very good summary of the current understanding of the toxicity
information for the parent PCP.
Reviewer 2:
In humans:
•
The most common exposure to PCP is reported to be inhalation in workplace. PCP is
toxic in contact with skin and if swallowed, very toxic by inhalation, irritating to eyes,
respiratory system and skin. Also abdominal pain, fever, and nausea may result from
occupational exposure.
•
Chronic toxicity observed results also from impurities (e.g. chlorodibenzo-p-dioxins
and furans) present in technical PCP.
•
Several studies carried out on animal models are available on the effects from
ingestion: increase in relative liver and kidney weights, and significantly decreased
serum thyroxine concentrations have been reported. Studies carried out on rats indicate
that PCP does not cause reproductive effects.
•
As to carcinogenicity, the International Agency for Cancer Research (IARC) classified
PCP as possibly carcinogenic to humans (group 2b).
Ecotoxicity:
• The European Union has classified pentachlorophenol as very toxic to aquatic
organism, because of the many studies that proved that it may cause long-term adverse
effects in the aquatic environment, (particularly on the organism growth and on the
reproductive system).
Reviewer 3:
• The dossier concludes that pentachlorophenol meets the indicative value for toxicity.
•
However, the conclusion in the dossier that PCP is slightly toxic to practically non-toxic to
bird species cannot be drawn from the available data in the dossier.
•
The used ecotoxicological data seems to be based to a large extent on the factsheet for
pentachlorophenol as a priority substance under the European Water Framework Directive
and on a report by EuroChlor. At least the pentachlorophenol factsheet is based on rather
old data. An update has been given in 2001 (Verbruggen et al 2001), containing some
additional data.
•
Further, the addendum gives some more recent data.
•
Nevertheless, the conclusion drawn for pentachlorophenol in the dossier on toxicity remains
unchanged. This conclusion that the indicative value for toxicity is met is supported.
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Reviewer 4:
• There is a multitude of studies on acute and chronic human effects, and on acute, sub-acute
and chronic animal effects. Also, there are a number of ecotoxicity studies. The
interpretation of many of the studies is hampered by the fact, that technical PCP
contaminated with dioxins has been used.
•
PCP is toxic to very toxic humans by inhalation, by ingestion and when in contact with
skin. Most chronic data stem from occupational exposure settings. A variety of effects on
the respiratory, circulatory and CN system have been reported. Liver, neurological and
genotoxic effects are reported for chronic occupational exposure via inhalation at air
concentration ranging from 0.3 – 180 mg/m3. It is, however, not de-scribed in the data
whether the PCP was technical or pure grade and whether the effects esp. on the liver can
thus be ascribed to PCP or to dioxins.
•
PCP is a possible carcinogen (IARC Group 2b).
•
PCP is most toxic to aquatic organisms. LC50 values in the range of 20 - 600 μg/l have
been reported for fish; of 240 - 2000 μg/l for Daphnia, snails and oligochaetes. EC50 values
for algae are in the range of 4 – 6.7 μg/l, for aquatic plants 80 - 7000 μg/l (96 h).
•
Chronic NOEC values for fish are reported to be 2 - <15 μg/l.
•
Effects on reproduction, larval survival and reproduction, hatchability and larval growth
have been reported for fish with NOELs ranging from 6 - >130 μg/l.
Reviewer 5:
•
Based on the data provided in dossier it can be concluded that pentachlorophenol fulfills the
indicate values for toxicity criterion.
•
PCP is highly toxic when ingested by humans and moderately toxic via inhalation and
dermal routes. Threshold level PCP in air is 0,003 ng/m3 (3 ×10-6 mg/m3), but levels of
PCP in air, which have effect on humans are 0,3-180 mg/m3
•
Potential synergy effect with other POPs
Pentachloroanisole
Reviewer 1:
• There is no toxicity information for pentachloroanisole.
•
PCA is demethylated back to PCP, which is more easily excreted. Therefore, it would be
reasonable to believe PCA would have similar systemic toxicity pattern when compared to
PCP but with higher potential bioaccumulation concern.
Reviewer 2:
6
•
No Comments
Reviewer 3:
• For pentachloroanisole no toxicity data are available.
•
A substance with BCF values as high as pentachloroanisole can be expected to cause
toxicity in aquatic organisms at very low concentrations, only on the basis of narcotic
effects.
•
If demethylation within the organisms occurs, this may lead to effects equivalent to those of
pentachlorophenol, but at lower external concentrations, because of the higher BCF values.
Reviewer 4:
• No Comments about the toxicity concern for Pentachloroanisole (PCA).
Reviewer 5:
• Based on the data provided in the dossier can be conclude that PCA fulfills the indicate
values for the POP criteria.
C. Persistence:
Criteria from Executive Body Decision 1998/2 on information to be submitted and the
procedure for adding substances to annexes I, II or III to the Protocol on Persistent
Organic Pollutants
“Evidence that the substance's half-life in water is greater than two months, or that its halflife in soils is greater than six months, or that its half-life in sediments is greater than six
months. Alternatively, evidence that the substance is otherwise sufficiently persistent to be
of concern within the scope of the protocol.”
General Conclusion:
All five reviewers concluded for the parent compound, pentachlorophenol (PCP), the
criteria for persistence are not met.
Individual Comments:
Pentachlorophenol
Reviewer 1:
• The dossier notes that the half-life of pentachlorophenol in water is below two month; and
half life in soil and sediments is far below 6 month. Therefore, it is reasonable to conclude
that pentachlorophenol does not meet the criteria for persistence in the environment.
Reviewer 2:
In water
• PCP is photo-mineralised by sunlight within a few days (Tamer 2006, Castillo et al
1997). This effect is enhanced by adsorption on solid matter. However, in deeper water
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layers light is attenuated and photo-degradation is therefore limited to the upper layers
of the water body. Degradation of photo-transformation products is completed by
micro-organisms. Scientific studies reported biodegradation half-lives in the order of 1
to 4 weeks.
•
PCP does not meet the criteria of persistence in water (> 2 months).
In sediment
• Normally, the major part of the sediment is generally anaerobic. PCP half-life for
primary degradation under anaerobic conditions ranges from less than 13 days to less
144 days. Two studies reported longer half-lives (46-1520 days under aerobic and
anaerobic conditions). These higher values seem to be due to a combination of
unfavourable environmental conditions.
•
Criterion of persistence for PCP in sediment (> 6 months) is not met.
In soil
• The degradation of PCP in soil occurs in anaerobic conditions. Several studies
examined the influence of environmental conditions on the anaerobic degradation
showing that, if these are normal, the microflora will adapt and biodegrade PCP in soil
less then 10 weeks. There are no studies reporting a half-life for PCP > 6 months.
•
PCP does not meet the criterion of persistence in soil (> 6 months).
Reviewer 3:
• It is concluded in the dossier that pentachlorophenol does not meet the indicative value for
persistence. This conclusion is supported.
•
However, the remarks in the dossier on adaptation, lag phase and co metabolism confuse
the discussion on persistence. In general, adaptation will not be relevant at low
concentrations in field situations and should thus not be regarded in the evaluation of
persistence.
Reviewer 4:
•
Half-lives in water (biodegradation) are reported to range between 2 – 14 d in pre-exposed
systems and 9 – 40 d in surface waters.
•
Half-lives in sediments are reported to be 13 - <144 d in anaerobic systems. Both in aerobic
and anaerobic sediments, rapid primary degradation is likely.
•
It has to be taken into account, that PCP is toxic for microorganisms above ~2.5 mg/l, thus
studies using high concentrations should be treated with caution.
•
Degradation half-lives in soil containing an adapted microflora ranged between 6 – 177 d.
Optimum pH is 7 and low oxygen levels reduce the degradation rate.
Reviewer 5:
• The fulfillment of the indicative value for persistence is not met. However, we should
remember, that easier degradation of PCP can promote for the creation of very toxic dioxins
and hexachlorobenzene.
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Pentachloroanisole
Reviewer 1:
•
PCA may be more environmentally persistent than pentachlorophenol was mentioned in
scientific literature (Englehardt, et al. 1986).
Reviewer 2:
•
Several studies reported that it is subject to long range environmental transport and that it
has a high bioaccumulation potential, while evidence for biomagnification has not been
produced.
Reviewer 3:
•
From the values presented in the section of the dossier on pentachloroanisole, it can be
doubted whether this substance is persistent in soil. Insufficient information is provided on
water and sediment to draw such a conclusion for these compartments. However, given the
fact that pentachloroanisole is detected in remote areas, this is an indication that
degradation is not rapid in all compartments.
Reviewer 4:
•
Its POPs characteristics have been described in the PCP dossier (May 2008) but not really
evaluated against the criteria. There is indication that PCA fulfills some of the POPs criteria
(e.g. bio-accumulation), but with the data available it is not possible to review this
degradation product.
Reviewer 5:
•
Based on the data provided in the dossier can be conclude that PCA fulfills the indicate
values for the POP criteria.
D. Bioaccumulation:
Criteria from Executive Body Decision 1998/2 on information to be submitted and the
procedure for adding substances to annexes I, II or III to the Protocol on Persistent
Organic Pollutants
“(i) Evidence that the BCF or BAF for the substance is greater than 5,000 or the log Kow
is greater than 5; or (ii) Alternatively, if the bio-accumulative potential is significantly
lower than (i) above, other factors, such as the high toxicity of the substance, that make it
of concern within the scope of the protocol.”
General Conclusion:
9
All five reviewers concluded for the parent compound, pentachlorophenol (PCP), the
criteria for bioaccumulation are not met.
Individual Comments:
Pentachlorophenol
Reviewer 1:
•
The dossier indicates that the log Kow for pentachlorophenol is between 1.3 – 5.86 and that
the BCF is below 5000.
•
The PMRA and USEPA concluded that log Kow is 5.05 and BCF in bluegill sunfish is 490.
As suggested in the dossier, because pentachlorophenol is subject to biotransformation, log
Kow would not be a good indicator of biotransformation.
•
Therefore, pentachlorophenol itself does not meet the criteria for bioaccumulation.
Reviewer 2:
•
Measured logKow varies between 1.3 and 5.86. This broad variation is mainly caused by
the different dissociation of PCP at different pH values: with decreasing pH, PCP is
undissociated and a higher logKow is measured. At contrary, under basic conditions the
dissociation of PCP increases and logKow decreases.
•
BCF values measured in crustacea, bivalves, aquatic and terrestrial worms and in some
species of fish, varies between 0.9 - 4900. Only a study (Gossiaux et al., 1996) reported
BCF > 5000, but interpretation of results is hampered by some characteristics of the study
design.
•
On the whole, it is concluded that PCP does not meet the indicative value of BCF > 5000.
Reviewer 3:
•
The log Kow is discussed as part of the bioaccumulation potential. It is stated that the shake
flask method is the most accepted method, but in fact this is the slow-stirring method for
substances with a log Kow higher than 5. A large range of values is presented. However,
these include both undissociated and dissociated values. As the log Kow only refers to the
undissociated species, this range is a much smaller range around but above log Kow 5.
However, many experimental bioaccumulation data are presented in the dossier. It is
concluded in the dossier that pentachlorophenol does not meet the indicative value for
bioaccumulation. Again, this conclusion is supported.
•
The high values for a mollusk species can be disregarded, given the amount of other data
and a second study for the same species.
Reviewer 4:
10
•
The log Kow of PCP is in the range of 1.3 – 5.86; the recommended values are 5.12 and
5.18. The values vary depending on the different dissociation of PCP with different pH
values.
•
BCF has been measured in a variety of taxa: measured BCF values are for crustaceans 18 –
640; for bivalves 0.9 – 461; for aquatic and terrestrial worms 71 – 3’830 and for fish 5 –
4’900.
Reviewer 5:
•
The fulfillment of the indicate values for bioaccumulation is doubtful and is not met. The
BCFs values are below the threshold.
Pentachloroanisole
Reviewer 1:
With the physical and chemical properties mentioned in the dossier, “pentachloroanisole is
highly hydrophobic. The estimated log Kow is 5.30.- 5,45. As indicted in the pentachlorophenol
task force, “several studies suggest that PCA may be rapidly taken up into tissues, and mostly
eliminated, though relatively more slowly”. In addition, PCA is found in biota in the arctic
region. It is reasonable to believe the compound has a high bioaccumulation potential.
Reviewer 2:
Pentachloroanisole (PCA), a metabolite of PCP, several studies reported that it is subject to
long range environmental transport and that it has a high bioaccumulation potential, while
evidence for biomagnification has not been produced.
Reviewer 3:
Pentachloroanisole shows a high bioaccumulation potential. In the letter from the
Pentachlorophenol Task Force it is stated that “several studies suggest that PCA may be
rapidly taken up into tissues, and mostly eliminated, though relatively more slowly”. Exactly
this behavior (high uptake, k1; low elimination, k2) is characteristic of a high bioaccumulation
potential. Although the dossier does not draw a conclusion on PCA, it can be concluded from
the presented data that pentachloroanisole meets the indicative value for bioaccumulation. This
is also not contradicted by the fact that pentachloroanisole is found in biota in the arctic region.
Reviewer 4:
Pentachloroanisole (PCA) is an important metabolite of PCP. Its POPs characteristics have
been described in the PCP dossier (May 2008) but not really evaluated against the criteria.
There is indication that PCA fulfills some of the POPs criteria (e.g. bio-accumulation), but
with the data available it is not possible to review this degradation product.
Reviewer 5:
Based on the data provided in the dossier can be conclude that PCA fulfills the indicate values
for the POP criteria.
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V.
Monitoring or equivalent scientific information suggesting long-range
transboundary atmospheric transport
Reviewer 1:
The dossier provided enough information to address suggesting long-range transboundary
atmospheric transport for both PCP and PCA. In addition, the addendum prepared by Ministry
of VROM (2009) and the Canadian Technical Comments (2009) provide additional useful
scientific information suggesting long-range transboundary atmospheric transport.
Reviewer 2:
PCP has been detected in population groups and different wildlife species in remote regions of
the Northern Hemisphere. Although suggestive of the presence of PCP in these region as a
consequence of LRTAP, this information cannot be considered conclusive, as PCP is it is a
major product of the metabolism of common pesticides in mammals
Reviewer 3:
Monitoring data are presented to show that pentachlorophenol and its degradation product
pentachloroanisole are found globally even in remote areas. This is also discussed under
potential for long range transport. For the POPs polychlorinated dibenzodioxins, dibenzofuran
and hexachlorobenzene, this has already been demonstrated before.
Reviewer 4:
The data provided do not allow a conclusion as to whether the measured levels in remote
regions, resulting from long-range transboundary atmospheric transport, would lead to
significant human and/or environmental effects. It is mentioned in the dossier that the general
population in industrialized countries as well as humans and wildlife in remote regions is
exposed to PCP and shows measurable levels in tissues. These levels are, however, not
quantified in the dossier and it is therefore not possible to evaluate the significance of these in
relation to experimentally determined effects or to observations from occupational exposure.
Reviewer 5:
It is not clearly summarized by the reviewer. However, the reviewer concluded “based
on the data provided in dossier….., pentachlorophenol fulfills the indicate values for
long range transport”.
VI. Sufficiency of the information to suggest that the substance is likely to have
significant adverse human and/or environmental effects resulting from its longrange transboundary atmospheric transport
Reviewer 1:
The acute toxicity data presented in the dossier, addendum, and Canadian technical comments
for pentachlorophenol are fairly extensive. All the information indicates pentachlorophenol is
very toxic to aquatic organisms. For human health, there is sufficient evidence to indicate that
the parent pentachlorophenol may pose health concerns through dermal, inhalation and oral
routes. The addendum did a very good summary of the current understanding of the toxicity
information for the parent PCP.
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Reviewer 2:
Available data do not allow to directly and adequately characterize adverse human and/or
environmental effects resulting from long-range transboundary atmospheric transport.
Reviewer 3:
The adverse effects of the use of pentachlorophenol to human health have already well been
established, especially for exposed workers. This is also well documented in the dossier. It is
not clear whether these effects are due to pentachlorophenol itself or due to its impurities. The
EPA has noted that dioxins in treated wood appear to be the largest quantified flow of dioxins
into the environment. Given the fact that these compounds together with hexachlorobenzene
and polychlorinated furans are already confirmed POPs, it is clear that the use of
pentachlorophenol poses a serious threat to human health, also at locations far away from the
source.
Reviewer 4:
With the data at hand, it is not possible to say whether sufficient information exists to
suggest that PCP is likely to have significant adverse human health and/or
environmental effects as a result of its long-range transboundary atmospheric transport.
Reviewer 5:
It is not clearly summarized by the reviewer. However, the reviewer indicate “ the
dossier provides evidence regarding the negative impact of PCP on the environment
and human health. PCP is highly toxic when ingested by humans and moderately toxic
via inhalation and dermal routes.
VII. Summary Comments
In the reviewing process, all five reviewers came to the same conclusions regarding
pentachlorophenol (PCP) itself. It meets the indicative numerical values in Executive Body
Decision 1998/2 for long-range transboundary atmospheric transport and toxicity concerns.
PCP itself does not meet the indicative numerical values for persistence and
bioaccumulation.
All five reviewers had concerns about pentachloroanisol (PCA). PCA is considered one of
the major metabolites in the environment and in biological systems. Based on available
and scientific information, all five reviewers considered PCA may fulfill some and/or all of
the POPs indicative numerical values in Executive Body Decision 1998/2. The POPs
indicative numerical values for the biological and environmental degradation products of
PCP are not clearly addressed. Therefore, based on available information, there are some
different opinions about the fate and biological effects resulting from PCP long-range
transboundary atmospheric transport.
Except from reviewer 1, who states that dioxins and furans are outside the scope of this
review, the other reviewers are quite unanimous in their judgement that the use of
pentachlorophenol is inseparably coupled to the emission of dioxins and furans, due to the
impurities as a result of all known production processes, due to burning of treated wood and
due to degradation in the environment.
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Summary Table of Comments
Pentachlorophenol (PCP)
UN-ECE POP Protocol Criteria
Reviewer 1
Potential long-range
atmospheric transport
Vapour pressure <1000 Pa
and atmospheric
half-life: >2 days
Toxicity
Potential to adversely
affect human health
and/or the environment
Persistence
Half-life in water: >2
months or half-life in
sediment: >6 months or
half-life in soil: >6 months
Bioaccumulation
log KOW: >5 or
bioconcentration factor
(BCF):
>5000 or bioaccumulation
factor (BAF): >5000
Reviewer 2
Reviewer 3
Reviewer 4
Reviewer 5
met
met
met
met
met
met
met
met
met
met
Not Met
Not Met
Not Met
Not Met
Not Met
Not Met
Not Met
Not Met
Not Met
Not Met
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Pentachlorophenol (PCP)
UN-ECE POP Protocol Criteria
The presence of microcontaminants (Dioxin,
Furans, and hexachlorobenzene (HCB)
Reviewer 1
Reviewer 2
Reviewer 3
Reviewer 4
These microcontaminants are
considered as
contaminants in
the
manufacturing
process and are
not considered in
this reviewing
process.
• PCP contains
dioxins as microcontaminants;
• These substances
are already
designated as
POPs.
• During the production
and use of PCP large
amounts of dioxins
and furans have been
formed. It has been
estimated that a large
amount of historic
and current
dioxin/furan levels
can be attributed to
PCP. It is however
not clear from the
documents what the
current relevance is.
• Burring of PCPtreated wood is
recognized to be
an important
source of
PCDD/F
production, in
particular, of
some PCDD
congeners.
• Because of the
emission of these
dioxins and
furans that is
inevitably
coupled to the
use of
pentachlorophen
ol as a wood
preservative, the
final conclusion
from reading the
dossier is that the
product
pentachlorophen
ol can be
considered
meeting the all
the indicative
values of
Executive
Decision 98/2 for
consideration as
a POP.
Reviewer 5
• PCP is a major
source of highest
hazards microcontaminants:
polychlorinated
dibenzo-p-dioxins
(PCDD),
polychlorinated
dibenzofurans
(PCDF) and
hexachlorobenzene.
• PCP is a source of
dioxins and furans,
elimination of PCP
will therefore also
results in the
elimination of a
source for these
unintentionally
produced POPs.
15
Pentachlorophenol (PCP)
UN-ECE POP Protocol Criteria
The presence of the
important metabolite of
PCP. Pentachlorophenol
(PCA)
Reviewer 1
Reviewer 2
Reviewer 3
Reviewer 4
Reviewer 5
• PCA may be
more
environmentally
persistent and
bioaccumulative
than PCP.
• Several studies
reported that PCA
is subject to long
range
environmental
transport and that it
has a high
bioaccumulation
potential, while
evidence for
biomagnification
has not been
produced.
• PCA is considered
to fulfil the
indicative value for
long range
transport and
bioaccumulation.
• During the production
and use of PCP large
amounts of dioxins and
furans have been
formed. It has been
estimated that a large
amount of historic and
current dioxin/furan
levels can be attributed
to PCP. It is however
not clear from the
documents what the
current relevance is.
• Pentachloroanisole
(PCA) fulfills the
indicate values for the
POP criteria.
• The presence of
PCA in the arctic
air may support
the long-range
transport of PCP
and/or its
degradation
products.
• No toxicity data are
available. With
high BCF, expect
to cause toxicity in
aquatic organisms
at very low
concentrations,
only on the basis of
narcotic effects.
• If demethylation
within the
organisms occurs,
this may lead to
effects equivalent
to those of PCP,
but at lower
external
concentrations,
because of the
higher BCF values.
• given the fact that
pentachloroanisole
is detected in
remote areas, this
is an indication that
degradation is not
rapid in all
compartments.
• PCP is a source of
dioxins and furans,
elimination of PCP will
therefore also results in
the elimination of a
source for these
unintentionally
produced POPs.
• PCA is an important
metabolite of PCP. Its
POPs characteristics
have been described in
the PCP dossier (May
2008) but not really
evaluated against the
criteria.
• There is indication that
PCA fulfills some of the
POPs criteria (e.g. bioaccumulation), but with
the data available it is
not possible to review
this degradation
product.
16