Substitution of Benzotriazole UV Absorbers in Plastics

© 2018 James H. Botkin dba BotkinChemie Page 1 of 19
Substitution of Benzotriazole UV Absorbers in Plastics
James H. Botkin dba BotkinChemie, Madison, NH
Presented at the SPE Thermoplastic Elastomers Conference, September 2018, Akron, OH
Abstract
Benzotriazole UV absorbers such as UV-328 have been extensively used as light stabilizers
in plastics and coatings for many years. However, increased regulatory compliance burdens
associated with designation of some products (including UV-328) as Substances of Very High
Concern (SVHC) in Europe are driving additive users around the world to phase-out their use by
substitution with safer alternatives. This paper discusses how UV-328 and other benzotriazoles
came to be classified as SVHC under REACH, and identifies potentially safer substitutes for
additive users based on the results of a hazard assessment.
Introduction
Benzotriazole UV absorbers are widely used as light stabilizers in plastics and coatings,
functioning by competitive absorption of harmful UV radiation. These useful additives feature
broad absorbance coverage over both the UV-A (λ = 315-400 nm) and UV-B (λ = 280-315 nm)
regions, minimal absorbance of visible light (λ > 400 nm), and excellent long-term photo-
stability. Benzotriazoles represent a versatile chemical platform in that products having a wide
range of secondary properties (physical form, melting point, volatility) have been developed and
are commercially available. However, new regulatory developments in Europe are creating
considerable pressure for phase-out or substitution of some products, including the widely used
UV-328.
This paper seeks to address the following questions associated with the regulation and
substitution of benzotriazole UV absorbers:
1. What exactly is happening and what are the implications?
2. What products are affected by regulatory developments?
3. Why are some products being regulated?
4. Will other products be regulated in the future?
5. How can better substitutes be identified?
6. How to formulate in new applications to minimize risks?
Affected Products, Status, & Implications
The subject products of this paper are ten different commercially available, solid
benzotriazole UV absorbers that have been historically been used as light stabilizers in plastics
and coatings applications. The common names (based on Ciba product nomenclature),
chemical names, CAS numbers, and chemical structures are provided in Table 1.
In 2014-2015, four of these substances (UV-320, UV-327, UV-328, and UV-350) were
placed on the Candidate List of Substances of Very High Concern (SVHC) by the European
Chemicals Agency (ECHA).[1] The basis for this development was the identification of these
substances as Persistent, Bioaccumulative, and Toxic (PBT) and/or very Persistent and very
Bioaccumulative (vPvB). Under the REACH regulation, there is a duty to communicate
information on these substances and other SVHC present above a cut-off concentration (0.1%
by weight) in articles, preparations, and chemical products.[2] Producers and importers of

articles containing SVHC may also need to submit a notification to ECHA. The increased
regulatory burden associated with the designation of these substances as SVHC has pressured
additive users to begin phasing out their use by substitution with functionally equivalent
alternatives.
In February 2018, ECHA recommended addition of UV-328, UV-320, UV-327, and UV-350
to the REACH Annex XIV List (“Authorisation List”).[3] This represents a more serious
regulatory development. Once added to the Authorisation List, companies using these
substances would be required to apply for authorization with ECHA in order to continue existing
uses. Substances on the Authorisation List may also be subject to a sunset date, after which
they cannot be used without authorization. This development has placed additional pressure on
additive users worldwide to phase-out the use of these products. The issue is particularly acute
for UV-328, which is a high volume product widely used in the plastics and coatings industries.
Other benzotriazole UV absorbers are also under scrutiny in Europe due to PBT concerns.
In 2014-2015, informal evaluations of five other benzotriazole UV absorbers (UV-P, UV-234,
UV-326, UV-329, and UV-928) were initiated under ECHA’s Public Activities Coordination Tool-
Risk Management Option Analysis (PACT-RMOA) program.[4] As of August 2018,
assessments of these substances are still under development. ECHA cautions that inclusion of
a substance in the PACT program only means that a Member State or ECHA is examining it, not
that it actually has PBT properties or that there is need for regulatory risk management
actions.[5] For any substance being assessed, the outcome may well be that it is not found to
have PBT properties based on available data. However, the fact that these potential alternative
products are being scrutinized makes it more difficult for additive formulators to identify
appropriate alternatives to UV-328.
In Japan, UV-320 came under regulation as a Class I Specified Chemical Substance in 2007
under the Chemical Substances Control Law (CSCL).[6] Class I Specified Substances are
regulated based on being found to be persistent, highly bioaccumulative and posing a risk of
long-term toxicity to humans or animals. Under the CSCL, prior permission is required for
manufacture and/or import, which constitutes a virtual prohibition except for uses designated as
essential. UV-327 and UV-350 are regulated under the CSCL as Monitoring Chemical
Substances based on concerns regarding persistence and bioaccumulation.[7] For these
substances, annual reporting is required if volumes of manufacturing or import are greater than
1 ton per year. The authority may also order manufacturers and importers to investigate long-
term toxicity for humans or animals. None of the other benzotriazole UV absorbers listed in
Table 1, including UV-328, are subject to restrictions in Japan under CSCL.
In the USA, no assessments of any of the benzotriazole UV absorbers listed in Table 1 have
been initiated to date by the EPA under the Toxic Substances Control Act (TSCA) Work Plan [8-
9] or under the amended TSCA.[10] However, UV-320, UV-328, and UV-329 have been listed
on chemicals of concern lists at the State level.
In Canada, a screening assessment was completed by Environment and Climate Change
Canada and Health Canada for UV-328 in 2016 with no further action recommended.[11]
Several other substances listed in Table 1 (UV-234, UV-326, UV-329, and UV-350) met the
criteria for screening under the Canadian Environmental Protection Act (CEPA) and may
possibly be subject to screening assessments in the future.
While no regulatory actions on UV-328 are pending in the USA, Japan, or Canada, the
importance of Europe in global supply chains continues to provide incentive to additive
formulators around the world to replace it with safer alternatives. As part of the search for

alternatives, it’s helpful to understand the reasons behind the regulatory issues associated with
UV-328, UV-327, UV-320, and UV-350.
Rationale for Regulation: Persistence, Bioaccumulation, & Toxicity
As described in the previous section, benzotriazoles are subject to regulatory scrutiny based
on concerns over their persistence, bioaccumulation, and toxicity. Chemicals known to be
persistent, bioaccumulative, and toxic (PBT); or very persistent and very bioaccumulative (vPvB)
are of particular concern for regulators since they can remain in the environment for a long time
and can bioaccumulate in animal tissues. Over time, releases of these chemicals have the
potential to accumulate to higher levels and may cause significant adverse impacts on human
health and/or the environment.
Persistence is defined as resistance of a chemical substance to environmental degradation
through natural chemical, biological, and photolytic processes. This can be inferred through
monitoring studies in water, soils, and sediments. Benzotriazoles were first recognized as
persistent based on monitoring studies conducted on sediments from locations near a former
production site for UV-327 and UV-328 in Rhode Island.[12] Regulators often assess the
persistence of a chemical substance by its degradation half-life times (T1/2) in water, sediment,
and soil, which can be determined by laboratory tests or the use of molecular modeling
software. The criteria for designation of substances as persistent (P) and very persistent (vP)
are set forth in Annex XIII of the REACH regulation.[13] In general, chemicals meet the criteria
for vP under REACH if their T1/2 in water is greater than 60 days and/or greater than 180 days in
soil or sediment. In the USA, the EPA has adopted similar criteria, and a chemical is
characterized as vP if its T1/2 in water, soil, or sediment is greater than 6 months.[14]
Based on information contained in the REACH dossiers [15-22] and the Candidate List
documentation [1] all of the benzotriazole UV absorbers listed in Table 1 are considered to meet
the criteria for vP under the REACH criteria, and would probably be characterized as vP under
the EPA criteria as well.
Bioaccumulation is defined as the tendency of a chemical substance to accumulate in living
organisms. This can be inferred through monitoring studies in wildlife or in humans.
Benzotriazole UV absorbers were first detected in monitoring studies conducted with marine
organisms in Japan,[23] and benzotriazole UV absorbers have since been found in monitoring
studies conducted with marine life in other parts of the world.[24-27] Regulators usually assess
then tendency of a substance to bioaccumulate using Bioconcentration Factor (BCF) or
Bioaccumulation Factor (BAF) values, which are determined by laboratory tests or through the
use of molecular modeling software. The criteria for designation of substances as
Bioaccumulative (B) and Very Bioaccumulative (vB) are set forth in Annex XIII of the REACH
regulation.[13] In general, substances having a BCF value greater than 2,000 are considered to
be B, and those having a BCF value greater than 5,000 are considered to be vB. In the USA,
the EPA considers a substance to be B if its BCF or BAF value is greater than or equal to 1,000,
and vB if its BCF or BAF value is greater than or equal to 5,000.
Based on BCF data contained in the REACH dossiers [18] and candidate list documentation
[1], UV-320, UV-327, UV-328, and UV-350 all meet the REACH and EPA criteria for vB.
Additionally, the BCF values for UV-234 [16] and UV-928 [22] meet the EPA criteria for B
(although they do not meet the REACH criteria for B). The remaining substances (UV-P, UV-
326, UV-329, and UV-360) are not considered to be B under either REACH or EPA criteria
based on BCF values less than 1,000.[15,17,19-21]

Toxicity is defined as the degree to which a substance can damage an organism. Toxicity
and eco-toxicity are assessed using test methods based on the UN Globally Harmonized
System (GHS) of hazard classification. The criteria for designation of a substance as toxic (T)
are set forth in Annex XIII of the REACH regulation. Benzotriazoles present varying degrees of
chronic toxicity and chronic aquatic toxicity. Based on data contained in the REACH dossier
[18] and candidate list documentation [1], UV-320 and UV-328 are considered T under REACH
criteria. The remaining substances (UV-P, UV-234, UV-326, UV-327, UV-329, UV-350, UV-360,
and UV-928) do not meet the REACH criteria for T based on candidate list documentation [1[ or
the REACH dossiers.[15,17,19-21]
As defined under the REACH regulation, UV-320, UV-327, UV-328, and UV-350 are all
considered to be PBT and/or vPvB substances, and this can be regarded as the root cause for
the current regulatory restrictions. The alternative products do not meet the criteria for either
PBT or vPvB based on available data, but all can be regarded as very Persistent (vP) and
present varying degrees of bioaccumulation and toxicity. However, as the criteria for
bioaccumulation and toxicity used by regulators may be subject to change, additive formulators
may desire to lower the risk of making a regrettable substitution by selecting alternatives based
on their bioaccumulation and toxicity characteristics, for example through a hazard assessment.
Identifying Safer Alternatives Using Hazard Assessments
Hazard assessments represent part of a larger alternatives assessment process, which
addresses other factors such as technical performance, cost, commercial availability, and
environmental life cycle attributes. Through the use of hazard assessments, users of chemicals
can select safer alternatives and avoid replacing one hazardous substance with another. In the
case of the benzotriazole UV absorbers, a hazard assessment is intended to support informed
decision-making by additive formulators and end users by providing a basis to rank the
attractiveness of alternatives based on their inherent hazard characteristics.
Some hazard assessment methods utilize numerical ratings or benchmarks in order to
facilitate comparisons between different alternatives. The best methods are based on criteria
developed by or consistent with those used by regulatory agencies for evaluating chemical
hazards, for example the UN Globally Harmonized System of Classification and Labeling of
Chemicals (GHS) and the EPA Design for the Environment Program Alternatives Assessment
Criteria for Hazard Evaluation (DfE).
Numerous hazard assessment methods have been developed. Examples include:
• GreenScreen®
for Safer Chemicals (“GreenScreen®
”)
• GreenScreen List Translator™
• Quick Chemical Assessment Tool (QCAT)
• EPA TSCA Work Plan Chemical Scoring
GreenScreen®
is a hazard assessment method developed by the NGO Clean Production
Action, that is designed for use by businesses, government agencies, and certification bodies to
identify chemicals of high concern and safer alternatives.[28-29] This comprehensive method
expands on the GHS and DfE methods, with a full GreenScreen®
assessment covering human
health and environmental effects data for a chemical substance based on 18 different hazard
endpoints (carcinogenicity, mutagenicity/genotoxicity, reproductive toxicity, developmental
toxicity, endocrine activity, acute human toxicity, respiratory sensitization, skin
irritation/corrosivity, eye irritation/corrosivity, acute aquatic toxicity, chronic aquatic toxicity, acute
and chronic neurotoxicity, skin sensitization, persistence, bioaccumulation, physical reactivity,

and flammability). Based on the results of the assessment, chemical substances are assigned
one of five benchmark scores: Benchmark-1 (avoid – chemical of high concern), Benchmark-2
(use but search for safer substitutes), Benchmark-3 (use but still opportunity for improvement),
Benchmark-4 (prefer – safer chemical), or Benchmark U (not classifiable due to lack of data).
The benchmark scoring makes the comparison of the hazards associated with different
alternatives a straightforward exercise. Use of the GreenScreen®
method would provide the
most authoritative differentiation between the benzotriazole UV absorbers under consideration.
However, due to its comprehensive nature, GreenScreen®
assessments are inherently time
consuming, and specialized training is recommended for personnel prior to conducting
assessments. For this reason, simpler methods may be appropriate for a preliminary screening.
The QCAT is a simplified hazard assessment method developed by the Washington State
Department of Ecology with the support of Clean Production Action.[30] This method utilizes a
smaller number of hazard endpoints (carcinogenicity, mutagenicity/genotoxicity, reproductive
toxicity, developmental toxicity, endocrine activity, acute mammalian toxicity, acute aquatic
toxicity, persistence, and bioaccumulation) and data sources than GreenScreen®
to reduce the
number data sources and time required to complete an assessment. Based on the results of
the assessment, chemical substances are assigned one of four grades: A (high concern,
avoid), B (moderate concern, use but search for safer alternatives), C (slight concern,
improvement possible), or D (few concerns, preferable). This method is recommended for use
to screen chemicals to determine whether a more in-depth assessment such as GreenScreen®
is necessary. In the case of the benzotriazole UV absorbers, the downside of this method is
that it does not cover known hazards such as chronic toxicity and chronic aquatic toxicity.
The GreenScreen List Translator™ screening tool developed for the rapid identification of
chemicals of high concern.[31] The method scores chemical substances based on information
from hazard lists developed by authoritative scientific bodies around the world. The results are
used to assign one of three List Translator scores: LT-1 (indicating the presence of a chemical
on at least one authoritative hazard list expected to result in a Benchmark-1 score if further
assessed with GreenScreen®
), LT-P1 (indicating presence of a chemical on at least one hazard
list that may possibly result in a Benchmark-1 score upon further assessment with
GreenScreen®
), or LT-UNK (indicating that the chemical is present on one or more lists but does
not meet any of the criteria to assign an LT-1 or LT-P1 score). If no information is found for a
chemical in any of the hazard lists, the substance is assigned a score of NoGSLT.
GreenScreen List Translator™ scores can be determined easily and quickly using online
services such as the Pharos Chemical and Material Library from the Healthy Building Network
NGO.[32} While the method is suitable for the identification of chemicals of high concern, more
comprehensive methods such as GreenScreen®
are more appropriate for use in the
identification of safer alternatives.
The TSCA Work Plan Chemical Scoring method is used by the EPA to identify potential
candidate chemicals for assessment under TSCA.[33] Chemicals are evaluated and given a
score based on three characteristics: Hazard, Exposure, and potential for Persistence and
Bioaccumulation. The Hazard and Persistence/Bioaccumulation Scores are derived from the
EPA DfE criteria based on 12 different endpoints (acute toxicity, carcinogenicity, mutagenicity/
genotoxicity, reproductive toxicity, developmental toxicity, neurotoxicity, chronic toxicity,
respiratory sensitization, acute aquatic toxicity, chronic aquatic toxicity). While this screening
process is intended mainly to support initial decisions by the EPA to determine the relative
priority of chemicals for further assessments, the Hazard and Persistence/Bioaccumulation
Scores are suitable for use as the basis for a simplified hazard assessment to identify chemicals

of concern and make a preliminary screening of alternatives. Note that the Exposure Score
relates to risks rather than the inherent hazards of a chemical substance, and therefore is not
appropriate for inclusion in a hazard assessment.
Hazard Assessment Screening of Benzotriazole UV Absorbers
A modified version of the EPA’s TSCA Work Plan Chemical Scoring method was used to
make a preliminary assessment of six different benzotriazole UV absorbers (UV-P, UV-234, UV-
326, UV-329, UV-360, and UV-928) as alternatives to UV-328. The method criteria [33] were
applied using data and interpretations from the EU REACH dossiers [15-22] to obtain the
Hazard and Persistence/Bioaccumulation scores. The alternatives were ranked based on the
Total Score, which was defined as the sum of the Hazard and Persistence/Bioaccumulation
Scores.
Hazard Scores were assigned for UV-328 and the alternatives based on 10 different
toxicological and eco-toxicological endpoints. Consistent with the TSCA Work Plan Chemical
Scoring methodology, the Hazard Score for each substance was assigned based the highest
hazard score from any individual hazard endpoint, and each substance was ranked as 3 (high),
2 (moderate), or 1 (low) for hazard. The scores for the reproductive toxicity, developmental
toxicity, and chronic toxicity endpoints were based on applying the scoring criteria to the No
Observed Adverse Effect Level (NOAEL) or No Observed Effect Level (NOEL) data rather than
the Lowest Observed Adverse Effect Level (LOAEL) or Lowest Observed Effect Level (LOEL)
data. For hazard endpoints where data from multiple studies were available, the hazard score
was based on the data giving the highest possible score. The only exception to this rule was
that data with a reliability score of 3 (not reliable) were deemed to be unreliable and not used to
determine the hazard score for that particular endpoint.
The raw hazard data for the individual endpoints are summarized in Tables 3-7. No data
were available for any of the benzotriazoles for neurotoxicity or respiratory sensitization and
therefore no scores could be assigned for those hazard categories.
The Hazard Scores for UV-328 and the alternatives are described below and summarized in
Table 2:
• UV-328 was assigned a Hazard Score of 3 (high) based on chronic toxicity (Table 6).
• UV-P was assigned a Hazard Score of 3 (high) based on chronic aquatic toxicity (Table 7).
• UV-234 was assigned a Hazard Score of 2 (medium) based on chronic toxicity (Table 6).
• UV-329 was assigned a Hazard Score of 2 (medium) based on chronic toxicity (Table 6).
The score was deemed to be of low confidence based on the use of structural analog data
for the chronic toxicity endpoint.
• UV-326, UV-360, and UV-928 were assigned Hazard Scores of 1 (low). The Hazard Score
for UV-928 was deemed to be of low confidence based on the use of structural analog data
for some of the hazard endpoints.
Bioaccumulation (B) Scores on a scale of 1 (low) to 3 (high) were assigned using
experimental BCF values from the REACH dossiers. The bioaccumulation data for each
substance and the corresponding B Scores are described below and are summarized in Table
8:
• UV-328 was assigned a Bioaccumulation Score of 3 (high) based on a BCF value of 5,580.
• UV-P was assigned a B Score of 1 (low) based on a BCF value of 494.
• UV-234 was assigned a B Score of 2 (medium) based on a BCF value of 1,286.

• UV-326 was assigned a B Score of 1 (low) based on a BCF value of 895.
• UV-329 was assigned a B Score of 1 (low) based on a BCF value of 461.
• UV-360 was assigned a B Score of 1 (low) based on a BCF value of 1.5.
• UV-928 was assigned a B Score of 2 (medium) based on a BCF value of 1,286. The score
was deemed to be of low confidence based on the use of structural analog BCF data.
All of the benzotriazoles were assumed to be very persistent and assigned Persistence (P)
Scores of 3 (high). The B and P Scores were normalized according to the TSCA Work Plan
Chemical Scoring method to give a consolidated Persistence/Bioaccumulation (PB) Score on a
scale of 1 (low) to 3 (high). The normalized PB Scores for each substance are described below
and are summarized in Table 8:
• UV-328, UV-234, and UV-928 were assigned normalized PB Scores of 3 (high). The PB
Score for UV-928 was deemed to be of low confidence based on the use of structural analog
data to assign the B score.
• UV-P, UV-326, UV-329, and UV-360 were assigned normalized PB Scores of 2 (medium).
A Total Score for each substance was determined from the sum of PB and T Scores on a
scale of 2 (low) to 6 (high). The Total Scores for each substance are described below and are
summarized in Table 8:
• UV-328 was assigned a Total Score of 6 (high).
• UV-P and UV-234 were assigned Total Scores of 5 (medium-high).
• UV-329 and UV-928 were assigned Total Scores of 4 (medium). The Total Scores for both
substances were deemed to be of low confidence based on low confidence of the Hazard
Score and/or PB Score.
• UV-326 and UV-360 were assigned Total Scores of 3 (medium-low).
Based on the Total Scores, the most preferred alternatives to UV-328 include UV-326, UV-
329, UV-360, and UV-928. UV-234 and UV-P appear to be less attractive alternatives based on
their higher Total Scores. More comprehensive hazard assessments of UV-P and UV-234 (for
example using the GreenScreen®
method) would be helpful to better understand their inherent
hazards and their suitability for use as alternatives to UV-328.
Conclusions
The benzotriazole UV absorbers UV-320, UV-327, UV-328, and UV-350 are facing
significant pressures for phase-out due to regulatory developments in Europe. These
substances were added to the Candidate List of Substances of Very High Concern (SVHC) in
2014 and were recommended for addition to the REACH Annex XIV List (the “Authorisation
List”) in 2018. The basis for regulation is the identification of these substances as Persistent,
Bioaccumulative, and Toxic (PBT) and/or Very Persistent and Very Bioaccumulative (vPvB)
according to the criteria set forth in Annex XIII of the REACH regulation. The issue is
particularly acute for UV-328, which is a high volume product widely used in plastics and
coatings.
Possible alternatives to UV-320, UV-327, UV-328, and UV-350 include UV-P, UV-234, UV-
326, UV-329, UV-360, and UV-928. None of the alternatives meet the criteria for regulation as
PBT or vPvB chemicals set out in REACH Annex XIII based on data currently available in the
REACH dossiers.
Hazard assessments can help additive users to identify chemicals of concern and safer
alternatives. The hazards of the alternatives relative to UV-328 were assessed using a modified

version of the EPA’s TSCA Work Plan Chemical Scoring method. Based on the results of the
hazard assessment, the most attractive alternatives include UV-326, UV-329, UV-360, and UV-
928. However, it should be cautioned that some of the data used to assign scores to UV-329
and UV-928 were deemed to be of low confidence.
Less desirable alternatives based on the results of the hazard assessment include UV-P and
UV-234. More comprehensive assessments of UV-P and UV-234 (for example using the
GreenScreen®
method) would be helpful to better understand the inherent hazards of these
products and their suitability for use as alternatives to UV-328.
It should be noted that testing of the benzotriazoles is ongoing, and hazard classifications
are subject to change based on new data.
Hazard assessments are suitable for use to identify other chemicals of concern (such as
flame retardants and plasticizers) and safer alternatives. The GreenScreen List Translator™ is
an excellent starting point for additive users based on its speed and simplicity.
In today’s regulatory environment, assessing hazards is as important as assessing
performance, cost, and commercial availability, and should be a part of the component selection
process for additive users.
Acknowledgements
Helpful advice and comments from Dr. Shari Franjevic of Clean Production Action are
gratefully acknowledged.
Disclaimer
Although the information and recommendations set forth herein (hereinafter "information")
are presented in good faith and believed to be correct as of the date hereof, BotkinChemie
makes no representation as to the completeness or accuracy thereof. Information is supplied
upon the condition that persons receiving it will make their own determinations as to its
suitability for their purpose prior to its use. In no event will BotkinChemie be responsible for
damages of any nature whatsoever resulting from the use of or reliance upon information. No
representations or warranties either expressed or implied, or merchantability, fitness for a
particular purpose or of any other nature are made hereunder with respect to information for any
substance to which information refers. No statements herein are to be construed as
inducements to infringe any valid patent.
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tetramethylbutyl)phenol, https://www.echa.europa.eu/web/guest/registration-dossier/-
/registered-dossier/13220.
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2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol),
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2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol),
22. European Chemicals Agency, Registration Dossier for 2-(2H-1,2,3-benzotriazol-2-yl)-6-(2-
phenylpropan-2-yl)-4-(2,4,4-trimethylpentan-2-yl)phenol,
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6920-6926.
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97-106.
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2013; pp 129-156.
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chemicals-under-tsca/tsca-work-plan-methods-document.

Table 1. Chemical Identity of Benzotriazole UV Absorbers.
Generic
Name
Chemical Name CAS No. Chemical Structure
UV-P 2-(2H-Benzotriazol-2-yl)-p-cresol 2440-22-4
UV-234 2-(2H-Benzotriazol-2-yl)-4,6-bis(1-
methyl-1-phenylethyl)phenol
70321-86-7
UV-320 2-Benzotriazol-2-yl-4,6-di-tert-
butylphenol
3846-71-7
UV-326 2-tert-Butyl-4-methyl-6-(5-
chlorobenzotriazol-2-yl)phenol
3896-11-5
UV-327 2,4-Di-tert-butyl-6-(5-
chlorobenzotriazol-2-yl)phenol
3864-99-1
UV-328 2-(2H-Benzotriazol-2-yl)-4,6-di-tert-
pentylphenol
25973-55-1
UV-329 2-(2H-Benzotriazol-2-yl)-4-(1,1,3,3-
tetramethylbutyl)phenol
3147-75-9
UV-350 2-(2H-Benzotriazol-2-yl)-4-(tert-
butyl)-6-(sec-butyl)phenol
36437-37-3
UV-360 2,2'-Methylenebis(6-(2H-
benzotriazol-2-yl)-4-(1,1,3,3-
tetramethylbutyl)phenol)
103597-45-1
UV-928 2-(2H-1,2,3-benzotriazol-2-yl)-6-(2-
phenylpropan-2-yl)-4-(2,4,4-
trimethylpentan-2-yl)phenol
73936-91-1

Table 2. Hazard Scoring Summary for UV-328 and Alternatives.
Acute
Toxicity
Carc. Muta. Repr.
Tox
Dev. Tox Neurotox. Chronic
Toxicity
Resp.
Sens.
Aquatic
Acute
Aquatic
Chronic
Hazard
Score
UV-P 1 1 1 1 1 - 2 - 1 3 3
UV-234 1 - 1 - 1 - 2 - 1 1 2
UV-326 1 1 1 1 1 - 1 - 1 1 1
UV-328 1 - 1 2 1 - 3 - 1 - 3
UV-329 1 - 1 1 1 - 2 - 1 1 2
UV-360 1 - 1 1 1 - 1 - 1 1 1
UV-928 1 - 1 - 1 - 1 - 1 1 1
Notes: Endpoint scores and Hazard Scores given in italics are deemed to be of low confidence.

Table 3. Acute Toxicity Data for UV-328 and Alternatives.
Generic
Name
Oral LD50
Reliability
Score
Inhalation LC50
Reliability
Score
Dermal LD50
Reliability
Score
Hazard
Score
UV-P Rat, 10,000 mg/kg
Mouse, >5,000 mg/kg
Rat, >5,000 mg/kg
Mouse, 6,500 mg/kg
Rat, >15,380 mg/kg
Mouse, >5,500 mg/kg
2
4
4
4
3
4
Rat (4 h), >0.59 mg/L
Rat (1.2 h), >163 mg/L
Rat (4 h), >1.42 mg/L
2
4
4
Rat, >2,000 mg/kg
Unk., >3,038 mg/kg
Rat, >1,000 mg/kg
4
3
2
1
UV-234 Rat, >7,750 mg/kg 2 No data - Rat, >2,000 mg/kg 1 1
UV-326 Rat, >2,000 mg/kg
Rat, >7,750 mg/kg
Mouse, >5,000 mg/kg
Rat, >5,000 mg/kg
Rat, >2,110 mg/kg
1
2
4
4
2
Rat (4 h), >0.27 mg/L 3 Rat, >2,000 mg/kg 2 1
UV-328 Rat, >7,750 mg/kg
Rat, >2,000 mg/kg
Rat, >7,100 mg/kg
Mouse, >5,000 mg/kg
Rat, >5,000 mg/kg
2
2
2
2
2
Rat (4 h), >0.4 mg/L
Rat (1 h) > 0.129 mg/L
2
2
Rabbit, >1,100 mg/kg 2 1
UV-329 Rat, >10,000 mg/kg 2 No data - Rabbit, >5,000 mg/kg 2 1
UV-360 Rat, >2,000 mg/kg
Rat, >5,000 mg/kg
-
2
No data - Rat, >2,000 mg/kg - 1
UV-928 Rat, >2,000 mg/kg
Rat, >2,000 mg/kg
Rat, >5,000 mg/kg
1
1
1
No data - Rat, >2,000 mg/kg
Rat, >2,000 mg/kg
Rabbit, >2,000 mg/kg
1
1
1
1
Notes: The benzotriazole UV absorbers generally present low acute toxicity by the oral and dermal routes, but only limited data are available for
the inhalation route. Data with a reliability score of 3 were deemed to be not reliable and were not used to determine the score. Applying the
TSCA Work Plan Chemical Scoring criteria yields a score of 1 (low) for all seven substances.

Table 4. Carcinogenicity and Mutagenicity/Genotoxicity Data for UV-328 and Alternatives.
Generic
Name
Carcinogenicity Reliability
Score
Hazard
Score
Mutagenicity/Genotoxicity Reliability
Score
Hazard
Score
UV-P Rat, OECD 452, negative
Mouse, OECD 451, negative
1
1
1 OECD 476, negative
OECD 471, negative
in vitro gene mutation in bacteria, negative
1
1
3
3
3
1
UV-234 No data - - OECD 471, negative
OECD 482, negative
OECD 474, negative
EPA OTS 798.5915, negative
2
2
2
2
1
UV-326 Mouse, OECD 451, negative
Rat, OECD 453, negative
2
2
1 OECD 473, negative
OECD 471, negative
OECD 471, negative
OECD 478, negative
OECD 474, negative
OECD 475, negative
1
1
2
2
2
2
1
OECD 473, negative
OECD 476, negative
2
1
1
1
OECD 473, negative
OECD 476, negative
in vitro DNA damage / repair study, negative
2
1
1
4
1
OECD 473, negative
OECD 476, negative
-
-
-
1
OECD 473, negative
OECD 476, negative
OECD 471, negative
1
1
1
1
1
Notes: UV-P and UV-326 are deemed to be negative for carcinogenicity based on the results of 2-year studies in rats and mice. Applying the TSCA Work Plan
Chemical Scoring criteria yields a score of 1 (low) for UV-P and UV-326. For the other substances no score could be assigned due to lack of data. No positive
results for mutagenicity/genotoxicity were obtained for UV-328 or the alternatives. Applying the TSCA Work Plan Chemical Scoring criteria yields a score of 1
(low) for all seven substances.

Table 5. Reproductive and Developmental Toxicity Data for UV-328 and Alternatives.
Generic
Name
Reproductive Toxicity Reliability
Score
Hazard
Score
Developmental Toxicity Reliability
Score
Hazard
Score
UV-P OECD 422 (rat), NOAEL 300 mg/kg/d 1 1 OECD 414 (rat), NOAEL 1,000 mg/kg/d
OECD 414 (mouse), NOEL 1,000 mg/kg/d
2
1
1
UV-234 Not deemed to be toxic to reproduction
based on a lack of reproductive effects
observed in 28 and 90-day repeated
dose studies (rats), and in an OECD
414 study. However, this may not be
sufficient to assign a score under the
TSCA Work Plan Chemical Scoring
criteria, and no hazard score was
assigned.
- - OECD 414 (rat), NOEL 3,000 mg/kg/d 2 1
UV-326 OECD 422 (rat), NOAEL 1,000 mg/kg/d 1 1 OECD 414 (rat), NOAEL 3,000 mg/kg/d
OECD 414 (mouse), NOAEL 3,000 mg/kg/d
2 1
UV-328 OECD 422 (rat), NOEL 250 mg/kg/d
(read across from structural analog)
2 2 OECD 414 (rat), NOAEL 1,000 mg/kg/d 2 1
UV-329 OECD 422 (rat), NOAEL 300 mg/kg/d
2 1 OECD 414 (rat), NOAEL 1,000 mg/kg/d
2 1
UV-360 OECD 415 (rat), NOEL 300 mg/kg/d
Fertility study (rat), NOEL 1,000
mg/kg/d
One generation study (rat), NOEL 1000
mg/kg/d
-
-
-
1 OECD 414 (rat), NOAEL 1,000 mg/kg/d - 1
UV-928 No data - - OECD 414 (rat), NOAEL 3,000 mg/kg/d
2 1
Notes: No reproductive toxicity data were available for UV-234 and UV-928, and therefore no score was assigned. The scores for the other
substances were obtained by applying the TSCA Work Plan Chemical Scoring criteria to the NOAEL or NOEL values from the studies. UV-328
was assigned a score of 2 (medium), and the remaining substances (UV-P, UV-326, UV-329, UV-360) were assigned scores of 1 (low). The
scores for UV-328 and UV-329 were deemed to be of low confidence since they are based on structural analog data.

Table 6. Chronic Toxicity Data for UV-328 and Alternatives.
Chronic Toxicity Reliability Score Hazard Score
UV-P OECD 422, rat, 42-53 d, NOAEL = 30 mg/kg/d
OECD 409, dog, 90 d, NOEL = 33 mg/kg/d
OECD 452, rat, 104 wk, NOEL = 1,000 ppm
OECD 408, rat, 90 d, NOEL = 2,000 ppm
OECD 409, dog, 90 d, NOEL = 1000 ppm
No guideline, rat, 6 d/wk for 4 wk, NOEL = 2,500 ppm
1
3
1
2
1
3
2
UV-234 OECD 408, rat, 90 d, NOAEL = 22.3 mg/kg/d
OECD 407, rat, 28 d, NOAEL = 933.8 mg/kg/d
2
2
2
UV-326 OECD 408, rat, 90 d, NOAEL = 637-740 mg/kg/d
OECD 422, rat, 42-53 d, NOAEL = 1000 mg/kg/d
OECD 453, rat, 104 wk, NOEL = 113.2-147.7 mg/kg/d
OECD 409, dog, 90 d, NOAEL = 153-168 mg/kg/d
OECD 407, rat, 28 d, NOAEL = 1,005.7 mg/kg/d
OECD 451, mouse, 104 wk, NOAEL = 59-62 mg/kg/d
No guideline, rat, 28 d, NOAEL = 500 ppm
2
1
2
2
2
2
3
1
UV-328 OECD 408, rat, 90 d, no NOAEL, LOAEL = 10 mg/kg/d
OECD 409, Dog, 90 d, NOAEL = 30 mg/kg/d
2
2
3
UV-329 OECD 422, rat, 42-53 d, NOAEL = 30 mg/kg/d (structural analog)
OECD 452, rat, 104 wk, NOAEL = 142-169 mg/kg/d (structural analog)
No guideline, rat, 28 d, NOAEL = 5,658 mg/kg/d
2
2
3
2
UV-360 OECD 408, rat, 90 d, NOAEL = 1,000 mg/kg/d
OECD 411, rat, 90 d, NOEL = 1,000 mg/kg/d
-
-
-
1
UV-928 OECD 408, rat, 90 d, NOEL = 1,000 mg/kg/d
OECD 408, rat, 90 d, NOAEL = 1,000 mg/kg/d
1
2
2
1
Notes: The chronic toxicity scores were obtained by applying the TSCA Work Plan Chemical Scoring criteria to the NOAEL or NOEL values from
the studies. Data with a reliability score of 3 were deemed to be not reliable and were not used to determine the score. UV-328 was assigned a
score of 3 (high), UV-P and UV-234 were assigned scores of 2 (medium), and the remaining substances (UV-326, UV-329, UV-360, UV-928) were
assigned scores of 1 (low). The score for UV-329 was deemed to be of low confidence since it was based on structural analog data.

Table 7. Acute and Chronic Aquatic Toxicity Data for UV-328 and Alternatives.
Generic
Name
Acute Aquatic Toxicity Reliability
Score
Hazard
Score
Chronic Aquatic Toxicity Reliability
Score
Hazard
Score
UV-P Fish (96 h), LC50 > 0.17 mg/L
Fish (96 h), LC50 > 100 mg/L
Fish (48 h), LC50 > 200 mg/L
Daphnia (24 h), EC50 > 1,000 mg/L
Algae (72 h), ErC50 > 0.0822 mg/L
1
2
2
2
1
1 Daphnia (21 d), NOEC = 0.013 mg/L 1 3
UV-234 Fish (96 h), LC50 > 67 mg/L
Daphnia (48 h), EC50 > 100 mg/L
Daphnia (24 h), LC50 > 10 mg/L
Algae (72 h), EC50 > 100 mg/L
2
1
4
3
2
1 Daphnia (21 d), NOEC ≥ 10 mg/L 1 1
UV-326 Fish (96 h), LC50 > 100 mg/L
Algae (24 h), EC50 > 100 mg/L
2
1
4
3
2
UV-328 Fish (96 h), LC50 > 100 mg/L
Fish (96 h), LC50 > 0.078 mg/L
Daphnia (48 h), EC50 > 0.083 mg/L
Algae (72 h), ErC50 > 0.016 mg/L
Algae (72 h), EC50 > 10 mg/L
2
2
4
4
2
2
2
1 No data - -
UV-329 Fish (96 h), EC50 >100 mg/L
Daphnia (24 h), EC50 = 15 mg/L
Algae (72 h), EC50 > 100 mg/L
2
1
4
3
2
UV-360 Fish (96 h), LC50 > 28.9 mg/L
Fish (96 h), LC50 > 10 mg/L
Fish (96 h), LC50 > 12.7 mg/L
Daphnia (48 h), LC50 > 65.9 mg/L
-
-
-
-
1 Fish (8 wk), NOEC > 1 mg/L
Daphnia (21 d), NOEC > 0.025 mg/L
-
-
1

Daphnia (48 h), EC50 > 50.2 mg/L
Algae (72 h), EC50 > 2 mg/L
Algae (72 h), EC50 > 2 mg/L
2
-
-
-
2
UV-928 Fish (96 h), LC50 > 0.33 mg/L
Fish (96 h), LC50 > 0.21 mg/L
Daphnia (48 h), EC50 > 0.9 mg/L
Algae (72 h), ErC50 > 0.66 mg/L
Algae (72 h), ErC50 > 0.41 mg/L
1
1
1
1
1
Notes: Applying the TSCA Work Plan Chemical Scoring criteria yields an acute aquatic toxicity score of 1 (low) for all seven substances. Data
with a reliability score of 3 were deemed to be not reliable and were not used to determine the score. No chronic aquatic toxicity data were
available for UV-328 and therefore no score was assigned. The chronic toxicity scores for the other substances were obtained by applying the
TSCA Work Plan Chemical Scoring criteria to the NOEC values from the studies. UV-P was assigned a chronic aquatic toxicity hazard score of 3
(high), and the remaining five substances (UV-234, UV-326, UV-329, UV-360, UV-928) were assigned chronic aquatic toxicity hazard scores of 1
(low).

Table 8. Bioaccumulation Scores, Persistence Scores, Total Scores, and Annex XIII Classifications for UV-328 and Alternatives.
BCF
Reliability
B Score P Score PB Score
Hazard
Score
Total Score Annex XIII Classification
UV-P 44-494 2 1 3 2 3 5 not PBT, not vPvB
UV-234 415-1,286
5.4-10.4
1
3
2 3 3 2 5 not PBT, not vPvB
UV-326 54-895 2 1 3 2 1 3 not PBT, not vPvB
UV-328 1,120-5,580
570-1,800
2
2
3 3 3 3 6 PBT, vPvB
UV-329 361-461 1 1 3 2 2 4 not PBT, not vPvB
UV-360 0.1-1.5 - 1 3 2 1 3 not PBT, not vPvB
UV-928 415-1,286
361-461
6-27
1
1
2
2 3 3 1 4 not PBT, not vPvB
Notes: The Bioaccumulation (B) scores were obtained by applying the TSCA Work Plan Chemical Scoring criteria to the maximum BCF values
from the REACH dossiers. UV-328 received a B Score of 3 (high), UV-234 and UV-928 received B Scores of 2 (medium), and the remaining four
substances (UV-P, UV-326, UV-329, UV-360) received B Scores of 1 (low). The B Score for UV-928 was deemed to be of low confidence as it
was based on structural analog data and is given in italics.
All of the benzotriazoles were assumed to be highly persistent and assigned Persistence (P) Scores of 3 (high). The B and P Scores were
normalized according to the TSCA Work Plan Chemical Scoring method to PB Scores. UV-234, UV-328, and UV-928 received PB Scores of 3
(high), and the remaining four substances (UV-P, UV-326, UV-329, UV-360) received PB Scores of 2 (medium). The PB Score for UV-928 was
deemed to be of low confidence since the underlying B Score was based on structural analog data, and is given in italics.
The PB and Hazard Scores (from Table 2) were added together to give a Total Score. UV-328 received a Total Score of 6 (very high), UV-P and
UV-234 received Total Scores of 5 (high), UV-329 and UV-928 received Total Scores of 4 (medium), and UV-326 and UV-360 received Total
Scores of 3 (medium-low). The Total Scores for UV-329 and UV-928 were deemed to be of low confidence since the underlying B and/or Hazard
Scores were based on structural analog data, and are given in italics.
The benzotriazoles were also rated according to the REACH Annex XIII criteria for PBT and vPvB chemicals. Based on the available data, only
UV-328 met the criteria for PBT or vPvB.

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