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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

gene mutation in bacteria

source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8): GLP, similar to OECD Guideline 471, Klimisch 1, S. typhimurium strains TA 1535, TA 1537, TA 98 and TA 100, +/-S9, negative

source substance Phosphorodithioic acid, mixed O,O-bis(1,3 -dimethylbutyl and iso-Pr) esters, zinc salts (CAS 84605 -29 -8): GLP, similar to OECD Guideline 471, Klimisch 1, S. typhimurium TA 1535, TA 1537, TA 98 and TA 100 +/-S9, negative

gene mutation in mammalian cells

source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8): similar to OECD Guideline 490, Klimisch 1, L5178Y mouse lymphoma cell line, -S9 negative, +S9 equivocal

source substance Phosphorodithioic acid, mixed O,O-bis(1,3 -dimethylbutyl and iso-Pr) esters, zinc salts (CAS 84605 -29 -8): similar to OECD Guideline 490, Klimisch 1, L5178Y mouse lymphoma cell line, -S9 negative, +S9 positive

source substance Phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts (CAS 68457 -79 -4): similar to OECD Guideline 490, Klimisch 1, L5178Y mouse lymphoma cell line, -S9 negative, +S9 negative

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Several ZDDP category members were tested in in vitro bacterial and mammalian gene mutation and in in vivo chromosomal aberration assays (HPV, 2005). Frequencies of reverse mutations in bacteria were not significantly changed after exposure to the zinc dialkyldithiophosphates. All tested substances were negative for mutagenic activity, with and without metabolic activation. In vitro mutation studies in mammalian cells indicate that the zinc dialkyldithiophosphates do not consistently display mutagenic activity in the absence of metabolic activation, however, upon biotransformation, these materials showed mutagenic activity. All test substances were negative for clastogenicity in in vivo assays (HPV, 2005). Positive results in some tests were considered to be governed by zinc, because other organic zinc compounds were mutagenic in similar test systems (HPV, 2005). “However, genotoxicity studies conducted in a variety of test systems have failed to provide unequivocal evidence for mutagenicity of zinc” (ATSDR, 1992, cited in HPV, 2005). “In summary, the weight of evidence supports the conclusion that zinc dialkyldithiophosphates have a low potential genotoxicity, and that these substances do not present a significant risk for mutagenicity or carcinogenicity in humans”.

The overall weight-of-evidence indicates thus that ZDDP category members are non-mutagenic (HPV, 2005). The two source chemicals were also non-mutagenic in the bacterial mutagenicity tests. Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other mode of actions or toxicity effects. Toxicokinetic behavior of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). Thus, it is not likely that the presence of structurally dissimilar alerts i.e. alkyl chain rests of the target substance would result in binding to DNA leading to mutations. Therefore, a positive result in bacterial test system is not likely for the target substance. The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance would not possess mutagenic activity if it was tested in a bacterial mutagenicity test.
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Conclusions:
negative with metabolic activation
negative without metabolic activation
Executive summary:

The substance was tested in S. typhimurium strains TA 1535, TA 1537, TA 98 and TA 100 similar to OECD Guideline 471 with and without metabolic activation. The substance was negative in all strains tested with and without metabolic activation.

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Several ZDDP category members were tested in in vitro bacterial and mammalian gene mutation and in in vivo chromosomal aberration assays (HPV, 2005). Frequencies of reverse mutations in bacteria were not significantly changed after exposure to the zinc dialkyldithiophosphates. All tested substances were negative for mutagenic activity, with and without metabolic activation. In vitro mutation studies in mammalian cells indicate that the zinc dialkyldithiophosphates do not consistently display mutagenic activity in the absence of metabolic activation, however, upon biotransformation, these materials showed mutagenic activity. All test substances were negative for clastogenicity in in vivo assays (HPV, 2005). Positive results in some tests were considered to be governed by zinc, because other organic zinc compounds were mutagenic in similar test systems (HPV, 2005). “However, genotoxicity studies conducted in a variety of test systems have failed to provide unequivocal evidence for mutagenicity of zinc” (ATSDR, 1992, cited in HPV, 2005). “In summary, the weight of evidence supports the conclusion that zinc dialkyldithiophosphates have a low potential genotoxicity, and that these substances do not present a significant risk for mutagenicity or carcinogenicity in humans”.

The overall weight-of-evidence indicates thus that ZDDP category members are non-mutagenic (HPV, 2005). The two source chemicals were also non-mutagenic in the bacterial mutagenicity tests. Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other mode of actions or toxicity effects. Toxicokinetic behavior of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). Thus, it is not likely that the presence of structurally dissimilar alerts i.e. alkyl chain rests of the target substance would result in binding to DNA leading to mutations. Therefore, a positive result in bacterial test system is not likely for the target substance. The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance would not possess mutagenic activity if it was tested in a bacterial mutagenicity test.
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Additional information on results:
Test article precipitate was observed on the plates at doses equal to or greater than 3000 µg/plate.
Conclusions:
negative with metabolic activation
negative without metabolic activation
Executive summary:

A study was performed similar to OECD Guideline 471 according to GLP. The strains S. typhimurium TA 1535, TA 1537, TA 98 and TA 100 were tested with and without metabolic activation. The results were negative in all tested strains with and without metabolic activation.

Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other modes of action or toxicity effects. Toxicokinetic behaviour of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance does not possess a mutagenic activity.
Species / strain:
mouse lymphoma L5178Y cells
Remarks:
L5178Y TK+/-3.7.2c mouse lymphoma cell line
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
mouse lymphoma L5178Y cells
Remarks:
The L5178Y TK+/-3.7.2c mouse lymphoma cell line
Metabolic activation:
with
Genotoxicity:
ambiguous
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid

(1) The initial toxicity test performed on test material in the absence of S-9 indicated a threshold level of complete toxicity at 0.05 µl/ml. Based on these data, the test material was tested in a mutagenesis assay in the absence of S-9 over a range of concentrations from 0.05 µl/ml to 0.00067 µl/ml. After two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.0089, 0.0067, 0.0050, 0.0038, 0.0028, 0.0021, 0.0016, 0.0012, 0.00089 or 0.00067 µl/ml test material. These concentrations produce a range in suspension growth of 37 % to 91 %. None of the cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 35 % to 98 %.

 

(2) An initial toxicity test was conducted in the presence of S-9 on the test material. The results indicated a threshold level of complete toxicity at 0.05 µl/ml. Based on these data, the test material was tested in a mutagenesis assay in the absence of S-9 over a range of concentrations from 0.05 µl/ml to 0.00067 µl/ml. After two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.021, 0.016, 0.012, 0.0089, 0.0067, 0.0050, 0.0038, 0.0028, 0.0021 or 0.0016 µl/ml test material. These concentrations produce a range in suspension growth of 25 % to 97 %. One culture (0.021 µl/ml) that was cloned exhibited a mutant frequency which was 2.3 times the mean mutant frequency of the solvent controls. The total growth of this culture was 22 %. None of the remaining cultures that were cloned exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. The total growth of these cultures ranged from 91 % to 117 %.

 

(3) Two mutagenesis assays in the presence of S-9 were conducted as follow-up studies to the original assays. In the first assay the cultures were treated in triplicate with a range of test article concentrations from 0.030 to 0.017 µl/ml. After a two day expression period, 18 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.022, 0.021, 0.020, 0.019, 0.018 or 0.017 µl/ml. These concentrations produced a range in suspension growth of 7 % to 76 %. All the cultures that were cloned exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. The increases in mutant frequency ranged from 9.4 to 2.2 times the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 3~71 %.

 

(4) The assay (described under (3)) was repeated due to some contamination and an erratic toxic response. The repeat assay was conducted over the same dose range. After a two day expression period, 7 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.021, 0.018 or 0.017 µl/ml. These concentrations produced a range in suspension growth of 7 % to 47 %. All the cultures that were cloned for which complete results were obtained exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. The increases in mutant frequency ranged from 11.3 to 3.1 times the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 3~44 %.

 

(5) A second sample of the test material was tested. The initial toxicity test indicated a complete toxicity in the presence of S-9 at 0.05 µl/ml. Based on the results, the test material was tested in a mutagenesis assay in the presence of S-9 over a range of concentrations from 0.05 µl/ml to 0.00067 µl/ml. After a two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.021, 0.016, 0.012, 0.0089, 0.0067, 0.0050, 0.0038, 0.0028, 0.0021 or 0.0016 µl/ml. These concentrations produced a range in suspension growth of 31 % to 100 %. None of the cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 27 % to 96 %. However, a dose-dependent increase in mutant frequency was noted. The increase ranged from 1.0 to 1.9 times the mean mutant frequency of the solvent controls.

 

(6) Calcium dialkyl dithiophosphate was tested concurrently. None of the cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. However, a dose-related response was noted.
Conclusions:
negative without metabolic activation
ambiguous with metabolic activation

The test material produced a equivocal response in the presence of exogenous metabolic activation and a negative response in the absence of metabolic activation.
Executive summary:

The study was conducted similar to OECD Guideline 490 using the thymidine kinase, TK+/-, locus of the L5178Y mouse lymphoma cell line in the presence and absence of Aroclor induced rat liver S-9. The S-9 activated cultures were cloned over a range of test article concentrations which produced from 22 % to 117 % total growth.

The highest test article concentration cloned in the S-9 activated culture exhibited a mutant frequency which was more than twice the mean mutant frequency of the solvent controls. None of the nonactivated cultures that were cloned exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. 

The results indicated that, under the conditions of this test, the test material produced a negative response in the absence of exogenous metabolic activation and an equivocal response in the presence of metabolic activation.

Three assays were conducted on the test material in the presence of S-9 as follow-up studies to that reported above. In the first assay, the cultures that were cloned were treated with a range of test article concentrations which produced from 3 % to 71 % total growth. There was some contamination in this assay and complete results were obtained for 11 of the 18 cultures that were cloned. However, all the 11 cultures exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. The assay was repeated due to the contamination and the erratic does-response relationship in toxicity in the treated cultures. All the cultures that were cloned exhibited mutant frequencies which were more than twice the mean mutant frequency of the solvent controls. Previous studies with the test material had also demonstrated a precipitous toxic response. In the second experiment, the cultures that were cloned were treated with a range of concentrations which produced from 3 % to 44 % total growth. 7 of the 7 cultures that were cloned exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. In a third experiment, conducted concurrently with an assay on Calcium Dialkyl Dithiophosphate and with a second sample of test material, the cultures that were cloned were treated with a range of concentrations which produced from 27 % to 96 % total growth. None of the cultures that were cloned exhibited mutant frequencies which were significantly greater then the mean mutant frequency of the solvent controls. However, a dose-dependent response was noted. 

 

Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other modes of action or toxicity effects. Toxicokinetic behaviour of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance does not possess a mutagenic activity.
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid

(1) The initial toxicity test performed on test material in the absence of S-9 indicated a threshold level of complete toxicity at 0.05 µl/ml. Based on these data, the test material was tested in a mutagenesis assay in the absence of S-9 over a range of concentrations from 0.01 µl/ml to 0.00013 µl/ml. After two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.01, 0.0075, 0.0056, 0.0042, 0.0032, 0.0024, 0.0018, 0.00075 or 0.00056 µl/ml test material. These concentrations produced a range in suspension growth of 27% to 109%. None of the cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 17% to 120%.

 

However, the toxic response at the highest doses was erratic and an acceptable range in toxicity was not achieved. Therefore the assay was repeated over a range of concentration from 0.05 to 0.00067 µl/ml. After two day expression period, 9 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.0067, 0.0050, 0.0038, 0.0028, 0.0021, 0.0016, 0.0012, 0.00089 or 0.00067 µl/ml test material. These concentrations produced a range in suspension growth of 13% to 100%. One culture that was cloned exhibited a mutant frequency which were 2.3 times the mean mutant frequency of the solvent controls. The total growth of this culture was 6%. None of the remaining cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 22% to 101%.

 

(2) An initial toxicity test was conducted in the presence of S-9 on test material the results indicated a threshold level of complete toxicity at 0.05 µl/ml. Based on these data, the test material was tested in a mutagenesis assay in the absence of S-9 over a range of concentrations from 0.05 µl/ml to 0.005 µl/ml. After two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.031, 0.024, 0.018, 0.011, or 0.005 µl/ml test material. These concentrations produce a range in suspension growth of 6% to 99%. Cultures treated with 0.031, 0.024, or 0.018 µl/ml test material exhibited mutant frequency which ranged from 16.3 to 2.0 times the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 1% to 72%. None of the remaining cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 78% to 88%.
Conclusions:
negative without metabolic activation
positive with metabolic activation

The test material produced a positive response in the presence of exogenous metabolic activation and a negative response in the absence of metabolic activation.
Executive summary:

The study was conducted according to a method that was designed to assess the potential mutagenecity of the test material on the thymidine kinase, TK+/-, locus of the L5178Y mouse lymphoma cell line in the presence and absence of Aroclor induced rat liver S-9.

The nonactivated cultures were cloned over a range of test article concentrations which produced from 6% to 101% total growth. The S-9 activated cultures were cloned over a range of test article concentrations which produced from 1% to 88% total growth.

The highest test article concentration cloned in the non-activated culture exhibited a mutant frequency which was more than twice the mean mutant frequency of the solvent controls. The result is not considered significant since mutant frequencies observed at such highly toxic levels may be due to epigenetic events. 4 S-9 activated cultures exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. 

Conclusion

The results indicated that, under the conditions of this test, test material produced a negative response in the absence of exogenous metabolic activation and a positive response in the presence of metabolic activation.
Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other modes of action or toxicity effects. Toxicokinetic behaviour of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance does not possess a mutagenic activity.
Species / strain:
mouse lymphoma L5178Y cells
Remarks:
TK+/-3.7.2c
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid

1. The initial toxicity test performed on test material in the absence of S-9 indicated a threshold level of complete toxicity at 0.1 µl/ml. Based on these data, the test material was tested in a mutagenesis assay in the absence of S-9 over a range of concentrations from 0.01 µl/ml to 0.0013 µl/ml. After two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.013, 0.010, 0.0075, 0.0056, 0.0042, 0.0032, 0.0024, 0.0018, or 0.0013 µl/ml test material. These concentrations produced a range in suspension growth of 11% to 96%. Two of the cultures (0.013 and 0.010 µl/ml) that were cloned exhibited mutant frequencies which were 10.8 and 2.5 time respectively, the mean mutant frequency of the solvent controls. The total growth of the cultures was 2% and 4%. None of the remaining cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 20% to 92%.

 

2. An initial toxicity test was conducted in the presence of S-9 on test material the results indicated a threshold level of complete toxicity at 0.05 µl/ml.Based on these data, the test material was tested in a mutagenesis assay in the absence of S-9 over a range of concentrations from 0.1 µl/ml to 0.0013 µl/ml. After two day expression period, 10 cultures were cloned based on their degree of toxicity. The cultures that were cloned were treated with 0.024, 0.018, 0.013, 0.010, 0.0075, 0.0056, 0.0042, 0.0032, 0.0024, or 0.0018 µl/ml test material. These concentrations produce a range in suspension growth of 11% to 82%. One culture that was cloned (0.024 µl/ml) exhibited mutant frequency which was 7.2  times the mean mutant frequency of the solvent controls. The total growth of the cultures was 6%. None of the remaining cultures that were cloned exhibited mutant frequency which were significantly greater then the mean mutant frequency of the solvent controls. The total growth of the cultures ranged from 77% to 125%.
Conclusions:
The test material produced a negative response in the presence and absence of exogenous metabolic activation.
Executive summary:

The study was conducted similar to OECD Guideline 490 using the thymidine kinase, TK+/- locus of the L5178Y mouse lymphoma cell line in the presence and absence of Aroclor induced rat liver S-9.

The non-activated cultures were cloned over a range of test article concentrations which produced from 47% to 123% total growth in one assay and from 2% to 92% total growth in a second assay. The S-9 activated cultures were cloned over a range of test article concentrations which produced from 6% to 125% total growth.

The highest test article concentrations cloned in the S-9 activated cultures exhibited a mutant frequency which was more than twice the mean mutant frequency of the solvent controls. Two of the non-activated culture were significantly greater than the mean mutant frequency of the solvent controls. These results are not considered significant as the total growth of these cultures was less than 10%. TFR resistance observed at these highly toxic levels may be due to epigenetic events.

Conclusion

The results indicated that, under the conditions of this test, test material produced a negative response in the presence and absence of exogenous metabolic activation. In the presence of metabolic activation, the total growth of the treated cultures that were cloned did not cover the critical range of survival (10-40%). A precipitous toxic response was induced by the test article. The cultures treated with the two highest concentrations of test article had 6% and 77% total growth. It was felt that a repeated assay would not provide any additional information since the difference in concentration between the cultures having 6% and 77% total growth was only 0.006 µl/ml.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8): GLP, according to OECD Guideline 474, Klimisch 1, mouse, intraperitoneal, negative

source substance Phosphorodithioic acid, mixed O,O-bis(1,3 -dimethylbutyl and iso-Pr) esters, zinc salts (CAS 84605 -29 -8): GLP, according to OECD Guideline 474, Klimisch 1, mouse, intraperitoneal, negative

Based on the result of the two substances, which are the same, the key value for CSA is obvious: no adverse effect observed (negative) in genetic toxicity in vivo

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other modes of action or toxicity effects. Toxicokinetic behaviour of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance does not possess a mutagenic activity.
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Positive controls validity:
valid
Conclusions:
negative
Executive summary:

In the “Mammalian Erythrocyte Micronucleus Test”, according to GLP and OECD Guideline 474 mice (CD-1, male/female) were treated intraperitoneal with the test material EC224 -235 -5 (6, 12 and 24 mg/kg bw). No statistically significant increases in micronucleated polychromatic erythrocytes over the levels observed in the vehicle controls were observed in either sex, or at any harvest time point, or dose levels in mice.

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
Please refer also to the read-across statement attached in section 13

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
The target and the source substances are structurally similar substances that share the common organometallic core structure consisting of a central zinc metal bonded to four alkyldithiophosphate esters (ligands) by coordinate covalent bonds -Zn[(S2P(OR)2]2. Structural variations between the target and the source substances are related only to the alkyl (R) groups of the alkyldithiophosphate ligands. The substances in this category give thus rise to an (identical) common compound Phosphorodithioic acid moiety that can be released by the breakage of ester bonds and dissociation from the Zinc complex to which the organism would be exposed if the target substance was tested in the toxicity studies. Exposure to the parent compounds (non-transformed constituents) and to the counter alkyl alcohols, possibly released by hydrolysis of P-O bonds – non-common compounds – would not influence the prediction of the (eco)toxicological properties because they are considered to have the same biological targets and to cause the same type of effects through a common underlying mechanism due to the same functional groups (zinc cation, phosphorodithioic cation and aliphatic alcohol anionic moieties). The impurities of the target and the source substances are not expected to impact the prediction because they are identical or, if slightly structural different, belong to the same class of compounds with the same functional groups and their percentages are very low.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Since the main constituents of the target substance are structurally similar to the constituents of the source substances with the same functional groups and the alkyl chain lengths of phosphoroditioate moieties are in the range of the established ZDDP category (C3-C12), the same mode of toxicological action is expected for the target and the source substances. The constituents of the target substance do not possess functional groups associated with other modes of action or toxicity effects. Toxicokinetic behaviour of the constituents of the target substance is expected to be essentially the same as that of the source substance. Based on the results of the mutagenicity studies with the source substances and other ZDDP category members it is evident that the structural dissimilarities – the alkyl rests with different chain lengths – did not result in different mutagenic activity. “The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter” (HPV, 2005). The impurities of the target substance are considered not to contribute to mutagenicity potential because they are also structurally similar to the impurities of the source substances and consist of substances of simple structure without specific mode of action and do not contain functional groups leading to DNA binding and subsequently to mutations. Therefore, it is predicted that the target substance does not possess a mutagenic activity.
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Conclusions:
negative
Executive summary:

In the “Mammalian Erythrocyte Micronucleus Test”, according to GLP and OECD Guideline 474 mice (CD-1, male/female) were treated intraperitoneal with the test material EC 283 -392 -8 (7.13, 14.3 and 28.5 mg/kg bw/day). No statistically significant increases in micronucleated polychromatic erythrocytes over the levels observed in the vehicle controls were observed in either sex, or at any harvest time point, or dose levels in mice.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

in vitro gene mutation in bacteria:

The source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8) and the source substance Phosphorodithioic acid, mixed O,O-bis(1,3 -dimethylbutyl and iso-Pr) esters, zinc salts (CAS 84605 -29 -8) were tested in S. typhimurium strains TA 1535, TA 1537, TA 98 and TA 100 similar to OECD Guideline 471 with and without metabolic activation. The substances were negative in all strains tested with and without metabolic activation (Lawlor 1997a, b).

in vitro gene mutation in mammalian cells:

The source substances Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8), Phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts (CAS 68457 -79 -4) and Phosphorodithioic acid, mixed O,O-bis(1,3 -dimethylbutyl and iso-Pr) esters, zinc salts (CAS 84605 -29 -8) were tested in studies similar to OECD Guideline 490 using the thymidine kinase, TK+/-, locus of the L5178Y mouse lymphoma cell line in the presence and absence of Aroclor induced rat liver S-9. The following results were obtained:

CAS number: 68457-79-4

-S9: negative

+S9: negative

Remarks: The highest test article concentrations cloned in the S9 activated cultures exhibited a mutant frequency which was more than twice the mean mutant frequency of the solvent controls. Two of the non-activated culture were significantly greater than the mean mutant frequency of the solvent controls. These results are not considered significant as the total growth of these cultures was less than 10%. TFR resistance observed at these highly toxic levels may be due to epigenetic events.

 

CAS number: 84605-29-8

-S9: negative

+S9: positive

Remarks: The non-activated cultures were cloned over a range of test article concentrations which produced from 6% to 101% total growth. The S-9 activated cultures were cloned over a range of test article concentrations which produced from 1% to 88% total growth.

The highest test article concentration cloned in the non-activated culture exhibited a mutant frequency which was more than twice the mean mutant frequency of the solvent controls. The result is not considered significant since mutant frequencies observed at such highly toxic levels (6 % total growth) may be due to epigenetic events. 4 S-9 activated cultures exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. 

 

CAS number: 4259-15-8

3 studies - overall result:

-S9: negative

+S9: ambiguous

Remarks: The S-9 activated cultures were cloned over a range of test article concentrations which produced from 22 % to 117 % total growth. The highest test article concentration cloned in the S-9 activated culture exhibited a mutant frequency which was more than twice the mean mutant frequency of the solvent controls. None of the non-activated cultures that were cloned exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. The results indicated that, under the conditions of this test, the test material produced a negative response in the absence of exogenous metabolic activation and an equivocal response in the presence of metabolic activation.

Three assays were conducted on the test material in the presence of S-9 as follow-up studies to that reported above. In the first assay, the cultures that were cloned were treated with a range of test article concentrations which produced from 3 % to 71 % total growth. There was some contamination in this assay and complete results were obtained for 11 of the 18 cultures that were cloned. However, all the 11 cultures exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. The assay was repeated due to the contamination and the erratic does-response relationship in toxicity in the treated cultures. All the cultures that were cloned exhibited mutant frequencies which were more than twice the mean mutant frequency of the solvent controls. Previous studies with the test material had also demonstrated a precipitous toxic response. In the second experiment, the cultures that were cloned were treated with a range of concentrations which produced from 3% to 44% total growth. 7 of the 7 cultures that were cloned exhibited mutant frequencies which were significantly greater than the mean mutant frequency of the solvent controls. In a third experiment, conducted concurrently with an assay on Calcium Dialkyl Dithiophosphate and with a second sample of test material, the cultures that were cloned were treated with a range of concentrations which produced from 27% to 96% total growth. None of the cultures that were cloned exhibited mutant frequencies which were significantly greater then the mean mutant frequency of the solvent controls. However, a dose-dependent response was noted. 

in vivo micronucleus assay:

Source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8):

In the “Mammalian Erythrocyte Micronucleus Test”, according to GLP and OECD guideline 474 mice (CD-1, male/female) were treated intraperitoneal with the test material EC 224 -235 -5 (6, 12 and 24 mg/kg bw). No statistically significant increases in micronucleated polychromatic erythrocytes over the levels observed in the vehicle controls were observed in either sex, or at any harvest time point, or dose levels in mice.

Source substance Phosphorodithioic acid, mixed O,O-bis(1,3 -dimethylbutyl and iso-Pr) esters, zinc salts (CAS 84605 -29 -8):

In the “Mammalian Erythrocyte Micronucleus Test”, according to GLP and OECD guideline 474 mice (CD-1, male/female) were treated intraperitoneal with the test material EC 283 -392 -8 (7.13, 14.3 and 28.5 mg/kg bw/day). No statistically significant increases in micronucleated polychromatic erythrocytes over the levels observed in the vehicle controls were observed in either sex, or at any harvest time point, or dose levels in mice.

Conclusion

The source substances CAS 4259-15-8 and CAS 84605-29-8 were tested in four tester strains of Salmonella typhimurium (TA 1535, TA 1537, TA 98 and TA 100) with and without metabolic activation. The studies were conducted according to test guideline OECD 471. The frequencies of reverse mutations in bacteria were not significantly changed after exposure to various concentrations of these testsubstances (Lawlor, 1997a, b). The source substances 2-ethylhexyl derivative (CAS 4259 -15 -8), iso-Bu and pentyl derivative (CAS 68457 -79 -4) and 1,3 -dimethylbutyl and iso-propyl derivative (CAS 84605 -29 -8) were tested in studies similar to OECD Guideline 490 using the thymidine kinase, TK+/-, locus of the L5178Y mouse lymphoma cell line in the presence and absence of Aroclor induced rat liver S-9. All substances were negative without metabolic activation. Metabolic activation brought equivocal results. While CAS 68457-79-4 was negative with metabolic activation, CAS 84605-29-8 was positive and CAS 4259-15-8 was ambiguous. These results are in accordance with the results for other members of the ZDDP category. Several ZDDP category members were tested in in vitro bacterial and mammalian gene mutation assays, and in in vivo clastogenicity assays (HPV, 2005). “Frequencies of reverse mutations in bacteria were not significantly changed after exposure to the zinc dialkyldithiophosphates. All tested substances were negative for mutagenic activity, with and without metabolic activation. In vitro mutation studies in mammalian cells indicate that the zinc dialkyldithiophosphates do not consistently display mutagenic activity in the absence of metabolic activation, however, upon biotransformation, these materials showed mutagenic activity.The findings in bacterial and mammalian cells did not vary in proportion to the alkyl chain length or any other physicochemical parameter”(HPV, 2005). In addition, all ZDDP test substances were negative for clastogenicity in in vivo assays (HPV, 2005). Positive results in some gene mutation tests were considered to be governed by zinc because other organic zinc compounds were mutagenic in similar test systems. This is further supported by the fact that no mutagenic activity was attributed to a calcium dialkyldithiophosphate (HPV, 2005). Although positive in some test systems, there is no unequivocal evidence for the mutagenicity of zinc (ATSDR, 1992, cited in HPV, 2005). “In summary, the weight of evidence supports the conclusion that zinc dialkyldithiophosphates have a low potential genotoxicity, and that these substances do not present a significant risk for mutagenicity or carcinogenicity inhumans” (HPV, 2005).

Justification for classification or non-classification

Based on the results for the source substances the registered substance does not have to be classified according to Regulation (EC) No 1272/2008.


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