Zinc, O,O-mixed (iso-Bu), (iso-Pr), (pentyl) phosphorodithioate

Endpoint summary

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

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

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 the CLP Regulation (EC) No 1272/2008.