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

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Toxicity to reproduction, screening:

source substance Zinc bis(O,O-diisobutyl dithiophosphate) (CAS 68457 -79 -4): GLP, according to OECD Guideline 422, Klimisch 1, rat, oral (gavage), NOEL = 160 mg/kg bw/day

source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8): GLP, according to OECD Guideline 421, Klimisch 1, rat, oral (gavage), NOAEL = 30 mg/kg bw/day

 

Based on the available data and based on the performed studies for CSA as key value the lowest value of all category members was choosen. Differences in the values of each category-member are obvious, but this is in range with the category approach, where nevertheless the members of one category may have different values, because all results show, that no substance has to be classified according to Regulation (EC) No 1272/2008.

 

Toxicity to reproduction, ext. one-gen repro-tox:

The extended one generation reproductive toxicity study does not need to be conducted because there are no results from available repeated dose toxicity studies that indicate adverse effects on reproductive organs or tissues or reveal other concerns in relation with reproductive toxicity.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

30 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

High due to guideline studies.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Toxicity to reproduction, screening:

source substance Zinc bis(O,O-diisobutyl dithiophosphate) (CAS 68457 -79 -4)

In a guideline repeated dose and reproduction / developmental screening study (OECD 422) conducted according to GLP, the potential toxic effects of phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts in rats were evaluated. This study was designed to evaluate the toxic effects, including neurobehavioral effects, of the test material to parental animals and to evaluate the potential to effect male and female reproductive performance such as gonadal function, mating behavior, conception, parturition, and early postnatal development. The test material was administered orally by gavage once daily to 3 groups of Crl:CD(SD) rats at levels of 10, 40 or 160 mg/kg/day. The low- and mid-dose groups each consisted of 10 rats/sex and the high-dose group consisted of 15 rats/sex. A concurrent control group of 15 rats/sex received the vehicle, mineral oil USP, on a comparable regimen. Ten males/group selected for pairing were dosed for 14 days prior to mating through 1 day prior to euthanasia for a total of 28 doses. Ten females/group selected for pairing were dosed for 14 days prior to mating through lactation day 3 for a total of 40-52 doses; females that failed to deliver were dosed through the day prior to euthanasia (post-mating day 25) for a total of 40 doses. The extra 5 males and 5 females in the control and high-dose groups were not used for mating and were treated beginning on study day 0; following 28 doses for the males and 40 doses for the females, these animals were assigned to the post‑treatment period and remained on study for a 14-day non-dosing period.

Under the conditions of this screening study, no test material-related effects on reproductive performance, gestation length, parturition, reproductive organs, or neurobehavioral parameters were noted at any dosage level. Based on these results, a dosage level of 160 mg/kg/day was considered to be the no-observed-effect level (NOEL) for reproductive toxicity. Test item-related moribundity, clinical findings, and microscopic findings in the non glandular portion of the stomach, characterized by epithelial hyperplasia, hyperkeratosis, and inflammation, were observed in the 160 mg/kg/day group. The injury to the nonglandular portion of the stomach was localized and considered to be irritation from test item portal-of-entry effects. Based on these results, the NOEL for portal-of-entry effects was considered to be 40 mg/kg/day, and excluding the histologic injury to the nonglandular stomach, the no-observed-adverse-effect level (NOAEL) for systemic toxicity was considered to be 160 mg/kg/day.

 

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

This screening study according to GLP and OECD guideline 421 was designed to determine the potential adverse effects of Zinc O,O-diethylhexyldithiophosphate (ZDDP) on male and female reproduction in rats. The test material was administered orally by gavage to three groups of 12 F0 male and 12 F0 female Sprague Dawiey Crl:CD^®BR rats. Dosage levels were 30, 100 and 200 mg/kg/day. For comparative purposes, a control pup of identical design was concurrently dosed with Mazola^®corn oil on a comparable regimen. A dose volume of 5 ml/kg was used in all dose groups. All F0 animals were dosed for a minimum of 14 days prior to mating and through the day of necropsy for each F, animal. All animals were observed twice daily for appearance and behavior. Body weights were recorded weekly for both sexes prior to mating; maternal body weights were also recorded on gestation days 0, 7, 14 and 20 as well as lactation days 1 and 4. Food consumption was measured for corresponding intervals prior to mating, during gestation and during lactation. All of the surviving F0 females were allowed to deliver and rear their pups to lactation day 4. The offspring were also potentially exposed in utero and through nursing during lactation days 1-4 until euthanization on post-natal day 4. The surviving F, dams were necropsied on lactation day 4, following at least 43 days of dosing. The surviving F0 males were necropsied after the breeding period, following 28 days of dosing. F0 females with total litter loss were necropsied within 24 hours. F0 females which failed to deliver were necropsied on post-mating day 25 (evidence of mating) or 25 days following the breeding period (no evidence of mating). Organ weights were collected (all F0 treated groups) and microscopic examinations were conducted (control and high dose groups and all parental animals not surviving to the scheduled necropsies).

In conclusion, parental toxicity was exhibited at dose levels of 100 and 200 mg/kg/day by mortality and clinical signs. Parental toxicity was also exhibited at the 200 mg/kg/day dose level by inhibition of body weight gain in males and signs of gastric irritation. No parental toxicity was observed at the 30 mg/kg/day dose level. Slightly reduced fertility indices were observed at the 200 mg/kg/day dose level. Reproductive performance (fertility, mating, days between pairing and coitus, gestation and parturition) was unaffected by treatment at the 30 and 100 mg/kg/day dose levels. Neonatal toxicity (mortality) in the F1 generation was observed at the 100 and 200 mg/kg/day dose levels. Neonatal toxicity was also noted at the 200 mg/kg/day dose level by clinical signs. No neonatal toxicity was observed at a dose level of 30 mg/kg/day. Based on the results of this study, a dose level of 30 mg/kg/day was considered to be the NOAEL (no observable adverse effect level) for parental and neonatal toxicity.

 

Developmental toxicity

This requirement will be fullfiled by using data within the Category as soon as this data is available

Effects on developmental toxicity

Description of key information

Developmental toxicity / teratogenicity, screening:

source substance Zinc bis(O,O-diisobutyl dithiophosphate) (CAS 68457 -79 -4): GLP, according to OECD Guideline 422, Klimisch 1, rat, oral (gavage), NOAEL = 160 mg/kg bw/day

source substance Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259 -15 -8): GLP, according to OECD Guideline 421, Klimisch 1, rat, oral (gavage), NOAEL = 30 mg/kg bw/day

 

Based on the available data and based on the performed studies for CSA as key value the lowest value of all category members was choosen. Differences in the values of each category-member are obvious, but this is in range with the category approach, where nevertheless the members of one category may have different values, because all results show, that no substance has to be classified according to Regulation (EC) No 1272/2008.

 

Toxicity to reproduction, ext. one-gen repro-tox:

The extended one generation reproductive toxicity study does not need to be conducted because there are no results from available repeated dose toxicity studies that indicate adverse effects on reproductive organs or tissues or reveal other concerns in relation with reproductive toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

30 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

High due to guideline studies

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Developmental toxicity / teratogenicity, screening:

source substance Zinc bis(O,O-diisobutyl dithiophosphate) (CAS 68457 -79 -4)

In a guideline repeated dose and reproduction / developmental screening study (OECD 422) conducted according to Good Laboratory Practices, WIL Research Labs (2010) evaluated the potential toxic effects of phosphorodithioic acid, mixed O,O-bis(iso-Bu and pentyl) esters, zinc salts when administered to rats. This study was designed to evaluate the toxic effects, including neurobehavioral effects, of the test material to parental animals and to evaluate the potential to effect male and female reproductive performance such as gonadal function, mating behavior, conception, parturition, and early postnatal development. The test material was administered orally by gavage once daily to 3 groups of Crl:CD(SD) rats at levels of 10, 40 or 160 mg/kg/day. The low- and mid-dose groups each consisted of 10 rats/sex and the high-dose group consisted of 15 rats/sex. A concurrent control group of 15 rats/sex received the vehicle, mineral oil USP, on a comparable regimen. Ten males/group selected for pairing were dosed for 14 days prior to mating through 1 day prior to euthanasia for a total of 28 doses. Ten females/group selected for pairing were dosed for 14 days prior to mating through lactation day 3 for a total of 40-52 doses; females that failed to deliver were dosed through the day prior to euthanasia (post-mating day 25) for a total of 40 doses. The extra 5 males and 5 females in the control and high-dose groups were not used for mating and were treated beginning on study day 0; following 28 doses for the males and 40 doses for the females, these animals were assigned to the post‑treatment period and remained on study for a 14-day non-dosing period.

Test item-related moribundity, clinical findings, and microscopic findings in the non glandular portion of the stomach, characterized by epithelial hyperplasia, hyperkeratosis, and inflammation, were observed in the 160 mg/kg/day group. The injury to the nonglandular portion of the stomach was localized and considered to be irritation from test item portal-of-entry effects. Based on these results, the NOEL for portal-of-entry effects was considered to be 40 mg/kg/day, and excluding the histologic injury to the nonglandular stomach, the no-observed-adverse-effect level (NOAEL) for systemic toxicity was considered to be 160 mg/kg/day. In the absence of effects on the general physical condition of the F1 pups, the NOEL for neonatal toxicity was 160 mg/kg/day.

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

This screening study according to GLP and OECD guideline 421 was designed to determine the potential adverse effects of Zinc O,O-diethylhexyldithiophosphate(ZDDP) on male and female reproduction in rats. The test material was administered orally by gavage to three groups of 12 F0 male and 12 F0 female Sprague Dawiey Crl:CD^®BR rats. Dosage levels were 30, 100 and 200 mg/kg/day. For comparative purposes, a control pup of identical design was concurrently dosed with Mazola^®corn oil on a comparable regimen. A dose volume of 5 ml/kg was used in all dose groups. All F0 animals were dosed for a minimum of 14 days prior to mating and through the day of necropsy for each F, animal. All animals were observed twice daily for appearance and behavior. Body weights were recorded weekly for both sexes prior to mating; maternal body weights were also recorded on gestation days 0, 7, 14 and 20 as well as lactation days 1 and 4. Food consumption was measured for corresponding intervals prior to mating, during gestation and during lactation. All of the surviving F0 females were allowed to deliver and rear their pups to lactation day 4. The offspring were also potentially exposed in utero and through nursing during lactation days 1-4 until euthanization on post-natal day 4. The surviving F, dams were necropsied on lactation day 4, following at least 43 days of dosing. The surviving F0 males were necropsied after the breeding period, following 28 days of dosing. F0 females with total litter loss were necropsied within 24 hours. F0 females which failed to deliver were necropsied on post-mating day 25 (evidence of mating) or 25 days following the breeding period (no evidence of mating). Organ weights were collected (all F0 treated groups) and microscopic examinations were conducted (control and high dose groups and all parental animals not surviving to the scheduled necropsies).

In conclusion, parental toxicity was exhibited at dose levels of 100 and 200 mg/kg/day by mortality and clinical signs. Parental toxicity was also exhibited at the 200 mg/kg/day dose level by inhibition of body weight gain in males and signs of gastric irritation. No parental toxicity was observed at the 30 mg/kg/day dose level. Slightly reduced fertility indices were observed at the 200 mg/kg/day dose level. Reproductive performance (fertility, mating, days between pairing and coitus, gestation and parturition) was unaffected by treatment at the 30 and 100 mg/kg/day dose levels. Neonatal toxicity (mortality) in the F1 generation was observed at the 100 and 200 mg/kg/day dose levels. Neonatal toxicity was also noted at the 200 mg/kg/day dose level by clinical signs. No neonatal toxicity was observed at a dose level of 30 mg/kg/day. Based on the results of this study, a dose level of 30 mg/kg/day was considered to be the NOAEL (no observable adverse effect level) for parental and neonatal toxicity.

Toxicity to reproduction, ext. one-gen repro-tox:

It is proposed to use an integrated testing strategy (ITS) and to perform the tests in sequence. Data obtained will inform the protocols of the subsequent tests and the testing plan will be modified as necessary.

A 21 -day enhanced range-finding study using the dietary oral route using one substance in the category is proposed to be performed first, followed by further range-finding studies on two other substances.

Following these, an OECD 408 90-day repeat dose dietary study on one or more substances is proposed. After the completion of this study, an OECD 414 prenatal study will be performed on one substance. For Annex X substances in the category, following the completion of the OECD 414 study, an OECD 443 extended reproductive toxicity study will be performed on one substance. The data of these studies will be read-across to the other members of the category according to the testing proposal and the comprehensive category justification document for the ZDDP category (see document attached in section 13 of this dossier). If at any point there is a need to test additional members of the category then this will be done according to the testing proposal.

Justification for classification or non-classification

In accordance to the CLP Regulation (EC) No.1272/2008 classification of this substance is not required for reproductive toxicity occurring at maternally toxic doses.