Reaction mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

102 mg/m³

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

25

Modified dose descriptor starting point:

NOAEC

Explanation for the modification of the dose descriptor starting point:

The DNEL for systemic effects via the inhalation route is determined on the basis of extrapolation of developmental effects noted in the inhalation OECD 422 study with decamethyltetrasiloxane (141-62-8). In this study a NOAEC of at least 1210 mg/m³ was derived as there were no adverse effects up to the highest dose tested. The following correction was made to the NOAEC (inhalation): Correction for exposure duration: 6 h/8 h (default for workers). Correction for respiratory rate and volume (human worker): (6.7 m³/d/10 m³/d) (default) Therefore the corrected NOAEC is: 5083*(6/8)*(6.7 m3/d /10 m³/d) = 2554 mg/m³.

AF for dose response relationship:

1

Justification:

A clear NOAEC was established

AF for differences in duration of exposure:

1

Justification:

Not required as developmental toxicity is not duration-specific

AF for interspecies differences (allometric scaling):

1

Justification:

Default (inhalation route)

AF for other interspecies differences:

2.5

Justification:

Default

AF for intraspecies differences:

5

Justification:

Default

AF for the quality of the whole database:

1

Justification:

Guideline, GLP study

AF for remaining uncertainties:

2

Justification:

Additional assessment factor for use of screening data

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1 449 mg/kg bw/day

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

100

Modified dose descriptor starting point:

NOAEL

Value:

144 866 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The DNEL for systemic effects via the dermal route is determined on the basis of route-to-route extrapolation of developmental effects noted in the inhalation OECD 422 study with decamethyltetrasiloxane (141-62-8). In this study a NOAEC of at least 5083 mg/m³ was derived as there were no adverse effects up to the highest dose tested NOAEC ≥5083 mg/m³ The following correction was made to the NOAEC (inhalation) to derive a NOAEL (dermal): Correction for exposure duration: 6h / 8h (default for workers) Correction for respiratory volume: 0.38 m³/kg (default, rat, 8 hour). Correction for dermal penetration: based on read-across from decamethyltetrasiloxane (CAS 141-62-8) dermal penetration is approximately 0.03%, therefore a conservative value of 1% is used. Therefore the corrected NOAEL via the dermal route is: 5083*(6/8)*0.38*(100/1) = 144866 mg/kg bw/day. 

AF for dose response relationship:

1

Justification:

A clear NOAEC was established

AF for differences in duration of exposure:

1

Justification:

Not required as developmental toxicity is not duration-specific

AF for interspecies differences (allometric scaling):

4

Justification:

Default

AF for other interspecies differences:

2.5

Justification:

Default

AF for intraspecies differences:

5

Justification:

Default

AF for the quality of the whole database:

1

Justification:

Guideline, GLP study

AF for remaining uncertainties:

2

Justification:

Additional assessment factor for use of screening data

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - workers

There were no adverse effects in any of the available tests. However, since there is a data gap for developmental toxicity, which will be filled by testing, indicative DNELs are based on the current NOAEC for developmental toxicity from the screening study on decamethyltetrasiloxane (L4, CAS 141 -62 -8) for the purposes of initial risk characterisation.

DNELs for long-term exposure are considered adequate to protect against short-term exposures and no separate short-term DNELs are calculated.

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

25 mg/m³

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

50

Modified dose descriptor starting point:

NOAEC

Value:

1 271 mg/m³

Explanation for the modification of the dose descriptor starting point:

The DNEL for systemic effects via the inhalation route is determined on the basis of route-to-route extrapolation of developmental effects noted in the inhalation OECD 422 study with decamethyltetrasiloxane (141-62-8). In this study a NOAEC of at least 5083 mg/m³ was derived as there were no adverse effects up to the highest dose tested. NOAEC ≥5083mg/m³. The following correction was made to the NOAEC (inhalation): Correction for exposure duration: 6/24 (default for consumers) Therefore the corrected NOAEC is: 5083 mg/m³*(6/24) = 1271 mg/m³.

AF for dose response relationship:

1

Justification:

A clear NOAEC was established

AF for differences in duration of exposure:

1

Justification:

Not required as developmental toxicity is not duration-specific

AF for interspecies differences (allometric scaling):

1

Justification:

Default (inhalation)

AF for other interspecies differences:

2.5

Justification:

Default

AF for intraspecies differences:

10

Justification:

Default

AF for the quality of the whole database:

1

Justification:

Guideline, GLP study

AF for remaining uncertainties:

2

Justification:

Additional assessment factor for use of screening data

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

731 mg/kg bw/day

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

200

Modified dose descriptor starting point:

NOAEL

Value:

146 136 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The DNEL for systemic effects via the dermal route is determined on the basis of route-to-route extrapolation of developmental effects noted in the inhalation OECD 422 study with decamethyltetrasiloxane (CAS 141-62-8). In this study a NOAEC of at least 5083 mg/m³ was derived as there were no adverse effects up to the highest dose tested. NOAEC ≥5083 mg/m³ The following correction was made to the NOAEC (inhalation) to derive a NOAEL (dermal): Correction for exposure duration: 6h / 24h (default for workers) Correction for respiratory volume: 1.15 m³/kg (default, rat). Correction for dermal penetration: based on read-across from decamethyltetrasiloxane (CAS 141-62-8) dermal penetration is approximately 0.03%, therefore a conservative value of 1% is used. Therefore the corrected NOAEL for the dermal route is: 5083*(6/24)*1.15*(100/1) = 146136 mg/kg bw/day.

AF for dose response relationship:

1

Justification:

A clear NOAEC was established

AF for differences in duration of exposure:

1

Justification:

Not required as developmental toxicity is not duration-specific

AF for interspecies differences (allometric scaling):

4

Justification:

Default

AF for other interspecies differences:

2.5

Justification:

Default

AF for intraspecies differences:

10

Justification:

Default

AF for the quality of the whole database:

1

Justification:

Guideline, GLP study

AF for remaining uncertainties:

2

Justification:

Additional assessment factor for use of screening data

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified