2-Methoxy-4-methylphenyl methyl carbonate

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

7.64 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

75

Dose descriptor starting point:

NOAEL

Value:

650 mg/kg bw/day

Modified dose descriptor starting point:

NOAEC

Value:

573.03 mg/m³

Explanation for the modification of the dose descriptor starting point:

Regarding absorption, in the absence of reliable data for both the starting route (oral) and the end route (inhalation), worst case assumptions were made. It was assumed that a limited absorption occurs by the oral route, leading to a low (conservative) internal NOAEL. To secure a conservative external NOAEL, a maximum absorption should be assumed for the inhalation route (i.e.; 100%) leading to a low external NOAEL. Thus, in the case of oral-to- inhalation extrapolation, it is proposed to include a default factor of 2, i.e. the absorption percentage by oral route is half that of the inhalation absorption as suggested in ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012).

To convert the oral NOAEL into inhalatory NOAEC, a rat default respiratory volume was used corresponding to the daily duration of human exposure (sRVrat: 0.38 m3/kg bw/8 h). For workers a correction was added for the difference between respiratory rates under standard conditions (sRVhuman: 6.7 m3 for an 8 h exposure period) and under conditions of light activity (wRV: 10 m3 for an 8 h exposure period).

The corrected dose descriptor for inhalation is determined using the following equation:

Corrected Inhalatory NOAEC = 1/SRVrat x ABS(oral-rat)/ABS(inh-human) x sRVhuman/wRV

= [650 mg/kg bw/day] X  [1/0.38 m3/kg bw/day] X [1/2] X [6.7 m3/10m3].

Thus, the corrected dose descriptor for inhalation is 573.03 mg/m3 for workers.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

1

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in the metabolic rate/bw has already been taken into account in the corrected dose descriptor.

AF for other interspecies differences:

2.5

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in the metabolic rate/bw has already been taken into account in the corrected dose descriptor.

AF for intraspecies differences:

5

Justification:

Default factor for worker. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties.

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:

2.17 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

300

Dose descriptor starting point:

NOAEL

Value:

650 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

650 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

For systemic hazard assesment via the dermal route of exposure, route-to-route extrapolation from the oral NOAEL value was considered appropriate. As no data on dermal penetration are available, dermal absorption is considered to be the same as oral absorption (i.e. 100 %). Therefore the oral NOAEL is considered the same as the dermal NOAEL (ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012)).

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

5

Justification:

Default factor for worker. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

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

NOAEL (systemic toxicity) = >= 650 mg/kg bw/day (OECD 407, 2012)

NOAEL (fertility) = >= 650 mg/kg bw/day (OECD 421, 2017)

NOAEL (development) = >= 650 mg/kg bw/day (OED 421, 2017)

Long-term systemic hazard assessment for this substance is based on subacute toxicity studies conducted for repeated dose toxicity (OECD 407), and reproductive/developmental toxicity screening (OECD 421). In these studies, dose levels were based on a range-finding test conducted for the OECD 407 study, where adverse effects were observed at 1,000 mg/kg bw/day and 750 mg/kg bw/day (clinical signs and effects on body weight and food consumption). As a result, 650 mg/kg bw/day was considered the appropriate high dose level for the OECD 407 and OECD 421 studies.

The results of the subacute studies indicated no adverse effects at the top dose, meaning that the NOAELs for these studies were considered >= 650 mg/kg bw/day, due to the absence of adverse toxic effects at the highest dose tested. As this top dose was below the limit dose for subacute studies (1,000 mg/kg bw/day), a conservative approach was used for DNEL derivation, where 650 mg/kg bw/day was assumed as the lowest possible NOAEL for the substance. This is consistent with the precautionary principle and ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R8 (2012).

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.88 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

150

Dose descriptor starting point:

NOAEL

Value:

650 mg/m³

Modified dose descriptor starting point:

NOAEC

Value:

282.61 mg/m³

Explanation for the modification of the dose descriptor starting point:

Concerning absorption, in the absence of reliable data for both the starting route (oral) and the end route (inhalation), worst case assumptions were made. It was assumed that a limited absorption occurs by the oral route, leading to a low (conservative) internal NOAEL. To secure a conservative external NOAEL, a maximum absorption should be assumed for the inhalation route (i.e.; 100%) leading to a low external NOAEL. Thus, in the case of oral-to- inhalation extrapolation, it is proposed to include a default factor of 2, i.e. the absorption percentage by oral route is half that of the inhalation absorption as suggested in ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012).

To convert the oral NOAEL into inhalatory NOAEC, a rat default respiratory volume was used corresponding to the daily duration of human exposure (sRVrat: 1.15 m3/kg bw/24 h).

The corrected dose descriptor for inhalation is determined using the following equation:

Corrected Inhalator NOAEC = 1/sRVrat x ABSoral-rat/ABSinh-rat x ABSinh-rat/ABSinh-human

= [650 mg/kg bw/day] x [1/1.15 m3/kg bw/ day] x [1/2].

Thus, the corrected dose descriptor for inhalation is 282.61 mg/m3 for the general population.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

1

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in metabolic rate/bw has already been taken into account for the corrected dose descriptor.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

10

Justification:

Default factor for general population. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties.

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:

1.08 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

600

Dose descriptor starting point:

NOAEL

Value:

650 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

650 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

For systemic hazard assesment via the dermal route of exposure, route-to-route extrapolation from the oral NOAEL value was considered appropriate. As no data on dermal penetration are available, dermal absorption is considered to be the same as oral absorption (i.e. 100 %). Therefore the oral NOAEL is considered the same as the dermal NOAEL (ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012)).

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

10

Justification:

Default factor for general population. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties.

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:

DNEL (Derived No Effect Level)

Value:

1.08 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

600

Dose descriptor starting point:

NOAEL

Value:

650 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

No modification of the dose descriptor starting point is required. The endpoint used to derive the DNEL uses the oral route for exposure.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

10

Justification:

Default factor for good/standard quality of the database taken into account completeness, consistency and the standard information requirements for the tonnage band.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties.

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

Additional information - General Population

NOAEL (systemic toxicity) = >= 650 mg/kg bw/day (OECD 407, 2012)

NOAEL (fertility) = >= 650 mg/kg bw/day (OECD 421, 2017)

NOAEL (development) = >= 650 mg/kg bw/day (OED 421, 2017)

Long-term systemic hazard assessment for this substance is based on subacute toxicity studies conducted for repeated dose toxicity (OECD 407), and reproductive/developmental toxicity screening (OECD 421). In these studies, dose levels were based on a range-finding test conducted for the OECD 407 study, where adverse effects were observed at 1,000 mg/kg bw/day and 750 mg/kg bw/day (clinical signs and effects on body weight and food consumption). As a result, 650 mg/kg bw/day was considered the appropriate high dose level for the OECD 407 and OECD 421 studies.

The results of the subacute studies indicated no adverse effects at the top dose, meaning that the NOAELs for these studies were considered >= 650 mg/kg bw/day, due to the absence of adverse toxic effects at the highest dose tested. As this top dose was below the limit dose for subacute studies (1,000 mg/kg bw/day), a conservative approach was used for DNEL derivation, where 650 mg/kg bw/day was assumed as the lowest possible NOAEL for the substance. This is consistent with the precautionary principle and ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R8 (2012).