Tris(1,3-dihydroxyprop-2-yl) borate

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.93 mg/m³

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

25

Modified dose descriptor starting point:

NOAEC

Value:

48.46 mg/m³

Explanation for the modification of the dose descriptor starting point:

Long-term inhalation study not available.

AF for dose response relationship:

1

Justification:

NOAEL as starting point.

AF for differences in duration of exposure:

2

Justification:

Deafult for sub-chronic to chronic study (OECD 414)

AF for interspecies differences (allometric scaling):

1

Justification:

AF for allometric scaling not required as the differences in allometry were considered in the conversion of oral to inhalation starting dose.

AF for other interspecies differences:

2.5

Justification:

Default AF for remaining interspecies differences

AF for intraspecies differences:

5

Justification:

Default AF for worker population

AF for the quality of the whole database:

1

Justification:

Reliable GLP guideline study

AF for remaining uncertainties:

1

Justification:

None considered applicable.

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:

0.55 mg/kg bw/day

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

100

Modified dose descriptor starting point:

NOAEL

Value:

55 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

Long-term inhalation study not available.

AF for dose response relationship:

1

Justification:

NOAEL as starting point.

AF for differences in duration of exposure:

2

Justification:

Deafult for sub-chronic to chronic study (OECD 414)

AF for interspecies differences (allometric scaling):

4

Justification:

Default AF for rats

AF for other interspecies differences:

2.5

Justification:

Default AF for remaining interspecies differences

AF for intraspecies differences:

5

Justification:

Default AF for worker population

AF for the quality of the whole database:

1

Justification:

Reliable GLP guideline study

AF for remaining uncertainties:

1

Justification:

None considered applicable.

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

The reference substance (BAGE) is unstable in water and hydrolyses within less than an hour to its hydrolysis products: Boric acid and glycerol. Worker exposure to the hydrolysis products is therefore considered to be more applicable to evaluate than the substance itself as a worst case scenario. Therefore, DNELs have been derived for Boric acid, as this is the hydrolysis product of most concern (Glycerol is non-toxic and not classified and not considered to be of concern to human health). In addition, no toxicological testing was possible on the reference substance, so no data would be available to derive DNELs for BAGE.

Boric acid is currently classified as:

CLP: Repr. 1B, H360: May damage fertility or the unborn child (FD).

Inhalation:

Inhalation is not considered to be a significant route of exposure for boric acid due to its low volatility. However, a long-term systemic DNEL has been derived, based on the results of an OECD 414 study.

Long-term systemic effects:

A modification of the dose dsecrptior starting point (oral to inhalation) was conducted. It is assumed as a worst case assumption that the oral absorption rate is 50% of that of the inhalation absorption.

The corrected dose descriptor (NOAEC) for inhalation was calculated in accordance with the ECHA Guidance on information requirements and chemical safety assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health.

The conversion of an oral rat NOAEL into a corrected inhalatory NOAEC to assess human inhalatory exposure was performed using the modification of starting point equation as given in Figure R. 8-3 (see below) for workers (in the case of 8 hour exposure/day).

Default parameters for rats and humans (for 8 hour exposure) were used for the modification of starting point under the allometric scaling principle as given in Table R. 8-2 of the above ECHA guidance.

Conversion of an oral rate N(L)OAEL into a correct inhalatory N(L)OAEC to assess human inhalatory exposure:

For workers (in case of 8h exposure/day):

Corrected inhalatory N(L)OAEC = oral N(L)OAEL x (1 / sRVrat) x (ABSoral-rat / ABSinh-human) x (sRVhuman / wRV)

Corrected inhalatory N(L)OAEC =

55 mg/kg bw/day boric acid x (1 / 0.38 m³/kg/d) x (0.5) x (6.7 m³(8h) / 10 m³(8h)) = 48.46 mg/m³ boric acid

Where:

ABS: Absorption

sRV: standard Respiratory Volume

wRV: worker Respiratory Volume (light activity)

Default parametrs:

sRVrat (8 h): 0.38m³/kg bw

sRVhuman (8 h): 6.7 m³/ person

wRV (8 h): 10 m³/ person

The appropriate assessment factors were then applied to give an overall assessment factor of 25.

Long-term systemic DNEL (inhalation) = 1.93 mg/m³ boric acid

This long-term inhalation systemic effect DNEL is used in the quantitative assessment of risk for systemic toxicity to workers via the inhalation route.

This long term DNEL is also used to cover acute/short-term inhalation exposure.

Local inhalation effects are not considered to be of concern due to inhalation not being a significant route of exposure and the lack of local effects seen in acute studies.

Dermal:

A DNEL has been derived for long-term systemic effects by the dermal route, based on the results obtained from the OECD 414 study.

Long-term systemic DNEL (dermal) = 0.55 mg/kg bw/day boric acid

This long-term dermal systemic effect DNEL is used in the quantitative assessment of risk for systemic toxicity to workers via the dermal route.

DNELs for local effects have not been derived as boric acid is not a skin irritant or sensitiser.

The above DNELs are expressed in terms of boric acid. They may also be expressed in terms of elemental boron, in which case the DNELs would be:

 

Inhalation: 0.34 mg B/m³

Dermal: 0.096 mg B/kg bw/day

General Population - Hazard via inhalation 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

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:

no hazard identified

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

Additional information - General Population

There will be no exposure to consumers to the reference substance (BAGE) or it hydrolysis productions (Boric acid or glycerol).

The reference substance reverts back to boric and glycerol during the manufacture of contact lenses, and the hydrolysis products are removed from the contact lenses. Therefore, there will be no exposure to either boric acid or glycerol to the general population from use of the contact lenses.