2,6-bis(1,1-dimethylethyl)-4-(phenylenemethylene)cyclohexa-2,5-dien-1-one

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.75 mg/m³

Most sensitive endpoint:

effect on fertility

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

50

Modified dose descriptor starting point:

NOAEC

AF for differences in duration of exposure:

4

Justification:

Study duration extrapolation

AF for interspecies differences (allometric scaling):

2.5

Justification:

Default

AF for intraspecies differences:

5

Justification:

Default

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown (no further information necessary)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

hazard unknown (no further information necessary)

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown (no further information necessary)

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Most sensitive endpoint:

sensitisation (skin)

Route of original study:

Dermal

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

medium hazard (no threshold derived)

Additional information - workers

The substance is classified as a skin sensitiser but no DNEL can be derived using this result as the study doesnt give dose response data.

The substance showed some evidence of dermal irritation in an acute dermal toxicity study and skin irritation study. However, DNELs for acute/short-term local effects were not able to be derived from these studies.

The only DNEL derived was for long-term systemic effects via the inhalation route, in order to assess the risks from worker exposure.

The result used to derive the inhalation DNEL was the NOAEL result of 100 mg/kg bw/day, from the OECD 421 (Reproduction / Developmental Toxicity Screening Test) study. This result was choosen in preference to the 28 -day repeat dose toxicity NOAEL of 300 mg.kg bw/day, as it gives a more conservative DNEL value and hence represents a worst case DNEL. The OECD 421 study also had a longer exposure time for the test animals (42 days for males and upto 46 days for females) than the 28 -day study and was therefore considered appropriate to use in deriving the DNEL.

The longer exposure period of the OECD 421 study means that it was considered appropriate to reduce the standard study duration extrapolation factor of 6, for sub-acute studies (usually refering to 28 day stydy) to chronic studies (usually refering to a 1 -2 year study) to a factor of 4, as the OECD 421 study more closley resembles the sub-acute to sub-chronic (usually 90 day) duration band.

The corrected dose description of 87.50 mg/m³for 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 rate 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 (of the above guidance) for workers (in the case of 8 hour exposure/day), Default parameters for rats and human (for 8 hour exposure) were used for the allometric scaling principle.

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:

exposure based waiving

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

DNELs have not been derived for the general public as there will be no exposure to the general public/consumers.

The substance will only be used by industry and not by the public. Due to minimal release of the substance from industrial use, exposure to the general public is not anticipated.