N-(1,1,3,3-tetramethylbutyl)acrylamide

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

4.55 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

other: ECHA and ECETOC assessment factors with modifications see discussion for full justification

Overall assessment factor (AF):

30

Modified dose descriptor starting point:

NOAEC

Value:

136.4 mg/m³

Explanation for the modification of the dose descriptor starting point:

ECHA guidance recommends that a factor of 2 be applied when doing route to route extrapolation for oral to inhalation exposure, recognizing 100% absorption via the lungs while 50% absorption is assumed by the oral route. In addition allometric scaling is applied by taking account for the different breathing rates between rats and humans, as described in ECHA technical guidance the oral NOAEL in the rat mg/kg/day is divided by the factor of 2 then *1/0.38 * 6.7/10 = mg/m3 inhalation NOAEC for workers.  

AF for dose response relationship:

1

Justification:

Effects show a clear dose response

AF for differences in duration of exposure:

6

Justification:

ECHA guidance document Chapter R8, in Table 8-5, indicates that DNELs derived from subacute (28 day) studies to compensate for chronic exposure should use an assessment factor of 6 for this different duration.

AF for interspecies differences (allometric scaling):

1

Justification:

No additional factor as already included in the route to route extrapolation from the rat oral NOAEL to the equivalent human inhalation NOAEL

AF for other interspecies differences:

1

Justification:

ECETOC reported in 2010 after an extensive review (see discussion) that there is no justification for the suggested additional factor of 2.5 for this, therefore a factor of 1 has been applied.

AF for intraspecies differences:

5

Justification:

ECETOC reported in 2010 after an extensive scientific review that the appropriate fact for intraspecies differences for workers is 3 and not 5 as ECHA proposed. It has been suggested that adding 2 to cover all remaining differences is advisable giving the factor of 5 used. See discussion for detailed justification

AF for the quality of the whole database:

1

Justification:

The DNEL is calculated using NOAEL data from the OECD422 study on the substance to be registered, therefore the quality of the database is high and therefore a factor of 1 is applied.

AF for remaining uncertainties:

1

Justification:

All uncertainties are already included so a factor of 1 is applied.

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.29 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

other: other: ECHA and ECETOC assessment factors with minor modification see discussion

Overall assessment factor (AF):

120

Modified dose descriptor starting point:

NOAEL

Value:

155 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

ECHA guidance assumes that absorption for dermal exposure is the same as for oral exposure, which is a worst case assumption, as N-(1,1,3,3-tetramethylbutyl)acrylamide has very low dermal absorption.  

AF for dose response relationship:

1

Justification:

Effects show a clear dose response

AF for differences in duration of exposure:

6

Justification:

ECHA guidance document Chapter R8, in Table 8-5, indicates that DNELs derived from subacute (28 day) studies to compensate for chronic exposure should use an assessment factor of 6 for this different duration.

AF for interspecies differences (allometric scaling):

4

Justification:

A factor of 4 is applied based on ECHA guidance for allometric scaling of data from rats to humans.

AF for other interspecies differences:

1

Justification:

ECETOC reported in 2010 after an extensive review (see discussion) that there is no justification for the suggested additional factor of 2.5 for this, therefore a factor of 1 has been applied.

AF for intraspecies differences:

5

Justification:

ECETOC reported in 2010 after an extensive scientific review that the appropriate fact for intraspecies differences for workers is 3 and not 5 as ECHA proposed. It has been suggested that adding 2 to cover all remaining differences is advisable giving the factor of 5 used. See discussion for detailed justification.

AF for the quality of the whole database:

1

Justification:

The DNEL is calculated using NOAEL data from the OECD422 study on the substance to be registered, therefore the quality of the database is high and therefore a factor of 1 is applied.

AF for remaining uncertainties:

1

Justification:

All uncertainties are already included so a factor of 1 is applied.

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

low hazard (no threshold derived)

Additional information - workers

Selection of Assessment factors for Intra – Inter species variation for workers and the general population (consumers)    ECHA (2010) has produced guidance on the assessment factors to use to derive a DNEL for human exposure based the application of assessment factors (safety factors) to an NOAEL or LOAEL in animal studies. The guidance proposes that an assessment factor of 2 to be applied when extrapolating from an oral NOAEL to an inhalation DNEL, this is based on an assumption that absorption in the lungs will be 100% compared to 50% by the oral route. Therefore the default division by 2 was applied to the oral NOAEL, before the route to route extrapolation from rats to humans, to give the dose descriptor starting point.   The ECHA guidance proposes an assessment factor of 4 for theallometricscaling from rats to humans when calculating dermal DNELs. However it then proposes an additional factor of 2.5 to cover remaining differences (uncertainties). There is no clear scientific justification for this additional factor. ECETOC initsGuidanceon Assessment Factors to Derive aDNEL(2010) reviewed the scientific evidence and concluded that the factor of 4 for rats was sufficient to cover theallometricscaling from rats to humans and any remaining differences are of intra-species rather than interspecies variability. Based on this, the additional assessment factor of 2.5 for inter-species variability will not be used. This ECETOC guidance also reviewed the intra-species assessment factors, which ECHA proposed as 5 for workers and 10 for the general population. ECETOC originally proposed in 2003, based on the scientific evidence, that assessment factors of 3 for workers and 5 for the general population are sufficient for covering any intra-species variability, which includes the remaining differences factor of 2.5. A similar concept was developed for the GermanAuschussfürGefahrstoffe- AGS (2006), although arriving at a different factor. Apart fromallometricscaling, taking interspecies differences for metabolism andtoxicokineticsinto account, a separate factor for overall (inter- and intra-species) variability for the workplace of 5 is taken. AGS explicitly did not differentiate between inter- and intra-species variability. They did not specifically propose an assessment factor for the general population. However, following the same principle that the AGS applied for workers, increasing the factor of 5 proposed by ECETOC for the general population also by 2 gives a factor of 7.    After reviewing the three proposals, we have adopted the proposal from ECETOC as our default assessment factors. Where we have limited information or consider there to be the likelihood of addition intra species variation in response, then these factor may be increased for example as suggested by the GermanAuschussfürGefahrstoffeof an assessment factor of 5 for workers. Scientifically justified alternative factors for the general public will be selected on a case by case basis, with appropriate modification to the factor of 5 recommended by ECETOC, Examples of modified factors for the general public could be for example a factor of 7 following the approach of the AGS or 10 following the ECHA guidance This is considered a scientifically justified but still conservative approach, although the additional factor of 2.5 for remaining inter species differences as proposed by the ECHA guidance will not be used.   In this case to ensure additional intra-species variability is included the ECETOC assessment factor of 3 for workers will be increased by 2 to give a factor of 5, as described above following the approach of the AGS.   References:   ECHA, 2010 Guidance on information requirements and chemical safety assessment Chapter R.8:Characterisationof dose [concentration]-response for human health. December 2010   ECETOC, 2010Guidance on Assessment Factors to Derive aDNEL,TechnicalReport No.110,ISSN-0773-8072-110 (print),ISSN-2079-1562-110 (online), October 2010 GermanAuschussfür Gefahrstoffe(AGS) 2006. Technische Regeln für Gefahrstoffe. Begründungen und Erläuterungen zu Grenzwerten in der Luft am Arbeitsplatz. AusschussfürGefahrstoffe. TRGS 901,BArbBl. Heft 1/2006.www.baua.de

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.61 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

other: ECHA and ECETOC assessment factor with minor modification see discussion.

Overall assessment factor (AF):

42

Modified dose descriptor starting point:

NOAEC

Value:

67.4 mg/m³

Explanation for the modification of the dose descriptor starting point:

ECHA guidance recommends that a factor of 2 be applied when doing route to route extrapolation for oral to inhalation exposure, recognizing 100% absorption via the lungs while 50% absorption is assumed by the oral route. In addition allometric scaling is applied by taking account for the different breathing rates between rats and humans, as described in ECHA technical guidance the oral NOAEL in the rat mg/kg/day is divided by the factor of 2 then *1/1.15 mg/m3 inhalation NOAEC for consumers.  

AF for dose response relationship:

1

Justification:

Effects show a clear dose response.

AF for differences in duration of exposure:

6

Justification:

ECHA guidance document Chapter R8, in Table 8-5, indicates that DNELs derived from subacute (28 day) studies to compensate for chronic exposure should use an assessment factor of 6 for this different duration.

AF for interspecies differences (allometric scaling):

1

Justification:

No additional factor as already included in the route to route extrapolation from the rat oral NOAEL to the equivalent human inhalation NOAEC.

AF for other interspecies differences:

1

Justification:

ECETOC reported in 2010 after an extensive review (see discussion) that there is no justification for the suggested additional factor of 2.5 for this, therefore a factor of 1 has been applied.

AF for intraspecies differences:

7

Justification:

ECETOC reported in 2010 after an extensive scientific review that the appropriate fact for intraspecies differences for the general population is 5 and not 10 as ECHA proposed. It has been suggested that adding 2 to cover all remaining differences is advisable giving the factor of 7 used. See discussion for detailed justification

AF for the quality of the whole database:

1

Justification:

The DNEL is calculated using NOAEL data from the OECD422 study on the substance to be registered, therefore the quality of the database is high and therefore a factor of 1 is applied.

AF for remaining uncertainties:

1

Justification:

All uncertainties are already included so a factor of 1 is applied

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.923 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

other: ECHA and ECETOC assessment factors with minor modification see discussion.

Overall assessment factor (AF):

168

Modified dose descriptor starting point:

NOAEL

Value:

155 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

ECHA guidance assumes that absorption for dermal exposure is the same as for oral exposure, which is a worst case assumption, as N-(1,1,3,3-tetramethylbutyl)acrylamide has very low dermal absorption.

AF for dose response relationship:

1

Justification:

Effects show a clear dose response

AF for differences in duration of exposure:

6

Justification:

ECHA guidance document Chapter R8, in Table 8-5, indicates that DNELs derived from subacute (28 day) studies to compensate for chronic exposure should use an assessment factor of 6 for this different duration.

AF for interspecies differences (allometric scaling):

4

Justification:

A factor of 4 is applied based on ECHA guidance for allometric scaling of data from rats to humans.

AF for other interspecies differences:

1

Justification:

ECETOC reported in 2010 after an extensive review (see discussion) that there is no justification for the suggested additional factor of 2.5 for this, therefore a factor of 1 has been applied.

AF for intraspecies differences:

7

Justification:

ECETOC reported in 2010 after an extensive scientific review that the appropriate fact for intraspecies differences for the general population 5 and not 10 as ECHA proposed. It has been suggested that adding 2 to cover all remaining differences is advisable giving the factor of 7 used. See discussion for detailed justification.

AF for the quality of the whole database:

1

Justification:

The DNEL is calculated using NOAEL data from the OECD422 study on the substance to be registered, therefore the quality of the database is high and therefore a factor of 1 is applied.

AF for remaining uncertainties:

1

Justification:

All uncertainties are already included so a factor of 1 is applied

Acute/short term exposure

Hazard assessment conclusion:

no DNEL required: short term exposure controlled by conditions for long-term

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

no DNEL required: short term exposure controlled by conditions for long-term

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.923 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

other: ECHA and ECETOC assessment factor with minor modification see discussion

Overall assessment factor (AF):

168

Modified dose descriptor starting point:

NOAEL

Value:

155 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

Test data in rats is for the same oral route of exposure as the general population .

AF for dose response relationship:

1

Justification:

Effects show a clear dose response

AF for differences in duration of exposure:

6

Justification:

ECHA guidance document Chapter R8, in Table 8-5, indicates that DNELs derived from subacute (28 day) studies to compensate for chronic exposure should use an assessment factor of 6 for this different duration.

AF for interspecies differences (allometric scaling):

4

Justification:

A factor of 4 is applied based on ECHA guidance for allometric scaling of data from rats to humans.

AF for other interspecies differences:

1

Justification:

ECETOC reported in 2010 after an extensive review (see discussion) that there is no justification for the suggested additional factor of 2.5 for this, therefore a factor of 1 has been applied.

AF for intraspecies differences:

7

Justification:

ECETOC reported in 2010 after an extensive scientific review that the appropriate fact for intraspecies differences for the general population 5 and not 10 as ECHA proposed. It has been suggested that adding 2 to cover all remaining differences is advisable giving the factor of 7 used. See discussion for detailed justification.

AF for the quality of the whole database:

1

Justification:

The DNEL is calculated using NOAEL data from the OECD422 study on the substance to be registered, therefore the quality of the database is high and therefore a factor of 1 is applied.

AF for remaining uncertainties:

1

Justification:

All uncertainties are already included so a factor of 1 is applied

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

low hazard (no threshold derived)

Additional information - General Population

Selection of Assessment factors for Intra – Inter species variation for workers and the general population (consumers)    ECHA (2010) has produced guidance on the assessment factors to use to derive a DNEL for human exposure based the application of assessment factors (safety factors) to an NOAEL or LOAEL in animal studies.   The guidance proposes that an assessment factor of 2 to be applied when extrapolating from an oral NOAEL to an inhalation DNEL, this is based on an assumption that absorption in the lungs will be 100% compared to 50% by the oral route. Therefore the default division by 2 was applied to the oral NOAEL, before the route to route extrapolation from rats to humans, to give the dose descriptor starting point.   The ECHA guidance proposes an assessment factor of 4 for theallometricscaling from rats to humans when calculating dermal DNELs. However it then proposes an additional factor of 2.5 to cover remaining differences (uncertainties). There is no clear scientific justification for this additional factor. ECETOC initsGuidanceon Assessment Factors to Derive aDNEL(2010) reviewed the scientific evidence and concluded that the factor of 4 for rats was sufficient to cover theallometricscaling from rats to humans and any remaining differences are of intra-species rather than interspecies variability. Based on this, the additional assessment factor of 2.5 for inter-species variability will not be used. This ECETOC guidance also reviewed the intra-species assessment factors, which ECHA proposed as 5 for workers and 10 for the general population. ECETOC originally proposed in 2003, based on the scientific evidence, that assessment factors of 3 for workers and 5 for the general population are sufficient for covering any intra-species variability, which includes the remaining differences factor of 2.5. A similar concept was developed for the GermanAuschussfürGefahrstoffe- AGS (2006), although arriving at a different factor. Apart fromallometricscaling, taking interspecies differences for metabolism andtoxicokineticsinto account, a separate factor for overall (inter- and intra-species) variability for the workplace of 5 is taken. AGS explicitly did not differentiate between inter- and intra-species variability. They did not specifically propose an assessment factor for the general population. However, following the same principle that the AGS applied for workers, increasing the factor of 5 proposed by ECETOC for the general population also by 2 gives a factor of 7.    After reviewing the three proposals, we have adopted the proposal from ECETOC as our default assessment factors. Where we have limited information or consider there to be the likelihood of addition intra species variation in response, then these factor may be increased for example as suggested by the German AuschussfürGefahrstoffe of an assessment factor of 5 for workers. Scientifically justified alternative factors for the general public will be selected on a case by case basis, with appropriate modification to the factor of 5 recommended by ECETOC, Examples of modified factors for the general public could be for example a factor of 7 following the approach of the AGS or 10 following the ECHA guidance This is considered a scientifically justified but still conservative approach, although the additional factor of 2.5 for remaining inter species differences as proposed by the ECHA guidance will not be used.   In this case to ensure additional intra-species variability is included the ECETOC assessment factor of 3 for workers will be increased by 2 to give a factor of 5, as described above following the approach of the AGS. For Consumers we have taken the ECETOC recommended factor of 5 and again added an additional 2 to give a factor of 7 to cover any additional variability.   References:   ECHA, 2010 Guidance on information requirements and chemical safety assessment Chapter R.8:Characterisationof dose [concentration]-response for human health. December 2010   ECETOC, 2010Guidance on Assessment Factors to Derive a DNEL,Technical Report No.110,ISSN-0773-8072-110 (print),ISSN-2079-1562-110 (online), October 2010 GermanAuschussfür Gefahrstoffe(AGS) 2006. Technische Regeln für Gefahrstoffe. Begründungen und Erläuterungen zu Grenzwerten in der Luft am Arbeitsplatz. AusschussfürGefahrstoffe. TRGS 901,BArbBl. Heft 1/2006.www.baua.de