Potassium dicyanoaurate

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.071 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

Modified dose descriptor starting point:

NOAEC

Value:

5.29 mg/m³

Explanation for the modification of the dose descriptor starting point:

Corrected inhalatory NOAEC: oral NOAEL*1/sRVrat*ABSoral-rat/ABSinh-human*sRVhuman/wRV Where; ABS: Absorption; sRV: standard Respiratory Volume; wRV: worker Respiratory Volume; Therefore: 3 mg/kg/day divided by (0.38 m3/kg*6.7 m3/10 m3) = 5.29 mg/m3

AF for dose response relationship:

1

Justification:

The starting point is a NOAEL

AF for differences in duration of exposure:

6

Justification:

Extrapolation from subacute animal study to chronic human exposure

AF for interspecies differences (allometric scaling):

1

Justification:

Not required for inhalation

AF for other interspecies differences:

2.5

Justification:

Default factor in the absence of specific toxicodynamic data

AF for intraspecies differences:

5

Justification:

Default factor for Worker populations

AF for the quality of the whole database:

1

Justification:

Complete data set in accordance with regulations

AF for remaining uncertainties:

1

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown (no further information necessary)

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)

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.1 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

Modified dose descriptor starting point:

NOAEL

Value:

3 mg/kg bw/day

AF for dose response relationship:

1

Justification:

The starting point is a NOAEL

AF for differences in duration of exposure:

6

Justification:

Extrapolation from subacute animal study to chronic human exposure

AF for interspecies differences (allometric scaling):

4

Justification:

Default scaling factor from oral to dermal

AF for other interspecies differences:

2.5

Justification:

Default factor in the absence of specific toxicodynamic data

AF for intraspecies differences:

5

Justification:

Default factor for Worker populations

AF for the quality of the whole database:

1

Justification:

Complete data set in accordance with regulations

AF for remaining uncertainties:

1

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

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 DNEL calculations were prepared following the ECHA Guidance on information requirements and chemical safety assessment, Chapter R.8: Characterisation of dose (concentration)-response for human health. No correction was made for gold content in the test substance.

The DNEL calculations have been conducted only for worker exposure (not consumer). Whilst consumers would be exposed to articles plated with gold as a consequence of using potassium dicyanoaurate during the plating process, the consumer would not actually be exposed to the test substance itself. Also as oral intake is not considered relevant for workers, only the values for dermal and inhalation have been presented using route to route extrapolation.

The DNELs have been derived for a threshold endpoint since the OECD TG422 study has provided confirmation of this. The apparent non-threshold toxicity shown by potassium dicyanoaurate in the skin sensitisation LLNA studies is unusual and could be the consequence of absorption characteristics.

Default assessment factors have been used to derive the DNELs.

Potassium dicyanoaurate is significantly irritant to the eye but no DNEL can be set for this endpoint from the data available.

Oral acute toxicity testing of potassium dicyanoaurate indicates a classification of acute category 2 and a dermal acute study indicates no classification required for this route. Irritancy studies do not provide dose response data so threshold levels could not be identified resulting in difficulty in deriving appropriate irritancy DNELs. However, dermal DNELs are derived by route to route extrapolation from oral exposure. Generally speaking, a long-term DNEL is protective of acute exposure unless there are peak exposures significantly above the average daily exposure (determined from worker exposure studies) so acute DNELs for workers will not be required. The determination of the inhalation DNEL also takes into consideration the Dustiness data for the test substances. These data indicated that the particle size and dosimetry would suggest only extremely marginal exposure to the respiratory airways. Consequently, it is considered that the corrected inhalatory NOAEC should remain unaltered.

When considering the potential for reproductive effects, the OECD422 study for the test substance revealed oral NOAEL for general toxicity that was equal to or below dose levels causing any reproductive, fertility or developmental effects. Therefore, by using the lowest NOAEL from the OECD422 study as the point of departure for DNEL estimation would indicate that the DNELs are also protective of the reproductive toxicity endpoints.

General Population - Hazard via inhalation route

Systemic 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

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

General Population - Hazard via dermal route

Systemic 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

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)

General Population - Hazard via oral route

Systemic 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

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

hazard unknown (no further information necessary)

Additional information - General Population

The DNEL calculations have been conducted only for worker exposure (not consumer). Whilst consumers would be exposed to articles plated with gold as a consequence of using potassium dicyanoaurate during the plating process, the consumer would not actually be exposed to the test substance.