Registration Dossier

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

3.5 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

25

Modified dose descriptor starting point:

NOAEC

Value:

88.2 mg/m³

Explanation for the modification of the dose descriptor starting point:

No dose descriptor for the inhalation route is available;

therefore route to route extrapolation is used to convert the oral NOAEL.

Detailed information is given in the additional information - worker.

AF for dose response relationship:

1

Justification:

The starting point for the DNEL calculation is a NOAEL, therefore the default assessment factor of 1 for a standard procedure is considered appropriate.

AF for differences in duration of exposure:

2

Justification:

Default factor for extrapolation sub-chronic to chronic

AF for interspecies differences (allometric scaling):

1

Justification:

It is not necessary to apply an allometric scaling factor because the starting point has been corrected for differences in respiratory volume and this takes account of differences in metabolic rates.

AF for other interspecies differences:

2.5

Justification:

Due to the absence of toxicokinetic data an additional factor of 2.5 for other interspecies differences is applied according to TGD 8.

AF for intraspecies differences:

5

Justification:

The default factor of 5 for workers will therefore be used to take account of intraspecies variability.

AF for the quality of the whole database:

1

Justification:

The key studies were conducted according to modern regulatory standards and were adequately reported.

AF for remaining uncertainties:

1

Justification:

No additional AF was deemed necessary.

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

10.5 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL derivation method:

ECHA REACH Guidance

DNEL extrapolated from long term DNEL

Explanation for the modification of the dose descriptor starting point:

No dose descriptor for the inhalation route is available;

therefore route to route extrapolation is used to convert the oral NOAEL.

Detailed information is given in the additional information - worker.

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

100

Modified dose descriptor starting point:

NOAEL

Value:

100 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

No dose descriptor for the dermal route is available;

therefore route to route extrapolation is used to convert the oral NOAEL. Detailed information is given in the additional information - worker.

AF for dose response relationship:

1

Justification:

The starting point for the DNEL calculation is a NOAEL, therefore the default assessment factor of 1 for a standard procedure is considered appropriate.

AF for differences in duration of exposure:

2

Justification:

Default factor for extrapolation sub-chronic to chronic

AF for interspecies differences (allometric scaling):

4

Justification:

The starting point is an oral dose descriptor from a rat study. It is therefore necessary to include an allometric scaling factor of 4 to take account of differences in basal metabolic rates between rats and humans.

AF for other interspecies differences:

2.5

Justification:

Due to the absence of toxicokinetic data an additional factor of 2.5 for other interspecies differences is applied.

AF for intraspecies differences:

5

Justification:

The default factor of 5 for workers will be used to take account of intraspecies variability.

AF for the quality of the whole database:

1

Justification:

The key study was conducted according to modern regulatory standards and was adequately reported.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

medium hazard (no threshold derived)

General considerations

Short-term data

Data on acute toxicity are available for the oral, inhalation and dermal route. Guanidine nitrate has to be classified for acute oral and inhalation toxicity Hazard Category 4. No classification is required for the dermal route.

Long-term data

Data relevant for long-term toxicity are available from an oral sub-chronic toxicity study and a developmental toxicity study, both in rats.

For Developmental toxicity a NOAEL of 350 mg/kg bw/day was established, no effects on prenatal data, litter data, foetal external, visceral, skeletal and craniofacial parameters were observed up to the highest dose level. Maternal toxicity was observed at 450 and 350 mg/kg bw/day based on mortality (450 mg/kg bw/day) and statistically significantly reduced body weight gain and food consumption. The NOAEL for maternal toxicity is 150 mg/kg bw/day.

A NOAEL of 100 mg/kg bw/day was derived from sub-chronic toxicity study, based on a nephropathy observed at 300 mg/kg bw/day. A (NOEL) could not be established, due to the local irritant effects of Guanidine hydrochloride in the glandular stomach of all dose groups.

Taken together the relevant dose descriptor used as starting point for DNEL derivation is the lowest NOAEL of 100 mg/kg bw/day.

For derivation of DNEL see attached document chapter 13.2 "DNEL derivation for fertility and developmental toxicity".

Irritation/ corrosion

In vivo data from a skin irritation study does not indicate a requirement for classification. However, under stressed conditions like an occlusive dressing, abraded skin or extended exposure for 24 hours skin irritation was observed.

Data from an in-vivo eye irritation study indicate only mild irritating effects but since they are not reversible in one animal, guanidine nitrate has to be classified with H318 “Causes serious eye damage”; Category 1 according to CLP (EU-GHS) Regulation (EC) No 1272/2008. Respiratory irritation was not reported from two acute toxicity studies by inhalation route.

Sensitization:

No skin sensitization potential of Guanidine Nitrate has been assessed in a skin sensitization study using the Buehler method.

Genetic toxicity:

The results from gene mutation assays in bacteria and mammalian cells, as well as chromosome aberration in mammalian cells are consistently negative. Thus, there is no evidence for a genotoxic potential of guanidine nitrate.

Allocated hazard category for qualitative assessment:

The most critical effect of guanidine nitrate for the allocation of a hazard category to be used for qualitative assessment is the classification with H318 “Cause serous eye damage”; Category 1 according to CLP (EU-GHS) Regulation (EC) No 1272/2008. Thus the moderate hazard category has to be assigned according to TGD part E.

DNEL_{long –term
systemic inhalation}

Route to route extrapolation oral to inhalation

Starting point: NOAEL (rat) of 100 mg/kg bw/day from sub-chronic toxicity study

For the derivation of a NOAEC for worker the following corrections have to be applied to the oral NOAEL (rat).

The oral NOAEL (rat) is multiplied with 1/0.38 m³/kg bw/8h (default respiratory volume in rat, table R.8.2 of CSR guidance) to give the corresponding rat inhalation 8h-NOAEC (no-observed adverse effect concentration).

To obtain the starting point for workers, a factor of 0.67 is applied to the NOAEC to account for the differences in inhalation rates between animals at rest and humans involved in light activity.

Due to the absence of route specific information a default factor of 2 is included by assuming 50 % for oral absorption (ABS oral-rat) and 100 % absorption after inhalation (ABS inh-human).

For workers the corrected inhalation NOAEC is calculated according to the following equation:

corrected inhalation NOAEC = oral NOAEL x 1/sRVratx ABSoral-rat/ ABSinh-humanx sRVhuman/ wRV1

= 100 x 1/0.38 x 50/100 x 6.7/10

The corrected inhalation NOAECworker(8h) is therefore:

= 88.2 mg/m³(8h-TWA)

DNEL_{short
–term systemic inhalation}

For guanidine nitrate an acute toxicity hazard leading to a classification according to CLP (EU-GHS) Regulation (EC) No1272/2008 acute toxicity Category 4 for the inhalation route has been identified. However, a reliable dose descriptor for acute systemic effects could not be derived from the available inhalation studies.

High peak exposure cannot be entirely excluded as guanidine nitrate is a solid and the particle size distribution shows that 9.2 % of particles being < 125 µm and thus belong to the respirable fraction.

Considering high peak exposure the DNEL for acute toxicity was set for a reference period of 15 minutes at 3 times the value (default 3) of the long-term DNEL. This approach is appropriate because similar mechanisms of actions are probably involved in the responses to single and repeated exposure (TGD R8).

DNEL_{long –term
systemic dermal}

Route to route extrapolation oral to dermal

Starting point: NOAEL (rat) of 100 mg/kg bw/day from sub-chronic toxicity study

No toxicokinetic studies are available for guanidine nitrate. Guanidine nitrate is soluble in water and has a log P value of -1.7, therefore absorption has to be expected. After oral exposure signs of systemic toxicity including death were observed in acute toxicity studies, thus absorption of guanidine nitrate has occurred. As a consequence it is likely the substance will also be absorbed if it is inhaled. This assumption is supported by read-across data from an acute toxicity study by inhalation route, were systemic effects were observed. As data from a dermal acute toxicity study show no systemic effects at the limit dose of 2000 mg/kg bw/d, guanidine nitrate is expected to be not favourable for dermal absorption. The stratum corneum provides its greatest barrier function against hydrophilic compounds. If water solubility is above 10,000 mg/L and the log P value below 0 the substance may be too hydrophilic to cross the lipid rich environment of the stratum corneum. Dermal uptake for guanidine nitrate is considered to be low, due to the water solubility of 256,000 mg/L and the log P value of -1.7.

Based on these findings and as a worst case assumption the dermal NOAEL is determined to be equal to the oral NOAEL.

Thus no additional assessment factor deemed necessary for oral-to-dermal extrapolation.

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.87 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

50

Modified dose descriptor starting point:

NOAEC

Value:

43.5 mg/m³

Explanation for the modification of the dose descriptor starting point:

No dose descriptor for the inhalation route is available; therefore route to route extrapolation is used to

convert the oral NOAEL. Detailed information is given in the additional information - general population.

AF for dose response relationship:

1

Justification:

The starting point for the DNEL calculation is a NOAEL, therefore the default assessment factor of 1 for a standard procedure is considered appropriate.

AF for differences in duration of exposure:

2

Justification:

Default factor for extrapolation sub-chronic to chronic

AF for interspecies differences (allometric scaling):

1

Justification:

It is not necessary to apply an allometric scaling factor because the starting point has been corrected for differences in respiratory volume and this takes account of differences in metabolic rates.

AF for other interspecies differences:

2.5

Justification:

Due to the absence of toxicokinetic data an additional factor of 2.5 for other interspecies differences is applied according to TGD 8.

AF for intraspecies differences:

10

Justification:

The default factor of 10 for general population will therefore be used to take account of intraspecies variability.

AF for the quality of the whole database:

1

Justification:

The key studies were conducted according to modern regulatory standards and were adequately reported.

AF for remaining uncertainties:

1

Justification:

No additional AF was deemed necessary.

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.5 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

200

Modified dose descriptor starting point:

NOAEL

Value:

100 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

No dose descriptor for the dermal route is available;

therefore route to route extrapolation is used to convert the oral NOAEL. Detailed information is given in the additional information - general population.

AF for dose response relationship:

1

Justification:

The starting point for the DNEL calculation is a NOAEL, therefore the default assessment factor of 1 for a standard procedure is considered appropriate.

AF for differences in duration of exposure:

2

Justification:

Default factor for extrapolation sub-chronic to chronic

AF for interspecies differences (allometric scaling):

4

Justification:

The starting point is an oral dose descriptor from a rat study. It is therefore necessary to include an allometric scaling factor of 4 to take account of differences in basal metabolic rates between rats and humans.

AF for other interspecies differences:

2.5

Justification:

Due to the absence of toxicokinetic data an additional factor of 2.5 for other interspecies differences is applied.

AF for intraspecies differences:

10

Justification:

The default factor of 10 for general population is used to take account of intraspecies variability.

AF for the quality of the whole database:

1

Justification:

The key study was conducted according to modern regulatory standards and was adequately reported.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.5 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

200

Modified dose descriptor starting point:

NOAEL

Value:

100 mg/kg bw/day

AF for dose response relationship:

1

Justification:

The starting point for the DNEL calculation is a NOAEL, therefore the default assessment factor of 1 for a standard procedure is considered appropriate.

AF for differences in duration of exposure:

2

Justification:

Default factor for extrapolation sub-chronic to chronic

AF for interspecies differences (allometric scaling):

4

Justification:

The starting point is an oral dose descriptor from a rat study. It is therefore necessary to include an allometric scaling factor of 4 to take account of differences in basal metabolic rates between rats and humans.

AF for other interspecies differences:

2.5

Justification:

Due to the absence of toxicokinetic data an additional factor of 2.5 for other interspecies differences is applied.

AF for intraspecies differences:

10

Justification:

The default factor of 10 for general population is used to take account of intraspecies variability.

AF for the quality of the whole database:

1

Justification:

The key study was conducted according to modern regulatory standards and was adequately reported.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

Hazard assessment conclusion:

low hazard (no threshold derived)

Hazard assessment conclusion:

medium hazard (no threshold derived)

General considerations

Short-term data

Data on acute toxicity are available for the oral, inhalation and dermal route. Guanidine nitrate has to be classified for acute oral and inhalation toxicity Hazard Category 4. No classification is required for the dermal route.

Long-term data

Data relevant for long-term toxicity are available from an oral sub-chronic toxicity study and a developmental toxicity study, both in rats.

For Developmental toxicity a NOAEL of 350 mg/kg bw/day was established, no effects on prenatal data, litter data, foetal external, visceral, skeletal and craniofacial parameters were observed up to the highest dose level. Maternal toxicity was observed at 450 and 350 mg/kg bw/day based on mortality (450 mg/kg bw/day) and statistically significantly reduced body weight gain and food consumption. The NOAEL for maternal toxicity is 150 mg/kg bw/day.

A NOAEL of 100 mg/kg bw/day was derived from sub-chronic toxicity study, based on a nephropathy observed at 300 mg/kg bw/day. A (NOEL) could not be established, due to the local irritant effects of Guanidine hydrochloride in the glandular stomach of all dose groups.

Taken together the relevant dose descriptor used as starting point for DNEL derivation is the lowest NOAEL of 100 mg/kg bw/day.

For derivation of DNEL see attached document chapter 13.2 " DNEL derivation for fertility and developmental toxicity".

Irritation/ corrosion

In vivo data from a skin irritation study does not indicate a requirement for classification. However, under stressed conditions like an occlusive dressing, abraded skin or extended exposure for 24 hours skin irritation was observed.

Data from an in-vivo eye irritation study indicate only mild irritating effects but since they are not reversible in one animal, guanidine nitrate has to be classified with H318 “Causes serious eye damage”; Category 1 according to CLP (EU-GHS) Regulation (EC) No 1272/2008. Respiratory irritation was not reported from two acute toxicity studies by inhalation route.

Sensitization:

No skin sensitization potential of Guanidine Nitrate has been assessed in a skin sensitization study using the Buehler method.

Genetic toxicity:

The results from gene mutation assays in bacteria and mammalian cells, as well as chromosome aberration in mammalian cells are consistently negative. Thus, there is no evidence for a genotoxic potential of guanidine nitrate.

Allocated hazard category for qualitative assessment:

The most critical effect of guanidine nitrate for the allocation of a hazard category to be used for qualitative assessment is the classification with H318 “Cause serous eye damage”; Category 1 according to CLP (EU-GHS) Regulation (EC) No 1272/2008. Thus the moderate hazard category has to be assigned according to TGD part E.

DNEL_{long –term
systemic inhalation}

Route to route extrapolation oral to inhalation

Starting point: NOAEL (rat) of 100 mg/kg bw/day from sub-chronic toxicity study

For the derivation of a NOAEC for the general population the following corrections have to be applied to the oral NOAEL (rat). Due to the absence of route specific information a default factor of 2 is included by assuming 50 % for oral absorption (ABS oral-rat) and 100 % absorption after inhalation (ABS inh-human).

For general population in case of 24h exposure/d the corrected inhalation NOAEC is calculated according to the following equation:

corrected inhalation NOAEC = oral NOAEL x 1/sRVrat1 x ABSoral-rat/ ABSinh-human

= 100 x 1/1.15 x 50/100

The corrected inhalation NOAEC_{general population}(24h) is therefore:

= 43.5 mg/m3

DNEL_{long –term
systemic dermal}

Route to route extrapolation oral to dermal

Starting point: NOAEL (rat) of 100 mg/kg bw/day from sub-chronic toxicity study

No toxicokinetic studies are available for guanidine nitrate. Guanidine nitrate is soluble in water and has a log P value of -1.7, therefore absorption has to be expected. After oral exposure signs of systemic toxicity including death were observed in acute toxicity studies, thus absorption of guanidine nitrate has occurred. As a consequence it is likely the substance will also be absorbed if it is inhaled. This assumption is supported by read-across data from an acute toxicity study by inhalation route, were systemic effects were observed. As data from a dermal acute toxicity study show no systemic effects at the limit dose of 2000 mg/kg bw/d, guanidine nitrate is expected to be not favourable for dermal absorption. The stratum corneum provides its greatest barrier function against hydrophilic compounds. If water solubility is above 10,000 mg/L and the log P value below 0 the substance may be too hydrophilic to cross the lipid rich environment of the stratum corneum. Dermal uptake for guanidine nitrate is considered to be low, due to the water solubility of 256,000 mg/L and the log P value of -1.7.

Based on these findings and as a worst case assumption the dermal NOAEL is determined to be equal to the oral NOAEL.

Thus no additional assessment factor deemed necessary for oral-to-dermal extrapolation.