Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
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EC number: 200-795-6 | CAS number: 73-22-3
Toxicological Summary
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 664 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):
- 10
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 6 637 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- assessment factor for route-to-route extrapolation: 1
- AF for dose response relationship:
- 1
- Justification:
- default assessment factor
- AF for differences in duration of exposure:
- 2
- Justification:
- default assessment factor
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- allometric scaling is not applied in the case of systemic effects after inhalation
- AF for other interspecies differences:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
- AF for intraspecies differences:
- 5
- Justification:
- default assessment factor
- AF for the quality of the whole database:
- 1
- Justification:
- default assessment factor
- AF for remaining uncertainties:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
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:
- 941 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):
- 40
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 37 640 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- assessment factor route-to-route extrapolation 1, default assessment factor for oral to dermal exposure
- AF for dose response relationship:
- 1
- Justification:
- default assessment factor
- AF for differences in duration of exposure:
- 2
- Justification:
- default assessment factor
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- default assessment factor
- AF for other interspecies differences:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
- AF for intraspecies differences:
- 5
- Justification:
- default assessment factor
- AF for the quality of the whole database:
- 1
- Justification:
- default assessment factor
- AF for remaining uncertainties:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
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
DNEL Long-term - inhalation, systemic effects
Relevant dose descriptor for the endpoint concerned: NOAEL of 3764 mg/kg bw/day in rats in a 90-day oral toxicity study with GLP compliance according to OECD Guideline 408
Correction of starting point:
Differences in respiratory volumes: respiratory volume of the rat in 8 h corresponds to 0.38 m3/kg bw, additional correction for the higher standard respiratory volumes of workers compared to resting persons: correction factor = (1 ÷ 0.38) * (6.7 ÷ 10) = 1.76
Overall correction factor: 1.76
Corrected starting point: 3764 * 1.76 = 6637 mg/m3
Assessment factors relating to the extrapolation procedure:
Interspecies: not considered, as an allometric scaling is not applied in the case of systemic effects after inhalation
Intraspecies: 5 (default assessment factor for workers)
Time extrapolation: 2 (default assessment factor for sub-chronic to chronic study)
Route to route extrapolation: 1 (as L-Tryptophan is an essential amino acid for humans and rats bioavailability following oral administration is considered to be high )
Dose-response: 1 (default assessment factor for a reliable NOAEL)
Quality of whole database: 1 (default assessment factor for completeness of the available data)
Overall assessment factor:5 * 2 * 1 * 1 * 1 = 10
DNEL Long-term - inhalation, systemic effects: 6637 mg/m3 ÷ 10 = 664 mg/m3
DNEL Long-term - dermal, systemic effects
Relevant dose descriptor for the endpoint concerned: NOAEL of 3764 mg/kg bw/day in rats in a 90-day oral toxicity study with GLP compliance according to OECD Guideline 408
Correction of starting point:
Differences in absorption: Oral absorption is assumed to be 100%,
while dermal absorption is assumed to be 10% absorption.
Corrected starting point: 3764 * 100 / 10 = 37640 mg/m3
Assessment factors relating to the extrapolation procedure:
Interspecies: 4 (default assessment factor for allometric scaling; an additional assessment factor of 2.5 for “remaining differences” was not considered as L-tryptophan is an essential amino acid for all mammalian species)
Intraspecies: 5 (default assessment factor for workers)
Time extrapolation: 2 (default assessment factor for sub-chronic to chronic study)
Route to route extrapolation: 1 (default assessment factor for oral to dermal exposure)
Dose-response: 1 (default assessment factor for a reliable NOAEL)
Quality of whole database: 1 (default assessment factor for completeness of the available data)
Overall assessment factor: 4 * 5 * 2 * 1 * 1 * 1 = 40
DNEL Long-term - dermal, systemic effects: 37640 mg/kg bw/day ÷ 40 = 941 mg/kg bw/day
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 164 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):
- 20
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 3 273 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- assessment factor route-to-route extrapolation 1
- AF for dose response relationship:
- 1
- Justification:
- default assessment factor
- AF for differences in duration of exposure:
- 2
- Justification:
- default assessment factor
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- allometric scaling is not applied in the case of systemic effects after inhalation
- AF for other interspecies differences:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
- AF for intraspecies differences:
- 10
- Justification:
- default assessment factor
- AF for the quality of the whole database:
- 1
- Justification:
- default assessment factor
- AF for remaining uncertainties:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
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:
- DNEL (Derived No Effect Level)
- Value:
- 471 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):
- 80
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 37 640 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- assessment factor route-to-route extrapolation 1, default assessment factor for oral to dermal exposure
- AF for dose response relationship:
- 1
- Justification:
- default assessment factor
- AF for differences in duration of exposure:
- 2
- Justification:
- default assessment factor
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- default assessment factor
- AF for other interspecies differences:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
- AF for intraspecies differences:
- 10
- Justification:
- default assessment factor
- AF for the quality of the whole database:
- 1
- Justification:
- default assessment factor
- AF for remaining uncertainties:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
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:
- DNEL (Derived No Effect Level)
- Value:
- 47 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):
- 80
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 3 764 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- assessment factor route-to-route extrapolation 1,
- AF for dose response relationship:
- 1
- Justification:
- default assessment factor
- AF for differences in duration of exposure:
- 2
- Justification:
- default assessment factor
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- default assessment factor
- AF for other interspecies differences:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
- AF for intraspecies differences:
- 10
- Justification:
- default assessment factor
- AF for the quality of the whole database:
- 1
- Justification:
- default assessment factor
- AF for remaining uncertainties:
- 1
- Justification:
- L-tryptophan is an essential amino acid for all mammalian species
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
DNEL Long-term - inhalation, systemic effects
Relevant dose descriptor for the endpoint concerned: NOAEL of 3764 mg/kg bw/day in rats in a 90-day oral toxicity study with GLP compliance according to OECD Guideline 408
Correction of starting point:
Differences in respiratory volumes: respiratory volume of the rat in 24 h corresponds to 1.15 m3/kg bw, correction factor 1 ÷ 1.15 = 0.87
Overall correction factor: 0.87
Corrected starting point: 3764 * 0.87 = 3273 mg/m3
Assessment factors relating to the extrapolation procedure:
Interspecies: not considered, as an allometric scaling is not applied in the case of systemic effects after inhalation
Intraspecies: 10 (default assessment factor for general population)
Time extrapolation: 2 (default assessment factor for sub-chronic to chronic study)
Route to route extrapolation: 1 (as L-Tryptophan is an essential amino acid for humans and rats bioavailability following oral administration is considered to be high)
Dose-response: 1 (default assessment factor for a reliable NOAEL)
Quality of whole database: 1 (default assessment factor for completeness of the available data)
Overall assessment factor:10 * 2 * 1 * 1 * 1 = 20
DNEL Long-term - inhalation, systemic effects: 3273 mg/m3 ÷ 20 = 164 mg/m3
DNEL Long-term - dermal, systemic effects
Relevant dose descriptor for the endpoint concerned: NOAEL of 3764 mg/kg bw/day in rats in a 90-day oral toxicity study with GLP compliance according to OECD Guideline 408
Correction of starting point:
Differences in absorption: Oral absorption is assumed to be 100%,
while dermal absorption is assumed to be 10% absorption is.
Corrected starting point: 3764 * 100 / 10 = 37640 mg/m3
Assessment factors relating to the extrapolation procedure:
Interspecies: 4 (default assessment factor for allometric scaling; an additional assessment factor of 2.5 for “remaining differences” was not considered as l-tryptophan is an essential amino acid for all mammalian species)
Intraspecies: 10 (default assessment factor for general population)
Time extrapolation: 2 (default assessment factor for sub-chronic to chronic study)
Route to route extrapolation: 1 (default assessment factor for oral to dermal exposure)
Dose-response: 1 (default assessment factor for a reliable NOAEL)
Quality of whole database: 1 (default assessment factor for completeness of the available data)
Overall assessment factor: 4 * 10 * 2 * 1 * 1 * 1 = 80
DNEL Long-term - dermal, systemic effects: 37640 mg/kg bw/day ÷ 80 = 471 mg/kg bw/day
DNEL Long-term - oral, systemic effects
Relevant dose descriptor for the endpoint concerned: NOAEL of 3764 mg/kg bw/day in rats in a 90-day oral toxicity study with GLP compliance according to OECD Guideline 408
Starting point: 3764 mg/kg bw/day
Assessment factors relating to the extrapolation procedure:
Interspecies: 4 (default assessment factor for allometric scaling; an additional assessment factor of 2.5 for “remaining differences” was not considered as l-tryptophan is an essential amino acid for all mammalian species)
Intraspecies: 10 (default assessment factor for general population)
Time extrapolation: 2 (default assessment factor for sub-chronic to chronic study)
Route to route extrapolation: not considered, as same route
Dose-response: 1 (default assessment factor for a reliable NOAEL)
Quality of whole database: 1 (default assessment factor for completeness of the available data)
Overall assessment factor: 4 * 10 * 2 * 1 * 1 = 80
DNEL Long-term - oral, systemic effects: 3764 mg/kg bw/day ÷ 80 = 47 mg/kg bw/day
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
