Hazardous substance assessment: Benzyl alcohol

Identification

Chemical name:

Benzyl alcohol

CAS #:

100-51-6

Chemical composition:

C₇H₈O

Synonyms:

Benzenemethanol
Methanol, phenyl-
Phenolcarbinol
Benzenecarbinol

UN #:

No chemical-specific UN # available

Pictogram(s):

Figure 1. - Text Equivalent

The symbol within the pictogram is an exclamation mark. This symbol indicates that hazardous products with this pictogram can cause certain health effects for example:

• skin irritation
• eye irritation
• skin sensitization

WHMIS classification

Health hazards:

• Acute Toxicity (Oral) – Category 4
• Eye Irritation – Category 2A

Physical hazards:

• Flammable Liquids – Category 4

Health hazards

Acute Toxicity (Oral):

Category 4

Oral median lethal dose (LD₅₀): 1 570 milligrams per kilogram of body weight (mg/kg-bw) (rat)^{Footnote 1Footnote 2}.

A study performed similarly to the Organisation for Economic Co-operation and Development Test Guideline (OECD TG) 401 in Sprague-Dawley rats (5 per sex and dose) gavaged with a dose of 1 000, 1 410, 2 000 or 2 830 mg/kg-bw of benzyl alcohol in water reported an LD₅₀ of 1 570 mg/kg-bw and clinical signs of lethargy, prostration, ataxia, increased respiration, half closed eyes and piloerection in all treated animals^{Footnote 1Footnote 2Footnote 3}.

A non-guideline study in male Wistar rats (10 per dose) gavaged with a single dose of 1 045, 1 254, 1 463, 1 467, 2 090 or 2 195 mg/kg-bw of benzyl alcohol and observed for 14 days reported an LD₅₀ of 1 620 mg/kg-bw. At a dose of 1 254 mg/kg-bw or higher, clinical signs of sedation, side and prone-position, bloody eyes and reduction of general condition were reported^{Footnote 2}.

The available data meet the classification criteria for Acute Toxicity (Oral) – Category 4 [subsection 8.1.1(1) of the HPR].

Acute Toxicity (Dermal):

Does not meet criteria

Dermal LD₅₀: >2 000 mg/kg-bw (rabbit)^{Footnote 2}.

A study conducted similarly to United States Environmental Protection Agency (US EPA) Office of Toxic Substances (OTS) guideline 798.1100 (Acute Dermal Toxicity) in rabbits (4 per sex) exposed to a single dose of 2 000 mg/kg-bw of benzyl alcohol for 24 hours under occlusive conditions reported no mortality or adverse clinical signs of toxicity. The LD₅₀ was greater than 2 000 mg/kg-bw^{Footnote 2}.

The available data do not meet the classification criteria for a category of Acute Toxicity (Dermal).

Acute Toxicity (Inhalation – Gases):

Not applicable

Benzyl alcohol is not a gas. The classification criteria for Acute Toxicity (Inhalation – Gases) do not apply to this substance.

Acute Toxicity (Inhalation – Vapours):

No data available

No data are available to determine whether benzyl alcohol meets the classification criteria for a category of Acute Toxicity (Inhalation – Vapours).

Acute Toxicity (Inhalation – Dusts and Mists):

Does not meet criteria

Inhalation median lethal concentration (LC₅₀): >5.4 milligrams per litre (mg/L) (rat)^{Footnote 2}.

In an OECD TG 403-compliant study, Wistar rats (5 per sex and concentration) were exposed to a concentration of 3.3 or 4.2 mg/L of benzyl alcohol as an aerosol for 4 hours. No mortality was reported at either concentration. Rats exposed to 4.2 mg/L showed clinical signs of piloerection and slight bradypnea. The LC₅₀ was greater than 4.2 mg/L^{Footnote 2}.

The available data do not meet the classification criteria for a category of Acute Toxicity (Inhalation – Dusts and Mists).

Skin Corrosion / Irritation:

Does not meet criteria

An OECD TG 404-compliant (Acute Dermal Irritation/Corrosion) study in New Zealand White rabbits (n=3) exposed to 0.5 millilitres (mL) of undiluted benzyl alcohol for 4 hours under semi-occlusive conditions reported individual mean scores over 24, 48 and 72 hours after patch removal of 0 out of 4 for erythema in 2 of the animals and 0.7 out of 4 in 1 animal (fully resolved within 72 hours) and 0 out of 4 for edema in all 3 animals^{Footnote 2}.

A non-guideline study in New Zealand White rabbits (n=2) exposed to 0.5 mL of undiluted benzyl alcohol for 24 hours under semi-occlusive conditions reported individual mean scores over 24, 48 and 72 hours after patch removal of 0 out of 4 for both erythema and edema in both animals^{Footnote 2}.

In 2 additional studies in rabbits (n=3 and n=4) exposed to 0.5 mL of benzyl alcohol for 4 hours, primary irritation scores were 1.56 and 1.83, respectively, indicating mild irritation had occurred (maximum score of 8)^{Footnote 4}.

The available data do not meet the classification criteria for a category or subcategory of Skin Corrosion/Irritation.

Serious Eye Damage / Eye Irritation:

Category 2A

An OECD TG 405-compliant (Acute Eye Irritation/Corrosion) study in New Zealand White rabbits (n=3) exposed to 0.1 mL of undiluted benzyl alcohol for 24 hours (rinsed) reported individual mean scores over 24, 48 and 72 hours post-instillation of 1 out of 4 for corneal opacity in all 3 animals, 0 out of 2 for iritis in 2 animals and 0.3 out of 2 in 1 animal, 2 out of 3 for conjunctival redness in all 3 animals, and 1 out of 4 for chemosis in 1 animal and 0.7 out of 4 in 2 animals. Some effects persisted at day 14 but all were fully reversible within 21 days of observation^{Footnote 2}. The results meet classification criteria for Eye Irritation – Category 2A.

Another OECD TG 405-compliant study in New Zealand White rabbits (n=3) exposed to 0.1 mL of undiluted benzyl alcohol (unrinsed) reported individual mean scores over 24, 48 and 72 hours post-instillation of 2 out of 4 for corneal opacity in all 3 animals, 1 out of 2 for iritis in all 3 animals, 2 out of 3 for conjunctival redness in 1 animal, 2.3 out of 3 in another animal and 3 out of 3 in the third animal, and 1.7 out of 4 for chemosis in 1 animal, 2 out of 4 in another animal and 3 out of 4 in the third animal. Most effects were reversible within 11 days of observation except corneal opacity which was reversible within 18 days in 2 out of 3 rabbits^{Footnote 2}. The results meet classification criteria for Eye Irritation – Category 2A.

A couple of other studies in rabbits reported similar irritating effects^{Footnote 2Footnote 5}.

The available data meet the classification criteria for Eye Irritation – Category 2A [subsection 8.3.2(3) of the HPR].

Respiratory Sensitization:

No data available

No data are available to determine whether benzyl alcohol meets the classification criteria for a category or subcategory of Respiratory Sensitization.

Skin Sensitization:

Does not meet criteria

Humans: A number of positive skin sensitization studies with benzyl alcohol have been reported; however, the prevalence of sensitization is very low and usually seen in atopic individuals^{Footnote 2Footnote 6Footnote 7Footnote 8Footnote 9Footnote 10Footnote 11Footnote 12Footnote 13Footnote 14Footnote 15Footnote 16Footnote 17Footnote 18Footnote 19}.

Animals: An OECD TG 429-compliant (Skin Sensitisation: Local Lymph Node Assay) study in female CBA/Ca mice (4 per concentration) exposed to 0.025 mL of a solution of 2.5, 5, 10, 25 or 50% weight by volume (w/v) of benzyl alcohol in 1:3 ethanol:diethyl phthalate reported stimulation indices (SI) of 1, 0.9, 0.5, 0.6 and 1.2 for each concentration, respectively, and an estimated concentration needed to produce an SI of 3 (EC3) greater than 50%. This corresponds to a skin dose of greater than 12.5 milligrams per square centimetre (mg/cm²) The test substance was not sensitizing to skin at the concentrations tested^{Footnote 2}.

A modified Draize test in male and female Hartley guinea pigs (n=10) induced intradermally and challenged both intradermally and topically 14 days later with a 0.25% and a 10% solution of benzyl alcohol, respectively, reported no positive reactions (0 out of 10 animals). The test substance was non-irritating to very slightly irritating at the concentrations tested^{Footnote 2Footnote 20}. Several additional sensitization studies have also reported negative results^{Footnote 2Footnote 20}.

The available data do not meet the classification criteria for a category or subcategory of Skin Sensitization.

Germ Cell Mutagenicity:

Does not meet criteria

In vivo: An OECD TG 474-compliant (Mammalian Erythrocyte Micronucleus Test) study in male mice (6 per dose) administered a single dose of 50, 100 or 200 mg/kg-bw of benzyl alcohol in saline solution by intraperitoneal injection did not demonstrate induction of an increased number of micronuclei in polychromatic erythrocytes^{Footnote 21}.

A non-guideline replicative DNA synthesis test in male B6C3F₁ mice (4 or 5 per dose) gavaged with a single dose of 0, 400 or 800 mg/kg-bw of benzyl alcohol in corn oil did not demonstrate induction of replicative DNA synthesis in mice hepatocytes^{Footnote 22}.

In vitro: An OECD TG 471-compliant (Bacterial Reverse Mutation Test) study in Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 provided negative results with and without metabolic activation^{Footnote 2Footnote 23Footnote 24}.

An OECD TG 476-compliant (In Vitro Mammalian Cell Gene Mutation Tests using the Hprt and xprt genes) study in mouse lymphoma L5178Y cells provided negative results with and positive results without metabolic activation^{Footnote 25Footnote 26}.

A sister chromatid exchange assay in Chinese hamster ovary cells provided weakly positive results with and without metabolic activation^{Footnote 27}.

An OECD TG 473-compliant (In Vitro Mammalian Chromosomal Aberration Test) study in Chinese hamster ovary cells provided negative results without and weakly positive results with metabolic activation^{Footnote 2}.

Several additional in vitro studies in different cell types and using different guidelines provided mostly negative results for mutagenicity but a handful of the studies provided weakly positive or equivocal results^{Footnote 2Footnote 24Footnote 28Footnote 29Footnote 30Footnote 31Footnote 32Footnote 33Footnote 34}.

The available data do not meet the classification criteria for a category or subcategory of Germ Cell Mutagenicity.

Carcinogenicity:

Does not meet criteria.

Benzyl alcohol has not been reviewed by the International Agency for Research on Cancer (IARC) or the American Conference of Governmental Industrial Hygienists (ACGIH).

In OECD TG 451-compliant studies by the National Toxicology Program, there was no evidence of carcinogenesis in rats gavaged with a dose of 200 or 400 milligrams per kilogram of body weight per day (mg/kg-bw/day) of benzyl alcohol or in mice gavaged with a dose of 100 or 200 mg/kg-bw/day of benzyl alcohol for 2 years^{Footnote 34}.

The available data do not meet the classification criteria for a category or subcategory of Carcinogenicity.

Reproductive Toxicity:

Does not meet criteria

A non-guideline study was conducted in pregnant female CD-1 mice (50 per sex and dose) gavaged once daily with a dose of 0 or 750 mg/kg-bw/day of benzyl alcohol in distilled water from gestational day 7 to 14. Maternal toxicity was observed, as indicated by decreased body weight gain, hunched posture, tremors, inactivity, prostration, hypothermia, ataxia, dyspnoea, swollen or cyanotic abdomen and piloerection. Increased maternal mortality (19 out of 50 animals) was also noted and attributed to treatment. Significant reductions in pup body weight were reported^{Footnote 2Footnote 35Footnote 36}. This study was not used for classification as the developmental effect was concurrent with excessive maternal toxicity.

A non-guideline study in B6C3F₁ mice and Fischer 344 rats (10 from each species per sex and dose) gavaged once daily with a dose of 50, 100, 200, 400 or 800 mg/kg-bw/day of benzyl alcohol in corn oil for 5 days per week over 13 weeks reported clinical signs of toxicity, reduced body weight gain and/or histopathological changes in the brain of parental animals starting at a dose of 400 or 800 mg/kg-bw/day but no reproductive effects at any tested dose^{Footnote 2}.

An OECD TG 451-compliant carcinogenicity study was conducted in B6C3F₁ mice and Fischer 344 rats (50 from each species per sex and dose) gavaged once daily with a dose of 100 or 200 mg/kg-bw/day (mice) or of 200 or 400 mg/kg-bw/day (rats) of benzyl alcohol in corn oil for 5 days per week over 2 years. There were no clinical signs of toxicity and no reproductive effects in the parental animals^{Footnote 2Footnote 34}.

An OECD TG 412-compliant (Subacute Inhalation Toxicity: 28-Day Study) study in Sprague-Dawley rats (10 per sex and dose) exposed via nose-only inhalation to a concentration of 0, 0.041, 0.102, 0.290 or 1.072 mg/L of benzyl alcohol in aerosol or in a mixed aerosol/vapour atmosphere for 6 hours per day, 5 days per week for 4 weeks did not demonstrate any adverse clinical signs or effects on reproductive organs in parental animals^{Footnote 2}.

A non-guideline study in 50 pregnant female CD-1 mice administered a dose of 0 or 550 mg/kg-bw of benzyl alcohol once daily by gavage in corn oil on gestational days 6 to 15 did not demonstrate any effects on maternal body weight and body weight gain, gestation index, average number of live pups per litter, postnatal survival or pup body weight^{Footnote 2}.

The available data do not meet the classification criteria for a category or subcategory of Reproductive Toxicity.

Specific Target Organ Toxicity – Single Exposure:

Does not meet criteria

Oral Route of Exposure: A non-guideline study in Sprague-Dawley rats (5 per sex and dose) gavaged with a single dose of 1 000, 1 410, 2 000 or 2 830 mg/kg-bw of benzyl alcohol in water reported an LD₅₀ of 1 570 mg/kg-bw and clinical signs of lethargy, prostration, ataxia, increased respiration, half closed eyes and piloerection in all treated animals^{Footnote 1Footnote 2}.

A non-guideline study in Osborne-Mendel rats (5 per sex and dose) gavaged with unspecified doses reported an LD₅₀ of 1 230 mg/kg-bw with clinical signs of depression, coma and excitability^{Footnote 3}.

A non-guideline study in male Wistar rats (10 per dose) gavaged with a single dose of 1 045, 1 254, 1 463, 1 467, 2 090 or 2 195 mg/kg-bw of benzyl alcohol and observed for 14 days reported an LD₅₀ of 1 620 mg/kg-bw. At a dose of 1 254 mg/kg-bw or higher, clinical signs of sedation, side and prone-position, bloody eyes and reduction of general condition were reported^{Footnote 2}.

Dermal Route of Exposure: A study conducted similarly to US EPA OTS guideline 798.1100 in rabbits (4 per sex) exposed to a single dose of 2 000 mg/kg-bw of benzyl alcohol under occlusive conditions reported no mortality or adverse clinical signs of toxicity. The LD₅₀ was greater than 2 000 mg/kg-bw^{Footnote 2}.

Inhalation Route of Exposure: In an OECD TG 403-compliant study, Wistar rats (5 per sex and concentration) were exposed to a concentration of 3.3 or 4.2 mg/L of benzyl alcohol as an aerosol for 4 hours. No mortality was reported. Rats exposed to a concentration of 4.2 mg/L showed clinical signs of piloerection and slight bradypnea^{Footnote 2}.

The available data do not meet the classification criteria for a category of Specific Target Organ Toxicity – Single Exposure.

Specific Target Organ Toxicity – Repeated Exposure:

Does not meet criteria

Oral Route of Exposure: A 16-day study with rats and mice administered a dose of 120, 250, 500, 1 000 or 2 000 mg/kg-bw/day of benzyl alcohol in corn oil by gavage for 12 days of the 16-day period demonstrated lethargy, blood around the mouth and nose, subcutaneous hemorrhages, blood in the urinary and gastrointestinal tract and urinary bladder and death in animals at the two highest doses tested. Animals in the 120, 250 and 500 mg/kg-bw/day dose groups did not demonstrate any adverse effects^{Footnote 34}. The doses at which effects were observed exceed the guidance values for classification.

Rats and mice administered a dose of 50, 100, 200, 400 or 800 mg/kg-bw/day of benzyl alcohol in corn oil by gavage for 5 days per week for 13 weeks exhibited a staggering gait, respiratory difficulty and lethargy as well as lesions and necrosis of the dentate gyrus of the hippocampus at the 800 mg/kg-bw/day dose^{Footnote 34}. This dose exceeds the guidance values for classification.

In an OECD TG 451-compliant study in rats gavaged with 200 or 400 mg/kg-bw/day or in mice gavaged with 100 or 200 mg/kg-bw/day of benzyl alcohol in corn oil for 5 days per week for 2 years, no significant signs of systemic toxicity were observed^{Footnote 34}.

In another study, mice (10 per sex and dose) were administered a dose of 0, 160, 325, 645, 1 300 or 2 595 mg/kg-bw of benzyl alcohol once daily by gavage for 8 days. Hunched posture, piloerection, ataxia and subdued behaviour were seen in mice in the 3 highest dose groups. Animals receiving 1 300 or 2 595 mg/kg-bw/day of benzyl alcohol also became prostrate and showed signs of ataxia, body tremors, dyspnea, hypoactivity, hypothermia and polypnea^{Footnote 35}.

A study in which rats (5 per sex and dose) received a dose of 50, 150 or 500 mg/kg-bw/day of benzyl alcohol in propylene glycol for 6 days per week for 3 weeks did not demonstrate any signs of systemic toxicity^{Footnote 37}.

Dermal Route of Exposure: No data available

Inhalation Route of Exposure: An OECD TG 412-compliant study of Sprague-Dawley rats (10 per sex and concentration) exposed via nose-only inhalation to a concentration of 0, 0.041, 0.102, 0.290 or 1.072 mg/L of benzyl alcohol in aerosol or in a mixed aerosol/vapour atmosphere for 6 hours per day, 5 days per week for 4 weeks reported no significant signs of systemic toxicity^{Footnote 2}.

Another OECD TG 412-compliant study in which male rats (6 per concentration) exposed to a concentration of 216 to 270 parts per million (ppm) of benzyl alcohol (physical form unspecified) for 4 hours per day for 4 weeks reported no significant signs of systemic toxicity^{Footnote 2}.

The available data do not meet the classification criteria for a category of Specific Target Organ Toxicity – Repeated Exposure.

Aspiration Hazard:

No data available

No human data are available and benzyl alcohol is not a liquid hydrocarbon.

Biohazardous Infectious Materials:

Not applicable

Benzyl alcohol is not a microorganism, protein, or nucleic acid.

Physical hazards

Explosives:

Not evaluated*

* Explosives are excluded from the HPAand its regulations. Explosives are regulated under the Explosives Act. For more information, visit Natural Resources Canada.

Flammable Gases:

Not applicable

Benzyl alcohol is not a gas. The classification criteria for Flammable Gases do not apply to this substance.

Aerosols:

Not evaluated

Classification of a hazardous product in the Aerosols hazard class is product dependent.

Oxidizing Gases:

Not applicable

Benzyl alcohol is not a gas. The classification criteria for Oxidizing Gases do not apply to this substance.

Gases Under Pressure:

Not applicable

Benzyl alcohol is not a gas. The classification criteria for Gases Under Pressure do not apply to this substance.

Flammable Liquids:

Category 4

Benzyl alcohol has a flash point of 93°C (closed cup)^{Footnote 38}.

The available data meet the classification criteria for Flammable Liquids – Category 4 [subsection 7.6.1(2) of the HPR].

Flammable Solids:

Not applicable

Benzyl alcohol is not a solid. The classification criteria for Flammable Solids do not apply to this substance.

Self-reactive Substances and Mixtures:

Does not meet criteria

Benzyl alcohol has a boiling point of 206°C^{Footnote 38}. Self-reactive substances and mixtures must have a self-accelerating decomposition temperature of 75°C or less to meet the minimum classification criteria for a category of this hazard class [subsection 7.8.1(3) of the HPR].

The available data do not meet the classification criteria for a category of Self-reactive Substances and Mixtures.

Pyrophoric Liquids:

Does not meet criteria

Benzyl alcohol has a flash point of 93°C (closed cup)^{Footnote 38}. Pyrophoric liquids react at room temperature.

The available data do not meet the classification criteria for a category of Pyrophoric Liquids.

Pyrophoric Solids:

Not applicable

Benzyl alcohol is not a solid. The classification criteria for Pyrophoric Solids do not apply to this substance.

Self-heating Substances and Mixtures:

Does not meet criteria

Benzyl alcohol has a boiling point of 206°C^{Footnote 38}, which is well above the maximum spontaneous ignition temperature of 50°C for classification [subsection 7.11.1(3) of the HPR].

The available data do not meet the classification criteria for a category of Self-heating Substances and Mixtures.

Substances and Mixtures Which, in Contact with Water, Emit Flammable Gases:

Excluded from classification

Benzyl alcohol has a chemical structure that does not contain metals or metalloids, and is, therefore, excluded from classification [paragraph 7.12.1(1)(a) of the HPR].

Oxidizing Liquids:

Does not meet criteria

Paragraph 7.13.1(1)(b) of the HPR excludes from classification any organic liquid that contains oxygen, fluorine or chlorine if those elements are chemically bonded only to carbon or hydrogen. Benzyl alcohol contains oxygen which is chemically bonded only to carbon and hydrogen.

Oxidizing Solids:

Not applicable

Benzyl alcohol is not a solid. The classification criteria for Oxidizing Solids do not apply to this substance.

Organic Peroxides:

Not applicable

Benzyl alcohol is not an organic peroxide. The classification criteria for Organic Peroxides do not apply to this substance.

Corrosive to Metals:

No data available

No data are available to determine whether benzyl alcohol meets the classification criteria for a category of Corrosive to Metals. Although compatibility information related to benzyl alcohol and stainless steel or aluminum is available in chemical resistance charts, these listings are solely a guide and require confirmation by a chemical resistance test^{Footnote 39Footnote 40Footnote 41}.

Combustible Dusts:

Not applicable

Benzyl alcohol is not a solid. The classification criteria for Combustible Dusts do not apply to this substance.

Simple Asphyxiants:

Not applicable

Benzyl alcohol is not a gas. The classification criteria for Simple Asphyxiants do not apply to this substance.

Chemicals Under Pressure:

Not evaluated

Classification of a hazardous product in the Chemicals Under Pressure hazard class is product dependent.

Regulatory and other information

Regulatory information:

Hazardous substance assessments are prepared by Health Canada as educational and information resources. Under the HPA, suppliers of hazardous products must, upon the sale or importation of a hazardous product, provide a safety data sheet and label that meet the requirements set out in the HPR.

Other information:

The information and classifications contained in these hazardous substance assessments are based on publicly available sources, such as peer-reviewed literature or reports by international bodies. New information, including proprietary information, could have an impact on the classification of substances or hazardous products containing them. It is the responsibility of the supplier to ensure the accuracy, sufficiency and reliability of their hazardous product classifications.

Last updated:

2025

Prepared by:

Workplace Hazardous Materials Bureau, Health Canada