Phenol

Exposure related observations in humans: other data

Administrative data

Endpoint:

exposure-related observations in humans: other data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets scientific standards but partly limited documentation (e.g. details about volunteers).

Data source

Reference

Reference Type:

publication

Title:

The production of urinary phenols by gut bacteria and their possible role in the causation of large bowel cancer

Author:

Bone, E, Tamm A, Hill M

Year:

1976

Bibliographic source:

Am J Clin Nutrit 29: 1448-1454

Materials and methods

Type of study / information:

Measurement of phenol excreted via urine as a bacterial amino acid metabolite in humans.

Endpoint addressed:

not applicable

Principles of method if other than guideline:

Conjugated phenol in urine of volunteers as a results of bacterial amino acid metabolism determined.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Phenol

EC Number:

203-632-7

EC Name:

Phenol

Cas Number:

108-95-2

Molecular formula:

C6H6O

IUPAC Name:

phenol

Details on test material:

no details

Method

Ethical approval:

not specified

Details on study design:

A 24 h-urine sample was collected from each of 10 healthy volunteers; urinary phenol measured by GC methods after enzymatic hydrolysis of conjugates.

Exposure assessment:

not specified

Details on exposure:

Presumably no exposure of the volunteers to phenol except via the gut by bacterial metabolism of amino acids within the framework of protein digestion.

Results and discussion

Results:

Excretion of phenol conjugates via urine. Bacterial tyrosine metabolism assumed as possible source.
The mean excretion rate in 10 volunteers was 9.8 mg/day/person (ca. 160 µg/kg bw/day).
In 4 normal women the mean value was 7.0 mg/day/person (range 2.7 -10.7 mg/day). In 6 men the mean value was 11.7 mg/day/person (range 6.8 -20.3). Interindividual differences and day-to-day variations (demonstrated in further examinations in one woman and 2 men) were shown and might be related to nutrition (ingestion of proteins).
In further in vitro experiments with isolated gut bacteria it has been shown that aerobic bacteria (but not anaerobic bacteria) fed with tyrosine produced phenol.

Applicant's summary and conclusion

Conclusions:

Phenol is detected in urine of non-exposed humans; the mean excretion rate ist 9.8 mg/day/person (ca. 160 µg/kg bw/day). It is suggested that phenol is liberated in the gut of humans due to aerobic baterial metabolism of amino acids (e.g. tyrosine).

Executive summary:

Study meets scientific standards but partly limited documentation (e.g. details about volunteers).

A 24 h-urine sample was collected from each of 10 healthy volunteers; urinary phenol was measured by GC methods after enzymatic hydrolysis of conjugates. There was presumably no exposure of the volunteers to phenol except via the gut by bacterial metabolism. The mean excretion rate was 9.8 mg/day/person (ca. 160 µg/kg bw/day). Interindividual differences and day-to-day variations (demonstrated in further examinations in one woman and 2 men) were shown and might be related to nutrition (ingestion of proteins).

In further in vitro experiments with isolated gut bacteria it has been shown that aerobic bacteria fed with tyrosine produced phenol.

Conclusion: Phenol is detected in urine of non-exposed humans; the mean excretion rate ist 9.8 mg/day/person (ca. 160 µg/kg bw/day). It is suggested that phenol is liberated in the gut of humans due to aerobic baterial metabolism of amino acids (e.g. tyrosine).