Benzene

Exposure related observations in humans: other data

Administrative data

Endpoint:

exposure-related observations in humans: other data

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, non-guideline statistical evaluation of human workplace generated data. Statistical analysis of previous data generated contributing to a weight of evidence.

Data source

Reference

Reference Type:

publication

Title:

Evidence that humans metabolize benzene via two pathways.

Author:

Rappaport SM, Kim S, Lan, Q, Vermeulen R, Waidyanatha S, Zhang L, Li G, Yin S, Hayes RB, Rothman N and Smith MT.

Year:

2009

Bibliographic source:

Environ. Health Persp., 117, 946-952

Materials and methods

Type of study / information:

Michaelis-Menten-like models were applied to levels of urinary benzene metabolites and the corresponding air concentrations for 263 non-smoking Chinese females.

Endpoint addressed:

basic toxicokinetics

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Statistical evaluation of human urinary metabolite data to investigate whether human metabolism of benzene is better fitted by a kinetic model having two pathways rather than one.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Benzene

EC Number:

200-753-7

EC Name:

Benzene

Cas Number:

71-43-2

Molecular formula:

C6H6

IUPAC Name:

benzene

Details on test material:

The Shanghai workers were exposed to essentially pure benzene, whereas all Tianjin workers were co-exposed to toluene, and some were exposed to low levels (< 5 ppm) of other volatile organic compounds.

Method

Ethical approval:

confirmed and informed consent free of coercion received

Details on study design:

Study subjects derive from two cross-sectional molecular epidemiology studies of Chinese benzene-exposed and control workers carried out in Shanghai in 1992 and in Tianjin in 2000–2001.

Exposure assessment:

estimated

Details on exposure:

Workers with occupational exposure to benzene were employed in factories where benzene was present, and control workers were exposed to airborne benzene in the general environment, as determined by measurement of urinary benzene. The Shanghai workers were exposed to essentially pure benzene, whereas all Tianjin workers were co-exposed to toluene, and some were exposed to low levels (< 5 ppm) of other volatile organic compounds.
The estimated median exposure to benzene among the non-smoking female subjects was 0.644 ppm, with 10th and 90th percentile values of 0.002 ppm and 8.97 ppm, respectively

Results and discussion

Results:

The results indicate that a non-smoking woman would metabolize about three times more benzene from the ambient environment under the two-pathway model (184 μM/ppm) than under the one-pathway model (68.6 μM/ppm).

Applicant's summary and conclusion

Conclusions:

The results indicate that a non-smoking woman would metabolize about three times more benzene from the ambient environment under the two-pathway model (184 μM/ppm) than under the one-pathway model (68.6 μM/ppm).