Appendix D - Dossier (PDF) - Tera

date: 20–JUL–2005
5. Toxicity Substance ID: 71–43–2
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Type: other: effects on female reproductive hormones
Method: SUBJECTS
The study population comprised 50 female workers (mean age
28.1 yr, mean period of employment 7.3 yr) from an undefined
petrochemicals facility in the Peoples Republic of China,
with potential exposure to benzene, toluene and xylene
(isomer undefined). An "internal control group" was
recruited from the locale of the plant (35 subjects, mean
age 27.9 yr) while an "external control group" (35 subjects)
was recruited from the vicinity of a plant manufacturing
chemical fibres. The selection criteria included avoidance
of oral contraceptives for over 6 mo, greater than 1 yr
since having an abortion, no more than 1 abortion or
miscarriage and no history of reproductive disease.
EXPOSURE ASSESSMENT
Air was collected from the breathing zone using a 100 ml
syringe, which was sealed and subsequently analysed using GC
for benzene, toluene and xylene (no information on timing or
frequency). Ambient exposure data were collected in the
morning, afternoon and evening on 3 consecutive days.
ANALYSIS OF HORMONE LEVELS
A 5 ml early morning urine sample was collected from each
subject and stored at –20 degrees C (no further details of
number or collection frequency or storage). Samples were
analysed by GC for FSH, pregnanediol–3–glucuronide and
(undefined) estrone conjugate.
MENSTRUAL CYCLE CHARACTERISTICS
Each subject maintained a daily record of menstrual cycle
details (no further information).
STATISTICAL METHODS
The data were analysed using one way ANOVA, Newman–Keuls
test and Chi Square test. Hormone levels are presented as
the geometric mean.
Remark: Reviewer’s note: Original paper in Chinese, information
obtained from translation, some study details unclear.
Appendix D: Benzene SIDS Dossier
The authors conclude that exposure to low concentrations of
benzene, toluene and xylene can interfere with normal levels
of FSH, oestrogens and progesterones in the
hypothalmic–pituitay–ovarian axis in female workers. However
there are significant shortcomings in the exposure
assessment underpinning this conclusion, and only graphical
data (with no statistical indicators) are presented in the
results. These may limit the overall reliability of the
paper.
It is also stated that around one–fifth of the exposure
measurements were 20–fold greater than the prevailing
Chinese national standard of 40 mg/m3 (13 ppm) ie a
significant number of subjects were exposed to whole–shift
benzene concentrations of 800 mg/m3 (260 ppm). More
– 602/957 –