Observations of Reproductive Functions among Workers
in an Oil Refinery -- Louisiana
In 1981, male employees in the wastewater treatment plant of an
oil refinery in Louisiana expressed concern about an apparent
excessive rate of spontaneous abortions among their wives. By
means
of a questionnaire, consultants to the company studied the results
of
pregnancies among wives of the male workers (1). The reported rate
(17%) of spontaneous abortions during the period the husbands were
employed at the plant (from 1976, when the plant opened, to 1981)
was
over twice the rate (8%) for the period before the husbands began
working at the plant (1934-1976) (p = 0.07).
Because of methodologic limitations of the study and continuing
concern among the workers, union representatives of workers at the
plant requested an investigation by the National Institute for
Occupational Safety and Health (NIOSH). In 1982, NIOSH
investigators
conducted a cross-sectional evaluation of male reproductive
functions
among the workers. Observations of sperm morphology and tests for
sperm concentration were made on the semen of 42 of the 62 male
employees in the plant who had not had vasectomies or other known
causes of infertility (2,3). For comparison, 74 persons working in
other areas of the refinery or in administrative positions not at
the
same site were similarly examined.
Adjusting the data for differing periods of sexual abstinence,
the
mean sperm concentrations for the control group (79.9 million
spermatozoa/cc of semen) did not differ significantly from that
(68.2
million/cc) of the workers at the wastewater treatment plant (p =
0.16). The observed proportions of sperm with abnormal morphology
for
the test group (49%) and the comparison group (45%) were also
similar.
Using a stepwise regression model, investigators also explored
the
relationship between sperm concentration and the number of hours
worked in the plant during the previous 6 months. The duration of
sexual abstinence before sample collection was most closely
correlated
with sperm concentration, while the number of hours worked
correlated
poorly with sperm concentration (p = 0.22). Sperm concentration
was
not significantly correlated with age, history of urologic
abnormality, recent fever or illness, smoking, use of alcohol,
marijuana, and other drugs, or frequent sauna or baths. Moreover,
none of these factors was significantly associated with observed
abnormalities in sperm morphology.
Reported by Reproductive Health Activity, Industrywide Studies Br,
Hazard Evaluations and Technical Assistance Br, Div of
Surveillance,
Hazard Evaluations, and Field Studies, National Institute for
Occupational Safety and Health, CDC.
Editorial Note
Editorial Note: Since azoospermia (absence of motile spermatozoa
in
the semen) and oligospermia (deficiency of spermatozoa in the
semen)
were noted in 1977 among chemical workers exposed to
dibromochloropropane (DBCP), the effect of occupational exposures
on
semen has received increasing attention as an index of
occupationally
impaired reproductive function. The degree of reproductive risk
that
may be inferred from observed changes in sperm involves several
links. First, recent evidence from human studies confirms earlier
results from animal studies that certain exposures of males can
increase the chance of spontaneous abortion in their mates,
independent of female reproductive factors (4). Second, increases
in
abnormally shaped spermatozoa and decreases in the concentration of
spermatozoa in the semen have been associated with infertility
(5,6)
and, to some extent, with a greater frequency of spontaneous fetal
loss in the mates (7,8). Finally, research in animals and humans
suggests that the concentration and morphology of spermatozoa may
be
sensitive indicators of impaired spermatogenesis and testicular
function (9).
The findings presented here indicate a lack of effect of
occupational exposures on the concentration and morphology of
spermatozoa among workers at the time of study. Several factors
must
be considered in viewing these results in light of those of the
earlier questionnaire survey. A comparison of rates of spontaneous
abortion for 1976-1981 with those in 1934-1976 may involve a recall
bias that could reduce the reliability of the findings. In
addition,
the questionnaire survey involved a small population with a
necessarily small expectation of spontaneous abortions, which
increases the possible influence of random fluctuations in a
biologic
event.
If, however, it is assumed that the results of the
questionnaire
accurately reflected the situation at that time, there are
scientifically credible explanations for an observed increase in
the
rate of spontaneous abortions, such as: (1) genetic defects may
have
been present in the spermatozoa of some workers, leading to
fertilizations by abnormal spermatozoa and subsequent fetal loss;
(2)
a significant toxic exposure may have been present in the past, but
the effects were not detectable during the period of the NIOSH
study;
(3) spermatic abnormalities capable of producing fetal loss may
have
been present but not detectable by the methods used by NIOSH; and
(4)
embryotoxic substances on fomites, such as contaminated clothing or
skin of the workers, may have been transmitted to the wives and led
to
fetal loss after normal fertilization.
References
Morgan RW, Kheifets L, Obrinsky DL, Whorton MD, Foliart DE.
Fetal
loss and work in a waste water treatment plant. J Amer Public
Health 1984;74:499-501.
National Institute for Occupational Safety and Health. Health
hazard evaluation report. Cincinnati, Ohio: National
Institute
for Occupational Safety and Health, l983. (HETA 82-387-1392).
Rosenberg MJ, Wyrobek AJ, Ratcliffe J, et al. Sperm as an
indicator of reproductive risks among petroleum refinery
workers.
Br J Ind Med 1985;42:123-7.
Hemminki K, Kyyronen P, Niemi M-L, et al. Spontaneous
abortions
in an industrialized community in Finland. Am J Public Health
1983;73:32-7.
Spira A, Mayauz MJ, Schwartz D, Jouannet P, Czyglik F, David G.
Quelques aspects methodologiques d'une enquete retrospective
comparant 484 hommes feconds et 2,768 hommes infeconds. Rev
Epidem et Sante Publ 1980;28:13-20.
Aitken RJ, Best FS, Richardson DW, et al. An analysis of sperm
function in cases of unexplained infertility: conventional
criteria, movement characteristics, and fertilizing capacity.
Fertil Steril 1982;38:212-21.
Czeizel E, Hancsok M, Viczian M. A habitualisan vetelo
asszonyok
ferjeinel vegzett ondovizsgalat jelentosege. Orv Hetil
1967;108:1591-5.
Furuhjelm M, Jonson B, Lagergren CG. The quality of human
semen
in spontaneous abortion. Int J Fertil 1962;7:17-21.
Wyrobek AJ, Gordon LA, Burkhart JG, et al. An evaluation of
human
sperm as indicators of chemically induced alterations of
spermatogenic function: a report of the U.S. Environmental
Protection Agency Gene-Tox Program. Mutat Res 1983;115:73-148.
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