Studies
on the effects of toxic
(poisonous) substances on pregnancy do not always agree.
For many substances, no studies have been done. If you have
a question about a substance, ask your health care provider.
He or she may be able to check with national sources for
the latest information.
Substances
that are known to harm a fetus if a woman is exposed during
pregnancy are called teratogens.
They can cause miscarriages, birth
defects, or problems that appear later in life.
There are only a few things known to be teratogens, some of which are drugs.
What may be toxic to one fetus may not be to another--it depends on how sensitive
the fetus is to that substance. The effects of teratogens on pregnancy depend
on factors such as:
- The
type of substance: Some things are more toxic than others.
- The
amount of exposure: How much and how long?
- When
a woman had contact with the substance: Before pregnancy,
or early or late in pregnancy?
Some substances
found in the workplace are known to be harmful (see table). But
there are many other substances in question. Talk to your
health care provider about specific substances. The presence
of a toxic substance in the workplace does not mean that workers
are exposed to dangerous levels of it.
Good ventilation and equipment such as gloves, protective clothing, or respirators
can prevent exposure. If protection is not possible, talk with your employer. You
may be able to move to another job on a temporary basis.
Substances
in the Workplace Known to Harm the Fetus
| Substance |
Workers
Exposed |
Effects |
Chemotherapy
(methotrexate
(Mexate)
and aminopterin) |
(eg, Health
care workers, such as nurses and pharmacists |
Increased
rate of miscarriage,
various birth
defects |
| Lead |
Workers
in industries involving lead smelting, paint
manufacture and use, printing, ceramics, glass
manufacturing, pottery glazing, and battery manufacturing;
toll booth attendants and people working on heavily
traveled roads |
Increased
rate of miscarriage and stillbirths |
| Ionizing
radiation |
X-ray
technicians; some
physicists and researchers |
Growth
and mental retardation |
The type
of radiation found in X-rays is called ionizing radiation.
It can be harmful to a fetus. If you are pregnant, it is
best to avoid exposure to ionizing radiation if you can.
If you are exposed to ionizing radiation on the job and are
planning a pregnancy, you should ask for monthly readings
of the amount of radiation to which you have been exposed.
The amount is reported in units called rads. The U.S. Occupational
Safety and Health Administration sets limits for workers'
exposure to ionizing radiation at 1.25 rads per calendar
quarter or 5 rads per year. The National Council on
Radiation Protection suggests that occupational ionizing
radiation exposure to the fetus should not exceed 0.5 rad
total dose for the pregnancy or 0.05 rad in any 1 month of
the pregnancy. If you have a chest X-ray, the radiation exposure
to your fetus will
be about 0.008 rad.
Radiation
from video display terminals, color televisions, and microwave
ovens is called nonionizing radiation. Current research suggests
that this radiation is not harmful.
