Exposure to Anesthetic Gases:
Effects on Pregnancy and Health
©G.M. Woerlee, 2005–2023
Work in operating theaters means exposure to high levels of stress and possible exposure to trace concentrations of waste anesthetic gases. Early in the 1970's concern arose about the possible effects of the risks of exposure to trace concentrations of waste anesthetic gases exerting effects upon nervous system and other body functions. Evidence for the reality of these concerns was seemingly confirmed by articles showing that:
- those working in operating theaters without adequate removal of trace concentrations of waste anesthetic gases reported experiencing more headaches, decreased reaction time, memory impairment, nausea and tiredness than healthcare workers working outside the operating theater (Saurel-Cubizolles 1992),
- men working in operating theaters had a higher than normal chance of developing liver disease, and their wives had a higher than normal chance of giving birth to babies with birth defects (Cohen 1974),
- while women working in operating theaters had a higher than expected chance of developing cancer, liver disease, renal disease, or having a miscarriage (Cohen 1971, Cohen 1974),
- as well as having a higher than normal chance of delivering a baby with a birth defect (Knil-Jones-1972, Corbett 1974).
All these general health and reproductive problems were attributed to trace concentrations of waste anesthetic gases in the operating theater air. Accordingly, an ad hoc committee of the American Society of Anesthesiologists (ASA) advised measures to reduce the trace concentrations of anesthetic gases in operating theaters (ASA advisory 1974). However, critical analyses of these studies during the later years of the 1980's revealed many of them to be seriously flawed. The main problem with all these earlier studies was that they were retrospective studies based upon voluntary responses to questionaires. Not everyone responds to such questionaires, and those most likely to respond are those who have had problems. This is why the results of these earlier studies were never confirmed by subsequent properly conducted prospective studies (Tannenbaum 1985, Mazze 1985, Buring 1985). So what is the truth regarding exposure to trace concentrations of waste anesthetic gases?
The concerns and the questions
Before proceeding any further, it is well worth examining the concerns of people about the possible effects of trace concentrations of anesthetic gases. These concerns are:
- What are the mental and psychological effects of exposure to trace concentrations of anesthetic gases?
- What are the effects of trace concentrations of anesthetic drugs on general health, development of cancer, liver disease, and kidney disease?
- What are the effects of trace concentrations of anesthetic gases upon pregnancy? Do trace concentrations of anesthetic gases increase the chance of miscarriage, of giving birth to an abnormal child, or of stillbirth?
Because most people working in operating theaters are young women in their reproductive years, it is well worth examining the results of normal pregnancies.
Pregnancy concerns
Pregnancy is an important life event, so it is only natural for everyone to be concerned. A pregnant woman has many questions, hopes, and fears. All hope for the delivery of a happy healthy baby. But not all pregnancies end this way. So what are the normal incidences, or percentage chances of events such as miscarriage, of ectopic pregnancy, of stillbirth, or of giving birth to a child with a birth defect?
The table below gives the percentage chances for miscarriage, ectopic pregnancy, and stillbirth for all births in Denmark from 1978 to 1992 (Nybo Andersen-2000). These statistics are comparable to those of other developed Western countries.
Chance of miscarriage, ectopic pregnancy, and stillbirth from Danish data for the years 1978-1992 derived from Nybo Andersen-2000
| Age group | Chance of Miscarriage (%) | Chance of Ectopic Pregnancy (%) | Chance of Stillbirth (%) |
|---|---|---|---|
| less than 20 | 10.6% | 1.6% | 0.4% |
| 20-24 | 8.9% | 1.5% | 0.4% |
| 25-29 | 9.5% | 2.0% | 0.4% |
| 30-34 | 12.0% | 3.1% | 0.4% |
| 35-39 | 19.7% | 4.6% | 0.4% |
| 40-44 | 40.8% | 6.3% | 0.4% |
| 45+ | 74.7% | 7.9% | 0.1% |
This table clearly shows that the most ideal age range for a woman to have children is in her 20's. Increasing maternal age is strongly associated with increased chance of miscarriage or ectopic pregnancy. Factors other than age predisposing to miscarriage are:
- A history of previous miscarriage is associated with increased chance of miscarriage in a subsequent pregnancy (Risch 1988).
- Alcohol abuse during pregnancy (Abel 1997).
- Psychological stress during pregnancy (Arck-2001, O'Hare 1995).
This brings us to the subject of the chance of giving birth to an abnormal baby, otherwise termed a baby with a birth defect. The chances of giving birth to a baby with a birth defect in different parts of the world are given in the table below. As with the chances of miscarriage, the most optimal age range for any woman to have a baby is in her 20's.
| Age group | % Birth Defects (Victoria 1983-1998) | % Birth Defects (Singapore 1994-2000) | % Birth Defects (Dallas-USA 1988-1994) |
|---|---|---|---|
| less than 20 | 3.5% | 2.8% | 3.5-3.7% |
| 20-24 | 3.2% | 2.3% | 3.5% |
| 25-29 | 3.3% | 1.6% | 3.9% |
| 30-34 | 3.4% | 2.2% | 3.9% |
| 35-39 | 4.2% | 3.2% | 4.4% |
| 40+ | 6.2% | 5.3% | 5.0% |
Trace concentrations of waste anesthetic gases and health - Current views
Most women working in the stressful environment of operating theaters are younger women in their reproductive years. The tables above clearly show there is about a 10% chance of miscarriage and a 3% chance of giving birth to a child with a birth deficit in the general populations of countries distributed across the world. These figures are significant. They mean that in any operating theater complex where many women work, one or more of these women will certainly experience a miscarriage or give birth to a child with a birth defect, even if there is no pollution of the air with trace concentrations of waste anesthetic gases.
So what is the current state of knowledge regarding the effects of trace concentrations of anesthetic gases? Careful analyses of all studies reveals there is no relationship between the presence of trace concentrations of waste anesthetic gases and abnormal health in people working in operating theaters. There is no increased chance of miscarriage, or of giving birth to babies with birth defects by women working in operating theaters, nor in the female partners of men working in operating theaters. In fact, careful review of studies performed during the 1970's reveal them to be flawed, and subsequent studies fail to show any relationship between cancer, liver and kidney disease, and disturbances of pregnancy related to trace concentrations of waste anesthetic gases (McGregor 2000).
Trace concentrations of waste anesthetic gases - Recommendations
Trace concentrations of anesthetic gases in the atmosphere of operating theaters have no known adverse effects on general health or pregnancy. Nonetheless, it is always better to limit exposure of trace concentrations of anesthetic gases to low concentrations you know are low, rather than take the chance of health problems due to unknown concentrations of these same anesthetic gases. For this reason, many countries have instituted, and enforce, strict regulations for acceptable levels of trace concentrations of waste anesthetic gases in operating theaters (McGregor 2000a, Mazze 1985). This is simply good workplace practice to ensure the health and wellbeing of all working there.
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