A health-based recommended occupational exposure limit for nitrous oxide using experimental animal data based on a systematic review and dose-response analysis

Occupational hazards and pregnancy in orthopaedics: female surgeons are at increased risk of infertility and pregnancy complications

Female surgeons have increased rates of infertility and pregnancy complications compared to the general population. Reported infertility rates in surgeons are 32% compared to 10.9% in the general population. Reported pregnancy complication rates in surgeons range from 25% to 35%. In the orthopaedic operating theatre occupational hazards that have an effect on pregnancy outcomes include radiation, exposure to methyl methacrylate in bone cement, surgical smoke, sharps injuries, exposure to anaesthetic waste gases and the effects of the physical demands of surgery including prolonged work hours and night shift work. Outside the operating theatre exposure to nitrous oxide, formaldehyde, surgical scrub also have evidence of negative pregnancy outcomes. This review summarizes the available evidence as it relates to specific occupational hazards that face health workers in an orthopaedic operating theatre. This information, while targeted at orthopaedic health workers, is also relevant to anaesthetists, radiographers, nursing staff, medical device company representatives and female surgeons in other specialties.

Establishing a health-based recommended occupational exposure limit for isoflurane using experimental animal data: a systematic review protocol

BACKGROUND

Isoflurane is used as an inhalation anesthetic in medical, paramedical, and veterinary practice. Epidemiological studies suggest an increased risk of miscarriages and malformations at birth related to maternal exposure to isoflurane and other inhalation anesthetics. However, these studies cannot be used to derive an occupational exposure level (OEL), because exposure was not determined quantitatively and other risk factors such as co-exposures to other inhalation anesthetics and other work-related factors may also have contributed to the observed adverse outcomes. The aim of this systematic review project is to assess all available evidence on the effects of isoflurane in studies of controlled exposures in laboratory animals to derive a health-based recommended OEL.

METHODS

A comprehensive search strategy was developed to retrieve all animal studies addressing isoflurane exposure from PubMed, EMBASE, and Web of Science. Title-abstract screening will be performed by machine learning, and full-text screening by one reviewer. Discrepancies will be resolved by discussion. We will include primary research in healthy, sexually mature (non human) vertebrates of single exposure to isoflurane. Studies describing combined exposure and treatments with >  = 1 vol% isoflurane will be excluded. Subsequently, details regarding study identification, study design, animal model, and intervention will be summarized. All relevant exposure characteristics and outcomes will be extracted. The risk of bias will be assessed by two independent reviewers using an adapted version of the SYRCLE's risk of bias tool and an addition of the OHAT tool. For all outcomes for which dose-response curves can be derived, the benchmark dose (BMD) approach will be used to establish a point of departure for deriving a recommended health-based recommended OEL for 8 h (workshift exposure) and for 15 min (short-term exposure).

DISCUSSION

Included studies should be sufficiently sensitive to detect the adverse health outcomes of interest. Uncertainties in the extrapolation from animals to humans will be addressed using assessment factor. These factors are justified in accordance with current practice in chemical risk assessment. A panel of experts will be involved to reach consensus decisions regarding significant steps in this project, such as determination of the critical effects and how to extrapolate from animals to humans.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022308978.

Occupational Exposure to Inhalational Anesthetics and Teratogenic Effects: A Systematic Review

(1) Background: In the current healthcare environment, there is a large proportion of female staff of childbearing age, so, according to existing conflicting studies, the teratogenic effects that inhalational anesthetics may have on exposed pregnant workers should be assessed. This investigation aims to analyze the teratogenic effects of inhalational anesthetics in conditions of actual use, determining any association with spontaneous abortion or congenital malformations. (2) Methods: A systematic review was carried out according to the PRISMA statement based on PICO (problem of interest–intervention to be considered–intervention compared–outcome) (Do inhalational anesthetics have teratogenic effects in current clinical practice?). The level of evidence of the selected articles was evaluated using the SIGN scale. The databases used were PubMed, Embase, Scopus, Web of Science, Google academic and Opengrey. Primary studies conducted in professionals exposed to inhalational anesthetics that evaluate spontaneous abortions or congenital malformations, conducted in any country and language and published within the last ten years were selected. (3) Results: Of the 541 studies identified, 6 met all inclusion criteria in answering the research question. Since many methodological differences were found in estimating exposure to inhalational anesthetics, a qualitative systematic review was performed. The selected studies have a retrospective cohort design and mostly present a low level of evidence and a low grade of recommendation. Studies with the highest level of evidence do not find an association between the use of inhalational anesthetics and the occurrence of miscarriage or congenital malformations. (4) Conclusions: The administration of inhalational anesthetics, especially with gas extraction systems (scavenging systems) and the adequate ventilation of operating rooms, is not associated with the occurrence of spontaneous abortions or congenital malformations.

Nitrous oxide-induced reproductive risks: Should recreational nitrous oxide users worry?

BACKGROUND

Nitrous oxide (N₂O) is a frequently used anaesthetic. Since the year 2000, recreational use of N₂O, also known as 'laughing gas', became popular as a recreational drug due to its mild psychedelic effect. In the 1980s, several reports warned against N₂O-induced reproductive risks among healthcare personnel, questioning the occupational safety of N₂O in health care.

METHODS

Data about the reproductive risks of N₂O were collected from literature.

RESULTS

Particularly in the past, professionals working in dental and midwifery practices, operating theatres and ambulance transport were exposed to high levels of N₂O. Adverse reproduction effects included congenital anomalies, spontaneous abortion and reduced fertility rates in females. Following occupational measures, like maximal exposure limits for ambient N₂O, this occupational risk was considerably reduced. Recreational users of N₂O, however, voluntarily and repeatedly expose themselves to (very) high doses of N₂O. As such, they exceed the health exposure limits some hundred times, but they are fully unaware of the related reproductive risks.

CONCLUSION

We advocate to increase the awareness in recreational N2O-users about its potential reproductive risks, especially in heavy users, pregnant users or those who intend to become pregnant.