INTRODUCTION

Hospital personnel, both those involved directly and indirectly with promoting the well-being of patients, and in maintaining the proper functioning of the hospital, may be exposed to chemicals with potential reproductive, respiratory and carcinogenic hazards. Exposure to anaesthetic gases is linked to genotoxic effects among operating theatre staff.¹ Sterilants, such as ethylene oxide, methyl methacrylate, xylene gas, microbial vapor from the incubator and various organic reagents and solvents may induce genetic damage, cancer, congenital malformation, still-birth, and spontaneous abortion.^2,3,4

Inhaled substances may directly injure the pulmonary epithelium at various levels of the respiratory tract, leading to a wide range of disorders from tracheitis and bronchiolitis to pulmonary oedema.⁵ They may also be absorbed, resulting in systemic toxicity. Strikingly, under many exposure situations, the inhalation and absorption routes may be common.⁶ Thus, determining the mechanism of respiratory insufficiency, whether it is a result of direct injury of respiratory tract or systemic toxicity, is difficult. Accordingly, it is best to classify inhaled agents as airway irritants and systemic toxins.⁵ For instance, formaldehyde exposure has been found to be associated with nasopharyngeal tumours and increased risk of cancer of certain sites, particularly the brain and lymphohematopoietic system.⁷

In the acute and chronic pulmonary responses, the lungs are primarily affected by toxicity.⁸ Thus, this commentary discusses the gaseous inhalation hazards associated with laboratory and hospital staff.

Pathogenesis

Inhaled toxic vapour, mist, gases or dust particles (less than 10 micron thick in diameter) may rapidly pass through capillaries of the lungs and enter the circulatory system, which can result in inflammation of the respiratory tract, occupational asthma due to allergic reactions to these substances and pneumoconiosis.⁹ However, concentration of inhaled gases, duration of inhalation and particle size may determine the degree of toxicity in the system.¹⁰

Inhalants and Exposure Risks

Formaldehyde

Formaldehyde is a colourless, flammable gas with strong irritating smell. When dissolve in water it is called formalin. As a chemical it is widely used in hospitals as disinfectant, tissue preservative.¹¹ Acute airborne formaldehyde exposure leads to eye irritation, upper respiratory tract irritation, lower airway irritation (cough, chest tightness, and wheezing), pulmonary oedema, inflammation, pneumonia and eventually death.¹¹ Evidence has it that formaldehyde can provoke skin reactions in sensitized subjects, not only by contact but also by inhalation.^12,13 Studies have linked chronic inhalation of high concentration of formaldehyde to cancers such as leukaemia.¹⁴ Also, a positive association has been observed between exposure to formaldehyde and sino-nasal cancer.^12,15 An investigation of reproductive function in female workers exposed to formaldehyde in the garment industry revealed increased incidence of menstrual disorders, inflammatory disease of the reproductive tract, sterility, anaemia, and low birth weights among offspring. Interestingly, some studies suggest that inhalation of formaldehyde leads to increased micronuclei frequencies in nasal and/or buccal mucosa cells.^12,13,16

Waste anaesthetic gases  

Waste anaesthetic gases are small amounts of volatile anaesthetics gases that leak from the patient’s anaesthetic breathing circuit into the air of operating rooms during delivery of anaesthesia. These gases may also be exhaled by patients recovering from anaesthesia. Waste anaesthetics gases include both nitrous oxide and halogenated anaesthetics’ such as halothane, enflurane, isoflurane, desflurane, sevoflurane, and methoxyflurane.¹⁷ These gases pose a lot of health hazard to hospital workers.¹⁸ It is understood that exposure to high concentrations of waste anaesthetic gases even for a short time may cause health hazards such as headache, irritability, fatigue, nausea, drowsiness, difficulties with judgment, birth defects, infertility, Liver and kidney disease.^1,19

Some studies have reported that long-term exposure to low concentrations of waste anaesthetic gases causes miscarriages, genetic damage, and cancer among operating-room workers.²⁰ Strikingly is the report that waste anaesthetic gases induced miscarriages in the spouses of exposed workers and caused birth defects in their offspring.²⁰

Xylene

Xylene is a colourless aromatic hydrocarbon with an irritating smell. It is widely used in the hospital laboratory for tissue processing and in the industries for production of paint, dye and polish. Xylene is mixable with a lot of organic solvents. It is not soluble in water because it is less dense than water hence it floats on the surface of water.²¹ Nervous Toxicity of xylene is through inhalation, ingestion, eye or skin contact. The main effect of inhaling xylene is depression of central system, with symptoms like headache, dizziness, mental confusion, nausea and vomiting.^22,23 Exposure to xylene at a level of 200 ppm causes irritation of the lungs, chest pains and dyspnoea. Extreme exposure will cause pulmonary oedema.^22,24

Inhalation of xylene at the concentration of 100-200 ppm can lead to nausea and headache. Further increase to 200-500 ppm may result in dizziness, weakness, irritability and vomiting. Exposure to 800-10,000 ppm will also result to more complicated health issues such as confusion, loss of balance, and ringing sensation in the ear, while loss of consciousness and death may occur when exposed to concentration of >100,000 ppm.²¹

Conclusion

Studies have established the deleterious effect of gaseous inhalation which health workers are exposed to through inhalation, ingestion and body contact. Precautionary measures such as proper handling, disposal and decontamination of infectious material should be applied. The use of protective equipment such as disposable gloves, chemical goggles, lab coats, nose mask and chlorine water to decontaminate all the culture samples before disposal is recommended. All the microbial culture and sensitivities should be done in a fume cupboard. Monitoring of the exposure limits of formaldehyde gas using formalin meter and proper labelling of all the chemical bottles and warning labels are equally advised.

 AUTHORS’ CONTRIBUTIONS

UKE conceptualized the work, ET and OME searched for supportive literatures while HUC and OJA wrote and revised the manuscript.