Introduction

Laboratory diagnostics provide the majority of information in contemporary medicine. According to the WHO data, laboratory tests account for 75–90% of various types of diagnostics, and over 70% of medical decisions are made on the basis of laboratory data [1,2]. According to the estimates by Business Stat, in 2023 the laboratory diagnostics market in Russia amounted to 413.2 million tests. Compared with the 2021 level (482.7 million tests), the figure fell by 14%. The main reason was a decline in the number of tests for COVID-19. However, the decline was mitigated by steady demand for ‘traditional’ tests: clinical blood tests and the ‘hospital quartet’ (detection of antibodies to HIV, hepatitis B and C, and syphilis) [3]. Consequently, the number of operational PCR laboratories has changed (decreased), and the nature and working conditions of specialists may have changed.

Domestic hygiene publications address occupational health issues in modern clinical diagnostic laboratories [4–7], yet comprehensive studies of working conditions and health risk factors for PCR laboratory staff are virtually non-existent. The most comprehensive findings relate to the thermal status of healthcare workers in these units, driven by the mandatory use of personal protective equipment (PPE) during the COVID-19 pandemic and its impact on heat exchange [8–11]. A comparative assessment of the working conditions of PCR laboratory staff during the COVID-19 pandemic and in non-pandemic times is of interest.

The aim of the study was to conduct a comparative assessment of the working conditions of healthcare workers in PCR laboratories during the COVID-19 pandemic and during a routine epidemic situation, in order to provide a physiological and hygienic justification for the duration of the working shift, the actual workload and the labour costs of staff when performing PCR testing.

Materials and methods

The study was carried out at the PCR laboratory of the State Budgetary Healthcare Institution ‘City Children’s Clinic No. 2’ in Volzhsky (1); the PCR laboratory of the Federal Budgetary Institution of Public Health ‘Centre for Hygiene and Epidemiology in the Volgograd Region’ (2), and the immunological laboratory of the State Budgetary Healthcare Institution ‘Volgograd Regional Centre for the Prevention and Control of AIDS and Infectious Diseases’ (3).

The measurement and assessment of physical factors in the workplace were carried out using standard methods and calibrated equipment for occupational health and safety studies. The microclimate parameters in the production areas of PCR laboratories were studied: temperature, relative humidity, and air velocity (measured using a Testo 400 instrument). A TKA-PKM-24 thermohygrometer was used to calculate the thermal stress index (TSI) of the air environment in accordance with the requirements of the Methodical Guidelines MUK 4.3.2756–10¹. Lighting environment parameters were measured using the ‘Ecolight-01’ luxmeter-luminance meter-pulsometer; sound levels were measured using the OKTAVA-110A-B3 sound level meter and spectrum analyser. Measurements and assessment of local vibration parameters complied with the requirements of GOST 31192.1–2004² and GOST 31192.2–2005³. An ASSISTANT V3RT analyser of accuracy class 10 was used. Further evaluation of all data obtained was carried out in accordance with SanPiN 1.2.3685–21⁴ and the ‘R 2.2.2006–05’ Guidelines⁵.

To assess the severity and intensity of work for PCR laboratory staff, time (chronometric) and-motion studies were carried out (a total of 7 person-shifts). All data obtained were processed using a variational-statistical method with the calculation of mean values (M) and representativeness errors (± m); the significance of differences was determined using Student’s t-test. The study was conducted in strict compliance with the ethical standards set out in the 1975 Declaration of Helsinki, as amended in 2008. Medical staff at the PCR laboratories completed the ‘Informed Voluntary Consent to Participate in the Study’ form, developed in accordance with the requirements of the local ethics committee of Volgograd State Medical University.

Results

The professional functions of a medical laboratory technician and a paramedic-laboratory technician in PCR laboratories involved working in the ‘dirty’ zone of the workstations (preparing reagents, preparing samples for amplification and loading samples into the amplifier) and in the ‘clean’ zone at the computer (interpreting amplification results using the amplifier’s software module, and handling documentation and reports). These tasks were carried out by the same employee, moving from one zone to the other. One of the key occupational factors affecting these specialists’ working conditions is biological, as their work involves potential contact with microorganisms of pathogenicity group II. During the pandemic, this primarily refers to the SARS-CoV-2 virus. According to the results of a special working conditions assessment (SWCA), PCR laboratories are classified as Class 3, Grade 3 hazardous due to biological factors (based on the potential risk of infection with highly contagious pathogens).

The identification of working conditions based on physical factors at the workstations of laboratory doctors and laboratory paramedics in PCR laboratories revealed that microclimate, lighting and local vibration parameters require further study and assessment. Microclimate parameters in the PCR laboratory premises were maintained by water heating during the cold season and by air conditioning during the warm season. The results obtained did not differ significantly across the base (1, 2, 3) laboratories. Average parameters in the ‘clean’ zone: air temperature +22.34 ± 1.82°C, relative humidity 58.72 ± 3.66%, air velocity 0.2 ± 0.02 m/s. Average parameters in the ‘contaminated’ zone: air temperature +22.6 ± 2.23°C, relative humidity 62.32 ± 4.54%, air velocity 0.2 ± 0.02 m/s. The indicators complied with permissible working conditions (class 2).

A comparative assessment of lighting at the main workstations in PCR laboratories was carried out as a professionally significant factor. All rooms had natural and artificial lighting. As a rule, this was a combination of both, which provided specialists with optimal visibility conditions when carrying out laboratory tests and procedures. Time-recording data showed that the relative duration of visual work whilst looking at the work surface was at least 70%.

The work surface was horizontal, with the plane 0.8–1 m above the floor. Taking these characteristics into account, the standardized parameters of Sanitary Norms and Rules SanPiN 1.2.3685–21 and the actual lighting parameters are presented in Table 1.

Artificial lighting of the workstations was provided by combined and integrated lighting created by fluorescent and LED lamps. At all workstations, the parameters of natural and artificial lighting complied with health and safety requirements. The analysis of lighting uniformity showed that it was uniform in all laboratory rooms. Thus, the illuminance levels at workstations can be classified as belonging to the second permissible class of working conditions in accordance with the requirements of R 2.2.2006–05.

No differences were identified in the organisation of lighting in the main rooms of PCR laboratories during the COVID-19 pandemic compared to a typical epidemic situation.

Particular attention was paid to the factor of vibration when assessing the working conditions of PCR laboratory staff. It was found that during the first stage of each analysis, PCR laboratory staff must place each Eppendorf-type tube containing biomaterial and added reagents onto the platform of a Vortex-type shaker and hold it there for (approximately) ≈ 10 seconds. Similar actions are repeated in the second stage when working with Eppendorf-type mini-tubes. Overall, during a shift, an employee is exposed to intermittent local vibration for between 1.5 and 2.5 hours. Local vibration parameters were measured (Table 2) whilst working on a Vortex V3 shaker with a conical universal adapter during the first, second and third stages of the PCR reaction. The rotational speed of the shaker platform and the Eppendorf tube held on it was within the range of 75–200 Hz, which corresponds to medium-frequency vibration. It is known that exposure to medium-frequency local vibration poses the greatest risk of adverse health effects on workers [12, 13]. This study found that the level of local vibration exposure exceeded the permissible exposure limit (PEL) at octave frequencies ranging from 8 to 63 Hz. The greatest deviations from occupational health standards were recorded along the Y-axis, which is perpendicular to the worker’s palm, and the Z-axis, which is parallel to the forearm. The maximum exceedance was recorded along the Y-axis (11.5 dB), which corresponds to Class 3, Grade 4 working conditions.

Chronometric observation made it possible to assess the labour conditions of PCR laboratory staff in terms of the severity and intensity of the work process. It was found that carrying out PCR testing involves a large number of minor manual tasks: at each stage, it is necessary to take a test tube, open its cap, open the reagent vial, draw the reagent into the pipette, close the reagent vial, dispense the reagent into the test tube and close its cap, move the test tube a distance of 2–3 m, place it on the conical adapter of a Vortex-type shaker (Vortex), hold it in place whilst switching it on, and later switch it off. Subsequently, take the test tube, return it to the laminar flow hood and place it on a special tray for loading into the amplifier. Thus, working with just one test tube at each stage involves 12–14 repetitive actions. As during the pandemic, a laboratory assistant or doctor analyzed between 350 and 800 samples, the number of small, repetitive movements per shift ranged from 8,000 to 22,000 in the first stage. Similar actions are performed in the second stage of the diagnostic procedure and, to some extent, in the third stage. Overall, the number of small repetitive movements per shift reached 41,000–45,000, which corresponds to working conditions class 3.1 by severity During periods of a calm epidemic situation, the number of samples drops sharply, not exceeding 180–200 per shift, which allows the severity of work for PCR laboratory staff to be classified as acceptable (Class 2) according to this criterion. The working posture of medical staff whilst performing their main professional duties is characterized as uncomfortable, as certain operations are performed with the torso bent or twisted, and with arms raised above shoulder level (Order of the Russian Ministry of Labour No. 817n of 21 November 2023)⁶.  According to time-recording data, during the pandemic period these actions account for more than 50% of the working shift (working conditions class 3.1), whilst during a calm epidemic situation: no more than 25% (working conditions class 2). An assessment of the indicators of work intensity for PCR laboratory staff has enabled their work to be classified as harmful of the first degree in accordance with the requirements of Guideline R 2.2.2006–05: six indicators are rated as class 3.1, whilst the remaining indicators fall into classes 1 and/or 2. During non-pandemic periods, the labour of medical staff in PCR laboratories is classified as acceptable due to a reduction in two indicators (time spent looking at video screens and working under time pressure).

Discussion

The issue of COVID-19 is of particular relevance to healthcare workers (doctors, nurses and junior staff), as well as non-medical staff who come into contact with patients [14]. This applies in full to doctors and laboratory technicians in PCR laboratories. In terms of the risk of contracting coronavirus infection, the work of staff in these departments is classified as high-risk [15–17]. The work of medical staff in PCR laboratories during the pandemic has specific characteristics linked to the epidemiological situation. Thus, the high intensity of work, accompanied by a significant increase in the number of laboratory samples, may lead to working conditions that do not meet hygiene requirements. 

As this study has shown, in PCR laboratories, intermittent local vibration is one of the leading and determining factors for potential risks to workers’ health, alongside biological factors.  The effect of local vibration exposure depends on its level and the duration of exposure.

During the pandemic, the duration of exposure to a source of medium frequency intermittent local vibration reached 2.5 hours. Prolonged exposure to low- and medium-frequency vibration primarily leads to the development of angiodystonic syndrome and musculoskeletal disorders [18]. Early signs of upper limb damage include vascular disorders, reduced hand muscle strength, and changes in tendon structure. In the present study, we observed the effects of local vibration in combination with physical overload caused by a large number of repetitive movements involving the muscles of the hands and fingers whilst holding small objects (Eppendorf-type tubes and mini-tubes of this type), which, according to a number of authors, may exacerbate the effects of vibration [19, 20].

A comparative assessment has revealed differences in the working conditions of PCR laboratory staff in terms of the severity and intensity of the work process during the COVID-19 pandemic (class 3.1) and during periods of low epidemic activity (class 2). This is explained by a 4–5-fold increase in the number of tests performed and, consequently, greater work intensity. The large number of PCR tests per shift during the COVID-19 pandemic may be a cause of nucleic acid contamination in laboratories, which also poses a risk of false-positive results and necessitates the suspension of laboratory testing, whilst decontamination measures are carried out and their effectiveness is monitored [21, 22]. All this increases the time staff spend in uncomfortable working positions (cleaning and disinfecting rooms and laminators). The differences identified by this study in the assessment of working conditions for healthcare workers in PCR laboratories during the COVID19 pandemic and during a routine epidemic situation confirm the authors’ view that the scaling up of testing volumes during the pandemic is limited by the technological, material and human capacities of existing laboratories [23].

Conclusion

The identified differences in the working conditions of healthcare workers in PCR laboratories during the COVID-19 pandemic and during a routine epidemic situation suggest a higher risk of developing occupational diseases associated with functional overuse of the finger joints, wrists and the musculotendinous apparatus of the hand when working with intermittent local vibration during the COVID-19 pandemic. A physiological and hygienic justification is required for the duration of healthcare workers’ shifts, taking into account the actual workload and labour costs of laboratory staff when carrying out PCR testing. Further research is also required into the optimization of the workplace for PCR laboratory specialists, as ergonomic, engineering and technical, and vibration-damping interventions can be highly effective in reducing occupational risks arising from the nature and conditions of work.

¹ MUK 4.3.2756–10 Guidelines for the measurement and assessment of the microclimate in industrial premises. 

² State Standard GOST 31192.1–2004 (ISO 5349–1:2001) Measurement of local vibration and assessment of its effects on humans. Part 1. 

³ State Standard GOST 31192.2–2005 (ISO 5349–2:2001) Measurement of local vibration and assessment of its effects on humans. Part 2. 

⁴ Sanitary Rules and Norms SanPiN 1.2.3685–21 ‘Hygienic standards and requirements for ensuring the safety and (or) harmlessness to humans of environmental factors’. 

⁵ R 2.2.2006–05 Occupational hygiene. Guidance on the hygienic assessment of factors in the working environment and work processes. Criteria and classifications of working conditions.

⁶ Order No. 817n of 21 November 2023 ‘On the approval of the methodology for conducting a special assessment of working conditions, the classification of harmful and/or hazardous occupational factors, the form of the report on the special assessment of working conditions, and instructions for completing it’.