Abstract
BACKGROUND:
The safety and health of healthcare workers employed in pathology laboratories and exposed to formaldehyde (FA) is a matter of concern worldwide, as several health effects have been observed in workers resulting from exposure to FA, both short and long-term.
OBJECTIVE:
The study was aimed to describe the strategy implemented in a hospital pathology laboratory to minimize workers’ exposure to FA through interventions to working environment and workforce.
METHODS:
The NIOSH 2016 method for detecting gaseous FA was adopted to perform personal and area active sampling of FA. The samples were subsequently analyzed by High Performance Liquid Chromatography. The exposure to FA was measured before and after improvement interventions.
RESULTS:
The pre-intervention step showed FA levels exceeding the threshold limit values (TLV) established by ACGIH, both the time-weighted average (TLV-TWA) and short term exposure limit (TLV-STEL); after the improvement interventions, the median concentrations of personal and area FA sampling were respectively of 0.025 ppm (Range = 0.023–0.027) and 0.023 ppm (Range = 0.022–0.028) and significantly lower than pre-intervention step (p < 0.05) and below the TLV-TWA and TLV-STEL established by ACGIH.
CONCLUSIONS:
In our study the workers’ involvement in the risk management of FA exposure together with engineering improvements revealed a strategic way to minimize the FA pollution in the studied laboratory. Healthcare companies should consider the need to ensure the workers’ participation in the management of occupational hazards, including FA, to reach the goal of healthy workplaces.
Introduction
The safety of workers exposed to formaldehyde (FA) in pathology laboratories is a special concern spread the world. In healthcare sector, although FA is largely used to process and preserve biopsy tissue and it has long been used to maintain the via-bility of tissue specimens, a growing literature has been showing several health effects that have been observed in workers resulting from exposure to FA (both short and long-term), including nausea, head-ache, irritation of the eyes, nose and upper and lower respiratory airways, nerve toxicity, ocular irritation, contact dermatitis [1–4], congenital defects, nasopharyngeal cancer and myeloid leukemia [5–7]. In 2004 the International Agency for Research on Cancer (IARC) classified FA as a known human carcinogen (group 1) on the basis of induction of nasopharyngeal cancer [8]; in 2012 IARC provided sufficient evidence for linking FA to leukemia [9]. The American Conference of Government Industrial Hygienists (ACGIH) has established that a threshold limit value of formaldehyde in workplace is 0.1 ppm (time-weighted average) and 0.3 ppm (short-term exposure limit) [10], but during the activities in pathology laboratories FA vapors are emitted, exposing workers to high levels of FA, frequently exceeding the above mentioned limit values [3]. To date chromosomal aberrations and DNA damage related to FA exposure have been revealed by consistent literature [11–16]; in particular Costa et al. [17] studied the effects of exposure to FA in the human peripheral blood lymphocytes of anatomy pathology laboratory workers who were occupationally exposed to FA and tested for chromosomal aberrations and DNA damage (comet assay). The findings of this study showed a potential health risk for anatomy pathology laboratory workers exposed to FA airborne concentrations of 0.38 ppm. In anatomy pathology laboratories FA is currently used to fix and preserve human tissues to be examined by pathology workers; examinations of the anatomic samples from autopsies or biopsies are performed in different steps that expose the workers to FA vapors; particularly in the “sampling” step where workers handle the anatomic piece from the container filled with formalin and, before slicing, rinse it under running water for 10–15 minutes [18]. This step might imply the workers’ exposure to FA vapors due to their proximity to the FA. Many studies showed the effectiveness of preventive actions aimed to minimize the use of FA and to improve local exhaust ventilation systems to reduce the exposure to FA in anatomy laboratories [3]. Zarbo et al. [19] and recently Metovic et al. [20] and Mastracci et al. [21] highlighted the effectiveness of vacuum sealing technologies to minimize FA use by anatomy pathology laboratories; the authors described vacuum sealing systems as promising technologies for preserving fresh human specimens that can promote a safer environment by markedly reducing formalin use in operating room theaters. In the hospital pathology laboratory described in our study, although local exhaust ventilation systems were installed surrounding workplaces and formalin storage tanks, and vacuum sealing technologies were adopted, the work environment needed to be improved. The present study describes the strategic interventions focused on the improvement of workplace and workforce with the aim to minimize FA exposure in a hospital pathology laboratory.
Methods
Anatomic pathology laboratory
The study was performed in a hospital anatomic pathology laboratory in which were employed doctors and technicians and where 15.000 analysis were conducted annually. Workers handled the pathological samples treated with formalin on laminar tables, to which down-flow push-pull ventilation systems were attached. The hospital adopted the vac-uum sealing technology for packaging, transporting and storing specimens. In the laboratory the air flow was controlled by general ventilation with mechanical force. The storage tanks containing diluted for-malin solution were located in the area subjected to push-pull ventilation. There were sinks located in the laboratory and the ventilation systems were installed behind the sinks. The exposure to FA was measured by personal and area active monitoring. Personal and area samples were analyzed according to the NIOSH Manual of Analytical Methods (NMAM) 2016 method [22] for the active samples. The NIOSH 2016 method for detecting gaseous FA is based on active sampling and on using 2,4-dinitrophenylhydrazine (DNPH) as reagent on a filter. The samples were subsequently analyzed by High Performance Liquid Chromatography. The exposure to FA was measured before and after improvement interventions as following described. Personal exposures to FA and indoor concentrations of FA before and after such interventions were compared. The pre and post-intervention steps were performed in the period between November 2018 and March 2019.
Interventions to the workplace and workforce
Engineering interventions and workers’ training were performed to minimize exposure to FA in the studied hospital laboratory; engineering level interventions consisted in improving the general ventilation to ensure both an increased number of air-changes (> 12 per hour) and negative room pressure (–10 Pa). Although the storage tanks containing diluted formalin solution were placed in the area subjected to the push-pull ventilation, visual investigation showed that FA-containing waste fluid tanks were without efficient caps; given this issue, efficient caps were installed to close these tanks.
All the workers employed in the laboratory were trained on the working procedures to minimize the risk due to FA exposure, in accordance to the OSHA guide to FA [23]. Workers were also asked not to block the ventilators on the laminar tables while han-dling the samples and not to keep the formalin-conta-ining waste fluid tank open. Prior to this intervention, the waste fluid tanks were often kept open.
Italian ventilation and microclimate parameters for hospital laboratories
The Italian standard for indoor ventilation and microclimate in hospital laboratories, (provided by the Italian National Unification and by the Italian National Institute for Occupational Safety and Prevention [ISPESL]), established a number of air changes of 8 per hour, a temperature of 20±2 °C (winter) and 26°C (summer), relative humidity of 35–45%(winter) and 50–60%(summer), and air velocity of 0.05–0.10 m/sec [24]. Italian legislation does not provide for threshold limit values of FA. For this reason, in the detected laboratory the TLV TWA of 0.1 ppm (0,12 mg/m3) and TLV STEL of 0.3 ppm (0,370 mg/m3) established by ACGIH were adopted for the risk assessment of FA exposure.
Statistical analysis
Data were analyzed with the SPSS software package (Statistical Package for Social Sciences), version 14.0. Comparisons between groups were performed with the Mann-Whitney U test for nonparametric data in the case of two independent groups. The statistical significance was set at p < 0.05 for all analyses.
Results
During the pre-intervention step the personal and area sampling showed median concentrations of FA respectively of 1.36 ppm (Range 0.39–3.07) and 0.20 ppm (Range 0.02–0.45) (Fig. 1). The laboratory workers exposed to FA were classified at significant risk due to FA air pollution. Before the improvement interventions the average air velocity measurements was > 70 ft/min (0.36 m/sec), the average temperature was 22.7°C and average relative humidity was 42.6%; the number of air-changes was 11 per hour, the room pressure was negative (–5 Pa). After the improvement interventions, the median concentrations of personal and area FA sampling were respectively of 0.025 ppm (Range = 0.023–0.027) and 0.023 ppm (Range = 0.022–0.028) (Fig. 1), and significantly lower than pre-intervention step (p < 0.05) and below the TLV-TWA and TLV-STEL established by ACGIH; the average temperature was 20.9 °C and average relative humidity was 44.3%, the average air velocity measurements were > 70 ft/min (0.36 m/sec); the number of air-changes was 12.80 per hour and the room pressure was negative (–10 Pa). Using the visual investigation, we found improved working procedures, in fact workers did not block the ventilators on the laminar tables while handling the samples and did not keep the formalin-containing waste fluid tank open.
- Formaldehyde area and personal exposure levels (median and range) compared to threshold levels.
In this study the implementation of improvement interventions focused on workplace and workforce showed effective to lower the concentrations of FA in a hospital pathology laboratory. Although local exhaust ventilation systems, sufficient number of air changes and vacuum seal system, high concentrations of FA were found in the pre-intervention step and strategic interventions were required to improve the working conditions. In the pre-intervention step the personal samplings showed FA concentrations significantly higher than area samplings; this finding gave us suggestions about the need to improve the workers’ behavior when managing FA and to increase the number of air changes, ensuring a condition of negative room pressure to avoid the FA diffusion in other rooms. In the post intervention step the number of air changes per hour resulted higher than pre-intervention step (12.80 vs 11); the aim of this intervention was to quick remove the FA pollution; a negative room pressure (–10 Pa) was ensured by a ventilation system that removed more exhaust air from the room than air was allowed into the laboratory. Based on visual investigation, were detected workers’ behavioral concerns related to FA indoor pollution (i.e. blocking the ventilators on the laminar tables while handling the samples, keeping the formalin-containing waste fluid tank open). In agreement with the OSHA guide to FA [23] we took action for workers’ training aimed to improve the awareness of FA toxicity and, consequently, to increase workers’ compliance to safety procedures effective to lower FA concentrations in the laboratory. Indications were given about the need not to block the ventilators on the laminar tables while handling the samples and not to keep the formalin-containing waste fluid tank open, to maintain formalin-containing waste fluid tanks with caps, in order to avoid FA diffusion. The training was organized by the Occupational Health and Safety Service of the same Hospital in which the laboratory was located, and involved all the workers employed in the laboratory; a video showed the critical moments of FA diffusion during the working phases in the laboratory and the consequent corrective actions to be adopted to avoid the FA pollution. Moreover, the workers’ training focused the health outcomes reported by literature in workers exposed to FA, due to FA toxicity (both short and long-term) and cancerogenicity (nasopharyngeal cancer and myeloid leukemia) [6, 25–27].
Workers’ learning levels were measured by administering a 24-item nasopharyngeal cancer and myeloid leukemia multiple choice questionnaire, with four answers for each question; all participants obtained a positive score, thus passing the final verification.
Conclusions
Although many studies showed [3, 28] the effectiveness of interventions targeted only on ventilation systems to lower FA air pollution in anatomy laboratories below the TLV-TWA and the TLV-STEL established by the ACGIH, in our study the workers’ involvement in the risk management of FA exposure together with engineering improvements revealed a strategic way to minimize the FA pollution in the studied anatomic laboratory. Healthcare companies should consider the need of multilevel interventions focused on both the physical work environment and the workers’ skills in managing occupational hazards, including FA, to reach the goal of healthy workplaces.
There were several limitations in this study: 1) the period investigated is short to draw strong conclusions about the effectiveness of the improvement interventions to minimize FA exposure levels; 2) the results were measured on 1 day only, and this was not a long-term evaluation 3) the results of this study are referred to the FA exposure levels and do not take into account other pollutants in the hospital pathology laboratory.
Conflict of interest
The authors declare that they have no financial or personal relationship with people or organizations that could inappropriately influence the work.
Ethical approval
The study was performed as part of the obligatory evaluation of work related stress, required by Italian Legislative Decree 81/08, and needed no formal approval by the local ethics committee.