One academic year laboratory and student breathing zone formaldehyde level, measured by gas-piston hand pump at gross anatomy laboratory, Siriraj Hospital, Thailand

The effects of enhanced formaldehyde clearance in a gross anatomy laboratory by floor plan redesign and dissection table adjustment

Formaldehyde has carcinogenic properties. It is associated with nasopharyngeal cancer and causes irritation of the eyes, nose, throat, and respiratory system. Formaldehyde exposure is a significant health concern for those participating in the gross anatomy laboratory, but no learning method can substitute cadaver dissection. We performed a formaldehyde level study in 2018, which found that most of the breathing zone (S-level) and environment (R-level) formaldehyde levels during laboratory sessions at the Faculty of Medicine Siriraj Hospital exceeded international ceiling standards. In the academic year 2019, we adapted the engineering rationale of the NIOSH hierarchy of controls to facilitate formaldehyde clearance by opening the dissection table covers and increasing the area per dissection table, then measured formaldehyde ceiling levels by formaldehyde detector tube with a gas-piston hand pump during (1) body wall, (2) upper limb, (3) head-neck, (4) thorax, (5) spinal cord removal, (6) lower limb, (7) abdomen, and (8) organs of special senses dissection sessions and comparing the results with the 2018 study. The perineum region data were excluded from analyses due to the laboratory closure in 2019 from the COVID-19 outbreak. There were statistically significant differences between the 2018 and 2019 S-levels (p < 0.001) and R-levels (p < 0.001). The mean S-level decreased by 64.18% from 1.34 ± 0.71 to 0.48 ± 0.26 ppm, and the mean R-level decreased by 70.18% from 0.57 ± 0.27 to 0.17 ± 0.09 ppm. The highest formaldehyde level in 2019 was the S-level in the body wall region (1.04 ± 0.3 ppm), followed by the S-level in the abdomen region (0.56 ± 0.08 ppm) and the spinal cord removal region (0.51 ± 0.29 ppm). All 2019 formaldehyde levels passed the OSHA 15-min STEL standard (2 ppm). The R-level in the special sense region (0.06 ± 0.02 ppm) passed the NIOSH 15-min ceiling limit (0.1 ppm). Three levels for 2019 were very close: the R-level in the head-neck region (0.11 ± 0.08 ppm), the abdomen region (0.11 ± 0.08), the body wall region (0.14 ± 0.12 ppm), and the S-level in the special sense region (0.12 ± 0.04 ppm). In summary, extensive analysis and removal of factors impeding formaldehyde clearance can improve the general ventilation system and achieve the OSHA 15-min STEL standard.

Evaluation of formaldehyde exposure among gross dissection after modified embalming solution and health assessment

Mainly embalming fixative contains formaldehyde which is classified as a carcinogen. People who work with cadavers have been at higher risk of cancer after formaldehyde exposure. We have formulated a less-formalin fixative (contained 3.6% formaldehyde,23.8% ethanol, 15% glycerin, and 0.2% phenol in the water) for preserving cadavers. Therefore, the objective of the present study was to evaluate the level of atmospheric formaldehyde indoors and the breathing exposure of medical students during dissection classes. We also analyzed the pulmonary parameters and effects of formaldehyde. The levels of atmospheric formaldehyde indoors and personal breathing exposure were sampled during anatomy dissection classes (musculoskeletal system, respiratory system, and abdominopelvic organ system) using sorbent tubes with air sampling pumps. Samples were then analyzed using Gas Chromatography with Flame Ionization Detector (GC-FID). The mean level of formaldehyde indoor air among the three classes was 0.518 ± 0.156 ppm whereas the formaldehyde level in the personal breathing zone was 0.956±0.408 ppm, which exceeded the recommended exposure standards of international agencies, including NIOSH agency and PEL of Thailand legislation. The laboratory had high humidity, high room temperature, and poor air ventilation. There was a significant difference in FVC, FEV1, and PEF (p < 0.05) between the sexes of students. Comparison pulmonary parameters between students and instructors showed that all parameters of the pulmonary function test had no significant differences. General fatigue and burnings of eyes and nose associated with strong odor were the most common symptoms reported during the dissection classes. The modified embalming fixative was used less formalin with ethanol-glycerin mixture, and it was suitable for the study of medical students, with few side effects of respiratory problems. However, the modified exhaust ventilation with local table-exhaust ventilation and heating-ventilation-air conditioning system performance were urgent issues for reducing levels of formaldehyde indoor air in the dissection room.

Formaldehyde exposure and atmospheric biomonitoring with lichen Cladonia verticillaris in an anatomy laboratory

Formaldehyde is one of the most toxic contaminants of indoor environments and very common in the anatomy laboratory. In this work, we investigated the level of formaldehyde exposure to staff and students who attended an anatomy lab and in nearby environments in the same university building. We also performed atmospheric biomonitoring of the sites with the lichen Cladonia verticillaris. Quantification samplings were performed over four weeks, on 7 days with and 7 days without practical classes, totaling 70 samples. The samples were collected in five different locations, three points inside the laboratory and two points outside the laboratory, representing nearby and susceptible environments to contamination. The results showed CHOH concentrations from 0.20-3.76 ppmv for days with practical courses and 0.17-3.06 ppmv for days without practical classes. Although the laboratory was more contaminated than the surrounding environments, the concentration of formaldehyde in these areas is not negligible, showing a dispersion of formaldehyde from the laboratory. Potential dose (PD) and cancer risk (CR) were calculated for an individual exposed to the same levels analyzed for 8 h daily and 30 years of work. The study on C. verticillaris lasted 90 days and evaluated the variation of chlorophyll and pheophytin (photosynthetic pigments). The results showed a significant difference in the production of chlorophylls a and b and total chlorophyll when compared to control, and there was also a progressive increase of the total pheophytin/total chlorophyll ratio. The results also showed the correlation between the increase in chlorophylls and the studied environments with less ventilation since these places provided greater accumulation of formaldehyde in the long run. Thus, measurable evidence was obtained of biological disorders in a living organism caused by exposure to formaldehyde.

An efficient strategy for the enhancement of adsorptivity of microporous carbons against gaseous formaldehyde: Surface modification with aminosilane adducts

In an effort to develop a cost-effective mitigation tool for volatile organic compounds, particularly formaldehyde (FA), microporous activated carbon (AC) was modified into three different forms of AC-1, AC-2, and AC-3 using a raw commercial AC product (AC-0). First, AC-1 and AC-2 were produced by the modification of AC-0 with N/S heteroatoms using identical mixture of dicyandiamide and thiourea precursors through either solvothermal (AC-1) or microwave-assisted calcination (AC-2) synthesis. Second, aminosilane-functionalized AC (AC-3) was prepared solvothermally using N-[3-(Trimethoxysilyl)propyl]ethylenediamine reagent. The relative adsorption performances for gaseous FA (1 ppm) in terms of 10% breakthrough volume (BTV10: L atm g^-1) at near-ambient conditions (25 °C and 1 atm) were AC-3 (132) > AC-2 (66.5) > AC-1 (14.2) > AC-0 (10.4). In a comparison based on partition coefficients (mole kg^-1 Pa^-1) at BTV10, AC-3 outperformed AC-0 by a factor of 214, while the adsorption performance of AC-2 was 36-times higher than AC-1. The enhanced performance of AC-2 over AC-1 reflected the effect of the microwave synthesis protocol on the improvement of surface chemistry (e.g., N/S doping) and texture (e.g., surface area and pore volume) of AC-based adsorbents as compared to conventional solvothermal method. Further, the prominent role of surface chemistry (e.g., relative to textural properties), as observed with the increases in the amount of doped functional elements (including N:C and silicon:C ratios), is supported by the apparent dependence of performance on the selected modification procedures. Based on kinetic and X-ray photoelectron spectroscopy analyses, the superiority of aminosilylated AC-3 can be attributed to a synergistic effect between physisorption (e.g., pore diffusion) and chemical interactions of the FA carbonyl (C=O) group with amine and silica functionalities (via Mannich coupling [Schiff base] and cycloaddition reaction mechanisms, respectively). This confirms the significance of surface chemistry, relative to pore diffusion, in achieving maximum adsorption of gaseous FA molecules.