Reduction of formaldehyde concentrations in the air and cadaveric tissues by ammonium carbonate

Efficacy of urea solution reperfusion to a formalin-embalmed cadaver for surgical skills training

Formaldehyde has been traditionally used for embalming human cadavers for gross anatomy education and surgical skills training. However, exposure to formaldehyde negatively affects human health. This study aimed to assess the efficacy of reperfusing urea solution to a formalin-embalmed cadaver for surgical skills training and then investigate the cadaver's tissue elasticity alteration after being soaked into the urea solution. Twelve surgeons evaluated the similarity of tissue characteristics between the cadaver (embalmed by formalin solution and reperfused by urea solution) and a living human body. Furthermore, the tissue formaldehyde content and mechanical properties of the formalin-fixated femoral skin and artery specimens with or without soaking into urea solution were measured. Results showed that the tactile assessment, skin incision, vessel ligation and suture, and decollement were better and more useful in the cadaver reperfused by urea solution than in the cadaver merely fixated by formalin solution. In the urea-reperfused cadaver, the volatilized, or tissue formaldehyde levels declined. The stiffness and Young's modulus of the femoral skin and artery were also lower in the specimen than in the mere formalin-fixated specimen. In conclusion, reperfusion of urea solution to the formalin-fixated cadaver makes anatomical education and surgical skills training more efficient with fewer requirements for cadaver management.

Low cost and effective reduction of formaldehyde in gross anatomy: long throw nozzles and formaldehyde destruction using InfuTrace™

Formaldehyde is extraordinarily effective for fixation of human corpses and is routinely used in embalming solutions in anatomical dissection courses all over the world. High concentrations in vapors emitted from corpses embalmed with formaldehyde make it necessary to reduce the emission from cadavers for fulfilling tightening permissible exposure limits (PEL) worldwide. The study provides possible solutions to a problem faced by many anatomy labs. The emission of 50 human corpses was examined using 240 active personal and stationary samples with sampling tubes placed in the breathing area of probands or directly above the corpses. For measuring formaldehyde exposures along the dissection course, air samples were collected during the progress of dissection. Best results were achieved by a combination of post-embalming treatment with InfuTrace™, a formaldehyde binding solution applied to corpses fixed with 3% formaldehyde, and a modified ventilation system consisting of three long throw nozzles mounted vertically at the ceiling above the longitudinal axis of each dissection table. In this scenario, the inhalative exposure for students and teachers did not exceed 0.1 ppm during muscle dissection and 0.041 ppm during organ dissection, which are both dissection steps linked to high emission rates. The data emphasizes the necessity to use a combination of different methods - chemical polymerization of formaldehyde combined with a modified ventilation system - to reduce formaldehyde air loads far below the German PEL (0.3 ppm) and even the Japanese PEL (0.1 ppm) when using a standard 3%-formaldehyde fixation.

Flammability and combustion hazard of preserved human tissues

Preservation techniques have evolved over the years to respond to the need of longer dissection periods, with formaldehyde being widely used for this purpose. In recent years, efforts have been focusing on reducing the health hazards of this fixative and the rigidity of the tissues embalmed with it. With every embalming technique that they are either developing or resurrecting from various protocols, institutions need to assess the fire and health hazards of all the chemicals being used. Compliance with the storage and handling safeguards listed in the Material Safety Data Sheet of each chemical, needs to be accompanied by infrastructure changes. To reduce the health hazards of formaldehyde, institutions are taking appropriate countermeasures directed at the source itself, by using substitutes or injecting formaldehyde chelating agents, and are adopting high performance air extraction systems to protect the users. However, little is known about the flammability risk of embalmed human bodies. During a recent visit to McGill University morgue by architects and safety inspectors to expand it, we were asked about the flammability risk of the embalmed specimens, so we carried out a flashpoint test to evaluate the flammability potential of specimens embalmed with each of our three embalming techniques: formaldehyde-based, Thiel, and phenol-based. With the phenol-based embalming showing the most risks, attention should be drawn to all institutions who are experimenting with various embalming techniques to evaluate the flammability potential of their embalmed specimens.

Spraying urea solution reduces formaldehyde levels during gross anatomy courses

Formaldehyde (FA) is frequently used to embalm human cadavers that are employed to teach gross anatomy to medical and dental students. However, exposure to FA is harmful to both students and educators. The aim of this study was to reduce the FA levels in the anatomy dissection hall by spraying an FA scavenger solution. We measured the changes in FA levels after administering FA scavenger solutions to liquid, wet paper towels, organs, and cadavers containing FA. Among L-cysteine, N-ethyl urea, and urea, the latter was found to have the strongest scavenging power towards the FA in the liquid. The molar concentration of urea that most efficiently reduced the levels of volatilized FA from the wet paper towels was the same as that of the FA. After spraying the urea solution, the volatilized FA levels immediately decreased, reaching their minimum at 60 min, and remained low even after 240 min. Spraying the urea solution onto the organs reduced the levels of FA volatilized from the surfaces of organs but not those from the insides of the organs. In the dissection hall used for the gross anatomy course at Tokyo Medical University, the FA levels were significantly decreased after spraying the urea solution onto the cadavers. Moreover, dissection could be performed without the cadavers putrefying during the 4-month course. These results indicate that various institutes could use urea solution spray to effectively reduce the FA levels in the dissection hall and thus ensure the safety of students and educators.

Neutralizing formaldehyde in chicken cadaver with urea and urea fertilizer solution

This study demonstrated the potential of using urea and urea fertilizer to neutralize formaldehyde (Fd) in chicken cadavers. Initially, in vitro Fd neutralization with various concentrations of urea solution (US) and urea fertilizer solution (UFS) was conducted; subsequently, 18% US and 27% UFS were selected for infusing into the formalinized chickens. The measurement at 48 hr after infusion showed that both solutions could effectively lower Fd in chicken cadavers to below a permissible exposure limit without affecting cadaveric and histological quality. In addition, neutralizing power of 18% US was approximately 1.3 times that of 27% UFS. This is the first demonstration of neutralizing potential of US and UFS against Fd both in vitro and in vivo.

The toxic effects of formaldehyde on the nervous system

Formaldehyde (FA) is found in the polluted atmosphere of cities, domestic air (e.g., paint, insulating materials, chipboard and plywood, fabrics, furniture, paper), and cigarette smoke, etc.; therefore, everyone and particularly susceptible children may be exposed to FA. FA is also widely used in industrial and medical settings and as a sterilizing agent, disinfectant, and preservative. Therefore, employees may be highly exposed to it in there settings. Of particular concern to the authors are anatomists and medical students, who can be highly exposed to formaldehyde vapor during dissection sessions. Formaldehyde is toxic over a range of doses; chances of exposure and subsequent harmful effects are increased as (room) temperature increases, because of FA's volatility. Many studies have been conducted to evaluate the effects of FA during systemic and respiratory exposures in rats. This review compiles that literature and emphasizes the neurotoxic effects of FA on neuronal morphology, behavior, and biochemical parameters. The review includes the results of some of the authors' work related to FA neurotoxicity, and such neurotoxic effects from FA exposure were experimentally demonstrated. Moreover, the effectiveness of some antioxidants such as melatonin, fish omega-3, and CAPE was observed in the treatment of the harmful effects of FA. Despite the harmful effects from FA exposure, it is commonly used in Turkey and elsewhere in dissection laboratories. Consequently, all anatomists must know and understand the effects of this toxic agent on organisms and the environment, and take precautions to avoid unnecessary exposure. The reviewed studies have indicated that FA has neurotoxic characteristics and systemic toxic effects. It is hypothesized that inhalation of FA, during the early postnatal period, is linked to some neurological diseases that occur in adults. Although complete prevention is impossible for laboratory workers and members of industries utilizing FA, certain precautions can be taken to decrease and/or prevent the toxic effects of FA.

Effects of postnatal formaldehyde exposure on pyramidal cell number, volume of cell layer in hippocampus and hemisphere in the rat: a stereological study

The purpose of the present study was to determine whether exposure of neonatal rats to formaldehyde (FA) had either early or delayed effects on the numbers of pyramidal cells in the cornu ammonis (CA) of the hippocampus. Neonatal Wistar rats were exposed to 0 ppm (control group), 6 ppm and 12 ppm (high concentration group) of FA concentrations throughout the 30-day period following the birth by placing them for 6 h/day in a glass chamber containing FA vapor. Then, some of the animals from each FA-treated group were anesthetized and decapitated at the day 30, and the remaining ones were killed at the day 90. The brains were removed immediately and fixed in 10% neutral-buffered FA solution. The Cavalieri principle was used to determine the volumes of the CA and the entire cerebral hemisphere. The optical fractionator counting method was used to estimate the total number of pyramidal cells in the CA. The appearance of pyramidal cells was normal under light microscopy at both postnatal day (PND) 30 and PND 90 in all groups. There were concentration-related volume changes of CA at PND 30 and PND 90; low concentration of FA significantly increased, whereas high concentration decreased the volume of CA in comparison of the control at PND 30. Importantly, high concentration of FA at PND 90 increased the volume of CA in comparison of the low concentration but not with the control. Furthermore, low and high concentrations of FA decreased the volume of hemisphere at PND 30, whereas a reverse effect of these concentrations was observed at the hemisphere of PND 90 in comparison of the control. In both CA and cerebral hemisphere, an age-related volume decrease in both control and low/high concentration groups were found. On the other hand, there were significant age-related reductions in the total number of pyramidal cells at 90 days of age irrespective of the groups examined. Rats treated with high concentration FA were seen to have significantly fewer pyramidal cell neurons than either the animals treated with low concentration FA or control groups (p<0.01). These observations indicate that pyramidal cells in the hippocampus may be vulnerable to FA exposure during the early period of life.

A new system to reduce formaldehyde levels improves safety conditions during gross veterinary anatomy learning

Dissection is a very useful method of learning veterinary anatomy. However, formaldehyde, which is widely used to preserve cadavers, is an irritant, and it has recently been classified as a carcinogen. In 1997, the Instituto Nacional de Seguridad e Higiene en el Trabajo [National Institute of Workplace Security and Hygiene] found that the levels of formaldehyde in our dissection room were above the threshold limit values. Unfortunately, no optimal substitute for formaldehyde is currently available. Therefore, we designed a new ventilation system that combines slow propulsion of fresh air from above the dissection table and rapid aspiration of polluted air from the perimeter. Formaldehyde measurements performed in 2004, after the introduction of this new system into our dissection laboratory, showed a dramatic reduction (about tenfold, or 0.03 ppm). A suitable propelling/aspirating air system successfully reduces the concentration of formaldehyde in the dissection room, significantly improving safety conditions for students, instructors, and technical staff during gross anatomy learning.

Effects of formaldehyde exposure on granule cell number and volume of dentate gyrus: A histopathological and stereological study

The hippocampal formation is a complex region of the brain related to memory and learning. The purpose of the present study was to determine whether exposure of neonatal rats to formaldehyde (FA) had either early or delayed effects on the numbers of granule cells in the dentate gyrus (DG). After birth, the neonatal male Wistar rats were exposed throughout a 30-day period to various concentrations of FA: 0 (control group), 6 ppm (low concentration group) and 12 ppm (high concentration group). This was done by placing them for 6 h/day and 5 days per week in a glass chamber containing FA vapor. Then, five animals from each group were anesthetized and decapitated on postnatal day (PND) 30, and the remaining five animals were sacrificed on PND 90 by intracardiac perfusion using 10% neutral buffered FA solution. The Cavalieri principle of stereological approaches was used to determine the volume of the DG in these sections. The optical fractionator counting method was used to estimate the total number of granule cells in the DG. The appearance of granule cells was normal under light microscopy in all PND 30 and PND 90 groups. There were significant age-related reductions in the volume of the DG at PND 90 irrespective of which group was examined. Significant age-related neuron loss was also determined at PND 90 compared to that at PND 30. Rats treated with a high concentration FA were found to have fewer granule cells than either the animals treated with a low concentration FA or the control group (p<0.01 and p<0.01, respectively) at PND 90 but not at PND 30. These findings clearly indicate that granule cells in the DG may be vulnerable to stress and the concentration of FA to which they are exposed during early postnatal life, and also that a neurotoxic effect of high dose FA on cell number is only seen after a long time period. These results may explain why some disorders do not appear until later life.