Formaldehyde exposure levels and serum antibodies to formaldehyde-human serum albumin of Korean medical students

Indoor Formaldehyde Concentration, Personal Formaldehyde Exposure and Clinical Symptoms during Anatomy Dissection Sessions, University of Medicine 1, Yangon

The formaldehyde (FA) embalming method, the world's most common protocol for the fixation of cadavers, has been consistently used in medical universities in Myanmar. This study was designed to examine the indoor FA concentrations in anatomy dissection rooms, an exposed site, and lecture theater, an unexposed control site, and to access personal exposure levels of FA and clinical symptoms of medical students and instructors. In total, 208 second year medical students (1/2019 batch) and 18 instructors from Department of Anatomy, University of Medicine 1, participated. Thirteen dissection sessions were investigated from February 2019 to January 2020. Diffusive sampling devices were used as air samplers and high-performance liquid chromatography was used for measurement of FA. Average indoor FA concentration of four dissection rooms was 0.43 (0.09-1.22) ppm and all dissection rooms showed indoor concentrations above the occupational exposure limits and short-term exposure limit for general population. Personal FA exposure values were higher than indoor FA concentrations and the instructors (0.68, 0.04-2.11 ppm) had higher exposure than the students (0.44, 0.06-1.72 ppm). Unpleasant odor, eye and nose irritations and inability to concentrate were frequently reported FA-related symptoms, and the students were found to have significantly higher risks (p < 0.05) of having these symptoms during the dissection sessions than during lecture.

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.

Formaldehyde-Induced Aggravation of Pruritus and Dermatitis Is Associated with the Elevated Expression of Th1 Cytokines in a Rat Model of Atopic Dermatitis

Atopic dermatitis is a complex disease of heterogeneous pathogenesis, in particular, genetic predisposition, environmental triggers, and their interactions. Indoor air pollution, increasing with urbanization, plays a role as environmental risk factor in the development of AD. However, we still lack a detailed picture of the role of air pollution in the development of the disease. Here, we examined the effect of formaldehyde (FA) exposure on the manifestation of atopic dermatitis and the underlying molecular mechanism in naive rats and in a rat model of atopic dermatitis (AD) produced by neonatal capsaicin treatment. The AD and naive rats were exposed to 0.8 ppm FA, 1.2 ppm FA, or fresh air (Air) for 6 weeks (2 hours/day and 5 days/week). So, six groups, namely the 1.2 FA-AD, 0.8 FA-AD, Air-AD, 1.2 FA-naive, 0.8 FA-naive and Air-naive groups, were established. Pruritus and dermatitis, two major symptoms of atopic dermatitis, were evaluated every week for 6 weeks. After that, samples of the blood, the skin and the thymus were collected from the 1.2 FA-AD, the Air-AD, the 1.2 FA-naive and the Air-naive groups. Serum IgE levels were quantified with ELISA, and mRNA expression levels of inflammatory cytokines from extracts of the skin and the thymus were calculated with qRT-PCR. The dermatitis and pruritus significantly worsened in 1.2 FA-AD group, but not in 0.8 FA-AD, compared to the Air-AD animals, whereas FA didn't induce any symptoms in naive rats. Consistently, the levels of serum IgE were significantly higher in 1.2 FA-AD than in air-AD, however, there was no significant difference following FA exposure in naive animals. In the skin, mRNA expression levels of Th1 cytokines such as TNF-α and IL-1β were significantly higher in the 1.2 FA-AD rats compared to the air-AD rats, whereas mRNA expression levels of Th2 cytokines (IL-4, IL-5, IL-13), IL-17A and TSLP were significantly higher in 1.2 FA-naive group than in the Air-naive group. These results suggested that 1.2 ppm of FA penetrated the injured skin barrier, and exacerbated Th1 responses and serum IgE level in the AD rats so that dermatitis and pruritus were aggravated, while the elevated expression of Th2 cytokines by 1.2 ppm of FA in naive rats was probably insufficient for clinical manifestation. In conclusion, in a rat model of atopic dermatitis, exposure to 1.2 ppm of FA aggravated pruritus and skin inflammation, which was associated with the elevated expression of Th1 cytokines.

Effects of v-3 essential fatty acids against formaldehyde-induced nephropathy in rats

The aim of this study was to examine the toxicity of formaldehyde (FA) on the kidney and the protective effects of v-3 essential fatty acids against these toxic effects. Twenty-one male Wistar rats were divided into three groups. Rats in Group I comprised the controls, while the rats in Group II were injected every other day with FA. Rats in Group III received v-3 fatty acids daily while exposed to FA. At the end of the 14-day experimental period, all rats were killed by decapitation and the kidneys removed. Some of the kidney tissue specimens were used for determination of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities, and malondialdehyde (MDA) levels. The remaining kidney tissue specimens were used for light microscopic evaluation. The levels of SOD and GSH-Px were significantly decreased, and MDA levels were significantly increased in rats treated with FA compared with those of the controls. Furthermore, in the microscopic examination of this group, glomerular and tubular degeneration, vascular congestion and tubular dilatation were observed. However, increased SOD and GSH-Px enzyme activities, and decreased MDA levels were detected in the rats administered v-3 fatty acids while exposed to FA. Additionally, kidney damage caused by FA was decreased and structural appearance was similar to that of the control rats in this group. In conclusion, it was determined that FA-induced kidney damage was prevented by administration of v-3 essential fatty acids.

Toxic effects of formaldehyde on the urinary system

Formaldehyde is a chemical substance with a pungent odor that is highly soluble in water and occurs naturally in organisms. Formaldehyde, when taken into organisms, is metabolized into formic acid in the liver and erythrocytes and is then excreted, either with the urine and feces or via the respiratory system. Form-aldehyde is widely used in the industrial and medical fields, and employees in these sectors are frequently exposed to it. Anatomists and medical students are affected by formaldehyde gas during dissection lessons. Because full protection from formaldehyde is impossible for employees in industrial plants using this chemical and for workers in laboratory conditions, several measures can be implemented to prevent and/or reduce the toxic effects of formaldehyde. In this review, we aimed to identify the toxic effects of formaldehyde on the urinary system.

Student perceptions of an upper-level, undergraduate human anatomy laboratory course without cadavers

Several programs in health professional education require or are considering requiring upper-level human anatomy as prerequisite for their applicants. Undergraduate students are confronted with few institutions offering such a course, in part because of the expense and logistical issues associated with a cadaver-based human anatomy course. This study describes the development of and student reactions to an upper-level human anatomy laboratory course for undergraduate students that used a regional approach and contemporary, alternative teaching methods to a cadaver-based course. The alternative pedagogy to deliver the curriculum included use of commercially available, three-dimensional anatomical virtual dissection software, anatomical models coupled with a learning management system to offer Web-based learning, and a new laboratory manual with collaborative exercises designed to develop the student's anatomical skills and collaborative team skills. A Likert-scale survey with open-ended questions was used to ascertain student perceptions of the course and its various aspects. Students perceived that the noncadaver-based, upper-level human anatomy course with an engaging, regional approach is highly valuable in their learning of anatomy. anatomy.

Formaldehyde and tobacco smoke as alkylating agents: the formation of N-methylenvaline in pathologists and in plastic laminate workers

OBJECTIVE

Aim of this study was to investigate the relationships between the concentration of formaldehyde in air and the alkylation of hemoglobin to form a terminal N-methylenvaline residue in three occupationally exposed groups: a) technicians of pathology wards, b) workers of the plastic laminates industry, and c) a control group. All subjects recruited in this study were also tested on their smoking habits.

METHODS

Formaldehyde adsorbed on passive air samplers was quantified by HPLC with UV detection (360 nm), cotinine was quantified by GC-MS. Terminal hemoglobin N-methylenvaline was determined by treating globine under reducing conditions with pentafluorophenyl isothiocyanate to yield a derivative, subsequently detected by GC-MS. One-way analysis of variance was performed to compare among the three groups the biomarkers considered in this study.

RESULTS

For air-FA and N-methylenvaline a difference between the three groups was detected (p < 0.0001) and a significant higher concentration in the two professionally exposed groups was proved. Mean values for FA (μg/m(3)): group a) 188.6, group b) 210.1, and group c) 41.4; mean values for N-methylenvaline (nmol/g of globin): group a) 377.9, group b) 342.8, and group c) 144.8. Conversely, the comparison between the two professionally exposed groups, a) vs b), does not show any significant difference highlighting similar exposition to FA and, consequently, similar biological response. Tobacco smoke proves to have a minor impact on the formation of N-methylenvaline molecular adduct.

CONCLUSIONS

A positive correlation was demonstrated between professional exposition to air-formaldehyde and hemoglobin alkylation to form N-methylenvaline molecular adduct in two occupationally exposed groups of subjects considered in the present study. In comparison with occupational exposition, tobacco smoke proved to have a minor impact on the formation of N-methylenvaline molecular adduct.

Occupational exposure to formaldehyde in an institute of morphology in Brazil: a comparison of area and personal sampling

BACKGROUND, AIMS, AND SCOPE

Formaldehyde (FA) is a harmful chemical, which is classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. Solutions of FA that are used to preserve cadavers in research and education morphological institutes represent a risk to occupational health of professionals and students. During the dissection of cadavers in the anatomy laboratories, FA vapors are emitted, resulting in the exposure of students and their instructors to elevated levels of FA. The World Health Organization recommends an air quality guideline value of 0.1 mg m(-3) for exposure to FA. The limit of occupational exposure adopted by the Brazilian legislation (2.3 mg m(-3)) is markedly higher than those adopted by institutions of other countries around the world. The purpose of this study was to determine the levels of personal exposure and the area concentration of FA in the morphology department of the Federal Fluminense University, Brazil, and investigate and compare the relationship between them.

METHODS

Four rooms distributed in the three floors of the Morphology Department were evaluated: the embalming laboratory, the anatomy laboratories, the corridor of the teachers' rooms, and the entrance hall. Thirty-six samples in total were collected in the second semester of 2010 and first semester of 2011. The air sampling and FA analysis were performed according to the EPA TO-11A Protocol, using a diffusive sampling device for carbonyl compounds. Personal samples were collected from monitors using a sampling device pinned on each person's lapel. The samples were analyzed using rapid resolution liquid chromatography with UV-DAD detection at 360 nm.

RESULTS AND DISCUSSION

The concentrations of FA ranged from 0.20 and 0.18 mg m(-3) in the corridor between the teachers' rooms, 0.03 to 0.37 mg m(-3) in the entrance hall, 0.22 to 2.07 mg m(-3) in the anatomy laboratory, 2.21 to 2.52 mg m(-3), in the embalming room. The levels found in the corridor between the teachers' rooms and in the entrance hall were lower than in other compartments because of their large distances to the sources of FA and better ventilation. The other rooms presented higher levels of FA because of the activities carried there (embalming and dissection procedures). Even in the rooms that showed the lowest levels of FA, the values found were higher than those established by all international guideline limits, except the Brazilian legislation limit, although, the concentration level in the embalming room was even greater than the Brazilian guideline. These concentrations are 100-1,000-fold higher than those reported in an FA outdoor study. The exposure levels of monitors and students ranged from 1.89 to 4.82 mg m(-3), indicating that current practices at the Morphology Department at the university would represent a health risk. The simultaneous monitoring of area concentrations and personal exposure showed that the characteristics of classes and of cadavers' parts, the number of students in the room and even the activities of the monitors influence the FA concentrations.

CONCLUSION

This study revealed that the concentration of FA was low in the ventilated areas of the Morphology Department, and that the personal exposure when the person was close to the cadavers during the dissection procedure was higher than the mean FA concentration. This should be considered in the risk assessment of FA during these activities without effective protection equipment. It is suggested that the Brazilian legislation of exposure to formaldehyde requires an urgent update considering international legislation.

Non-cancer effects of formaldehyde and relevance for setting an indoor air guideline

There is considerable recent focus and concern about formaldehyde (FA). We have reviewed the literature on FA with focus on chemosensory perception in the airways and lung effects in indoor environments. Concentrations of FA, both personal and stationary, are on average in the order of 0.05 mg/m(3) or less in Europe and North America with the exception of new housing or buildings with extensive wooden surfaces, where the concentration may exceed 0.1 mg/m(3). With the eye the most sensitive organ, subjective irritation is reported at 0.3-0.5 mg/m(3), which is somewhat higher than reported odour thresholds. Objective effects in the eyes and airways occur around 0.6-1 mg/m(3). Dose-response relationships between FA and lung function effects have not been found in controlled human exposure studies below 1 mg/m(3), and epidemiological associations between FA concentrations and exacerbation of asthma in children and adults are encumbered by complex exposures. Neither experimental nor epidemiological studies point to major differences in susceptibility to FA among children, elderly, and asthmatics. People with personal trait of negative affectivity may report more symptoms. An air quality guideline of 0.1 mg/m(3) (0.08 ppm) is considered protective against both acute and chronic sensory irritation in the airways in the general population assuming a log normal distribution of nasal sensory irritation.

Irritant and adjuvant effects of gaseous formaldehyde on the ovalbumin-induced hyperresponsiveness and inflammation in a rat model

BACKGROUND

Formaldehyde (FA) is a common indoor air pollutant that can cause asthma in people experiencing long-term exposure. While FA and other man-made chemicals contribute to the stimulation of asthma in the general population, the underlying molecular pathogenesis of this relationship is not yet well understood.

OBJECTIVE

To explore FA as an irritant for the onset of asthma and as an adjuvant for the induction of allergy.

METHODS

In the present study, 40 Wistar rats in five experimental groups were exposed to: (i) saline; (ii) ovalbumin (OVA); (iii) OVA + FA at 417 ppb; (iv) OVA + FA at 2500 ppb; and (v) FA at 2500 ppb. Current and prior occupational exposure limits in China were established at 417 ppb and 2500 ppb, respectively. Gaseous FA was administrated to the animals for 6 h/day before and during OVA immunization or saline treatment. Measured outcomes included in situ lung function analysis, cytokine measurement, and histological changes in the rat lungs.

RESULTS

The airway reactivity, lung histological changes, pulmonary interleukin-4 secretion, and eosinophil infiltration in the OVA and FA exposed rats were significantly higher after gaseous FA exposures of 417 and 2500 ppb. While FA exposure alone did not induce significant structural changes to the airway, and the rate of inflammatory cell infiltration was the same as for the control group, pulmonary levels of interferon-gamma were significantly elevated in the exposed rats.

CONCLUSIONS

FA may be an irritant as well as serve as an adjuvant for the onset of asthma or asthma-like symptoms.

Protective effect of melatonin against formaldehyde-induced kidney damage in rats

This study was undertaken to investigate the protective effects of melatonin against formaldehyde-induced renal damage in rats. For this purpose, 21 male Wistar rats were divided into three groups. The animals in Group I were used as a control, whereas the rats in group II were injected every other day with formaldehyde. The rats in group III received melatonin daily while exposed to formaldehyde. At the end of the 14-day experimental period, all rats were killed by decapitation, and the kidneys were removed. Some of the renal tissue specimens were used for determination of superoxide dismutase, glutatione peroxidase enzyme activities, and malondialdehyde levels. The remaining kidney tissue specimens were used for light microscopic evaluation. The renal tissue activities of superoxide dismutase and glutatione peroxidase were significantly decreased, and malondialdehyde levels were significantly increased in rats treated with formaldehyde compared with those of the control animals. In the light microscopic evaluation of this group, degenerative glomerules, vacuolization and dilatation of distal tubules, and vascular congestion were detected. However, an increase was observed in activities of superoxide dismutase and glutatione peroxidase enzymes, and a decrease of malondialdehyde levels in animals treated with formaldehyde plus melatonin was observed. Furthermore, the histopathological changes caused by formaldehyde were disappeared except for minimal tubular dilatation in this group. In conclusion, the biochemical and histological findings of our study suggest that melatonin administration prevents formaldehyde-induced oxidative renal damage in rats.

Prospective study of clinical symptoms and skin test reactions in medical students exposed to formaldehyde gas

Previous investigators have reported the occurrence of both allergic and non-allergic systemic complications due to exposure to formaldehyde gas. However, little is known about the pathogenic link between formaldehyde-induced clinical symptoms and patch test results, or about the long-term effects of formaldehyde exposure. In the present study, a questionnaire was administered to 143 medical students, and 60 of them were tested by patch test for formaldehyde at the beginning and end of a human anatomy laboratory course. Another group of 76 students who had finished the course 2-4 years previously were administered another questionnaire, and the patch test was carried out on 58 of them. The frequencies of skin irritation, eye soreness, lacrimation, eye fatigue, rhinorrhea, throat irritation, general fatigue and mood swings increased after repeated exposure. Two (3.3%) of 60 students became positive to 1% formaldehyde at the end of the anatomy course (one male with allergic hand dermatitis due to direct contact with formaldehyde, and one female with an atopic background with unbearable physical symptoms) while the remaining 58 showed a negative reaction throughout the study period. The vast majority of students complained of various non-allergic, physical symptoms, and recovered from such symptoms without subsequent complications. No progression to multiple chemical sensitivity was found. Students with an episode of atopic dermatitis and allergic rhinitis were susceptible to formaldehyde exposure, and developed mucocutaneous symptoms, probably due to the impaired barrier function and remodeling of the skin and mucosa.

Protective effects of omega-3 essential fatty acids against formaldehyde-induced neuronal damage in prefrontal cortex of rats

The aim of this study was to examine the neurotoxicity of formaldehyde on prefrontal cortex and the protective effects of omega-3 essential fatty acids against these toxic effects. For this purpose, 21 male Wistar rats were divided into three groups. The rats in group I comprised the controls, while the rats in group II were injected every other day with formaldehyde (FA). The rats in group III received omega-3 fatty acids daily while exposed to formaldehyde. At the end of the 14-day experimental period, all rats were killed by decapitation. The brains of the rats were removed and the prefrontal cortex tissues were obtained from all brain specimens. Some of the prefrontal cortex tissue specimens were used for determination of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels. The remaining prefrontal cortex tissue specimens were used for light microscopic and immunohistochemical evaluation. The levels of SOD and GSH-Px were significantly decreased, and MDA levels were significantly increased in rats treated with formaldehyde compared with those of the controls. Furthermore, in the microscopic examination of this group, formation of apoptotic bodies, pycnotic cells, and apoptotic cells including nuclear fragmentation and membrane budding were observed. However, increased SOD and GSH-Px enzyme activities, and decreased MDA levels were detected in the rats administered omega-3 fatty acids while exposed to formaldehyde. Additionally, cellular damage caused by formaldehyde was decreased, and structural appearance was similar to that of the control rats in this group. The biochemical and histological findings observed in all groups were also confirmed by immunohistochemical evaluation. It was determined that formaldehyde-induced neuronal damage in prefrontal cortex was prevented by administration of omega-3 essential fatty acids.

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

The reduction of formaldehyde by ammonium carbonate was examined in cadavers and in vitro. Formaldehyde concentrations in the air (10 cm above human cadavers) and in various cadaveric tissues were measured with or without perfusion of ammonium carbonate solution into formaldehyde-fixed cadavers. Air samples were monitored using Kitagawa gas detector tubes. For measurement of formaldehyde in tissues, muscles and organs were cut into small pieces and tissue fluids were separated out by centrifugation. These specimen fluids were diluted, supplemented with 3-methyl-2-benzothiazolinone hydrazone hydrochloride and quantified by spectrophotometry. In five cadavers without ammonium carbonate treatment, the formaldehyde concentrations in the air above the thorax and in various tissue fluids were 1.2-3.0 p.p.m. and 0.15-0.53%, respectively. Arterial reperfusion of saturated ammonium carbonate solution (1.0, 1.5 or 2.0 L) into five formaldehyde-fixed cadavers successfully reduced the formaldehyde levels, both in the air (0.5-1.0 p.p.m.) and in various tissue fluids (0.012-0.36%). In vitro experiments demonstrated that formaldehyde concentrations decreased, first rapidly and then gradually, with the addition of ammonium carbonate solution into fluids containing formaldehyde. It was confirmed that formaldehyde reacted with the ammonium carbonate and was thereby changed into harmless hexamethylenetetramine. The application of ammonium carbonate solution via intravascular perfusion and, if necessary, by infusion into the thoracic and peritoneal cavities, injection into muscles and spraying on denuded tissues can be anticipated to reduce formaldehyde to satisfactorily low levels in cadaveric tissues and, consequently, in the air, which may provide safe and odorless dissecting rooms.

Video exposure assessments demonstrate excessive laboratory formaldehyde exposures

Video exposure assessments were conducted in a comparative anatomy laboratory using formaldehyde-preserved sharks and cats. Work in the facility using time-integrated samplers indicated personal and area concentrations generally below the current OSHA permissible exposure limit. However, complaints about room air quality were frequent and routine. Using a photoionization detector with an integral data logger, total ionizables present were sampled as a surrogate for formaldehyde. After synchronizing time tracks from the datalogger concentrations with simultaneously created videotapes of laboratory tasks, composite video exposure overlays were generated. Use of this video exposure method revealed very short-lived, excessively high peak exposure events, whereas conventional time-weighted averages indicated the majority (30/32) of personal exposures were below the OSHA limit of 0.75 ppm. These legally acceptable exposure levels were associated with self-reported symptoms of burning nose and eyes and eye irritation. Thus, transient peak formaldehyde concentrations not detected by longer term averaging studies could be responsible for the health effects reported. The video exposure monitoring method demonstrated that close dissection work, opening peritoneal cavities, and specimen selection activities were most likely the causes of elevated student exposures. Teaching assistants' exposures were the highest, exceeding OSHA limits on several occasions. The utility of the video monitoring method for conducting enhanced, critical task exposure assessments is discussed.

Identification and quantification of in vitro adduct formation between protein reactive xenobiotics and a lysine-containing model peptide

Formation of in vitro adducts between different classes of xenobiotics and the lysine-containing peptide Lys-Tyr was monitored by high-performance liquid chromatography and electrospray ionization mass spectrometry. The molecular structures of the main resulting products could be sensitively analyzed by mass spectrometry (flow injection analysis), enabling the detection of characteristic binding formations. Aldehydes such as formaldehyde, acetaldehyde, and benzaldehyde were shown to form stable linkages to lysine amino groups via Schiff bases. Other electrophilic substances (e.g., toluene-2,4-diisocyanate, 2,4-dinitro-1-fluorobenzene, 2,4,6-trinitrobenzene sulfonic acid, dansyl chloride, and phthalic acid anhydride) also formed covalent adducts with lysine residues. The reactivity of the compounds was quantified by measuring the amount of peptide that remained unchanged after incubation for a certain period with the xenobiotic. Although reactivity levels within this group of aldehydes varied only to a small extent, as would be expected, extreme differences were seen among the structurally heterogeneous group of nonaldehyde xenobiotics. These results support the hypothesis that simple chemical reactions may lead to the adduction of nucleophilic macromolecules such as peptides or proteins. Such reactions, in particular, Schiff base formation of aldehydes, have previously been shown to be capable of specifically interfering with costimulatory signaling on T cells. Our results suggest that electrophilic xenobiotics of other classes may also inherit the capacity to exert similar effects. Forming covalent linkage to peptides may represent a possible molecular mechanism of electrophilic xenobiotics in vivo, yielding immunotoxic effects. The model utilized in this study is appropriate for monitoring the adduction of xenobiotics to basic peptides and for analyzing the resulting molecular structures.

The use of noncancer endpoints as a basis for establishing a reference concentration for formaldehyde

Published studies involving formaldehyde were selected for quality and relevance for determining whether noncancer endpoints could be used to derive a reference concentration for formaldehyde. Chamber studies provided the highest quality data for determining the presence of eye, nose, or throat irritation at a known level of formaldehyde. Some individuals begin to sense irritation at about 0.5 ppm, 5-20% report eye irritation at 0.5 to 1 ppm, and greater certainty for sensory irritation appears at 1 ppm or greater. These levels of formaldehyde do not appear to impact asthmatics even though these individuals are thought to be more sensitive to irritants. Mild, reversible changes in pulmonary function (forced expiratory volume at 1 s and midexpiratory flow) can occur in sensitized individuals at levels approaching 2 ppm. Studies in the manufacturing setting, while confounded by multiple exposures, provide useful information for setting boundaries for sensory irritation or changes in pulmonary function. Community surveys do not provide the specificity nor sensitivity needed to establish a reference concentration. Histological studies of the nasal mucosa suffer significant methodological and technological shortcomings in addition to issues commonly associated with the design of residential and workplace studies. Based on the review of chamber, community, and workplace studies of human exposures to formaldehyde, it is not possible to identify a specific no observed adverse effect level or lowest observed adverse effect level for formaldehyde. Ranges of exposures associated with acute sensory irritation can be derived and do include sensitive subpopulations. However, given the quality and variability of the data, human studies alone, especially those involving sensory irritation, are not adequate to serve as a reference concentration for estimating risk, or lack thereof, for a lifetime of exposure to formaldehyde. Alternative approaches, such as modeling cellular changes observed in animal studies, may be more useful for quantitative risk assessment of noncancer endpoints and should be used as an adjunct to interpreting human sensory studies.