Pulmonary function test in formalin exposed and nonexposed subjects: A comparative study.

BACKGROUND: The main function of the lung is gas exchange, which can be assessed in several ways. A spirometer measures the flow and the volumes of the inspired and expired air. The thoracic and abdominal muscle strength plays an important role in pulmonary function and diffusing lung capacity. AIMS AND
OBJECTIVES: The aim of this study was to assess the effects of formalin exposure on the pulmonary function to compare with healthy individuals. To assess the chronic effects of formalin exposure on Pulmonary function tests (PFTs) in the faculties, lab technicians and attender of the Department of Anatomy and Pathology of SRM Medical Hospital and Research Centre, Kattankulathur.
MATERIALS AND METHODS: This prospective study was carried out in 50 healthy formalin exposed subjects (at least 5 years exposure) from Department of Anatomy and Pathology of SRM Medical College Hospital and Research Centre, Kattankulathur and 50 healthy controls of same age group of this study were included after obtaining ethical clearance and consent 'Easy One Pro Spirometer (Ndd Medical Technologies, Cheshire SK 101LT, United Kingdom) was used to find out the PFT.
RESULTS: Student's t-test was applied to compare the PFT parameters between formalin exposed and formalin nonexposed group. There was a significant difference in mean and standard deviation of pulmonary parameters with the P < 0.005 in formalin exposed, which shows that they have lesser ventilatory drive.
CONCLUSION: The formalin exposed subjects in our study presented with a mixed disorder of both obstructive and restrictive type. We also found that there was a negative correlation of pulmonary function with that of the degree and duration of exposure to formalin.

The main function of the lung is gas exchange, which can be assessed in several ways. A spirometer measures the flow and the volumes of the inspired and expired air. The thoracic and abdominal muscle strength plays an important role in pulmonary function and diffusing lung capacity. Formaldehyde is the simplest aldehyde that can be obtained from its cyclic trimer trioxane and the polymer paraformaldehyde. Aqueous solutions of formaldehyde are referred to as formalin. In 1867, the German chemist August Wilhelm Von Hofmann discovered formaldehyde.[1] Formaldehyde solutions are used as a fixative for microscopy and histology. Formaldehyde-based solutions are also used in embalming to disinfect and temporarily preserve human and animal remains. This is prepared by mixing the commercially available formalin solution with tap water in the proportion of 3:1.[2]

Occupational exposure to formaldehyde by inhalation is mainly from three types of sources: thermal or chemical decomposition of formaldehyde-based resins, formaldehyde emission from aqueous solutions (e.g. embalming fluids), and the production of formaldehyde resulting from the combustion of a variety of organic compounds (e.g. exhaust gases).[3] Formaldehyde enters in the body by breath or when it comes in contact with our skin. Formaldehyde is quickly observed into the nose and the upper part of the lungs. Once observed, formaldehyde is very quickly broken down. Almost every tissue in the body has the ability to break down formaldehyde. It is usually converted to a nontoxic chemical called formate, which is excreted in the urine and is converted to carbon-di-oxide and breathed out of the body. However, formaldehyde can be toxic and allergenic, and carcinogenic.[4]

Formaldehyde has been reported to cause an assortment of acute and chronic health effects. It has been suggested that formaldehyde may produce physiological alterations of the respiratory system. Owing to its high water solubility, >95% of inhaled formaldehyde is absorbed in the upper respiratory tract and very little formaldehyde, if any, will reach the alveolar membranes of the lung. The toxic effects of formaldehyde on the upper respiratory tract are described as an irritant and sensitizer.[5] Occupational data suggests that small but significant changes may occur in lung functions following prolonged exposure in the workplace.[678] Upper airway irritation is the most common respiratory effect reported by the workers and occurs over a wide range of concentrations most frequently above 1 ppm. However, airway irritation has occurred in some workers with exposures to formaldehyde as low as 0.1 ppm.

Symptoms of upper airway irritation include dry or sore throat, itching and burning sensations of the nose and nasal congestion. Tolerance to this level of exposure may develop within 1–2 h. This tolerance can permit workers remaining in an environment of gradually increasing formaldehyde concentrations to be unaware of their increasingly hazardous exposure.[910111213] Formaldehyde has also been reported to produce allergic contact dermatitis,[14] neurobehavioral changes[15] and carcinogenesis.[16] Formaldehyde may on rare occasions induce bronchial asthma at relatively high exposure doses. The approach to formaldehyde-induced symptoms should be one of the careful documentation of objective physiologic changes.[17] The annual production of formaldehyde (around 2005) was 21 million tons (46 billion pounds). In view of its widespread use, toxicity and volatility, exposure to formaldehyde is a significant consideration for human health hazards.[3] Several European countries restrict the use of formaldehyde, including the import of formaldehyde-treated products and embalming. From September 2007, the European union banned the use of formaldehyde due to its carcinogenic properties as a biocide (including embalming) under the Biocidal Products Directive (98/8/EC).[1819] Various studies have revealed the effect of formalin by artificial exposures of volunteers under controlled environmental condition.[910111213] A few studies have characterised formaldehyde emission rates in gross anatomy laboratory.[20]

WHO defines obesity as “A condition with excessive fat accumulation in the body to the extent that the health and wellbeing are adversely affected.” According to Dorland's Medical Dictionary for Health Consumers, “obesity is defined as an increase in body weight beyond the limitation of skeletal and physical requirements, as the result of excessive accumulation of body fat” medically meaningful distinction between lean and obese is somewhat arbitrary. There is no clear-cut difference between normal and abnormal fat levels. That is why obesity is quantitatively defined as the level of adiposity that leads to adverse health.

Materials and Methods

This prospective study was carried out in 50 healthy formalin exposed subjects from Department of Anatomy and Pathology of SRM Medical College Hospital and Research Centre, Kattankulathur and 50 healthy controls of same age group.

The study was approved by the Institutional Ethical Committee and a written consent form from the subjects was obtained for carrying out the study after explaining to them the protocol of the study and the benefits of the study.

Project instruments

Questionnaire and examination proforma for obtaining medical history and for recording clinical examination

Portable weighing machine was used to record the weight in kg

Measuring tape was used to measure the standing and sitting height in centimeters

The ndd EasyOne Pro (Computerized Spirometer, Cheshire SK 101LT, United Kingdom) respiratory analysis system available in the research lab of Department of Physiology, SRM Medical College Hospital and Research Centre was used to perform the pulmonary function tests (PFTs).

History and clinical examination

A thorough history was collected from all the participants including personal history such as name, age, sex, ethnicity, address, habit of smoking and medical history including history of any respiratory and cardiac diseases. All the subjects underwent an anthropometrical assessment including standing height and weight. The subjects for this study were recruited based on the following criteria: Formalin exposed subjects (at least 5 years in their field) were included, asthmatic and chronic obstructive pulmonary disease subjects were excluded.

For the study parameters include flow volume loop (FVL) tidal, slow vital capacity (SVC), maximum ventilation volume or maximum voluntary ventilation (MVV).

They are,

FVL tidal components are forced vital capacity (FVC) [L], forced expiratory volume 1 s (FEV1) [L], FEV1/FVC, forced expiratory flow (FEF) 25–75% [L/s], peak expiratory flow (PEF) [L/s], forced expiratory time (FET) [s], forced inspiratory vital capacity (FIVC) [L] and peak inspiratory flow (PIF) [L/s]

SVC components are vital capacity (VC) [L], VCex [L], VCin [L], inspiratory reserve volume (IRV) [L], inspiratory capacity (IC) [L] tidal volume (VT) [L] and respiratory frequency (Rf) [1/min]

MVV components: are MVV6 [L/min], MVV time [s], VT [L], f [BPM] and MVV [L/min].

The procedure for dong test parameters for FVC, the subjects, asked for breath as per the instruction to record parameters. This test was repeated 2 or 3 times, and the best value were obtained. For MVV, the subjects were asked to inhale and exhale as deep and the fact as possible over a period of 12 s during which recordings were done.

The data collected were entered in the MS excel spreadsheet. Descriptive table was generated, and appropriate statistical analysis was performed using SPSS 17.0 software, IBM, Chicago, USA. Student's t-test was applied to compare the PFT parameters between formalin exposed and formalin nonexposed group. A significance level of “P” <0.05 was considered for the Student's t-tests. The data were expressed as mean ± standard deviation.

Results

The mean and standard deviation of the FVL tidal parameters FVC, FEV1, FEV1/FVC, FEF 25–75%, PEF, FET, FIVC and PIF for both study and control group were given in Table 1. All parameters except FET were found to be significantly lower in the formalin exposed group than the control group. The mean and standard deviation of the SVC components show that parameters VC, IRV, IC, VT and Rf was significantly lower in the formalin exposed group than the control group.

Table 1

Comparison of PFT variables between the formalin exposed and formalin nonexposed individuals

The mean and standard deviation of the MVV components shows that the parameters MVV6, MVV time, VT, f [BPM] and MVV was significantly lower in the study group than the control group while there was no significant change was noted for MVV time and VT.

The BMI value were correlated with all parameter of FVL tidal, SVC, MVV and found to have a significant “P” value for IRV (‘P’ - 0.03), VT (‘P’ - 0.009). All other parameters were insignificant with BMI [Table 2].

Table 2

Correlation of PFT parameters with BMI

Discussion

In our study, we found that all the FVL tidal parameters such as FVC, FEV1, FEV1/FVC, FEF 25–75%, PEF, FIVC and PIF except FET were found to be significantly lower in the formalin exposed group than the control group. The other parameters like VC, IRV, IC, VT, Rf, MVV6, f [BPM] and MVV also were found to be significantly lower in the formalin exposed group than the control group. However there was no significant change was noted for MVV time and VT. The formalin exposed subjects in our study presented with a mixed disorder of both obstructive and restrictive type. The results of our study are in concordance with the results of other studies.[202122] Khaliq et al., found that FVC decreased in subjects immediately after their first exposure. While all other lung function parameters remained unchanged, indicating some mild transient bronchoconstriction on acute exposure to formalin. On contrary, Chia, et al. studied 150 1st-year medical students exposed to formaldehyde during the dissection of cadavers in a gross anatomy laboratory and reported no significant differences in the pre- and post-exposure mean FEV1 and FVC.[20]

Green, et al., suggested possibility of the occurrence of asthmatic reactions, or even asthma.[9] Harving, et al., reported the inhalation of formaldehyde fumes causes bronchial hyperactivity.[23] and Alexanderson, et al., shows the reductions of air circulation speed as well. Moreover in other study revealed the increase of respiratory values. No asthmatic report noticed in our study group after chronic exposure (>5 years) of formaldehyde.[8] The question of whether changes in respiratory function are associated with shift long exposure to low levels of formaldehyde remains controversial. Studies by Malaka and Kodama and Holness and Nethercott et al., found no significant difference in the changes in pulmonary function variables across a shift.[242526] However, other studies showed that pulmonary function of workers exposed to formaldehyde decreased over the workshift.[27]

In a study performed by Kulle et al., on 19 healthy nonsmokers showed no significant changes in PFT variables at any dose ranging from 0 5 ppm to 3 ppm for up to 3 h.[26] In one other study, Schachter et al., performed a spirometry test under laboratory conditions on 15 nonsmoking, healthy subjects exposed to formaldehyde. No acute nor subacute changes in lung function occurred with 5, 15, 25, and 40 min exposures to 2 ppm formaldehyde during rest or exercise.[12]

A study by Schachter et al., showed that subjects’ exposure to 2 ppm formaldehyde for 40 min did not result in acute changes in respiratory function.[12] The United States Occupational Safety and Health Administration has gradually decreased the permissible exposure limit (PEL) for formaldehyde and the most recent amendment was to its current PEL of 0 75 ppm time weighted average as a way to reduce the risk of chronic occupational symptoms, eye, nose, and throat irritation, and sensitisation. Imbus and Tochilin done a cross-sectional study of 176 workers in the phenol-formaldehyde-resin coated wood industry found no association of cross-shift pulmonary function and formaldehyde exposure. The exposure of formaldehyde was low (≤0.05 ppm).[28] The selection bias in studied subjects and confounding effects of wood dust exposure limits the interpretation of the data.

Husain, et al., done a study of workers exposed to formaldehyde in a melamine house in a security paper mill in India along with 27 controls, increased symptoms of cough and dyspnea were observed in the exposed subjects compared to those in controls. Pulmonary function abnormalities were observed in 40% of the exposed subjects compared to 4.5% in controls. Lung functions were significantly lower in exposed subjects compared with unexposed controls.[29]

Conclusion

In our study, it was conducted to assess the pulmonary function in formalin exposed and formalin nonexposed individuals, we found that there was a definite correlation between formalin exposure and pulmonary function in otherwise healthy individuals, which was found to be negative, that is, formalin exposure has indeed been found to have a deleterious effect on pulmonary function. The formalin exposed subjects in our study presented with a mixed disorder of both obstructive and restrictive type. We also found that there was negative correlation of pulmonary function with that of the degree and duration of exposure to formalin.