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PubMed2004

The artificial evolution of an enzyme by random mutagenesis: the development of formaldehyde dehydrogenase.

A unique variant of glutathione independent formaldehyde dehydrogenase of Pseudomonas putida was obtained by random mutagenesis using the PCR-reaction. This YM042 mutant, S318G, was a cold-adapted formaldehyde dehyrogenase. The activity at 29 degrees C of the variant was 1.7-fold higher than that of the wild type. The K(m) values of the mutant at 37 degrees C were 0.40 mM for NAD(+) and 2.5 mM for formaldehyde, while those of the wild-type were 0.18 mM for NAD(+) and 2.1 mM for formaldehyde. The catalytic efficiency for formaldehyde was about 1.5-fold greater in the mutant than in the wild-type enzyme. The optimum pHs and temperatures of the mutant and the wild-type enzyme were 7.5, and 8.0 and 37 degrees C, and 47 degrees C, respectively. The thermal stability of the mutant was lower than that of the wild type.

Aldehyde Oxidoreductases↗
PubMed1991

Formaldehyde exposure and health status in households.

This report describes a case study concerned with acute and subacute health effects of formaldehyde in the indoor air, which is based on a large group of control houses and houses retroinsulated 4 to 5 years earlier with urea formaldehyde foam insulation (UFFI). Both groups underwent an environmental and health assessment on two occasions separated by an interval of 12 months, during which about one-half of the UFFI group performed remedial work on their houses. The results show that in the first survey of the study population, before remedial work, there was a moderate excess of many adverse health status indicators among the UFFI subset relative to the controls. This was associated with the presence of direct exposure-response relationships between formaldehyde levels in the UFFI houses and the prevalence of a number of symptoms. No comparable relationships were seen among the controls. At the second survey, performed following the removal of the UFFI, there was an appreciable reduction in the excess of most adverse health status indicators among the UFFI subjects. This improvement in health status among the UFFI removal subset was not associated with any significant diminution of formaldehyde exposures, although the previously observed exposure-response relationships had vanished. These observations imply that the findings obtained in the preremedial stage of the study cannot be explained by formaldehyde exposure alone.

Adult↗
PubMed1996

Closed-circuit apparatus for specific inhalation challenges with an occupational agent, formaldehyde, in vapor form.

Specific inhalation challenges are an important tool for confirming occupational asthma. In recent years, we have described two closed-circuit apparatuses that allow exposure to stable and controlled concentrations of particles and isocyanate gases. More recently, we developed a similar apparatus that generates chemicals in vapor form. The aim of this work is to describe its performance in the specific case of formaldehyde. This instrument is made of four parts: a generator as such, an exposure chamber, a monitor, and an automated regulatory system. This apparatus was assessed in four subjects suspected of having formaldehyde-induced asthma or alveolitis. The concentrations of formaldehyde were increased from 0.5 to 1 mg/m3 to 3 mg/m3 keeping the concentration at a value of 3 mg/m3 or less (threshold limit value). The dispersion of obtained values by comparison with the median data (6 values) was as follows: maximum value, 12 to 84%; minimum value, 20 to 58%; interquartile range, 0.13 to 0.9 mg/m3. We observed that target concentrations took a few minutes to be reached, but, once they were obtained, delivered concentrations were stable. The new vapor-delivery apparatus allows us to obtain concentrations of formaldehyde that are close to target concentrations with an acceptable dispersion of values around target concentration. Its use should be extended to other chemicals besides formaldehyde.

Administration, Inhalation↗
PubMed1978

Digestion of chromosomal proteins in formaldehyde treated chromatin.

Treatment of chromatin subunits (nucleosome monomers) with formaldehyde results in the formation of cross-links between DNA and histones and between histones and histones. Digestion of chromosomal proteins with proteinase K does not lower the protein/DNA weight ratio below 0.08 to 0.1 as determined by cesium chloride gradient centrifugation of the digestion product from formaldehyde-treated nucleosomes. In addition to proteinase K, formaldehyde-treated nucleosomes were tested for accessibility to trypsin and pronase. The CsCl gradient patterns show, that pronase digestion and proteinase K treatment yield similar results. Trypsin treatment of control and formaldehyde-treated nucleosomes shows, that the sites which are accessible for trypsin in native nucleosomes, are blocked after formaldehyde treatment. Analysis of the CsCl gradient peak fractions in polyacrylamide gels shows, that the reliability of DNA fragment size determinations depends on the completeness of deproteinization.

Animals↗
PubMed1976

Artificial insemination with spermatozoa in formaldehyde.

The ability of formaldehyde to preserve the integrity of the membranes of spermatozoa, as indicated by eosin staining (Dott & Foster, 1975), prompted an investigation to discover what other properties of spermatozoa were preserved by low concentrations of formaldehyde in vitro. In a series of experiments on bull, ram and boar spermatozoa it has been shown that spermatozoa rendered immotile by formaldehyde recovered their motility when the formaldehyde was removed by washing up to 12 hr afterwards (H.M. Dott & G.C. Foster, unpublished). To find out if fertility was preserved ewes and sows were inseminated with spermatozoa rendered immotile with formaldehyde.

Animals↗
PubMed2001

Effects of formaldehyde on the frog's mucociliary epithelium as a surrogate to evaluate air pollution effects on the respiratory epithelium.

The increasing use of alcohol as an alternative fuel to gasoline or diesel can increase emission of formaldehyde, an organic gas that is irritant to the mucous membranes. The respiratory system is the major target of air pollutants and its major defense mechanism depends on the continuous activity of the cilia and the resulting constant transportation of mucous secretion. The present study was designed to evaluate the effects of formaldehyde on the ciliated epithelium through a relative large dose range around the threshold limit value adopted by the Brazilian legislation, namely 1.6 ppm (1.25 to 5 ppm). For this purpose, the isolated frog palate preparation was used as the target of toxic injury. Four groups of frog palates were exposed to diluted Ringer solution (control, N = 8) and formaldehyde diluted in Ringer solution at three different concentrations (1.25, 2.5 and 5.0 ppm, N = 10 for each group). Mucociliary clearance and ciliary beat frequency decreased significantly in contact with formaldehyde at the concentrations of 2.5 and 5.0 ppm after 60 min of exposure (P<0.05). We conclude that relatively low concentrations of formaldehyde, which is even below the Brazilian threshold limit value, are sufficient to cause short-term mucociliary impairment.

Air Pollutants↗
PubMed2006

Badge-type diffusive sampler using 3-methyl-2-benzothiazolinone hydrazone for measuring formaldehyde in indoor air.

The evaluation of a badge-type diffusive sampler for measuring formaldehyde using 3-methyl-2-benzothiazolinone hydrazone (MBTH) was investigated. On average, the formaldehyde concentration in blanks was reduced by approximately 31% by cleaning procedures. The cleaning techniques did not significantly differ in effectiveness. The maximum sampling rate was 22.4 +/- 3.5 mL min(-1) at MBTH concentrations of 0.05%. The formaldehyde concentration in blanks did not appreciably increase over a period of about 1 month at room temperature, and was 0.36 +/- 0.03 microg, with a relative standard deviation of 8%. The diffusive sampler had good precision and accuracy for measuring formaldehyde in indoor environments. For a 24-h exposure time, the limits of detection and quantification calculated with the field blanks were 9.7 and 13.8 ppb, respectively. The minimum exposure times were calculated based on the measured and calculated limits of quantification, the sampling rate, and the atmospheric formaldehyde concentration. The capacity of the diffusive sampler with 0.5% MBTH was 3 ppm h(-1), approximately 1.5-times the capacity when the MBTH concentrations were 0.05%.

Air↗
PubMed2006

Effect of formaldehyde on biofilm activity and morphology in an ultracompact biofilm reactor for carbonaceous wastewater treatment.

The effects of formaldehyde on biofilm morphology and biomass activity were investigated in an ultracompact biofilm reactor (UCBR) for carbonaceous wastewater treatment. The wastewater contained a fixed amount of glucose (with a chemical oxygen demand concentration of 600 mg/L) and an increasing concentration of formaldehyde (ranging from 21.4 to 271.1 mg/L). An influent formaldehyde concentration higher than 75 mg/L could facilitate filamentous growth (on biofilm) control and lead to a higher biofilm density, which is desirable as it enhanced the UCBR performance stability. However, at an influent formaldehyde concentration higher than 214.4 mg/L, biomass production was inhibited and deteriorations of biofilm morphology and biomass activity were observed. This study showed that it was desirable to maintain an influent formaldehyde concentration lower than 202.2 mg/L, as this concentration could achieve a good biofilm morphology while not inhibiting its microbial activity.

Biodegradation, Environmental↗
PubMed2000

Formaldehyde prepared from paraformaldehyde is stable.

For critical histological investigations, tissue fixation is sometimes carried out in formaldehyde freshly prepared from paraformaldehyde by heating. The purity of formaldehyde produced in this way is superior to that of commercial stock solutions. We studied the stability of freshly prepared formaldehyde solutions by determination of pH and titration of acid, which reflect the formation of formic acid. It was found that very small amounts of acid are produced during the heating of paraformaldehyde. Prolonged heating or storage of freshly prepared formaldehyde for up to 8 days did not significantly increase the amount of acid. It was also found that heating of the paraformaldehyde is not necessary, since depolymerization may take place at room temperature. We conclude that formaldehyde prepared from paraformaldehyde remains stable for considerable periods of time, and it is therefore unnecessary to prepare it immediately prior to fixation. Also, in many cases, buffering of the fixative may be omitted, since only minor changes in the pH occur during fixation.

Animals↗
PubMed1996

Identification of formaldehyde as the metabolite responsible for the mutagenicity of methyl tertiary-butyl ether in the activated mouse lymphoma assay.

Methyl tertiary-butyl ether (MTBE), which is added to gasoline as an octane enhancer and to reduce automotive emissions, has been evaluated in numerous toxicological tests, including those for genotoxicity. MTBE did not show any mutagenic potential in the Ames bacterial assay or any clastogenicity in cytogenetic tests. However, it has been shown to be mutagenic in an in vitro gene mutation assay using mouse lymphoma cells when tested in the presence, but not in the absence, of a rat liver-derived metabolic activation system (S-9). In the present study, MTBE was tested to determine if formaldehyde, in the presence of the S-9, was responsible for the observed mutagenicity. A modification of the mouse lymphoma assay was employed which permits determination of whether a suspect material is mutagenic because it contains or is metabolized to formaldehyde. In the modified assay, the enzyme formaldehyde dehydrogenase (FDH) and its co-factor, NAD+ are added in large excess during the exposure period so that any formaldehyde produced in the system is rapidly converted to formic acid which is not genotoxic. An MTBE dose-responsive increase in the frequency of mutants and in cytotoxicity occurred without FDH present, and this effect was greatly reduced in the presence of FDH NAD+. The findings clearly demonstrate that formaldehyde derived from MTBE is responsible for mutagenicity of MTBE in the activated mouse lymphoma assay. Furthermore, the results suggest that the lack of mutagenicity/clastogenicity seen with MTBE in other in vitro assays might have resulted from inadequacies in the test systems employed for those assays.

Animals↗
PubMed1989

Biocidal activity of ozone versus formaldehyde against poultry pathogens inoculated in a prototype setter.

Ozone was evaluated as an alternative hatchery disinfectant to replace formaldehyde in the event that the Environmental Protection Agency regulates the use of formaldehyde under the Toxic Substances Control Act. Cultures of Staphylococcus, Streptococcus, and Bacillus species previously isolated from poultry hatcheries and selected culture collections of Escherichia coli, Pseudomonas fluorescences, Salmonella typhimurium, Proteus species, and Aspergillus fumigatus were spread-plated on open petri plates and independently fumigated with ozone or formaldehyde in a prototype laboratory poultry setter. Ozone (1.52% to 1.65% by weight) resulted in bacterial reductions of greater than 4 to 7 log10 and fungal reductions of greater than 4 log10, whereas formaldehyde achieved reductions of greater than 7 log10 and greater than 5 log10, respectively, after 8 min of exposure to either disinfectant. Potential mutagenic effects were observed in ozonated E. coli colonies resulting in decreased superoxide dismutase activity and increased catalase activity when compared with nonozonated control colonies. In this study ozone reduced microorganism counts but not as much as formaldehyde. Ozone may be used as a disinfectant against selected microorganisms, although further testing under actual hatchery conditions is needed before making recommendations to the industry.

Animals↗
PubMed1989

Bactericidal activity, eggshell conductance, and hatchability effects of ozone versus formaldehyde disinfection.

Ozone and formaldehyde were evaluated as disinfectants in a prototype laboratory setter against microorganisms that are naturally present on fertile, freshly laid, broiler hatching eggs. Significantly lower microbial counts of over 2.5 log10 (P less than .05) were observed for water-misted and ozonated (2.83% by weight) eggs or formaldehyde-fumigated (triple strength) eggs than for control and water-misted eggs. Eggshell conductance studies as measured by egg moisture losses in a desiccator showed no significant differences (P greater than .05) among untreated, water misted, ozonated (3.06% by weight) with water mist, or formaldehyde (triple strength)-fumigated eggs. Hatchability was significantly reduced (26.5 to 37.5%) following ozonation (3.03% ozone by weight, 2 h) in comparison with effects of no treatment or water misting. Misting with ozonation was equally as effective as formaldehyde fumigation in reducing microbial counts. However, ozone treatment at the concentrations tested significantly reduced hatchability when compared with results of either no treatment, water misting, or an average hatchability figure for formaldehyde fumigation. These findings indicate that ozone is a good disinfectant yet may adversely affect embryo development when given in the gaseous form.

Animals↗
PubMed1989

Comparison of ozone and formaldehyde as poultry hatchery disinfectants.

Ozone and formaldehyde were compared as poultry hatchery disinfectants in a poultry setter, and evaluated for effectiveness. Escherichia coli, Pseudomonas fluorescens, Salmonella typhimurium, and Proteus spp. were inoculated onto open petri plates and exposed to ozone or onto filter paper strips and exposed to ozone or formaldehyde in a poultry setter. Ozone (1.41 to 1.68% by weight) resulted in significant bacterial reductions of greater than 4 log10 on the open plates and greater than 3 log10 on filter paper strips, whereas formaldehyde (triple strength) resulted in greater than 7 log10 reduction on filter paper strips. Ozone was similarly lethal to organisms on filter paper strips at 90% relative humidity (RH) and 13.9 C, and at 50% RH and 37.7 C. Although under the conditions of this study formaldehyde (triple strength) was more lethal than ozone, ozone killed greater than 99.9% of the starting microbial populations. In the event that formaldehyde can no longer be used in the hatchery, an effective alternative may be ozone.

Animals↗
PubMed1990

Epidemiologic evidence on the relationship between formaldehyde exposure and cancer.

Over 30 epidemiologic studies have evaluated cancer risks associated with formaldehyde exposure. Excesses were reported for several sites, leukemia and cancers of the nasal cavities, nasopharynx, lung, and brain generating the greatest interest. The excesses of leukemia and brain and colon cancer found among professionals may not be related to formaldehyde exposure, since similar excesses were not observed among industrial workers. Inconsistencies among and within studies impede assigning formaldehyde a convincing causal role for the excesses of lung cancer found among industrial workers. A causal role for formaldehyde is the most probable for cancers of the nasopharynx and, to a less extent, the nasal cavities. Evidence of exposure-response relationships, the fact that direct contact with formaldehyde may occur at these upper respiratory sites, and the consistency of these findings with experimental studies make this assumption highly probable.

Brain Neoplasms↗
PubMed1988

Respiratory symptoms and pathophysiological effects of occupational exposure to formaldehyde and wood dust.

The hazards of exposure to formaldehyde have been widely discussed in recent years on account of the health complaints of exposed persons. Both domestic and occupational exposure to formaldehyde is common. In the present study the effects of formaldehyde alone and in combination with wood dust, another nasal irritant, on the upper and lower respiratory tract have been investigated. The effects were correlated with the duration and degree of exposure. Discomfort from both the upper and lower airways was more frequent in the exposed group than in the unexposed group. Nasal obstruction among the exposed subjects in general could not be detected by rhinomanometric measurements, but, for the group exposed to formaldehyde alone and with a history of nasal blocking, there was significant nasal mucosal swelling. The nasal mucociliary clearance was significantly delayed, and the sense of smell was significantly reduced in the exposed groups when they were compared with the referents. Spirometry showed a significantly decreased forced vital capacity in the exposed groups. There were no signs in this investigation that duration of exposure or level of exposure to formaldehyde would have any influence on the severity of symptoms or the impairment of physiological conditions.

Adult↗
PubMed1999

Intravesicular formaldehyde instillation and renal complications.

Intravesicular formaldehyde has been used for intractable hemorrhagic cystitis since the late 1960's. Initial reports described few complications, but in the 1970's both ureteral as well renal parenchymal damage were reported in the urology literature. This has been less appreciated by nephrologists perhaps related to the paucity of reports in the nephrology literature. Although the pathogenesis has not been rigorously studied ureteral toxicity may be secondary to intense edema, inflammation and subsequent fibrosis induced by the formaldehyde; while renal tubular injury may be secondary to systemic absorption of formaldehyde. Ureteral reflux as well as dosage of intravesicular formaldehyde seem to be risk factors for acute renal failure. We describe a case of acute renal failure secondary to intravesicular formaldehyde and review pathogenesis as well as potential prophylactic measures to prevent this complication.

Acute Kidney Injury↗
PubMed1998

Formaldehyde evaluation from endodontic materials.

The purpose of this study was to measure the amount of formaldehyde released from three types of endodontic sealing cement (AH-Plus, EZ-Fill, and AH-26). Formaldehyde release was analyzed using High Performance Liquid Chromatography, which could detect as low as 0.25 ppm. The data was tabulated after two runs. The two paste system of AH-Plus endodontic sealing cement had the least amount of formaldehyde release (0.00039%, 3.9 ppm). This was followed by EZ-Fill (0.054%, 540 ppm) endodontic cement and AH-26 (0.1347%, 1347 ppm) endodontic cement which yielded the greatest formaldehyde release. Both of these cements (EZ-Fill and AH-26 endodontic filling cements) are based on a powder-liquid mix. The relative minute amounts of formaldehyde released by the endodontic cements studied (AH-Plus and EZ-Fill) warrant their use as endodontic sealing cements.

Bismuth↗
PubMed1999

In vivo and in vitro effect of ozone and formaldehyde on human nasal mucociliary transport system.

The effect of ozone and formaldehyde on the nasal mucociliary transport system after short-term exposure was comparatively evaluated in human by using in vivo and in vitro test systems. Concentrations of ozone used were 10, 100, 500 and 1000 micrograms/m3 of ozone and of formaldehyde 100, 500 and 5000 micrograms/m3. The in vivo effect of ozone was monitored by measuring the saccharin transport time before and two hours after exposure to ozone. The in vitro effect of ozone and formaldehyde was evaluated by quantifying the ciliary beat frequency (CBF) of isolated respiratory epithelial cells before and after one, two, and three hours of exposure. Control experiments were performed using synthetic air. Ozone had no effect on the human nasal mucociliary transport system under the conditions tested here. Neither in vivo nor in vitro any significant changes of saccharin transport time nor CBF were measured. In contrast, formaldehyde significantly reduced (67.1%) CBF at the highest dosis (2 hours, 5000 micrograms/m3). These results will be discussed according to the environmental impact of ozone and formaldehyde in air pollutants and compared to sulphur dioxide and nitric oxide, which were tested under similar conditions, and to results revealed from animal experiments.

Adolescent↗