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PubMed1996

Experimental assessment of the sensitizing properties of formaldehyde.

Formaldehyde causes upper respiratory tract irritation and has been reported in some investigations to be a cause of occupational allergic asthma. The data are equivocal, however, and it has proved difficult to confirm that exposure to formaldehyde induces respiratory sensitization or provokes the production of specific immunoglobulin E (IgE) antibody. In this study the sensitizing properties of formaldehyde were examined experimentally. This chemical elicited strong positive responses in three independent methods for the prospective identification of contact sensitizing chemicals-the guinea pig maximization test, the occluded patch test of Buehler and the murine local lymph node assay. In contrast, in a novel predictive test method for assessment of respiratory sensitization potential-the mouse IgE test-formaldehyde at the same test concentrations was negative. Furthermore, formaldehyde induced in mice a pattern of cytokine secretion by draining lymph node cells inconsistent with the stimulation of IgE antibody responses or respiratory sensitization. These data indicate that, although formaldehyde is a potent contact allergen, it lacks a significant potential to cause sensitization of the respiratory tract.

Administration, Topical↗
PubMed1993

Flow injection analysis of formaldehyde leached from denture-base acrylic resins.

Formaldehyde is responsible for allergic inflammation in acrylic denture wearers and the quantitation of formaldehyde is necessary to study its leaching from denture-base materials. Flow injection analysis was developed to quantify the formaldehyde leached from acrylic resins. Different resins were immersed in aqueous solvents at 37 degrees C and the immersion solutions were directly injected into the flow system, in which formaldehyde was converted on-line to a fluorescent derivative and its fluorescence was detected. Under the optimized conditions, the leached formaldehyde could be quantified in a short time (within 4 min) with high sensitivity (pmol levels per injection) and high specificity (no fluorescent response to the other leachables). In leaching experiments, significant amounts of formaldehyde were leached from autopolymerized resins, but not from heat- and microwave-polymerized resins.

Acrylic Resins↗
PubMed1977

Adenine nucleotide metabolism of blood platelets. X. Formaldehyde stops centrifugation-induced secretion after A23187-stimulation and causes breakdown of metabolic ATP.

A23187 induced shape change, aggregation and secretion of platelets in plasma. When rapid cooling was used to stop secretion and centrifugation to separate the cells from the medium, maximal amounts of storage ATP plus ADP and preadsorbed [14C]serotonin were found in the supernatant immediately (less than 5 s) after A23187 addition. These results suggested that A23187 could cause shape change and aggregation through secreted ADP and not directly. When secretion was stopped with chilling and formaldehyde treatment before centrifugation, the secreted substances appeared after a lag of 60-120 s, i.e. after shape change was terminated and aggregation was well on its way. These two platelet responses thus seemed to be independent of secretion and induced directly by A23187. The absence of a lag period when secretion was stopped by chilling alone was thought to be due to centrifugation-induced secretion of platelets conditioned by A23187. Formaldehyde completely inhibited centrifugation-induced secretion. At 37 degrees C, formaldehyde caused rapid breakdown of metabolic ATP in platelets with a pattern dependent on the formaldehyde concentration: Below 50 mM, ATP was converted to inosine plus hypoxanthine via ADP, AMP and IMP and the adenylate energy charge was preserved. Above 100 mM, AMP was the end product with a drastic reduction in the adenylate energy charge. These changes were not due to lysis of the platelets, but were apparently caused by an formaldehyde-induced increase in cellular ATP consumption. Platelet secretion is usually associated with a conversion of metabolic ATP to hypoxanthine. Formaldehyde had to be used to stop secretion and since it caused breakdown of ATP, additional smaples were taken out for nucleotide determination during stirring of platelet-rich plasma with A23187. It was found that metabolic ATP was converted to inosine plus hypoxanthine only during the secretion step.

Adenosine Diphosphate↗
PubMed1989

Subchronic (13-week) inhalation toxicity study of formaldehyde in male rats: 8-hour intermittent versus 8-hour continuous exposures.

Male Wistar rats were exposed for 13 weeks, 5 days a week to 0 (controls), 1 or 2 ppm formaldehyde continuously (8 h a day), or to 2 or 4 ppm formaldehyde interruptedly (eight 30-min exposure periods separated by 30-min non-exposure periods a day). Histopathological changes were only found in the nose of animals (interruptedly) exposed to 4 ppm formaldehyde and comprised an increased degree and incidence of disarrangement and squamous metaplasia accompanied by basal cell hyperplasia and occasionally by keratinization of the respiratory epithelium. Two ppm formaldehyde was the non-toxic effect level. Cell proliferation studies demonstrated a slightly higher cell turnover of the nasal respiratory epithelium exposed (interruptedly) to 4 ppm formaldehyde than in controls. It was concluded that under the conditions of repeated exposure to marginally cytotoxic concentrations during a period of 13 weeks the exposure concentration rather than the total 'dose' (= concentration x exposure time) determined the severity of the cytotoxic effects of formaldehyde on the nasal epithelium.

Administration, Inhalation↗
PubMed2004

Formaldehyde degradation in an anaerobic packed-bed bioreactor.

The development of appropriate technologies for the treatment of formaldehyde discharged into the environment is important to minimize its impact. Aerobic systems have been employed, although alternative anaerobic treatments have also been widely studied, mainly due to their low energy consumption and sludge production. However, toxic substances can lead to disturbances in anaerobic reactors. Some research has already been developed on formaldehyde anaerobic biological treatment, but no consensus has yet been reached about its behavior nor has the most efficient system been identified. Aiming at finding supporting evidence for this issue, therefore, this study investigated the degradation and toxicity of formaldehyde in a Horizontal-Flow Anaerobic Immobilized Sludge Reactor. Formaldehyde concentrations of 26.2-1158.6 mg HCHO/L were applied in the reactor, resulting in formaldehyde and chemical oxygen demand removal efficiencies of 99.7% and 92%, respectively. Volatile fatty acids with up to five carbons, found during the degradation of formaldehyde, are believed to indicate that the degradation followed routes unlike those suggested in the literature, which reports the formation of intermediates such as methanol and formic acid. The Monod kinetic model adhered to the experimental data well, with apparent kinetic parameters estimated as r(app)max) = 2.79 x 10(-3) mg HCHO/mg SSVh and K (app)(s) = 242.8 mg HCHO/L.

Bacteria, Anaerobic↗
PubMed2004

Reevaluation of mortality risks from leukemia in the formaldehyde cohort study of the National Cancer Institute.

OBJECTIVE: To determine whether the National Cancer Institute's (NCI) recent suggestion of a causal association between formaldehyde exposure and mortality from leukemia and myeloid leukemia (ML) is robust with respect to alternative characterizations and categorizations of formaldehyde exposure and to alternative methods of data analysis. METHODS: The original authors provided the cohort data. We computed US and local county rate-based standardized mortality ratios (SMRs) and internal cohort rate-based relative risks (RR) by categories of four formaldehyde exposure metrics (highest peak, average intensity (AIE), cumulative, and duration), using both NCI categories and an alternative categorization based on tertiles of deaths from all leukemia among exposed subjects. For highest peak exposure, we computed RRs by the duration of time worked in the highest peak category and the time since highest peak exposure. For AIE, we computed RRs by the duration of exposure and the time since first exposure. RESULTS: Our external comparisons revealed that the elevated leukemia and ML RRs and associated trends reported by NCI for highest peak and AIE occurred because null (or slight) to moderate mortality excesses were compared with statistically significant baseline category deficits in deaths. Our alternative categorization of AIE yielded leukemia and ML SMRs close to 1.0 in the highest exposure category, and revealed weaker evidence of a trend in RRs for leukemia and ML. We corroborated NCI's finding of no association for cumulative and duration of formaldehyde exposure. We found no consistent evidence that leukemia or ML risks increased with increasing duration of time spent in a given highest peak exposure (or for AIE, duration of exposure in a given AIE category). We also found no consistent evidence that leukemia or ML risks were greater in the more relevant shorter (less than 20 years) versus longer (20+ years) periods of time from the first highest peak exposure (or for AIE, first exposure). CONCLUSIONS: Our reanalysis provided little evidence to support NCI's suggestion of a causal association between formaldehyde exposure and mortality from leukemia and ML. NCI's key findings for highest peak exposure and AIE do not adequately account for the inordinately large deficits in deaths in the categories used as the baselines for internal rate-based RRs. The NCI findings also do not adequately account for the duration of time subjects spent in the highest peak category (or for AIE, duration of exposure) or the time since their first peak exposure (or for AIE, time since first exposure). Our finding that NCI's suggestion of a causal association is not robust with respect to alternative categorizations of formaldehyde exposure and methods of data analysis casts considerable additional uncertainty regarding the validity of this suggested association.

Cohort Studies↗
PubMed2003

A novel sensitive high-performance liquid chromatography/electrochemical procedure for measuring formaldehyde produced from oxidative deamination of methylamine and in biological samples.

Formaldehyde is a well-known environmental toxic hazard. It is also a product of oxidative deamination of methylamine catalyzed by semicarbazide-sensitive amine oxidase (SSAO). Increased SSAO-mediated deamination has been implicated in some pathophysiological conditions, such as diabetic complications. The measurement of formaldehyde in the enzymatic reactions and in vivo production using conventional methods was not straightforward due to limitations of selectivity and sensitivity. A novel high-performance liquid chromatography (HPLC)/electrochemical procedure for the measurement of formaldehyde has been developed. The measurement is based on the formation of adducts between formaldehyde and dopamine. These adducts can be selectively purified and concentrated using a batch method of alumina absorption, separated by HPLC, and electrochemically quantified. The method is highly selective and substantially more sensitive, i.e., detection of picomole levels of formaldehyde, than the conventional methods. The procedure not only facilitates the assessment of SSAO activity in vitro but also is useful for assessing formaldehyde in tissues and biological fluids.

Animals↗
PubMed1984

Rapid isolation, hydrolysis and chromatography of formaldehyde-modified DNA.

Deoxyadenosine, deoxyguanosine, deoxycytidine and thymidine were reacted with formaldehyde. High-performance liquid chromatographic (HPLC) analysis indicated that each deoxynucleoside had formed one major product. With the exception of the thymidine product, these adducts were analyzed by nuclear magnetic resonance spectroscopy and identified as hydroxymethyl derivatives at the exocyclic amines. Calf thymus DNA was incubated with [3H]formaldehyde and, after purification, enzymatically hydrolyzed to nucleosides. HPLC analysis indicated the presence of a substantial proportion of noncovalently bound formaldehyde and the following hydroxymethyl adducts, listed in order of decreasing concentration: N6-hydroxymethyldeoxyadenosine much greater than N4-hydroxymethyldeoxycytidine greater than N2-hydroxymethyldeoxyguanosine. Incubation of Chinese hamster ovary (CHO) cells with [3H]formaldehyde resulted in metabolic incorporation of the formaldehyde into purines and pyrimidines plus an appreciable concentration of formaldehyde noncovalently associated with the DNA. However, HPLC analysis clearly indicated the presence of N6-hydroxymethyldeoxyadenosine in the CHO cell genome.

Animals↗
PubMed1978

Immunohistochemical analysis of formaldehyde- and trypsin- or pepsin-treated material.

Immunohistochemical studies of paraffin sections of formaldehyde-fixed material and formaldehyde-fixed cryostat sections treated with trypsin or other enzymes were undertaken. Formaldehyde treatment resulted mostly in partial or total loss of antigenicity, as visualized by fluorescent antibody technique in tissue sections. The digestion of sections with trypsin resulted usually in total or partial restitution of antigenicity, previously altered with formaldehyde. This effect is suggested to consist primarily in breaking formaldehyde-induced intermolecular cross-links. Restitution of antigenicity altered by formaldehyde can also be achieved on using pepsin or other proteolytic enzymes, or by some other technique. When the effect of one enzyme proves insufficient, it can readily be complemented by the action of another enzyme applied subsequently. Mild trypsin treatment preserves well the morphological structure of most tissues.

Animals↗
PubMed1988

Development of anti-N-like antibodies during formaldehyde reuse in spite of adequate predialysis rinsing.

The development of anti-N-like antibodies has been demonstrated with formaldehyde reuse of hemodialyzers. It has been recommended to pursue a postrinsing venous effluent formaldehyde concentration in the range of or below 2 to 10 ppm, in order to prevent the development of these anti-N-like antibodies. In the present study, we evaluated formaldehyde reuse in a population of 50 patients and whether the strict control of predialysis effluent formaldehyde concentration below 2 to 3 ppm could prevent the development of anti-N-like antibodies. Five of 50 patients (10%) became positive 6 to 14 months after the start of formaldehyde reuse, indicating that even a careful control of effluent formaldehyde concentration cannot prevent the occurrence of this abnormality.

Adult↗
PubMed2000

Development of highly selective and stable potentiometric sensors for formaldehyde determination.

Two types of biosensors selective to formaldehyde have been developed on the basis of pH-sensitive field effect transistor as a transducer. Highly or partially purified alcohol oxidase (AOX) and the permeabilised cells of methylotrophic yeast Hansenula polymorpha (as a source of AOX) have been used as sensitive elements. The response time in steady-state measurement mode is in the range of 10-60 s for the enzyme-based sensors and 60-120 s for the cell-based sensor. When measured in kinetic mode the response time of all biosensors developed was less than 5 s. The linear dynamic range of the sensor output signals corresponds to 5-200 mM formaldehyde for highly and partially purified alcohol oxidase, and 5-50 mM formaldehyde for the cells. The operational stability of the biosensors is not less than 7 h, and the relative standard deviation of intra-sensor response is approximately 2 and 5% for the enzyme- and cell-based sensors, respectively. When stored at 4 degrees C, the enzyme and cell sensor responses have been found stable for more than 60 and 30 days, respectively. Both types of biosensors demonstrate a high selectivity to formaldehyde with no potentiometric response to primary alcohols, including methanol, or glycerol and glucose. The possible reasons of such unexpected high selectivity of AOX-based FET-sensors to formaldehyde are discussed. The influence of the biomembrane composition and the effect of different buffers on the sensor response to formaldehyde are also discussed.

Alcohol Oxidoreductases↗
PubMed1984

Formaldehyde metabolism by Escherichia coli. In vivo carbon, deuterium, and two-dimensional NMR observations of multiple detoxifying pathways.

13C NMR has been used to demonstrate the metabolism of dilute solutions of labeled formaldehyde by Escherichia coli to methanol, formate, carbon dioxide, and several other unidentified metabolites which contain labeled CH2 groups. Aeration of bacterial suspensions within the spectrometer dramatically increased the rate of oxidation to formate and carbon dioxide. Deoxygenation with nitrogen gas virtually abolished all metabolism, as did the exposure of bacteria to very high formaldehyde concentrations. Deuterium NMR of whole cells in deuterium-depleted water further demonstrated the conversion of formaldehyde-d2 to methanol-d2, ruling out a formaldehyde dismutase as an important species. Two-dimensional proton-carbon chemical shift correlation was used to reveal the chemical shifts of the protons attached to 13C labels in metabolites. The results indicate that formaldehyde is efficiently detoxified by the bacterial cell through a route or routes which do not appear to involve tetrahydrofolate. This detoxification may be in competition with the lethal antibacterial processes associated with formaldehyde.

Carbon Isotopes↗
PubMed1997

Production of formaldehyde and DNA-adriamycin or DNA-daunomycin adducts, initiated through redox chemistry of dithiothreitol/iron, xanthine oxidase/NADH/iron, or glutathione/iron.

The reaction of the antitumor drugs adriamycin and daunomycin with the self-complementary DNA oligonucleotide (GC)4 to generate DNA-drug adducts was investigated as a function of redox reaction conditions. The redox systems dithiothreitol (DTT)/Fe(III) and xanthine oxidase/ NADH both gave the same distribution of four DNA-anthracycline adducts. In each of these adducts the anthracycline is bonded via a methylene linkage between the 3'-amino group of the drug and the 2-amino group of a deoxyguanosine of the DNA. The methylene linkage results from reaction of the drug and DNA with in situ-generated formaldehyde via Schiff base chemistry [Taatjes, D.J., Gaudiano, G., Resing, K., and Koch, T.H. (1997) J. Med. Chem. 40, 1276-1286]. Formaldehyde production is promoted by iron, inhibited by metal-chelating agents, and does not require drug. Iron enhances formaldehyde production by a factor of 30, EDTA inhibits its formation by a factor of 2, and Desferal inhibits its formation by a factor of more than 20. Hydrogen peroxide accumulates in significant quantities only with xanthine oxidase/NADH in the presence of Desferal. The results are explained in terms of Fenton oxidation of Tris buffer to formaldehyde. Biological reagents also cause DNA-drug adduct formation; reduction of ferric ion with glutathione in phosphate buffer in the presence of spermine produced the same DNA-drug adducts. The observations are discussed in terms of cytotoxicity resulting from iron chelated to adriamycin catalyzing in vivo production of formaldehyde which links adriamycin to DNA and tumor cell resistance resulting from factors which decrease formaldehyde.

Anaerobiosis↗
PubMed1998

Prebiotic amino acid thioester synthesis: thiol-dependent amino acid synthesis from formose substrates (formaldehyde and glycolaldehyde) and ammonia.

Formaldehyde and glycolaldehyde (substrates of the formose autocatalytic cycle) were shown to react with ammonia yielding alanine and homoserine under mild aqueous conditions in the presence of thiol catalysts. Since similar reactions carried out without ammonia yielded alpha-hydroxy acid thioesters (Weber, 1984a, b), the thiol-dependent synthesis of alanine and homoserine is presumed to occur via amino acid thioesters--intermediates capable of forming peptides (Weber and Orgel 1979). A pH 5.2 solution of 20 mM formaldehyde, 20 mM glycolaldehyde, 20 mM ammonium chloride, 23 mM 3-mercaptopropionic acid, and 23 mM acetic acid that reacted for 35 days at 40 degrees C yielded (based on initial formaldehyde) 1.8% alanine and 0.08% homoserine. In the absence of thiol catalyst, the synthesis of alanine and homoserine was negligible. Alanine synthesis required both formaldehyde and glycolaldehyde, but homoserine synthesis required only glycolaldehyde. At 25 days the efficiency of alanine synthesis calculated from the ratio of alanine synthesized to formaldehyde reacted was 2.1%, and the yield (based on initial formaldehyde) of triose and tetrose intermediates involved in alanine and homoserine synthesis was 0.3 and 2.1%, respectively. Alanine synthesis was also seen in similar reactions containing only 10 mM each of aldehyde substrates, ammonia, and thiol. The prebiotic significance of these reactions that use the formose reaction to generate sugar intermediates that are converted to reactive amino acid thioesters is discussed.

Acetaldehyde↗
PubMed2002

Cytotoxic effects of methanol, formaldehyde, and formate on dissociated rat thymocytes: a possibility of aspartame toxicity.

Aspartame is a widely used artificial sweetener added to many soft beverages and its usage is increasing in health-conscious societies. Upon ingestion, this artificial sweetener produces methanol as a metabolite. In order to examine the possibility of aspartame toxicity, the effects of methanol and its metabolites (formaldehyde and formate) on dissociated rat thymocytes were studied by flow cytometry. While methanol and formate did not affect cell viability in the physiological pH range, formaldehyde at 1-3 mmol/L started to induce cell death. Further increase in formaldehyde concentration produced a dose-dependent decrease in cell viability. Formaldehyde at 1 mmol/L or more greatly reduced cellular content of glutathione, possibly increasing cell vulnerability to oxidative stress. Furthermore, formaldehyde at 3 mmol/L or more significantly increased intracellular concentration of Ca2+ ([Ca2+]i) in a dose-dependent manner. Threshold concentrations of formaldehyde, a metabolite of methanol, that affected the [Ca2+]i and cellular glutathione content were slightly higher than the blood concentrations of methanol previously reported in subjects administered abuse doses of aspartame. It is suggested that aspartame at abuse doses is harmless to humans.

Animals↗
PubMed2002

Anaphylaxis due to formaldehyde released from root-canal disinfectant.

A 50-year-old woman developed anaphylaxis 8 h after application of a paraformaldehyde-containing root canal disinfectant. Radioallergosorbent test showed that she had a high level of formaldehyde-specific IgE in her serum. Prick tests to formaldehyde and paraformaldehyde showed immediate-type responses to both. We reviewed the literature describing cases with anaphylaxis/angioedma caused by formaldehyde in root canal disinfectants and found that about 1/2 of the reported cases developed symptoms over 2 h after dental treatment. We speculated that the delay in the manifestation of her symptoms was possibly due to gradual formaldehyde release from paraformaldehyde and time lag of penetrating and diffusing of formaldehyde outside the dentin. Patch testing showed that she also had delayed-type allergy to formaldehyde, paraformaldehyde and eugenol. Physicians should pay attention to root canal disinfectants, even if anaphylaxis occurs several hours after dental treatment.

Allergens↗
PubMed2001

A new fluorimetric method for the determination of formaldehyde in air based on the liquid droplet sampling technique.

A new, simple, sensitive, selective and in-field fluorimetric method for the determination of formaldehyde is proposed. The reaction of formaldehyde with hydralazine in acidic medium, heating on a boiling water-bath for 25 min, produces s-triazolo[3,4-a]phthalazine (Tri-P). The fluorescence intensity of the product formed (Tri-P) was determined at lambda em = 389 nm with lambda ex = 236 nm. The fluorescence intensity is linear over a formaldehyde concentration range of 1.2-33.0 micrograms l-1. The proposed method was applied successfully to the determination of formaldehyde sampled from the atmosphere using the liquid droplet technique. Formaldehyde vapour in a wind tunnel was produced by a mean of permeater. A linear curve was obtained between the concentration in the wind tunnel and that in the droplet. The detection limit for formaldehyde was 2.0 micrograms l-1 with RSDs varying from 3 to 12% in ambient air, using a droplet correction solution (boric acid and hydralazine). The effect of interfering substances on the determination shows that most cations and anions did not interfere. The results obtained were satisfactory compared with a reference method.

Air Pollutants↗
PubMed2002

Concentrations of formaldehyde and other carbonyls in environments affected by incense burning.

Burning incense to pay homage to deities is common in Chinese homes and temples. Air samples were collected and analyzed for carbonyls from a home and a temple in Hong Kong where incense burning occurs on a daily basis. Carbonyls in the air were trapped on a solid sorbent coated with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine, followed by thermal desorption and subsequent GC/MS analysis. The carbonyls identified include formaldehyde, acetaldehyde, acrolein, 2-furfural, benzaldehyde, glyoxal, and methylglyoxal. The levels of the above carbonyls correlate with the intensity of the incense-burning activities. The total mixing ratios of the carbonyls in the temple exceed those in the ambient air outside the temple by 11-23 times. Formaldehyde is the most abundant species, contributing to approximately 55% of the total carbonyl mixing ratios in both the temple and the home environments during incense burning. The mixing ratio of formaldehyde ranges from 108 to 346 ppbv in the temple and averages 103 ppbv in the home during incense burning. These values exceed the World Health Organization (WHO) air quality guideline of 100 microg m(-3) (88 ppbv) for formaldehyde. The highest formaldehyde level in the temple exceeds the WHO guideline by 3 times at peak incense burning hours. The mixing ratio of acrolein in the temple ranges from 20 to 99 ppbv, approaching or exceeding the WHO air quality guideline of 50 microg m(-3) (22 ppbv) for acrolein. Our measurements indicate that incense burning significantly elevates the concentrations of a number of carbonyls, most notably formaldehyde and acrolein, in the surrounding environments. This study provides preliminary insights on indoor air quality problems created by incense burning.

Air Pollution, Indoor↗