204,098 research outputs found

    Reduction of the formaldehyde content in leathers treated with formaldehyde resins by means of plant polyphenols

    Get PDF
    Formaldehyde has applications in many industrial processes, including synthesis of resins and syntans to be used in the retanning process of leather. When resins are employed, they can hydrolyse, releasing formaldehyde. Due to the carcinogenicity of formaldehyde, its presence in leather should be avoided or kept below allowable limits. The aim of this study is to determine the effect of polyphenols contained in vegetable compounds (mimosa, quebracho and tara) in the reduction of the formaldehyde content in leathers treated with resins synthesized with formaldehyde (melamine-formaldehyde and dicyandiamide-formaldehyde). The formaldehyde content in leathers treated only with resin increases with time while the formaldehyde content in leathers treated additionally with vegetable compounds is reduced. The lower the formaldehyde content in the leather, the higher the ability of vegetable compounds to reduce such content. Mimosa shows the strongest ability to reduce the formaldehyde content, and this capacity increases with ageing. The addition of 4% (on shaved wet-blue weight) of mimosa gives rise to an 85% reduction in the formaldehyde content 140 days after leather processing of split hides treated with a formaldehyde resin of low formaldehyde content. However, this reduction is 68% in splits hides treated with a resin of high formaldehyde content. This is of great importance in baby’s leather articles, in which the formaldehyde content is low; therefore, the addition of a small amount (3%) of vegetable compounds (especially mimosa) guarantees that the formaldehyde content is below the allowed limits (16 mg/kg in the most restrictive regulation). Reducing the formaldehyde content using the polyphenols contained in vegetable compounds constitutes a good alternative not only in the leather sector but also in other industrial sectors (wood, textile, etc.) that use formaldehyde resins.Peer ReviewedPostprint (published version

    Formaldehyde-releasers: relationship to formaldehyde contact allergy. Contact allergy to formaldehyde and inventory of formaldehyde-releasers

    Get PDF
    This is one of series of review articles on formaldehyde and formaldehyde-releasers (others: formaldehyde in cosmetics, in clothes and in metalworking fluids and miscellaneous). Thirty-five chemicals were identified as being formaldehyde-releasers. Although a further seven are listed in the literature as formaldehyde-releasers, data are inadequate to consider them as such beyond doubt. Several (nomenclature) mistakes and outdated information are discussed. Formaldehyde and formaldehyde allergy are reviewed: applications, exposure scenarios, legislation, patch testing problems, frequency of sensitization, relevance of positive patch test reactions, clinical pattern of allergic contact dermatitis from formaldehyde, prognosis, threshold for elicitation of allergic contact dermatitis, analytical tests to determine formaldehyde in products and frequency of exposure to formaldehyde and releasers. The frequency of contact allergy to formaldehyde is consistently higher in the USA (8-9%) than in Europe (2-3%). Patch testing with formaldehyde is problematic; the currently used 1% solution may result in both false-positive and false-negative (up to 40%) reactions. Determining the relevance of patch test reactions is often challenging. What concentration of formaldehyde is safe for sensitive patients remains unknown. Levels of 200-300 p.p.m. free formaldehyde in cosmetic products have been shown to induce dermatitis from short-term use on normal skin

    Detection of Formaldehyde Towards the Extreme Carbon Star IRC+10216

    Full text link
    We report the detection of H2CO (formaldehyde) around the carbon-rich AGB star, IRC+10216. We find a fractional abundance with respect to molecular hydrogen of x(H2CO)= (1.3 {+1.5}{-0.8}) x 10^{-8}. This corresponds to a formaldehyde abundance with respect to water vapor of x(H2CO)/x(H2O)=(1.1 +/- 0.2) x 10^{-2}, in line with the formaldehyde abundances found in Solar System comets, and indicates that the putative extrasolar cometary system around IRC+10216 may have a similar chemical composition to Solar System comets. However, we also failed to detect CH3OH (methanol) around IRC+10216 and our upper limit of x(CH3OH)/x(H2O) < 7.7 x 10^{-4}, (3 sigma), indicates that methanol is substantially underabundant in IRC+10216, compared to Solar System comets. We also conclude, based on offset observations, that formaldehyde has an extended source in the envelope of IRC+10216 and may be produced by the photodissociation of a parent molecule, similar to the production mechanism for formaldehyde in Solar System comet comae. Preliminary mapping observations also indicate a possible asymmetry in the spatial distribution of formaldehyde around IRC+10216, but higher signal-to-noise observations are required to confirm this finding. This study is based on observations carried out with the IRAM 30m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). (abridged)Comment: accepted to ApJ, 45 pages, 11 figure

    The Retention of Wet Strength Resins as Determined by the Kjeldahl Method

    Get PDF
    True wet strength is not a gauge of water proofness of paper, but is a measure of the residual strength of the paper gauged by the mullen, tear, burst, and fold, after the paper has been completely soaked in water and the resistance to water penetration has been completely broken (1). To increase the wet-strength of paper, a number of different resins may be applied, and these resins may be broadly classified as anionic or cationic in nature. Of these resins, three particular resins will be discussed, cationic melamine-formaldehyde, anionic urea-formaldehyde, and cationic urea-formaldehyde

    Mutations in pathways depending on BRCA1 and BRCA2 may increase cancer risks from an environmental carcinogen

    Get PDF
    Recently, the President&#x2019;s Cancer Panel [2008-2009] protested that preventive action is not taken when uncertainty exists about potential harm from a chemical, because the US regulatory approach demands that a hazard be incontrovertibly demonstrated. It is now incontrovertible that formaldehyde increases risks for leukemias. Evidence is also strong that formaldehyde causes some types of DNA damage in humans that are known to require repairs mediated by BRCA1/2 containing pathways. Homologous recombination repairs require BRCA1/2, Fanconi and ATM proteins in these pathways. Biallelic BRCA2 mutations interfere with these repairs and are clearly associated with leukemias, especially myeloid leukemias. Fanconi anemia homozygotes have very high risks for acute myeloid leukemias. Disabling BRCA1/2 related DNA repair processes prevents repair of formaldehyde related DNA damage in laboratory cells. DNA-protein cross links result in the accumulation of DNA double strand breaks in homologous recombination-deficient but not homologous recombination -proficient cells. ATM heterozygotes have increased risks for some leukemias that have been linked to formaldehyde in normal individuals. Weaker evidence suggests increased risk for rare nasopharyngeal or sinonasal cancers in heterozygous BRCA1/2 mutation carriers and in ATM mutation carriers. &#xd;&#xa;Formaldehyde is a pervasive environmental carcinogen that is theoretically more likely to cause malignancy in carriers of mutations that disable protective repair pathways. Because of this potential for harm, it is prudent for mutation carriers to immediately avoid formaldehyde, especially high level exposure. The EPA recommends four basic &#x201c;Steps to Reduce Exposure&#x201d; for everyone.&#xd;&#xa

    Automated analysis of oxidative metabolites

    Get PDF
    An automated system for the study of drug metabolism is described. The system monitors the oxidative metabolites of aromatic amines and of compounds which produce formaldehyde on oxidative dealkylation. It includes color developing compositions suitable for detecting hyroxylated aromatic amines and formaldehyde

    Vanadium oxide monolayer catalysts : The vapor-phase oxidation of methanol

    Get PDF
    The oxidation of methanol over vanadium oxide, unsupported and applied as a monolayer on γ-Al2O3, CeO2, TiO2, and ZrO2, was studied between 100 and 400 °C in a continuous-flow reactor. At temperatures from 150 to about 250 °C two main reactions take place, (a) dehydration of methanol to dimethyl ether and (b) partial oxidation to formaldehyde. A very slight direct oxidation to CO2 proceeds simultaneously. At higher temperatures two further reactions take place, i.e., (c) consecutive oxidation of the ether and/or formaldehyde to CO and (d) consecutive oxidation of CO to CO2. Selectivity to formaldehyde increased with decreasing reducibility of the catalyst, which in turn was a function of the catalyst-support interactions. Since the reducibility of V(V) has been shown to be related to the charge/radius ratio of the cation of the carrier, the selectivity to formaldehyde is also determined by this ratio
    corecore