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PubMed2002

Investigation of the stability of a mixture of single-based propellants and resins or polymers.

The stabilisation of single-based propellants (SBP) with equal quantities of bisphenol A-based epoxy resin (ER), bromine-containing epoxy resin (BER), chlorinated polyvinylchloride (PCV) and chlorinated rubber (CR) were investigated by viscosimetry and calorimetry. All compounds were thermodynamically compatible with SBP. The degree of stabilisation of SBP was measured after accelerated ageing and was evaluated by the loss of weight and by means of differential scanning calorimetry (DSC). All compounds produced a significant decrease in the loss of weight, typically by more than a factor of 15 compared with unstabilised SBP. The stability of the compounds decreased in the order: CR>BER>PCV>ER.

Aerosol Propellants↗
PubMed2002

Development of an enzyme-linked immunosorbent assay for bisphenol a using chicken immunoglobulins.

Bisphenol A was coupled, after derivatization into a suitable hapten, to bovine serum albumin and ovalbumin in order to produce immunizing and coating antigens. The immunizing antigens were injected into chickens, which allowed the isolation of specific bisphenol A immunoglobulins from the egg yolk. These antibodies were used in an indirect competitive enzyme-linked immunosorbent assay for the determination of bisphenol A in aqueous solutions. Various parameters, influencing the assay sensitivity, were evaluated. The applicability of the assay for the determination of bisphenol A in milk was also studied. The assay was not as sensitive as other analytical techniques used in bisphenol A analysis, since typical I(50) levels of 2.5 microM were reached in aqueous solutions. This study nevertheless illustrates the usefulness and the potency of chicken antibodies in the analysis of migration residues from packaging materials using immunochemical techniques. In addition, the assay showed to be quite specific for bisphenol A as well. Only for bisphenol A analogues, cross reactivities of about 40% were reached, enabling the use of the antibodies for the screening of bisphenol A and alike compounds.

Animals↗
PubMed1983

Combined effect of alpha-methyldopa and a new enzyme inducer, Zixoryn, on the hepatic mixed-function monooxygenase system in humans.

Based on previous studies with alpha-methyldopa (inhibitor of hepatic mixed-function monooxygenase system) and m-trifluoromethyl-alpha-ethylbenzhydrol, a new enzyme inducer Zixoryn, the authors studied the effect of the combined treatment of the two compounds on the hepatic drug-metabolizing enzyme activity in ten patients. There was no change in antipyrine half-life and its apparent volume of distribution (aVd) in the amount of D-glucaric acid excreted in the urine (indirect parameters of the mixed-function monooxygenase system's activity) after 1-week administration of 1000 mg alpha-methyldopa together with 300 mg Zixoryn per day. The two compounds counteracted each other's effects in the applied doses.

Adult↗
PubMed1984

Determination of extractable methylene dianiline in thermoplastic polyurethanes by HPLC.

Polyurethanes are finding increasing utilization in biomedical applications. Recently, the reported finding of methylene dianiline (4,4'-diaminodiphenylmethane, MDA) in the aqueous extracts of autoclaved 4,4'-diphenylmethane diisocyanate-based polyurethanes promoted our investigation of the origin and extent of extractable methylene dianiline in polyurethanes. A high-pressure liquid chromatography procedure using precolumn derivatization is utilized to selectively monitor the appearance of this diamine in the aqueous extracts of polyurethanes subjected to water immersion, heat aging, and various sterilization techniques. No MDA was found in the aqueous extracts of the treated polyurethane except for the case of prolonged steam autoclaving. The appearance of 3-5 ppb MDA in the extract under these conditions is attributed to hydrolysis of the polymer. The stability of the polyurethanes under most conditions renders these materials useful in biomedical applications.

Aniline Compounds↗
PubMed1991

High-performance liquid chromatographic determination of 4,4'-methylenedianiline in human urine.

A method is described for the determination of urinary 4,4'-methylenedianiline (MDA) by high-performance liquid chromatography (HPLC). MDA was extracted from hydrolyzed urine using C18 solid-phase extraction columns. The extract was analyzed by reversed-phase HPLC with electrochemical detection at a cell potential of 0.8 V. The method was very sensitive (detection limit 2.5 micrograms/l) and quantitation using 4,4'-ethylenedianiline as an internal standard correlated well with results by gas chromatography-mas spectrometry. Run-to-run precision (n = 25) averaged 8.9%. In analysis of more than 160 potentially exposed workers, MDA was detected in less than 20% of the urines and concentrations ranged up to 210 micrograms MDA per g of creatinine.

Aniline Compounds↗
PubMed2000

Isocyanate-specific hemoglobin adduct in rats exposed to 4, 4'-methylenediphenyl diisocyanate.

4,4'-Methylenediphenyl diisocyanate (MDI) is the most important of the isocyanates used as intermediates in the chemical industry. Among the main types of damage after exposure to low levels of MDI are lung sensitization and asthma. Protein adducts of MDI might be involved in the etiology of sensitization reactions. It is therefore necessary to have sensitive and specific methods for monitoring the isocyanate exposure of workers. To date, urine metabolites or protein adducts have been used as biomarkers in workers exposed to MDI. However, with these methods it is not possible to determine if the biomarkers result from exposure to MDI or to the parent aromatic amine 4,4'-methylenedianiline (MDA). This work presents a procedure for quantitating isocyanate-specific hemoglobin adducts. Blood proteins are used as markers of exposure and possibly as markers of dose size for the modifications of macromolecules in the target organs where the disease develops. For the quantitation of hemoglobin adducts, N(1)-[4-(4-isocyanatobenzyl)phenyl]acetamide (AcMDI) was reacted with the tripeptide valyl-glycyl-glycine and with valine yielding N-[4-(4-acetylaminobenzyl)phenyl]carbamoyl]valyl-glycyl-glycine and N-[4-[4-(acetylaminobenzyl)phenyl]carbamoyl]valine, respectively. N-[4-[4-(Acetylamino-3,5-dideuteriobenzyl)-2, 6-dideuteriophenyl]carbamoyl]valine was synthesized from valine, as was N(1)-[4-(4-isocyanato-3,5-dideuteriobenzyl)-2, 6-dideuteriophenyl]acetamide, for use as an internal standard. These adducts were cleaved in 2 M HCl to yield the corresponding hydantoins, 3-[4-(4-aminobenzyl)phenyl]-5-isopropyl-1, 3-imidazoline-2,4-dione (MDA-Val-Hyd) and 3-[4-(4-amino-3, 5-dideuteriobenzyl)-2,6-dideuteriophenyl]-5-isopropyl-1, 3-imidazoline-2,4-dione, respectively. In globin of rats exposed to MDI, MDA-Val-Hyd could be found in a dose-dependent manner. The adduct was identified by HPLC/MS/MS and quantified by GC/MS after derivatization with heptafluorobutyric anhydride. The amount of MDA-Val-Hyd found after acid hydrolysis of globin at 100 degrees C is about 12 times larger than the sum of N-acetyl-4, 4'-methylenedianiline (AcMDA) and MDA obtained from mild base hydrolysis of hemoglobin. The MDA-Val-Hyd is an isocyanate-specific adduct. MDA and AcMDA released after mild base hydrolyses result most likely from a sulfinamide adduct which is a typical adduct of arylamines. According to these results, higher amounts of isocyanate adducts than arylamine adducts should be expected in workers exposed to isocyanates.

Acetanilides↗
PubMed1994

Concomitant sensitization to triglycidyl isocyanurate, diaminodiphenylmethane and 2-hydroxyethyl methacrylate from silk-screen printing coatings in the manufacture of circuit boards.

A 48-year-old female silk-screen printer had worked in the manufacture of circuit boards for 12 years before she got the first symptoms of dermatitis on her wrists and lower arms. On the 1st patch test session, epoxy resin and the remainder of the standard series were negative, while a plastics and glues series gave an allergic reaction to 4,4'-diaminodiphenylmethane (DDM). The 2nd test session revealed allergic reactions to several acrylics, several epoxy compounds and 3 ink components. According to the material safety data sheets, 1 ink hardener contained DDM, but the causative agent in 1 ink and 1 ink hardener remained uncertain. The manufacturers of the 2 inks kindly provided us with their components for further patch tests. 2 of these components gave allergic reactions: triglycidyl isocyanurate (TGIC) and 2-hydroxyethyl methacrylate (2-HEMA). Our case report shows that the manufacture of circuit boards involves exposure to highly sensitizing chemicals. DDM, TGIC and 2-HEMA should be remembered as silk-screen printers' potential contact sensitizers in the manufacture of circuit boards.

Aniline Compounds↗
PubMed1985

Respiratory abnormalities among workers in an iron and steel foundry.

A study of the health of 78 workers in an iron and steel foundry in Vancouver, British Columbia, was carried out and the results compared with those found in 372 railway repair yard workers who were not significantly exposed to air contaminants at work. The foundry workers were exposed to PepSet, which consists of diphenyl methane diisocyanate (MDI) and phenol formaldehyde and their decomposition products as well as to silica containing particulates. A questionnaire was administered by trained interviewers, and chest radiography, allergy skin tests, pulmonary function tests, and methacholine inhalation tests were carried out as well as measurement levels of dust and MDI. Compared with the controls, the foundry workers had more respiratory symptoms and a significantly lower mean FEV1 and FEF25-75% after adjustments had been made for differences in age, height, and smoking habit. Three workers (4.8%) had radiographic evidence of pneumoconiosis and 12 (18.2%) had asthma defined as presence of bronchial hyperreactivity, cough, and additional respiratory symptoms such as wheeze, chest tightness, or breathlessness. Sensitisation to MDI is probably the cause of asthma in these workers.

Adult↗
PubMed2005

Risk evaluation of occupational exposure to methylene dianiline and toluene diamine in polyurethane foam.

Methylene diphenylisocyanate (MDI) and toluene diisocyanate (TDI) are widely used in industry to produce polyurethane foam products. Small amounts of methylenedianiline (MDA) and toluene diamine (TDA) are released during MDI and TDI polymerization and may be present in newly finished polyurethane foam parts. MDA and TDA concentrations in foam decline exponentially within several hours of demolding. MDA and the 2,4-isomer of TDA are known animal carcinogens and, in addition, have significant non-carcinogenic health effects. Our goal was to determine whether worker exposure to MDA or TDA in freshly produced polyurethane foams was associated with unacceptable health risks. Sampling and analysis of the fresh foam indicated that MDA and TDA concentrations varied considerably among products, but concentrations in all materials evaluated declined rapidly over time. We found that, under a worst-case exposure scenario, cancer risks from TDA exposure were approximately 5 x 10(-6), whereas cancer risks from MDA exposure resulted in a tumorigenic margin of exposure (MOE) of 85 000. Non-cancer chronic hazard indices were well below 1.0. Therefore, the potential cancer and non-cancer health risks from MDA or TDA exposure to newly manufactured foam parts appear to fall well within acceptable health risk criteria.

Aniline Compounds↗
PubMed1993

Characterization of acute 4,4'-methylene dianiline hepatotoxicity in the rat.

Methylene dianiline (DDM) is a chemical intermediate in the production of isocyanates and other industrial chemicals, and it is hepatotoxic in humans. The acute hepatotoxicity of orally administered DDM was characterized in rats. Rats receiving DDM (25-225 mg/kg, per os) demonstrated a dose-dependent elevation in serum alanine aminotransferase activity, g-glutamyltransferase activity, and serum bilirubin concentration. DDM also caused a decrease in bile flow and an elevation in liver weight. Significant changes in these markers of liver injury occurred between 8 and 12 hr after a single, oral administration of DDM. Histologically, DDM caused multifocal, necrotizing hepatitis with neutrophil infiltration. Changes in the portal regions consisted of bile ductular necrosis, portal edema, neutrophil infiltration, mild fibrin exudation, and segmental necrotizing vasculitis. The role of cytochrome P450 monooxygenase (MO)-mediated metabolism in DDM hepatotoxicity was evaluated using the MO inhibitors, aminobenzotriazole and SKF-525A and the MO inducers phenobarbital and beta-naphthoflavone. Aminobenzotriazole provided protection from DDM-induced hepatotoxicity, whereas SKF-525A had no effect. The effect of phenobarbital pretreatment depended on the dose of DDM administered. At a dose of DDM that produced a maximal hepatotoxic response, phenobarbital did not influence hepatotoxicity. However, phenobarbital pretreatment provided protection against the hepatotoxic effects of a lower dose of DDM. beta-naphthoflavone pretreatment had a more modest effect on DDM-induced hepatic insult. These results demonstrate that DDM causes acute hepatotoxicity in the rat that is dose and time dependent. Results using inducers and inhibitors of MO suggest that DDM requires bioactivation to exert toxicity; however, the relationship between metabolism and toxicity may be complex.

Administration, Oral↗
PubMed2001

Perinatal exposure to low doses of bisphenol A affects body weight, patterns of estrous cyclicity, and plasma LH levels.

The nonsteroidal estrogenic compound bisphenol A (BPA) is a monomer used in the manufacture of polycarbonate plastics and resins. BPA may be ingested by humans as it reportedly leaches from the lining of tin cans into foods, from dental sealants into saliva, and from polycarbonate bottles into their contents. Because BPA is weakly estrogenic--approximately 10,000-fold less potent than 17beta-estradiol--current environmental exposure levels have been considered orders of magnitude below the dose required for adverse effects on health. Herein we demonstrate measurable effects on the offspring of Sprague-Dawley female rats that were exposed, via their drinking water, to approximately 0.1 mg BPA/kg body weight (bw)/day (low dose) or 1.2 mg BPA/kg bw/day (high dose) from day 6 of pregnancy through the period of lactation. Offspring exposed to BPA exhibited an increase in body weight that was apparent soon after birth and continued into adulthood. In addition, female offspring exposed perinatally to the high dose of BPA exhibited altered patterns of estrous cyclicity and decreased levels of plasma luteinizing hormone (LH) in adulthood. Administration of neither the doses of BPA that caused effects during perinatal exposure nor a 10-fold higher dose was able to evoke a uterotropic response in ovariectomized postpubertal females. These data indicate an increased sensitivity to BPA during the perinatal period and suggest the need for careful evaluation of the current levels of exposure to this compound.

Administration, Oral↗
PubMed1991

Toxicity of 1,4-bis(aminocyclohexyl)methane.

1,4-Bis(aminocyclohexyl)methane (PACM; CAS No. 1761-71-3) is a white solid considered for use in polymeric systems. PACM is moderately toxic systemically, with the acute oral lethal dose in rats between 670 and 1000 mg kg-1. PACM is a weak dermal sensitizer in the guinea pig. Instillation of as little as 10 mg of PACM to the rabbit eye produces severe injury. This damage could be permanent and was not reduced by rinsing the eye with water. Dogs given oral doses of 50 mg PACM kg-1 5 days per week for up to 18 months showed kidney and liver damage, along with local irritation of the gastrointestinal tract. The chemical is highly irritating and contact with it should be avoided.

Administration, Oral↗
PubMed2005

Additional repression of activity-dependent c-fos and BDNF mRNA expression by lipophilic compounds accompanying a decrease in Ca2+ influx into neurons.

Recently, it has been proposed that a variety of environmental disruptors (EDs) disturb the neonatal development of the brain in mammals because of their lipophilic characteristics. Therefore, the synergism of these lipophilic compounds is important when evaluating the risk from EDs. In mouse cerebellar granule cells (CGCs), the activity-dependent expression of the brain-derived neurotrophic factor (BDNF) gene is activated through an influx of calcium ions (Ca2+) into CGCs caused by membrane depolarization, which is involved in the activity-dependent development of not only the cerebellum but also other regions of the brain after birth. In our previous study, we reported that permethrin and some other pyrethroid insecticides, which are suspected of being EDs, repressed the induction of c-fos and BDNF mRNA expression, accompanying a reduction of Ca2+ influx at doses non-toxic to CGCs. In the present study, we investigated whether other lipophilic compounds influenced the Ca2+ signal-induced expression of both genes as permethrin did and, if so, whether these effects were synergistic or additional. Pretreatment with p,p'-DDT, diethylstilbestrol (DES) or bisphenol A dose-dependently repressed the induction of both genes as well as the increase in the uptake of Ca2+ by CGCs. Simultaneous exposure of CGCs with permethrin, p,p'-DDT and DES, in addition, revealed an additional repression on the induction of the genes and the Ca2+ uptake. These results suggest that toxic effects of EDs might, at least additionally, occur in the brain even if the concentration of each compound is lower than the effective dose for humans.

Animals↗
PubMed2006

Comparative study of reactions of endocrine disruptors bisphenol A and diethylstilbestrol in electrochemical treatment and chlorination.

Transformations of diethylstilbestrol (DES) and bisphenol A (BPA) in conventional chlorination and electrochemically (EC) treated solutions were examined using spectrophotometry and chromatographic analyses. EC treatment was carried out using an undivided EC cell with a PbO2 anode and a stainless steel cathode. EC-treatment and conventional chlorination caused DES and BPA to undergo a rapid degradation accompanied by the generation of low molecular weight chlorinated organic species indicative of the breakdown of DES and BPA. The identified compounds were predominated by chloroacetic acids (HAAs), but approximately 80% of the total organic halogen (TOX) was comprised by unidentified species. For EC treatment, the HAA yields were lower and HAAs were predominated by monochloroacetic acid (MCAA), while in the case of conventional chlorination, trichloroacetic acid (TCAA) was predominant and MCAA was virtually absent. The changes in the HAA speciation and yields were concluded to be caused by the EC-driven reductive dehalogenation which, however, did not affect the unidentified fraction of TOX. This indicated that the unidentified part of TOX was comprised by aromatic chlorinated forms of BPA and DES. Their resistance to degradation in EC reactors indicates that these compounds may be stable in conditions typical for drinking water treatment and distribution.

Benzhydryl Compounds↗
PubMed2003

Isolation of methylene dianiline and aqueous-soluble biodegradation products from polycarbonate-polyurethanes.

Polycarbonate-polyurethanes (PCNUs) have provided the medical device industry with practical alternatives to oxidation-sensitive polyether-urethanes (PEUs). To date, many studies have focused on PCNUs synthesized with 4,4'-methylene diphenyl-diisocyanate (MDI). The relative hydrolytic stability of this class of polyurethanes is actually quite surprising given the inherent hydrolytic potential of the aliphatic carbonate group. Yet, there has been little information reporting on the rationale for the material's demonstrated hydrolytic stability. Recent work has shown that PCNU materials have a strong sensitivity towards hydrolysis when changes are made to their hard segment content and/or chemistry. However, knowledge is specifically lacking in regards of the identification of cleavage sites and the specific nature of the biodegradation products. Using high-performance liquid chromatography, radiolabel tracers and mass spectrometry, the current study provides insight into the distribution of biodegradation products from the enzyme-catalyzed hydrolysis of five different PCNUs. The hydrolytic sensitivity of the materials is shown to be related to the distribution of products, which itself is a direct consequence of unique micro-structures formed within the different materials. While an MDI-based polymer was shown to be the most hydrolytically stable material, it was the only PCNU that produced its diamine analog, in this case 4,4'-methylene dianiline (MDA), as a degradation product. Given the concern over aromatic diamine toxicity, this finding is important and highlights the fact that relative biostability is a distinct issue from that of degradation product toxicity, and that both must be considered separately when assessing the impact of biodegradation on biomaterial in vivo compatibility.

Aniline Compounds↗