Assessment of long-term health risks after accidental exposure using haemoglobin adducts of epichlorohydrin

A comparison of the exposure system of glycidol-related chemicals on the formation of glycidol-hemoglobin adducts

Glycidol fatty acid esters that are present in foods are degraded in vivo to the animal carcinogen glycidol, which binds to the N-terminal valine of hemoglobin (Hb) to form N-(2,3-dihydroxypropyl)valine (diHOPrVal) adducts. The existence of other chemicals that are converted to glycidol is unknown. To determine the effect of different exposure conditions on the formation of diHOPrVal adducts, several glycidol-related chemicals (3-monochloropropane-1,2-diol; 3-MCPD, epichlorohydrin, glyceraldehyde, acrylic acid, and 1,2-propanediol) were evaluated using in vitro and in vivo (single/repeated dose) methods. In vitro, the reaction of 3-MCPD or epichlorohydrin with human Hb produced 17% and 0.7% of diHOPrVal, as compared to equimolar glycidol, respectively. Following a single administration of glycidol-related compounds to ICR mice, diHOPrVal formation was observed only in the epichlorohydrin-treated group after day 5 of exposure. After 14 days of repeated dosing, the amounts of diHOPrVal produced by epichlorohydrin and 3-MCPD in vivo were <1% of diHOPrVal produced by an equal molar concentration of glycidol. Furthermore, glyceraldehyde group produced 0.2% of diHOPrVal at the same molar concentration of glycidol equivalents, in which diHOPrVal formation could not be confirmed by the in vitro assay. The results indicate the usefulness of diHOPrVal as an exposure marker for glycidol; however, the contribution of its formation in vivo by exposure to various chemicals will be necessary to validate and interpret the results.

Sorption of hazardous industrial organic liquids with environmentally friendly functionalized cellulosic sorbents

The performances of five cellulosic polymers with different functional groups (cellulose, cellulose acetate, cellulose phosphate, chitosan, and chitin) as sorbents of seven frequently used hazardous polar organic liquids (acrolein, butanone peroxide, epichlorohydrin, formaldehyde, furfuryl alcohol, propylene oxide, and vinyl acetate) are investigated in this study. Amongst the cellulosic sorbents, cellulose phosphate exhibited enhanced sorption properties (as high as 3.09–7.03 g/g) against all seven polar organic liquids investigated, and chitosan and chitin also demonstrated comparable sorption efficiencies (2.28–7.72 g/g and 2.55–5.86 g/g, respectively) to those of cellulose phosphate. According to our investigation, the enhanced sorption efficiency could be achieved due to low powder density of cellulose phosphate, which is caused by the weak intramolecular interaction amongst the polymer chains. In addition, cellulose phosphate, chitosan, and chitin also showed enhanced absorbed solvent recovery percents (71.4, 60.6, and 61.1%, respectively, in average) compared with that of pristine cellulose (43.8%). With excellent sorption efficiency, enhanced solvent recovery rate, and reusability after drying, these functionalized cellulosic sorbents can be excellent candidates to replace the conventional carbon and vermiculites-based sorbents, especially for liquid polar organic spill sorption.

Preclinical Safety Assessment of Chemically Cross-Linked Modified Mandua Starch: Acute and Sub-Acute Oral Toxicity Studies in Swiss Albino Mice

In the present era, 28 days of repeated-dose-toxicity study following the Organization for Economic Cooperation and Development (OECD) guidelines 407 is compulsory for every drug to go through phase 1 clinical trials. The increasing demand for high-resistant starch containing nutraceuticals and the applicability of modified starch in development of targeted drug delivery inspired us to investigate the toxic profile of mandua starch chemically cross-linked by epichlorohydrin and compare it with alkali-isolated starch in healthy adult Swiss albino mice, which can be the first step for exploring the use of epichlorohydrin-cross-linked mandua starch (ECC-MS) as a pharmaceutical excipient. Histopathological examinations of the kidney and liver did not expose noteworthy abnormalities in the treated mice. There were no clinical and mortality symptoms of toxicity observed during the repeated-dose-toxicity study. The oral consumption of ECC-MS did not pose any harm as it was neither lethal nor had any harmful hematological, biochemical, psychological, anatomical, and behavioral effects. The use of ECC-MS and alkali-isolated mandua starch (AMS) was found safe at a dose of 2000 mg/kg body weight in the acute toxicity study and at doses of 2000, 1500, and 1000 mg/kg body weight in the sub-acute toxicity study as no detrimental effects were observed after oral administration in mice for 14 and 28 days, respectively.

Quo vadis blood protein adductomics?

Chemicals are measured regularly in air, food, the environment, and the workplace. Biomonitoring of chemicals in biological fluids is a tool to determine the individual exposure. Blood protein adducts of xenobiotics are a marker of both exposure and the biologically effective dose. Urinary metabolites and blood metabolites are short term exposure markers. Stable hemoglobin adducts are exposure markers of up to 120 days. Blood protein adducts are formed with many xenobiotics at different sites of the blood proteins. Newer methods apply the techniques developed in the field of proteomics. Larger adducted peptides with 20 amino acids are used for quantitation. Unfortunately, at present the methods do not reach the limits of detection obtained with the methods looking at single amino acid adducts or at chemically cleaved adducts. Therefore, to progress in the field new approaches are needed.

Preparedness as a key factor for human biomonitoring programs after chemical incidents

BACKGROUND

Human biomonitoring (HBM) has been repeatedly recommended for and applied to post-incident chemical exposure assessment. The applicability of HBM and the validity of its results, however, closely depend on the existence and quality of preparatory measures such as information and instruction materials, sampling procedures, transport and storage facilities, and on the selection of appropriate biomarkers, sampling time, transport and storage conditions.

OBJECTIVE

To establish a standardized HBM program for emergency responders of a large chemical production site, considering the aforementioned aspects.

METHODS

An HBM program based on a comprehensive questionnaire, information and training of emergency responders, and availability of sampling material was established. The quantitative determination of metabolites of hazardous substances was carried out based on quality-controlled analytical methods.

RESULTS

The use of HBM after emergency operations was significantly increased immediately after the implementation of the program. Only in single cases, however, established HBM assessment values were exceeded. After one major incident, an increased exposure to benzene exceeding the internal action value was observed after firefighting and safeguarding.

SIGNIFICANCE

The experience with several minor and one major incident at a chemical production site suggests that the implementation of easily accessible and applicable routines is one paramount prerequisite for the success of HBM programs after chemical incidents.

The hemoglobin adduct N-(2,3-dihydroxypropyl)-valine as biomarker of dietary exposure to glycidyl esters: a controlled exposure study in humans

Fatty acid esters of glycidol (glycidyl esters) are heat-induced food contaminants predominantly formed during industrial deodorization of vegetable oils and fats. After consumption, the esters are digested in the gastrointestinal tract, leading to a systemic exposure to the reactive epoxide glycidol. The compound is carcinogenic, genotoxic and teratogenic in rodents, and rated as probably carcinogenic to humans (IARC group 2A). Assessment of exposure from occurrence and consumption data is difficult, as lots of different foods containing refined oils and fats may contribute to human exposure. Therefore, assessment of the internal exposure using the hemoglobin adduct of glycidol, N-(2,3-dihydroxypropyl)-valine (2,3-diHOPr-Val), may be promising, but a proof-of-principle study is needed to interpret adduct levels with respect to the underlying external exposure. A controlled exposure study was conducted with 11 healthy participants consuming a daily portion of about 36 g commercially available palm fat with a relatively high content of ester-bound glycidol (8.7 mg glycidol/kg) over 4 weeks (total amount 1 kg fat, individual doses between 2.7 and 5.2 µg/kg body weight per day). Frequent blood sampling was performed to monitor the 2,3-diHOPr-Val adduct levels during formation and the following removal over 15 weeks, using a modified Edman degradation and ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Results demonstrated for the first time that the relatively high exposure during the intervention period was reflected in corresponding distinct increases of 2,3-diHOPr-Val levels in all participants, following the expected slope for hemoglobin adduct formation and removal over time. The mean adduct level increased from 4.0 to 12.2 pmol 2,3-diHOPr-Val/g hemoglobin. By using a nonlinear mixed model, values for the adduct level/dose ratio (k, mean 0.082 pmol 2,3-diHOPr-Val/g hemoglobin per µg glycidol/kg body weight) and the adduct lifetime (τ, mean 104 days, likely the lifetime of the erythrocytes) were determined. Interindividual variability was generally low. 2,3-DiHOPr-Val was therefore proven to be a biomarker of the external dietary exposure to fatty acid esters of glycidol. From the background adduct levels observed in our study, a mean external glycidol exposure of 0.94 µg/kg body weight was estimated. This value is considerably higher than current estimates for adults using occurrence and consumption data of food. Possible reasons for this discrepancy are discussed (other oral or inhalational glycidol sources, endogenous formation, exposure to other chemicals also forming the adduct 2,3-diHOPr-Val). Further research is necessary to clarify the issue.

[Monitoring methods and their results in environmental medicine - implications for medical counsellors]

Besides effect and environmental monitoring, human biomonitoring (HBM) offers an attractive method for analyzing the distribution and intensity of anthropogenic environmental pollutants in individuals or in particular groups of the population. However, no assessment values of comparable reliability are available to enable an interpretation of the results of environmental studies from the viewpoint of environmental health. This must be taken into account when reporting findings of such studies as well as in medical consultation, in order to avoid overdiagnosis and unnecessary anxiety for the participant. In medical practice, care should be taken when dealing with monitoring results outside the normal range! Environmental or biomonitoring results provide only a part of the available information alongside medical history and clinical examinations. In the case of tests performed for private interests as well as tests carried out within the framework of an epidemiological environmental survey, communication of results and findings can be problematic. In epidemiological studies, a close co-operation between the participant's consultant physician and physicians conducting the study is beneficial in order to ensure professional advisory counselling for subjects with results outside the normal range.