1,721,053 research outputs found
A prototype algorithm to calculate Health-based occupational exposure limits for a safe use3 of pesticides
No full textDue to the limitations of the environmental monitoring in agriculture, and the potential advantages of biological monitoring, the identification of biological exposure limits for pesticide bio-monitoring is a timely and needed activity. We are therefore establishing algorithms to calculate some limits that take advantage of the availability, for most of the active ingredients of pesticides marketed in the EU, of the health-based limit “Acceptable Operator Exposure Level (AOEL)” and of an extensive toxicological information that often includes dermal absorption coefficients. The AOEL is the systemic dose of a pesticide that a worker can absorb during each working day without any long-term consequences for his health. However, the AOEL is expressed as a systemic dose, which is not directly comparable with measurable indicators. Therefore, the AOEL is mostly used in the pre-marketing risk assessment, when which the internal dose is calculated, rather than measured. This weakness hampers its preventive value for the routine monitoring of agricultural workers.
In order to calculate provisional biological limits of pesticides from their AOELs, we collected, in real life scenarios of Northern Italy, pesticide metabolite measurements in 24-hour urine, along with data on skin contamination levels, measured through skin pads. A plot of urinary excretion of pesticide metabolite vs. personal exposure referred to the AOEL limit (individual risk assessment) allows to calculate a tentative value for an Equivalent Biological Exposure Limit (EBEL). With this approach, we obtained two proof-of-principle results on a herbicide (propanil, EBEL=1 mg 3,4-DCA/L 24-h urine) and on a fungicide (mancozeb, EBEL=117 microg ETU/L 24-h urine).
The same approach allows foreseeing a provisional corresponding value for other related pesticides, based on the known use rates, absorption coefficients and respective AOELs, as demonstrated by a calculation that expands the EBEL limit as ETU to other dithiocarbamates.
This pilot study demonstrates that this method can be adopted to calculate “Health-Based Biological Exposure Limits” for biological monitoring of pesticide workers, and, in perspective, to establish EBELs in the pre-marketing phase to become part of the information made available when a new active ingredient is marketed
Electron impact mass spectrometry of substituted 1,3,8-triazaspiro[4,5]decan-4-ones
No full textThe neuroleptic butyrophenone drug spiroperidol (8-[4-fluorophenyl)-4-oxobutyl]-1-phenyl-1,3,8-triazaspiro [4,5]decan-4-one) and related compounds are valuable tools for mapping the dopamine receptors in the brain. During the development of the radiochemical synthesis of these compounds with very short-lived isotopes suitable for positron emission tomography studies, positive electron impact mass spectrometric information was obtained. Ion series are present in the spectra of all 12 compounds studied, which unambiguously allow recognition of type and site of substitution on the spiro system
Fast atom bombardment mass spectrometry of carbobenzyloxy-protected amino acids and peptides
No full textThe positive fast atom bombardment (FAB) mass spectra of 15 N-carbobenzyloxy derivatives of α-amino acids are presented together with those of some synthetic peptides containing other widely employed protecting groups. The data obtained allow a fragmentation pattern to be established for the N-carbobenzyloxy moiety and to obtain detailed structural information on the main fragment ions. A study of the ion current ratio vs. time pattern shows that important fragments derive from the parent protonated molecule through FAB-induced condensed-phase reactions
Semiquantitative discovery of ceramides by isoenergetic precursor ion scan in the triple quadrupole mass spectrometer: fundamental issues and proof-of-principle application
No full textThe triple quadrupole mass spectrometer (TSQ) has boosted discovery and quantification of trace components in biological samples using class-selective scan modes. The use of suitable molecular precursors and of characteristic fragment ions allows identifying and measuring ceramides with micro-heterogeneous fatty acid or sphingosine. Collision energy in the TSQ is a key parameter to extract information from MS-MS experiments for compounds of which authentic standards are not available.
We describe the theoretical basis and proof-of-principle application of a novel scan mode of a commercial TSQ by which the molecular precursor ions of all ceramides in a sample experiment the same Center-of-Mass Collision Energy (CoM-CE), irrespective of their different m/z values over a range of homologous or chemical analogs. At this value of CoM-CE, the different precursor ions have, for the same fragmentation channel, essentially the same fragment ion cross section, thus the same response factor for quantification. This scan mode can be applied to Precursor and Neutral Loss scans, and is performed by modulating the voltage drop of a scanning mass filter according to a specific linear function of precursor ion mass. Under this instrumental condition, all precursor ions collide under the same conditions and fragment to a common charged (in Precursor Ion scan) or neutral (in Neutral Loss scan) sub-structure, and response factors are thus intrinsically homogeneous, especially for first-generation fragments. As a proof-of-principle application in the sphingolipid field, isoenergetic fast scanning during LC separation of lipid extracts highlights the presence of unanticipated ceramides that can be quantified as equivalents of known analogs without resorting to the construction of individual calibration curves. The use of a scan mode coupled to the LC separation allows improving the amount of information on the sphingolipidome that can be extracted from complex samples, and discovering components with unusual or modified fatty acids. Among displayed proof-of principle examples are the sphingolipid fractions of organs and tissues of experimental animals, and of edible seeds and nuts
FD and FAB mass spectra of some oligopeptides of the tryptophyllin family
No full textMass spectra of some natural thryptophyllins and synthetic analogues have been obtained by using field desorption and fast atom bombardment as soft ionization techniques to overcome the low volatility of these oligopeptides. Field desorption spectra generally show the molecular ion as base peak; some fragments of thermal origin are present at higher emitter heating current, thus providing additional structural information. Fast atom bombardment mass spectra show a more regular fragmentation of the peptide backbone, which allow the complete amino acid sequence to be checked. The presence of two consecutive proline residues in some of the examined molecules affects their fragmentation pattern in both field desorption and fast atom bombardment mass spectrometry giving rise to spectral features which are useful from the diagnostic point of view. The two ionization methods are compared and the advantage of the combined use of both techniques is pointed out
Emerging health effects from pesticide exposure in Europe and in developing countries
No full textHuman exposure to agrochemicals brings about a significant portion of the global burden of disease. Although levels of exposure have been significantly reduced in Europe, they still remain high in the developing world, bringing about specific emerging health risks. The estimated number of acute pesticide poisoning is 250,000-500,000, with 3,000 to 30,000 deaths each year, mainly in developing countries. In these countries the highest rates of intentional poisonings also occur, with a total number of more than 870,000, most by pesticide ingestion. Acute pesticide poisoning can affect neurobehavioral functioning, perhaps through brain anoxia, but published literature suggests that also prolonged or repeated exposures can affect behavior. Neurobehavioral impairment in previously acutely poisoned subjects is documented, but neurobehavioral effects in chronically exposed subjects are still controversial, and different opinions are present. Existing evidence suggests that the risk is higher for the higher levels of exposure, such as those experienced in the developing world with, in some cases, mental health impairment, increased risk of depression and even suicide. Another emerging toxic effects currently under study is ‘endocrine disruption’ (ED), able to influence reproductive capability, thyroid function, risk of diabetes and to increase the risk for some specific tumors of hormone-controlled organs. As for cancer as a whole, despite the large number of studies available on the topic it can be concluded that there is not enough evidence that chronic pesticide exposure is responsible for cancer, apart from well known and nowadays forbidden carcinogenic compounds
Valutazione di rischio tossicologico in carenza di informazioni : contributo alla soluzione di un caso recente
No full textThis work analyzes the activities carried out by a plaster construction worker, describing the data obtained from the assessment of risk for upper limb biomechanical overload, through the application of checklist and the OCRA method, and the operator's energy expenditure, measured using portable calorimeter. By analyzing the pattern of energy expenditure in relation to the actions performed we observe a direct correlation between posture, force employed, and metabolic rate. The activity of plastering involves biomechanical overload of upper extremity and high energy expenditure
Scansioni MS/MS isoenergetiche dei precursori: proof-of-principle nell'analisi del ceramidoma
No full textQuale esempio di applicazione, abbiamo messo a punto una tecnica per la discovery semi-quantitativa di specie ceramidiche in standard di provenienza ignota e in miscele provenienti da estratti biologici ed analizzate mediante ESI+
- …
