Physico-chemical and toxicologo-hygienic aspects of using ethylene oxide for the sterilization of medical appliances. Part I. Sorption and diffusion of ethylene oxide in polymeric materials

Sorption ability of polymeric materials for medical purposes was studied with respect to the sterilizing gas - ethylene oxide - at 23, 35 and 55 degrees C. Sorption coefficients of ethylene oxide (EO) for the materials under study were calculated on the basis of results. Investigation of the kinetics of desorption of EO from the polymeric materials for medical purposes has shown that its content changes exponentially depending on the time of degassing. However, the lines in the 1g Q/Q0 - tau coordinates show a sharp break which testifies to a change in the mechanism of the process determining the character of the mentioned dependence. In the first region, corresponding to high concentrations and short periods of time, the determining process is diffusion while in the second region (low concentrations, long time intervals) - it is desorption of EO molecules most firmly bound to the polymer. Diffusion coefficients were calculated for the first region. The possibility of predicting the time periods of removing ethylene oxide from the polymeric materials was demonstrated for both stages on the basis of calculated diffusion coefficients and kinetic curves of degassing. Recommendations were given for the use of polymers for medical appliances and apparatuses.     

Terrestrial ecosystems from space: a review of earth observation products for macroecology applications

Aim Earth observation (EO) products are a valuable alternative to spectral vegetation indices. We discuss the availability of EO products for analysing patterns in macroecology, particularly related to vegetation, on a range of spatial and temporal scales. Location Global. Methods We discuss four groups of EO products: land cover/cover change, vegetation structure and ecosystem productivity, fire detection, and digital elevation models. We address important practical issues arising from their use, such as assumptions underlying product generation, product accuracy and product transferability between spatial scales. We investigate the potential of EO products for analysing terrestrial ecosystems. Results Land cover, productivity and fire products are generated from long‐term data using standardized algorithms to improve reliability in detecting change of land surfaces. Their global coverage renders them useful for macroecology. Their spatial resolution (e.g. GLOBCOVER vegetation, 300 m; MODIS vegetation and fire, ≥ 500 m; ASTER digital elevation, 30 m) can be a limiting factor. Canopy structure and productivity products are based on physical approaches and thus are independent of biome‐specific calibrations. Active fire locations are provided in near‐real time, while burnt area products show actual area burnt by fire. EO products can be assimilated into ecosystem models, and their validation information can be employed to calculate uncertainties during subsequent modelling. Main conclusions Owing to their global coverage and long‐term continuity, EO end products can significantly advance the field of macroecology. EO products allow analyses of spatial biodiversity, seasonal dynamics of biomass and productivity, and consequences of disturbances on regional to global scales. Remaining drawbacks include inter‐operability between products from different sensors and accuracy issues due to differences between assumptions and models underlying the generation of different EO products. Our review explains the nature of EO products and how they relate to particular ecological variables across scales to encourage their wider use in ecological applications.     

Laurus nobilis L. Extracts against Paenibacillus larvae: Antimicrobial activity,antioxidant capacity,hygienic behavior and colony strength

The aim of this work was to compare the antimicrobial activity against Paenibacillus larvae and the antioxidant capacity of two Laurus nobilis L. extracts obtained by different extraction methods. The hydroalcoholic extract was moreover added as supplementary diet to bees in field conditions to test behavioural effects and colony strength. Both laurel extracts were subjected to different phytochemical analysis to identify their bioactive compounds. Antimicrobial activity was analyzed by the minimal inhibitory concentration (MIC) determination by means the agar dilution method. The hydroalcoholic extract (HE) was able to inhibit the bacterial growth of all P. larvae strains, with 580 µg/mL mean value. This better antibacterial activity in relation to the essential oil (EO) could be explained by the presence of some phenolic compounds, such as flavonoids, evidenced by characteristic bands resulting from the Fourier Transform Infrared Spectroscopy (FTIR) analysis. Antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging ability and ferric reducing antioxidant power (FRAP) assays. The HE showed the highest antioxidant activity as measured by DPPH, with IC50 values of 257 ± 12 μg/mL. The FRAP assay method showed that the HE was 3-fold more effective reducing agent than the EO. When the bee colonies were supplied with laurel HE in sugar paste an improvement in their general condition was noticed, although neither the hygienic behavior nor the proportions of the breeding cells varied statistically due to the treatment. In conclusion, the inhibition power against P. larvae attributable to the phenolic compounds, the antioxidant capacity of the HE, and the non-lethal effects on adult honey bees on field trials suggest the HE of laurel as a promising substance for control American foulbrood disease.     

Effect of some hygienic factors on family health

On the basis of longitudinal observations of a large group of town habitants the author determined some hygienic factors of direct as well as indirect influence on their health. The author elaborated a series of sanitary and hygienic recommendations believing that even in case of complete dispensarization of the population and assurance of suitable medical assistance, the physicians have all the same to take into consideration concentrate living conditions of each family.     

Physico-chemical and toxico-hygienic aspects of using ethylene oxide for the sterilization of articles for medical use. Part 2. Toxicity and risk of ethylene oxide entering the organism by non-inhalation routes

Results of investigation of toxicity of ethylene oxide (EO) entering the organism by routes other than inhalation (subcutaneous, intramuscular, intraperitoneal, intravenous) have demonstrated that the substance causes intoxication characterized by polytropic effect on many vitally important organs and systems. The changes in most of the indices under study show a phasic character and dose-time dependence. In both the acute and chronic effect, impairment of the state of the nervous system, the liver, kidney, blood and reactivity of the organism come to the foreground. After one single entrance, EO becomes manifest as a low-risk (class 4) compound (Limac for subcutaneous, intraperitoneal and intravenous routes being 5.0, 0.5 and 1.0 mg/kg, respectively); after repeated exposure as a high-risk (class 2) compound (Limchr for subcutaneous and intraperitoneal route being 1.0 and 0.1 mg/kg, respectively). In comparison with the subcutaneous route, the intravenous and intraperitoneal routes are more dangerous. The obtained parameters of EO toxicometry can be used as a basis for the calculation of safe levels of residual quantities of the compound in articles for medical use.     

Elucidation of the mechanism and end products of glutaraldehyde crosslinking reaction by X-ray structure analysis

Glutaraldehyde has been used for several decades as an effective crosslinking agent for many applications including sample fixation for microscopy, enzyme and cell immobilization, and stabilization of protein crystals. Despite of its common use as a crosslinking agent, the mechanism and chemistry involved in glutaraldehyde crosslinking reaction is not yet fully understood. Here we describe feasibility study and results obtained from a new approach to investigate the process of protein crystals stabilization by glutaraldehyde crosslinking. It involves exposure of a model protein crystal (Lysozyme) to glutaraldehyde in alkaline or acidic pH for different incubation periods and reaction arrest by medium exchange with crystallization medium to remove unbound glutaraldehyde. The crystals were subsequently incubated in diluted buffer affecting dissolution of un-crosslinked crystals. Samples from the resulting solution were subjected to protein composition analysis by gel electrophoresis and mass spectroscopy while crosslinked, dissolution resistant crystals were subjected to high resolution X-ray structural analysis. Data from gel electrophoresis indicated that the crosslinking process starts at specific preferable crosslinking site by lysozyme dimer formation, for both acidic and alkaline pH values. These dimer formations were followed by trimer and tetramer formations leading eventually to dissolution resistant crystals. The crosslinking initiation site and the end products obtained from glutaraldehyde crosslinking in both pH ranges resulted from reactions between lysine residues of neighboring protein molecules and the polymeric form of glutaraldehyde. Reaction rate was much faster at alkaline pH. Different reaction end products, indicating different reaction mechanisms, were identified for crosslinking taking place under alkaline or acidic conditions.     

Intermittent exposure to toxic compounds in the working-zone atmosphere viewed from the aspect of hygienic standardization

Four highly cumulative substances (carbon tetrachloride, 1,1,2,2-tetrachloroethane, benzene and dimethylformamide) were studied at two exposure levels under a monotonous and an intermittent exposure regimen in subacute experiments on rats. The biological effect produced by the intermittent concentrations as compared with the stable concentrations under time-weighted average concentrations depended both on the physiochemical properties and biological action of the poisons as well as on the exposure level. The intermittent concentration rises within certain limits (threefold as a rule) were injurious with some of the substances at a relatively high exposure level, but were not detrimental as compared with stable concentrations at a low exposure level. The other substances showed no difference between the effect of the monotonous and the intermittent regimens at either low or high exposure levels. The results of these studies form an experimental basis for a dual hygienic standardization: the establishment of maximum and average-shift admissible concentrations for the compounds studied as well as other highly cumulative substances.     

Boron exposure from consumer products

For a natural substance that is mined and for which the world total production is in excess of 3 million tons, it would not be surprising to discover there is considerable exposure to boron (B) and its salts. Human exposure can arise from a variety of natural sources, such as soil and water, and artificially in soils via fertilizer and in waters via discharges through its use in household products and cosmetics, or via its use in pesticides, preservatives, and pharmaceuticals. Receiving waters can also obtain B through industrial usage. Indirect and probably insignificant consumer exposure can arise via the use of borates in glass products, flame retardants, and enamels, these applications comprising the major proportion of borate usage. The general intake of B via its presence in food and water is around 1-7 mg/d, but the range of intake values is large and depends on geographical region, dietary habits (with nuts, fresh and dried fruits, and wine providing particularly rich sources), as well as the method of analysis employed. Drinking waters typically contain <1 mg B/L, but the range is large, and some populations will be exposed to considerably more than 1 mg B/L. B via food and water represents the greatest source of exposure for the general consumer. Sodium borate and boric acid are widely used in consumer products, and perborate is used in detergents, but even though there is a high potential for exposure, the internal dose of B to consumers via its use in household and personal products is very low partly owing to insignificant amounts of dermal absorption across normal skin.     

Experimental studies to set hygienic standards for benzylpenicillin in the air of a work area

The character and level of benzylpenicillin toxic effect was studied in accordance with the methodic instruction for performance of the experiments on toxicological estimation and hygienic norms of antibiotics in the air of working areas in production premises. It was shown that the antibiotic was of low toxicity under conditions of a single exposure, did not cumulate and had no local irritating and resorbing effect. It was shown to be an allergen. Prolonged inhalation of benzylpenicillin in a concentration of 14 mg/m3 resulted in reversible changes in the function of the kidneys and liver of the animals, their sensitization and development of pronounced dysbacteriosis of the mouth and intestine mucosa. In a concentration of 1 mg/m3 benzylpenicillin had no general toxic and sensitizing effect but induced reversible changes in the normal autoflora. This allowed the authors to consider the above concentration to be maximum with respect to the antibacterial effect. On the basis of the experiments the maximum permissible norm (MPN) of the aerosol of benzylpenicillin disintegration was recommended at the level of 0.1 mg/m3.     

On hygienic and ecological approaches in radiation protection

In this paper the problem of substantiation of one of the basic radiation protection ensurance principle is considered: sufficiency of a man radiation safety ensuring for guaranteed ensuring of radiation safety of the environment living components. This paradigm formulated in ICRP recommendations and is often referred to as hygienic or anthropocentric approach to environment radiation protection is laid down the basis of all national, including Russian, regulations in the field of radiation safety. During the last 5-10 years a lot of papers have been published, in which the hygienic principle of environmental safety ensuring is considered as a matter of dispute and the certain logical basis and the quantitative comparative estimations of human exposure doses and most irradiated vulnerable parts of nature doses are given. Change of one of the main radiation protection paradigms will demand for resolution of the enormously difficult and labor-consuming scientific problems. In the present paper, on the basis of UNSCEAR models of critical population groups dose formation and consistent application of conservativeness principle it is shown that for the ground ecosystems today there is no strong reasons for refusal of a hygienic radiation protection principle for benefit of ecological one.     

Physico-chemical and hygienic property modifications of stainless steel surfaces induced by conditioning with food and detergent

The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/conditioning procedures resulted in a similar increase in the surface contamination with carbon, while the changes in the basic component of the surface free energy depended on the conditioning procedure. The passive film was also affected, the Fe/Cr ratio in particular. The hygienic status was also changed, especially with milk as shown by monitoring the number of residual adhering Bacillus cereus spores after contaminating the surface with spores followed by cleaning. The results show that in food environments, the presence and the nature of conditioning molecules play a major role in the hygienic status of SS surfaces.     

Physico-chemical and hygienic property modifications of stainless steel surfaces induced by conditioning with food and detergent

The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/conditioning procedures resulted in a similar increase in the surface contamination with carbon, while the changes in the basic component of the surface free energy depended on the conditioning procedure. The passive film was also affected, the Fe/Cr ratio in particular. The hygienic status was also changed, especially with milk as shown by monitoring the number of residual adhering Bacillus cereus spores after contaminating the surface with spores followed by cleaning. The results show that in food environments, the presence and the nature of conditioning molecules play a major role in the hygienic status of SS surfaces.     

Cytogenetic study of persons occupationally exposed to ethylene oxide.

Ten persons occupationally exposed to ethylene oxide (EO), used in the sterilization of medical instruments, were studied at a hospital. The estimated concentration to which they were exposed was 60-69 ppm, TWA. Peripheral blood samples from 10 workers and 10 controls of the same age and sex were taken to determine the frequency of sister-chromatid exchanges (SCE) and chromosomal aberrations (CA). The mean frequencies of SCE/cell (X = S) were 13.27 for the exposed workers and 6.05 for controls. Chromosome aberration frequencies in exposed individuals were significantly increased compared with controls. A significant relationship between the frequencies of SCE and CA and EO exposure was demonstrated. Blood chemistry parameters such as urea, creatinine, uric acid, lactic dehydrogenase, glutamic oxaloacetic and pyruvic transaminases, luteinizing gonadotropin and follicle stimulating gonadotropin and thyrotropin were also measured and found to be within the normal range.     

The modifying effect of nitrites, nitrates and increased temperature on 14C metabolism

The paper deals with the experimental findings regarding the effects of non-radiational factors, such as sodium nitrite and nitrate and increased temperature, on the metabolism kinetics of 14C inorganic and organic compounds (14C-sodium bicarbonate, 14C-glucose) in conditions of long-term internal exposure to the nuclide. The authors determined the time which elapses before the steady state is achieved as well as the maximum concentration, the accumulation factor and the dose strength. At a concentration of 3 g/l, nitrites and nitrates were shown to produce no significant modifying effect on the kinetics of 14C metabolism. In hyperthermic conditions, 14C metabolism proved to be more intensive. The findings reported herein may have practical applications in setting up hygienic norms and evaluating the hazards of 14C accumulation in the environment.     

Quantitation of polymerase chain reaction products by hybridization-based assays with fluorescent, colorimetric, or chemiluminescent detection.

In this report two nonradioactive assays for quantitative analysis of polymerase chain reaction (PCR) products are presented. In the first assay, magnetic beads coated with streptavidin were used to capture biotinylated PCR fragments. After hybridization with a hapten-labeled probe, these beads were analyzed either by flow cytometry (method A) or by immunoenzymatic reactions (method B). Using a dilution series of purified PCR products, we consistently found a lower detection limit of 1.5 fmol for method A than the 0.15-fmol limit for method B. In the second assay we used the peroxidase-based enhanced chemiluminescence system in combination with a cooled charge-coupled device camera to quantify PCR fragments that were spotted on membranes. A linear logarithmic response was observed between the amount of light produced within a certain time interval and the number of DNA molecules. With an exposure time of 5 min, a detection limit of 0.15 fmol was found. Longer exposure times did not result in a higher sensitivity. We conclude that the assays are of sufficient sensitivity for application in quantitative PCR strategies. The nonradioactive technology facilitates implementation of these assays in routine settings.     

Results obtained in short-term experiments and their application prospects in prognosticating threshold levels of chronic exposure to chemical compounds

Joint studies carried out by toxicologists of CMEA countries have led to the development of new ways of approach to the problem of rapid establishment of toxicometric parameters and hygienic standards (TSEL, MAC) for the working-zone atmosphere. One of the most promising approaches is the rapid establishment of MAC from the threshold of acute specific effect. Upon this principle, methodical directives for determining MAC values for specifically active irritants were elaborated. A study of the quantitative relations between toxicometric parameters and the physicochemical properties of substances in the working-zone atmosphere furnished methods for calculating TSEL values for noxious substances in this atmosphere. The essential possibility was confirmed of using isolated mitochondria as a model for preliminarily estimating the toxicity and establishing safe concentration levels of noxious substances in the working-zone atmosphere. The application of a complex of functional, biochemical and morphometric indices made it possible to foretell from short-term experiments minimal effective concentrations of a substance on chronic exposure. Ways of further research in the field of prognosticating toxicometric parameters and hygienic regulations for chemical compounds are outlined.     

Characterization of biodegradation intermediates of nonionic surfactants by MALDI-MS. 2. Oxidative biodegradation profiles of uniform octylphenol polyethoxylate in 18O-labeled water

This paper reports the characterization of the biodegradation intermediates of octylphenol octaethoxylate (OP(8)EO) by means of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The biodegradation test study was carried out in a pure culture (Pseudomonas putida S-5) under aerobic conditions using OP(8)EO as the sole carbon source and (18)O-labeled water as an incubation medium. In the MALDI-MS spectra of biodegraded samples, a series of OP(n)EO molecules with n = 2-8 EO units and their corresponding carboxylic acid products (OP(n)EC) were observed. The use of purified OP(8)EO enabled one to distinguish the shortened OPEO molecules as biodegradation intermediates. Furthermore, the formation of OP(8)EC (the oxidized product of OP(8)EO) supported the notion that terminal oxidation is a step in the biodegradation process. When biodegradation study was carried out in (18)O-labeled water, incorporation of (18)O atoms into the carboxyl group was observed for OPEC, while no incorporation was observed for the shortened OPEO products. These results could provide some rationale to the biodegradation mechanism of alkylphenol polyethoxylates.     

Formation of DNA adducts and induction of mutagenic effects in rats following 4 weeks inhalation exposure to ethylene oxide as a basis for cancer risk assessment

Ethylene oxide (EO) is mutagenic in various in vitro and in vivo test systems and carcinogenic in rodents. EO forms different adducts upon reaction with DNA, N7-(2-hydroxyethyl)guanine (N7-HEG) being the main adduct. The major objectives of this study were: (a) to determine the formation and persistence of N7-HEG adducts in liver DNA of adult male rats exposed to 0, 50, 100 and 200 ppm by inhalation (4 weeks, 5 days/week, 6 h/day) and (b) to assess dose-response relationships for Hprt gene mutations and various types of chromosomal changes in splenic lymphocytes.N7-HEG adducts were measured 5, 21, 35 and 49 days after cessation of exposure. By extrapolation, the mean concentrations of N7-HEG immediately after cessation of exposure ('day 0') to 50, 100 and 200 ppm were calculated as 310, 558 and 1202 adducts/10(8) nucleotides, respectively, while the mean concentration in control rats was 2.6 adducts/10(8) nucleotides. At 49 days, N7-HEG values had returned close to background levels. The mean levels of N-(2-hydroxyethylvaline) adducts in haemoglobin were also determined and amounted 61.7, 114 and 247 nmol/g globin, respectively. Statistically significant linear relationships were found between mean N7-HEG levels ('day 0') and Hprt mutant frequencies at expression times 21/22 and 49/50 days and between mean N7-HEG ('day 0') and sister-chromatid exchanges (SCEs) or high frequency cells (HFC) measured 5 days post-exposure. At day 21 post-exposure, SCEs and HFCs in-part persisted and were significantly correlated with persistent N7-HEG adducts. No statistically significant dose effect relationships were observed for induction of micronuclei, nor for chromosome breaks or translocations.In conclusion, this study indicates that following sub-chronic exposure, EO is only weakly mutagenic in adult rats. Using the data of this study to predict cancer risk in man resulting from low level EO exposures in conjunction with other published data, i.e., those on (a) genotoxic effects of EO in humans and rats, (b) DNA binding of other carcinogens, (c) natural background DNA binding and (d) genotoxic potency of low energy transfer (LET) radiation, it is not expected that long term occupational exposure to airborne concentrations of EO at or below 1 ppm EO produces an unacceptable increased risk in man.     

Specialty products made from goat milk

Although it may not be important in certain parts of the world, the contribution of goat milk to the economic and nutritional wellbeing of humanity is undeniable in many developing countries, especially in the Mediterranean, Middle East, Eastern Europe and South American countries. Goat milk has played a very important role in health and nutrition of young and elderly. Goat milk has also been known for its beneficial and therapeutic effects on the people who have cow milk allergy. These nutritional, health and therapeutic benefits enlighten the potentials and values of goat milk and its specialty products. The chemical characteristics of goat milk can be used to manufacture a wide variety of products, including fluid beverage products (low fat, fortified, or flavored) and UHT (ultra high temperature) milk, fermented products such as cheese, buttermilk or yogurt, frozen products such as ice cream or frozen yogurt, butter, condensed/dried products, sweets and candies. In addition, other specialty products such as hair, skin care and cosmetic products made from goat milk recently have gained a further attention. Nevertheless, high quality products can only be produced from good quality goat milk. The quality milk should have the potential to tolerate technological treatment and be transformed into a product that satisfies the expectations of consumers, in terms of nutritional, hygienic and sensory attributes. Taste is the main criteria used by consumers to make decisions to purchase and consume goat milk and its products. Typical goat taste is considered as a quality component in certain goat cheese products. Farmers can produce more value-added products for the economic sustainability of their business and the dairy goat industry in general.