Eija Skyttä

Polynuclear aromatic compounds and genotoxicity in particulate and vapor phases of ambient air: effect of traffic, season, and meteorological conditions

High-volume samples of ambient air were collected by glass-fiber filter (particulate) and XAD-2 resin (vapor) from three locations in Finland: two cities and a rural area. Samples were analyzed for polynuclear aromatic hydrocarbons (PAH) and selected other polynuclear compounds. Genotoxocity of the samples was assayed in the Ames Salmonella/microsome test and sister chromatid exchange assay before and after fractionation into four fractions of increasing polarity. The ratio of PAH in the vapor and particulate phases of the samples varied considerably with the season, and the scavenging effect of snow and rain was as well clearly demonstrated. The rural samples showed minimal or no genotoxic activity, whereas at the urban sites not only the particulate-phase but also the vapor-phase samples were mutagenic. The genotoxicity was mainly associated with the most polar fractions of both phases. Studies with the nitroreductase-deficient Salmonella strain TA98NR indicated, that in the urban air samples collected in winter, a considerable part of the mutagenicity detected in the Ames test was due to NO/sub 22/-substituted compounds. Traffic is suggested to be the major determinant for the genotoxic activity in the ambient air.

Polycyclic organic material (POM) in urban air. Fractionation, chemical analysis and genotoxicity of particulate and vapour phases in an industrial town in Finland

Abstract Polycyclic organic material (POM) was collected by high-volume sampling on filter and on XAD-2 resin from the air of a small industrial town in Finland. Concurrent chemical analysis and the assays for genotoxic activity were performed on the particulate and the vapour phases of ambient air POM and their chemical fractions. Furthermore, correlations between seasonal meteorological parameters and POM concentrations were studied to reveal characteristic POM profiles for various emission sources. The range of total POM concentrations varied from 115 to 380 ng m −3 in late spring and from 17 to 83 ng m −3 in early winter. No direct correlation of ambient POM was seen with the temperature, but rather with the wind direction from various emission sources. Especially the low molecular weight compounds were associated with wind direction from industrial sources. Genotoxic activity, as detected by the Ames Salmonella /microsome test and the SCE assay in CHO cells, was found not only in the paniculate phase samples but also in the vapour phase. The polar fractions of some of the samples showed genotoxic activity, and also direct mutagenicity was observed with both the assay systems; these facts support the significance of compounds other than conventional polycyclic aromatic hydrocarbons (PAH) in the samples.

Safety Evaluation of Sous Vide-Processed Products with Respect to Nonproteolytic Clostridium botulinum by Use of Challenge Studies and Predictive Microbiological Models

ABSTRACT Sixteen different types of sous vide-processed products were evaluated for safety with respect to nonproteolytic group IIClostridium botulinum by using challenge tests with low (2.0-log-CFU/kg) and high (5.3-log-CFU/kg) inocula and two currently available predictive microbiological models, Food MicroModel (FMM) and Pathogen Modeling Program (PMP). After thermal processing, the products were stored at 4 and 8°C and examined for the presence of botulinal spores and neurotoxin on the sell-by date and 7 days after the sell-by date. Most of the thermal processes were found to be inadequate for eliminating spores, even in low-inoculum samples. Only 2 of the 16 products were found to be negative for botulinal spores and neurotoxin at both sampling times. Two products at the high inoculum level showed toxigenesis during storage at 8°C, one of them at the sell-by date. The predictions generated by both the FMM thermal death model and the FMM and PMP growth models were found to be inconsistent with the observed results in a majority of the challenges. The inaccurate predictions were caused by the limited number and range of the controlling factors in the models. Based on this study, it was concluded that the safety of sous vide products needs to be carefully evaluated product by product. Time-temperature combinations used in thermal treatments should be reevaluated to increase the efficiency of processing, and the use of additional antibotulinal hurdles, such as biopreservatives, should be assessed.

Purity of recycled fibre-based materials.

In order to study the purity of recycled fibre-based materials, products containing recycled fibre as well as recycled pulp were examined with regard to their chemical impurities, toxicity and microbiological quality. The study was carried out to clarify both qualitatively and quantitatively the variations in microbiological quality. The levels of several classes of chemical substances were analysed and semi-volatile and volatile substances identified. The toxicity and mutagenicity of virgin fibre and recycled fibre materials were screened using the Photobacter toxicity test and the Ames Salmonella mutagenicity test. Preliminary chemical characterization of the mutagens was carried out. Identification of the compounds found in the mutagenic fractions was performed by gas chromatography/mass spectrometry (GC/MS). The concentration of various substances analysed was found to be low, although the variety of substances present appeared to be very broad. Preliminary chemical characterization revealed that some samples contained compounds known to have mutagenic or other toxic activity. Also, the recycled fibre pulps contained large amounts of various microbes, the microbial load consisting mainly of aerobic spore-forming bacteria. The paper-making process was found to clearly have reduced the total microbial counts.

Inhibition of growth of nonproteolytic Clostridium botulinum type B in sous vide cooked meat products is achieved by using thermal processing but not nisin.

The safety of refrigerated processed foods of extended durability (REPFEDs) with respect to nonproteolytic Clostridium botulinum is under continuous evaluation. In the present study, mild (P7.0(85.0) values 0 to 2 min [P, pasteurization value; z-value 7.0 degrees C; reference temperature 85.0 degrees C]) and increased (P7.0(85.0) values 67 to 515 min) heat treatments were evaluated in relation to survival of nonproteolytic C. botulinum type B spores in sous vide processed ground beef and pork cubes. The use of two concentrations of nisin in inhibition of growth and toxin production by nonproteolytic C. botulinum in the same products was also evaluated. A total of 96 samples were heat processed and analyzed for C. botulinum by BoNT/B gene-specific polmerase chain reaction and for botulinum toxin by a mouse bioassay after storage of 14 to 28 days at 4 and 8 degrees C. Predictably, after mild processing all samples of both products showed botulinal growth, and one ground beef sample became toxic at 8 degrees C. The increased heat processing, equivalent to 67 min at 85 degrees C. resulted in growth but not toxin production of C. botulinum in one ground beef sample in 21 days at 8 degrees C: in the pork cube samples no growth was detected. The increased heating of both products resulted in higher sensory quality than the milder heat treatment. Nisin did not inhibit the growth of nonproteolytic C. botulinum in either product; growth was detected in both products at 4 and 8 degrees C, and ground beef became toxic with all nisin levels within 21 to 28 days at 8 degrees C. Aerobic and lactic acid bacterial counts were reduced by the addition of nisin at 4 degrees C. The study demonstrates that the mild processing temperatures commonly employed in sous vide technology do not eliminate nonproteolytic C. botulinum type B spores. The intensity of each heat treatment needs to be carefully evaluated individually for each product to ensure product safety in relation to nonproteolytic C. botulinum.

Genotoxicity and PAC analysis of particulate and vapour phases of environmental tobacco smoke

Samples of indoor air were collected from an office room (88 m3) both before smoking and during experimental smoking of 96 cigarettes by 10 persons within 6 h. The particulates were collected on glass-fibre filters and the vapour-phase compounds on XAD-2 resin. The samples were extracted with acetone and analysed quantitatively for polycyclic aromatic compounds and qualitatively with GC-MS. The extracts of filters and XAD-2 resins were fractionated into neutral/acidic and 2 basic (strong and weak bases) fractions; all these fractions were tested with the sister-chromatid exchange (SCE) assay in Chinese hamster ovary (CHO) cells and with the Salmonella/microsome test (strain TA98). Total concentrations of PAC were 205 ng/m3 in the background sample and 1207 ng/m3 after contamination by cigarette smoking. The total PAC concentrations were 4-6 times higher in the vapour phase than in the particulate phase. The fractions of the particulate samples collected before smoking showed mainly marginal genotoxic activity, whereas after smoking their genotoxicity increased dramatically. The fractions of the vapour phase samples were not genotoxic before smoking, but after smoking the neutral/acidic and strong basic fractions induced responses in both assays. The SCE assay was more sensitive towards the vapour-phase mutagens of environmental tobacco smoke (ETS). The relative responses of the two basic fractions, whereas the fraction containing neutral and acidic compounds was the most potent in the SCE assay. In the Salmonella test, the mutagenic activity was mainly detected with metabolic activation, while the induction of SCE in CHO cells was also seen without an exogenous metabolic activation system.

Antimicrobial and Barrier Properties of LDPE Films Containing Imazalil and EDTA

Imazalil and ethylenediamine-tetraacetic acid (EDTA) were incorporated into low-density polyethylene (LDPE) aimed at producing antimicrobial packaging films for foodstuffs. Moulded plates (thickness 2mm) containing 5% of EDTA inhibited Bacillus subtilis, whereas 0.05–0.25% of imazalil had strong activity against Aspergillus niger. Further tests for antimicrobial activity, migration and oxygen and water vapor barrier properties were carried out using biaxially stretched LDPE films containing different combinations of both substances. The addition of imazalil and EDTA increased the oxygen transmission rates and water vapor permeabilities, although the effects with imazalil films were not as significant. Transparency of the EDTA containing films decreased rapidly as a function of added EDTA, whereas imazalil films were optically faultless. Total migration into 3% acetic acid and 10% ethanol was below 4 mg/dm2. Although imazalil retained its activity against A. niger on a high level (inhibition zones >30 mm), the activity of EDTA was gone. None of the samples inhibited Escherichia coli.

Shelf-life of prepeeled potato cultivated, stored, and processed by various methods.

The effects of cultivation conditions, winter storage, peeling method, browning prevention chemicals replacing sodium bisulfite, and packing methods on the sensory, nutritional and microbiological quality of pre-peeled potato were examined. Two different cultivation lots of the potato variety Van Gogh were used. Cultivation and harvesting conditions and peeling method were the most important facts reducing the sensory quality, especially the appearance, of prepeeled and sliced potatoes. Cooking and baking of potatoes decreased the appearance defects detected in raw potatoes. The levels of vitamin C in packaged samples decreased during winter storage. Cooking for 10 min and keeping potatoes at 60 degrees C for 1 h after cooking also decreased the content of vitamin C. In potato samples immediately after treatments aerobic bacteria were present at levels of 400 to 2,950 CFU/g and lactic acid bacteria at levels of 8 to 16 CFU/g. The number of aerobic bacteria did not increase during storage, and the number of lactic acid bacteria increased at the most to 90 CFU/g. Peeling, washing and packaging methods, cultivation conditions, and winter storage did not have important effects on the number of microbes present.

Characterisation of aerobically grown non-spore-forming bacteria from paper mill pulps containing recycled fibres

A total of 179 non-spore-forming bacteria aerobically growing on Nutrient Agar, Plate Count Agar or in specific enrichment conditions for salmonella, campylobacteria, listeria, yersinia or staphylococci, were isolated from 16 untreated paper mill pulps. After phenotypical screening the isolates were characterised by automated ribotyping and partial sequencing of the 16S rRNA gene. They could be divided into seven taxonomical classes representing 63 taxa (species): actinobacteria (11 species), bacilli (7), flavobacteria (3) alphaproteobacteria (10), betaproteobacteria (5), gammaproteobacteria (25) and sphingobacteria (2). Most of the gammaproteobacteria were enterobacteria, mainly species of the genera Enterobacter (7 species, 7 samples/3 mills) and Klebsiella (5 species, 6 samples/3 mills). Other commonly occurring bacteria were most closely related to Microbacterium barkeri (7 samples/3 mills), Cloacibacterium normanense (6 samples/2 mills), Pseudoxanthomonas taiwanensis (5 samples/2 mills) and Sphingobacterium composti (5 samples/1 mill). Sporadic isolates of Listeria innocua, L. monocytogenes, Enterococcus casseliflavus and Staphylococcus warneri were detected, from which only L. monocytogenes is considered to be a food pathogen. No isolates of the genera Campylobacter, Salmonella or Yersinia were detected. The detected bacteria may be harmful in process control, but the load of food pathogens with recycled fibres to paper machines is insignificant. Faecal contamination of the pulp samples was not indicated.

Ethanol, isobutanol, and biohydrocarbons as gasoline components in relation to gaseous emissions and particulate matter.

The exhaust emissions of three cars using different biofuels were explored at a temperature of -7 °C. The biofuels studied contained both low- and high-concentration ethanol blends, isobutanol, and biohydrocarbons. A multipoint fuel injection car (MPFI), direct-injection spark-ignition car (DISI), and flex-fuel car (FFV) represented three different spark-ignition-car technologies. At -7 °C, substantial emissions were observed for the three cars, and differences were found among ethanol, isobutanol, and biohydrocarbons as fuel components. For example, E85 resulted in high acetaldehyde, formaldehyde, ethanol, ethene, and acetylene emissions when compared to E30 or lower ethanol concentrations. Isobutanol-containing fuel showed elevated butyraldehyde, methacrolein, and isobutanol emissions. The highest particulate matter (PM) emissions, associated polyaromatic hydrocarbon (PAH) and indirect mutagenicity emissions were detected with the DISI car. Oxygenated fuels reduced PM emissions and associated priority PAH emissions in the DISI car. PM and PAH emissions from the MPFI and FFV cars were generally low. A combination of 10% ethanol and biohydrocarbon components did not change emissions significantly when compared to ethanol-only-containing E10 gasoline. Therefore, a combination of ethanol or isobutanol with biohydrocarbon components offers an option to reach high gasoline bioenergy content for E10-compatible cars.