Determining the Efficacy of Liquid Sporicides Against Spores of Bacillus subtilis on a Hard Nonporous Surface Using the Quantitative Three Step Method: Collaborative Study

A collaborative study was conducted to validate the quantitative Three Step Method (TSM), a method designed to measure the performance of liquid sporicides on a hard nonporous surface. Ten laboratories agreed to participate in the collaborative study; data from 8 of 10 participating laboratories were used in the final statistical analysis. The TSM uses 5 5 1 mm glass coupons (carriers) upon which spores have been inoculated and which are introduced into liquid sporicidal agent contained in a microcentrifuge tube. Following exposure to a test chemical and a neutralization agent, spores are removed from carriers in 3 fractions: passive removal (Fraction A), sonication (Fraction B), and gentle agitation (Fraction C). Liquid from each fraction is serially diluted and plated on a recovery medium for spore enumeration. Control counts are compared to the treated counts, and the level of efficacy is determined by calculating the log10 reduction (LR) of spores. The main statistical goals were to evaluate the repeatability and reproducibility of the LR values, to estimate the components of variance for LR, and to assess method responsiveness. AOAC Method 966.04Method II was used as a reference method. The scope of the validation was limited to testing liquid formulations against spores of Bacillus subtilis, a surrogate for virulent strains of B. anthracis, on a hard nonporous surface (glass). The test chemicals used in the study were sodium hypochlorite, a combination of peracetic acid and hydrogen peroxide, and glutaraldehyde. Each test chemical was evaluated at 3 levels of presumed efficacy: high, medium, and low. Three replications were required. The TSM was validated as it successfully met the statistical parameters for quantitative test methods. Satisfactory validation parameters, such as the repeatability standard deviation (Sr) and reproducibility standard deviation (SR), were obtained for control carrier counts and LR values. Both the TSM and the reference method were responsive to the efficacy levels of the test chemicals. For the 72 total TSM tests conducted, the mean ( standard error of the mean) log density of spores per control carrier was 6.86 ( 0.08); the Sr and SR were low at 0.15 and 0.27, respectively. Across the range of test chemicals, the Sr and SR estimates associated with LR were also acceptably low. The Sr rangedfrom 0.17 to 0.72 and the SR ranged from 0.34 to 1.43. Overall, the Sr and SR estimates associated with the efficacy data were within the ranges published for other quantitative methods and meet the performance characteristics necessary for validation.

Volatile organic compounds and formaldehyde as explaining factors for sensory irritation in office environments

This study's database comprised results of volatile organic compound (VOC) measurements from 176 office buildings. In 23 of the 176 buildings, formaldehyde measurements were also conducted. It was suspected that the buildings had indoor air problems, but a walk-through inspection did not reveal any clear, abnormal contaminant sources. The 50 most abundant VOCs and their concentrations in 520 air samples were analyzed. The irritation potency was estimated for 33 out of the 50 common VOCs and their mixtures, as well as for formaldehyde. This information was used to calculate the recommended indoor air levels (RILs) for the VOCs. The RILs were considerably higher than the measured mean indoor air concentrations in the buildings. However, the RIL for formaldehyde was exceeded in most of the 23 buildings studied. According to the evaluation of irritation potency, formaldehyde was a more likely cause of sensory irritation than the mixture of common nonreactive VOCs at the concentrations that occurred in the buildings without abnormal indoor sources. Furthermore, environmental symptoms of office workers were characterized in 20 office buildings (including the database of 176 office buildings) with the aid of an indoor air questionnaire. The most frequent symptoms related to the indoor environment were involved the upper respiratory tract. However, no relationship could be shown between the reported symptoms and the occurrence of VOC and formaldehyde concentrations in these buildings. Generally, the study results indicated that formaldehyde was the more likely agent causing sensory irritation than the mixture of the common nonreactive VOCs at the concentrations occurring in the buildings without abnormal indoor sources.

A multi-faceted approach to risk assessment of laboratory animal allergens at two facilities

BACKGROUND

Risk assessment of exposure to allergens is difficult because the relationship between exposure, sensitization, and symptoms has not been fully established. Laboratory animal allergens (LAA) are an important occupational health risk factor; 10-32% of workers exposed to these allergens develop allergic diseases. This article introduces a versatile approach to assessing the risks posed by LAA at two laboratory animal facilities.

METHODS

The risk assessment approach that was used at the laboratory animal facilities included questionnaires for management and employees, a hazard identification visit and measurements in the workplaces, as well as the creation of a list of generally recommended procedures to reduce allergen exposure.

RESULTS

The prevalence of work-related allergic symptoms was 17%. Suggested countermeasures at the sites included changes in ventilation and work practices, reduction of unnecessary exposure, recommendations for more comprehensive use of personal protective equipment, and wider communication about LAA risks.

CONCLUSIONS

The approach managed to identify critical points and potential means for controlling LAA exposure.

Serum IgG antibodies against Wallemia sebi and Fusarium species in Finnish farmers

BACKGROUND

Wallemia sebi and Fusarium species are common fungi in agricultural environments. Because Fusarium species are difficult to culture, and W. sebi has only recently been found in an agricultural environment with the use of a new culture medium, immunochemical methods may be important for evaluating exposure to these fungi.

OBJECTIVE

Immunoglobulin (Ig) G antibodies against W. sebi and two Fusarium species were measured in the sera of Finnish farmers to estimate exposure to fungi.

METHODS

Serum-specific IgG antibody levels against the fungi were determined in farmers with farmer's lung disease and asthma, as well as in asymptomatic farmers with low and high IgG antibody levels against other agricultural microorganisms, and in control persons (printing and office workers). Both enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunofiltration assay (ELIFA) techniques were used.

RESULTS

Significantly higher IgG antibody levels against the fungi studied were observed in farmer's lung patients and asymptomatic farmers with high IgG levels against other agricultural fungi, than in the control group. On the other hand, the development of IgG antibodies to the fungi in asthmatic farmers remained unclear because of a discrepancy between the ELISA and ELIFA results. Cross-reactivity between Fusarium species was detected.

CONCLUSIONS

The results indicate that Finnish farmers are exposed to W. sebi and Fusarium species in their work environment to a greater extent than has earlier been evaluated with air sampling and microbiologic methods.

Comparison of detection methods for trichothecenes produced by Fusarium sporotrichioides on fodder and grains at different air humidities

Growth and toxin production of a highly toxic strain of Fusarium sporotrichioides Sherb were studied on oat and wheat grains and on straw under experimental conditions, in which relative humidity (RH) of air was regulated. The materials were incubated at three different RH levels at a range of 84-100%. F. sporotrichioides grew well on oat and wheat grains at RH 97-100% but grew less well at RH 84-88% and on straw. Toxin production was measured with three biological toxicity tests (cytotoxicity test, dermotoxicity test, and yeast cell toxicity test), with chemical analysis, and T-2 ELISA assay. Cytotoxicity and production of trichothecene mycotoxins were detected in all the samples incubated at all three RH levels. On oat and wheat grains, T-2 toxin, neosolaniol, and diacetoxyscirpenol were found, and on straw T-2 toxin, HT-2 toxin, neosolaniol, and T-2 tetraol were determined. In the T-2 ELISA assay, all material samples were found to contain T-2 toxin. The cytotoxicity test was the most sensitive method for detecting biological toxicity of samples inoculated with fungus. The T-2 ELISA assay and chemical analysis were about equally sensitive to detect T-2 toxin in samples.

Dihydroergotamine in the prevention of hypotension associated with extradural anaesthesia

The efficacy of a single dose of dihydroergotamine (DHE) 0.5 mg i.v. in preventing the decrease in arterial pressure resulting from extradural anaesthesia was studied in 47 patients; 24 received DHE and 23 a placebo, in a randomized double-blind manner. Although the decrease in systolic arterial pressure was more pronounced in the placebo group than in the DHE group, the difference was not significant. Diastolic and mean arterial pressures were both significantly lower in the placebo group than in the DHE group during the initial phase of extradural anaesthesia. Administration of DHE did not cause any significant changes in heart rate. In both groups the heart rate decreased significantly during the 5-h period following the induction of extradural anaesthesia. The patients in the placebo group needed additional medication to increase unacceptably low arterial pressures or heart rate more frequently than the patients in the DHE group.