Evaluation of efficacy of disinfectants against Salmonella from the feed industry.

AIMS: To evaluate disinfectants against Salmonella under conditions relevant for the feed industry. MATERIALS AND RESULTS: A survey on the use of disinfectants in feed industry showed that a range of different types was used. Nine disinfectants, reflecting the most commonly used active ingredients, were tested for bactericidal activity on Salmonella isolated from the feed industry. All disinfectants were efficient against Salmonella in suspension. The bactericidal effect varied considerably between different types of active compounds on bacteria dried on surfaces or grown as biofilm. Tenside-based disinfectants and hypochlorite were found to have low bactericidal activity and the efficiency was significantly reduced when the ratio of amount disinfectant per cell decreased. It was shown that concentrations of 70-80% ethanol were effective against Salmonella. Among the disinfectants tested a product containing 70% ethanol was most efficient followed by Virkon S. CONCLUSIONS: Many disinfectants had low bactericidal activity against Salmonella at surfaces while Virkon S and a product containing 70% ethanol were most effective. Another advantage of ethanol-based disinfectants is evaporation of ethanol, resulting in low residual water after use. SIGNIFICANCE AND IMPACT OF THE STUDY: Use of the disinfectants found to be efficient against surface associated Salmonella, may assist the industry in combating Salmonella.

Social-class gradients in menarcheal age in Poland.

In a sample of approx. 19 000 Polish schoolgirls from the three largest cities of the Upper Silesia conurbation, menarcheal age was studied in relation to parental education (four levels) and father's occupation (12 groups). Menarcheal age tends to increase with decreasing parental education, although the gradient is not steep. When families below a certain level of economic standing are discarded from the best-educated and the least-well-educated groups, mean menarcheal age, surprisingly, decreases much more in the former than in the latter. Mean menarcheal ages for girls from different occupational groups range from 12.82 to 13.30 years and form the following sequence, in increasing order: managers--police--non-technical professionals--engineers, technicians and foremen--skilled industrial workers and small businessmen--unskilled workers--coal-miners. Mean menarcheal age for an occupational group is strongly dependent upon the group's socio-economic status, the latter being defined in terms of parental education, family income, family size, and dwelling conditions. However, daughters of men in the police force mature significantly earlier, and daughters of coal-miners significantly later, than would be expected from each group's rank in socio-economic status. The findings are compared with the results of other recent studies of social gradients in menarcheal age in Poland.

The final phase of growth in height.

Among 221 boys investigated, only 54% had the same (+/- 1 cm) body height at age 27 years as they had at age 19. Longitudinal observations of those boys indicate that the increment from 18 to 27 years is strongly dependent on skeletal maturation and even on such a distant event as age at peak height velocity. Average increment in stature was 2.13 cm, and the maximum increment was 7 cm. Late-maturing individuals are largely responsible for the differences in average stature observed in cross-sectional studies in the third decade of life.