The Duluth Boat Club (DBC) Beach, located in the Duluth-Superior harbor of Lake Superior, is frequently closed in summer due to high counts of Escherichia coli, an indicator of fecal contamination. However, the sources of bacteria contributing to beach closure are currently unknown. In this study, we investigated the potential sources of E. coli contaminating the DBC beach by using modified rep-PCR (HFERP) DNA fingerprinting. Over 3600 E. coli strains were obtained from 55 lake water, 25 sediment, and 135 sand samples taken from five transects at the DBC beach at 11 different times during the summer through fall months of 2004 and 2005. Potential sources of E. coli at this beach were determined by using a known-source DNA fingerprint library containing unique E. coli isolates from wildlife, waterfowl, and treated wastewater obtained near Duluth, MN. Amounts E. coli in the samples were enumerated by membrane filtration counting, and the presence of potentially pathogenic E. coli was determined by using multiplex PCR. E. coli counts in all samples increased during the summer and early fall (July to September). While E. coli in spring samples originated mainly from treated wastewater effluent, the percentage of E. coli from waterfowl increased from summer to fall. DNA fingerprint analyses indicated that some E. coli strains may be naturalized, and autochthonous members of the microbial community in the beach sand and sediments were examined. However, multiplex PCR results indicated that <1% of the E. coli strains at the DBC was potentially pathogenic. Our results also suggest that wave action may influence the early colonization and homogeneous distribution of E. coli in beach sand and the subsequent release of sand or sediment-borne E. coli into lake water. Taken together, these results indicate that sand and sediment serve as temporal sources and sinks of human and waterfowl-derived E. coli that contribute to beach closures.

OBJECTIVES. This study investigated the influence of psychosocial stress, maternal schooling, social support, psychological well-being, alcohol, and smoking on intrauterine growth retardation and premature delivery. METHODS. At a Copenhagen university hospital, 2432 pregnant women completed a questionnaire on general health, psychosocial stressors, and sociodemographic characteristics. RESULTS. In 212 cases (8.7%) the women delivered prematurely. Preterm delivery as associated with psychosocial stress (adjusted odds ratio [OR]=1.14 for each 1-point increase on the psychosocial stressor 5-point scale and 1.92 for the whole scale) and poor school education (adjusted OR=2.62 for 7-9 years of schooling, 1.91 for 10 years, and 1.0 for 11-13 years). In 152 cases (6.3%), infants had a birthweight below the 10th percentile. Intrauterine growth retardation was associated with smoking, daily drinking, school education, and social network variables. In a multiple logistic regression model, intrauterine growth retardation was associated with smoking habits (adjusted OR=2.40 for 0-9 cigarettes daily, 2.68 for 10-15 daily, and 2.88 for more than 15 daily). CONCLUSIONS. Psychosocial stressors and limited duration of schooling appeared to influence preterm delivery. Smoking habits influenced intrauterine growth retardation.

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Exposure to smog, floods, 1 or earthquakes 2 has been associated with a lower sex ratio (proportion of males) in offspring conceived at the time of the exposure episode. We hypothesised that exposure to severe life events before and during the periconceptional period might be associated with a decline in the sex ratio. Methods and resultsAll Danish women who gave birth from 1 January 1980 to 31 December 1992 were identified by the population based medical birth registry. By linking personal identification numbers to the Danish statistical office's fertility database, we identified all the women's partners and older children. A partner was defined as the father of the child or the partner with whom the woman was cohabiting on 1 January in the year of birth. Severe life events were defined as death or admission to hospital for cancer (codes 140 to 209 (excluding 208 polycythemia vera) of the international classification of diseases, eighth revision) or acute myocardial infarction (code 410) in the partner or older children. By linking the personal identification numbers to the mortality registry and to the national registry of patients, we identified all deaths and all admissions to hospital of partners and children between 1978 and 1992.We identified all women exposed to severe life events in the year of birth and the previous year but included only the women exposed before the second trimester. Women with diabetic partners were excluded, as it has been reported that the sex ratio in their offspring is higher. The time of exposure was recorded as the date of death or first admission to hospital. Information on the possible confounding variables was obtained from the registries.The exposed cohort consisted of 3072 singleton pregnancies exposed to severe life events and a control cohort of 20 337 singleton pregnancies randomly selected among all pregnancies without such exposure in the observation period. Of all the offspring, 945 had congenital malformations, chromosomal abnormalities, or hereditary diseases.Using logistic regression analysis, we found that the proportion of boys was 49.0% in the exposed group and 51.2% the control group, giving a crude overall lower ratio between the two sex odds (sex odds ratio) of 0.92 and an adjusted ratio of 0.91 (95% confidence interval 0.84 to 0.99) (table). Exclusion of offspring whose mothers were exposed during the first trimester and all offspring with congenital malformations gave similar results (data not shown).The nearer the exposure was to conception, the lower the overall sex odds ratio (test for trend P = 0.013) and the lower the sex ratio for exposure by an older sibling only (P = 0.035) and for exposure by death of a partner only (P = 0.016). CommentThe results show that severe life events may reduce the sex ratio, especially for exposures around the time of conception, because of differential conception or Adjusted sex odds ratios and percentage of boys as function of severe life events before and in periconceptional period and stratified for timing of exposur...