Andreas Tornevi

Precipitation effects on microbial pollution in a river: lag structures and seasonal effect modification.

Background The river Göta Älv is a source of freshwater for 0.7 million swedes. The river is subject to contamination from sewer systems discharge and runoff from agricultural lands. Climate models projects an increase in precipitation and heavy rainfall in this region. This study aimed to determine how daily rainfall causes variation in indicators of pathogen loads, to increase knowledge of variations in river water quality and discuss implications for risk management. Methods Data covering 7 years of daily monitoring of river water turbidity and concentrations of E. coli, Clostridium and coliforms were obtained, and their short-term variations in relation with precipitation were analyzed with time series regression and non-linear distributed lag models. We studied how precipitation effects varied with season and compared different weather stations for predictive ability. Results Generally, the lowest raw water quality occurs 2 days after rainfall, with poor raw water quality continuing for several more days. A rainfall event of >15 mm/24-h (local 95 percentile) was associated with a three-fold higher concentration of E. coli and 30% higher turbidity levels (lag 2). Rainfall was associated with exponential increases in concentrations of indicator bacteria while the effect on turbidity attenuated with very heavy rainfall. Clear associations were also observed between consecutive days of wet weather and decreased water quality. The precipitation effect on increased levels of indicator bacteria was significant in all seasons. Conclusions Rainfall elevates microbial risks year-round in this river and freshwater source and acts as the main driver of varying water quality. Heavy rainfall appears to be a better predictor of fecal pollution than water turbidity. An increase of wet weather and extreme events with climate change will lower river water quality even more, indicating greater challenges for drinking water producers, and suggesting better control of sources of pollution.

Evolution of Minimum Mortality Temperature in Stockholm, Sweden, 1901-2009.

Background: The mortality impacts of hot and cold temperatures have been thoroughly documented, with most locations reporting a U-shaped relationship with a minimum mortality temperature (MMT) at which mortality is lowest. How MMT may have evolved over previous decades as the global mean surface temperature has increased has not been thoroughly explored. Objective: We used observations of daily mean temperatures to investigate whether MMT changed in Stockholm, Sweden, from the beginning of the 20th century until 2009. Methods: Daily mortality and temperature data for the period 1901–2009 in Stockholm, Sweden, were used to model the temperature–mortality relationship. We estimated MMT using distributed lag nonlinear Poisson regression models considering lags up to 21 days of daily mean temperature as the exposure variable. To avoid large influences on the MMT from intra- and interannual climatic variability, we estimated MMT based on 30-year periods. Furthermore, we investigated whether there were trends in the absolute value of the MMT and in the relative value of the MMT (the corresponding percentile of the same-day temperature distribution) over the study period. Results: Our findings suggest that both the absolute MMT and the relative MMT increased in Stockholm, Sweden, over the course of the 20th century. Conclusions: The increase in the MMT over the course of the 20th century suggests autonomous adaptation within the context of the large epidemiological, demographical, and societal changes that occurred. Whether the rate of increase will be sustained with climate change is an open question. Citation: Oudin Åström D, Tornevi A, Ebi KL, Rocklöv J, Forsberg B. 2016. Evolution of minimum mortality temperature in Stockholm, Sweden, 1901–2009. Environ Health Perspect 124:740–744; http://dx.doi.org/10.1289/ehp.1509692

Intake and macronutrient content of human milk given to extremely preterm infants

Background: Human milk (HM) is the preferred basis of nutrition for infants, including those born prematurely. Information on HM macronutrient content is necessary to optimize nutritional support of preterm infants. Objectives: This study aimed to describe the types and amounts of enteral feeds given to Swedish extremely preterm infants during hospitalization and to investigate the energy and macronutrient contents in HM given to these infants. Methods: A population-based study of Swedish extremely preterm infants (n = 586) born before 27 gestational weeks was conducted. Data on ingested volumes of different milk during hospitalization and analyses of macronutrient content in HM samples were obtained from hospital records. Nutritional content of HM was determined by mid-infrared spectrophotometry analysis. Results: During the first 4 weeks of life, 99% of the infants were exclusively fed HM, and at 4 weeks of life, 70% of the infants received only mother’s own milk (MOM). Nutritional content in 821 MOM samples was analyzed. Protein content in MOM decreased significantly from 2.2 to 1.2 g/100 mL during the first 112 postpartum days, whereas fat and energy content were highly variable within and between MOM samples. In addition, 354 samples of donor milk were analyzed. Content of protein, fat, and energy in pooled donor milk (n = 129) was lower compared to single donor milk. Conclusion: Swedish extremely preterm infants receive MOM to a large extent during hospitalization. Protein, carbohydrates, and energy in MOM changed significantly with time. Weekly analyses of MOM during the first month of lactation would allow more individualized nutritional support for these vulnerable infants.

Field validation of the Ogawa diffusive sampler for NO2 and NOx in a cold climate

A small-scale field trial in Umeå, Sweden with Ogawa samplers and a chemiluminescence instrument indicated that the NO(2) concentration was underestimated with respect to the reference monitor, if calculated according to the manufacturers Ogawa sampling protocol. By co-locating Ogawa samplers and reference monitors at six sites in two Swedish cities, uptake rates were determined for NO(2) and NO(x) better applicable to the Swedish conditions and climate. The concentrations of NO(2) and NO(x) calculated according to the instruction manual of the sampler and using the field-determined uptake rates were compared with values derived from chemiluminescence monitors for each week over which samples were taken. When calculated according to the manufacturers suggested protocol, the Ogawa sampler underestimated the NO(2) concentrations by 9.1% on average for all samples (N = 53), with respect to the reference monitor. In contrast, NO(x) concentrations were overestimated by a mean value of 15% for all samples (N = 45). By using the field determined uptake rates for the calculation of NO(2) and NO(x) a better estimation of the concentrations was obtained. The ratio between concentrations determined with the Ogawa samplers and chemiluminescence monitors was then 1.02 for all measurements of NO(2) and 1.00 for NO(x). Precision, expressed as the mean coefficient of variation, was 6.4% for six, 6-replicate measurements of NO(2) and 3.7% for five, 6-replicate measurements of NO(x).

Association between Precipitation Upstream of a Drinking Water Utility and Nurse Advice Calls Relating to Acute Gastrointestinal Illnesses

Background The River Göta Älv is a source of fresh-water for the City of Gothenburg (Sweden). We recently identified a clear association between upstream precipitation and indicator bacteria concentrations in the river water outside the intake to the drinking water utility. This study aimed to determine if variation in the incidence of acute gastrointestinal illnesses is associated with upstream precipitation. Methods We acquired data, covering 1494 days, on the daily number of telephone calls to the nurse advice line from citizens in Gothenburg living in areas with Göta Älv as a fresh-water supply. We separated calls relating to gastrointestinal illnesses from other medical concerns, and analyzed their association with precipitation using a distributed lag non-linear Poisson regression model, adjusting for seasonal patterns and covariates. We used a 0–21-day lag period for precipitation to account for drinking water delivery times and incubation periods of waterborne pathogens. Results The study period contained 25,659 nurse advice calls relating to gastrointestinal illnesses. Heavy rainfall was associated with increased calls the same day and around 5–6 days later. Consecutive days of wet weather were also found to be associated with an increase in the daily number of gastrointestinal concerns. No associations were identified between precipitation and nurse advice calls relating to other medical concerns. Conclusion An increase in nurse advice calls relating to gastrointestinal illnesses around 5–6 days after heavy rainfall is consistent with a hypothesis that the cause could be related to drinking water due to insufficient barriers in the drinking water production, suggesting the need for improved drinking water treatment.

Precipitation and primary health care visits for gastrointestinal illness in Gothenburg, Sweden

Background The river Göta Älv is a source of freshwater for the City of Gothenburg, Sweden, and we recently identified a clear influence of upstream precipitation on concentrations of indicator bacteria in the river water, as well as an association with the daily number of phone calls to the nurse advice line related to acute gastrointestinal illnesses (AGI calls). This study aimed to examine visits to primary health-care centers owing to similar symptoms (AGI visits) in the same area, to explore associations with precipitation, and to compare variability in AGI visits and AGI calls. Methods We obtained data covering six years (2007–2012) of daily AGI visits and studied their association with prior precipitation (0–28 days) using a distributed lag nonlinear Poisson regression model, adjusting for seasonal patterns and covariates. In addition, we studied the effects of prolonged wet and dry weather on AGI visits. We analyzed lagged short-term relations between AGI visits and AGI calls, and we studied differences in their seasonal patterns using a binomial regression model. Results The study period saw a total of 17,030 AGI visits, and the number of daily visits decreased on days when precipitation occurred. However, prolonged wet weather was associated with an elevated number of AGI visits. Differences in seasonality patterns were observed between AGI visits and AGI calls, as visits were relatively less frequent during winter and relatively more frequent in August, and only weak short-term relations were found. Conclusion AGI visits and AGI calls seems to partly reflect different types of AGI illnesses, and the patients’ choice of medical contact (in-person visits versus phone calls) appears to depend on current weather conditions. An association between prolonged wet weather and increased AGI visits supports the hypothesis that the drinking water is related to an increased risk of AGI illnesses.

Determinants of personal exposure to some carcinogenic substances and nitrogen dioxide among the general population in five Swedish cities

Environmental levels of airborne carcinogenic and related substances are comparatively better known than individual exposure and its determinants. We report on a personal monitoring program involving five Swedish urban populations. The aim of the program was to investigate personal exposure to benzene, 1,3-butadiene, formaldehyde, and nitrogen dioxide (NO2). The measurements were performed among 40 inhabitants during seven consecutive days, in one urban area each year, during 2000–2008. The estimated population exposure levels were 1.95 μg/m3 for benzene, 0.56 μg/m3 for 1,3-butadiene, 19.4 μg/m3 for formaldehyde, and 14.1 μg/m3 for NO2. Statistical analysis using a mixed-effects model revealed that time spent in traffic and time outdoors contributed to benzene and 1,3- butadiene exposure. For benzene, refueling a car was an additional determinant influencing the exposure level. Smoking or environmental tobacco smoke were significant determinants of exposure to NO2, benzene, and 1,3-butadiene. Those with a gas stove had higher NO2 exposure. Living in a single-family house increased the exposure to formaldehyde significantly. In a variance component model, the between-subject variance dominated for 1,3-butadiene and formaldehyde, whereas the between-city variance dominated for NO2. For benzene, the between-subject and between-cities variances were similar.

Hyperglycemia in Extremely Preterm Infants—Insulin Treatment, Mortality and Nutrient Intakes

Objective To explore the prevalence of hyperglycemia and the associations between nutritional intakes, hyperglycemia, insulin treatment, and mortality in extremely preterm infants. Study design Prospectively collected data from the Extremely Preterm Infants in Sweden Study (EXPRESS) was used in this study and included 580 infants born <27 gestational weeks during 2004‐2007. Available glucose measurements (n = 9850) as well as insulin treatment and nutritional data were obtained retrospectively from hospital records for the first 28 postnatal days as well as 28‐ and 70‐day mortality data. Results Daily prevalence of hyperglycemia >180 mg/dL (10 mmol/L) of up to 30% was observed during the first 2 postnatal weeks, followed by a slow decrease in its occurrence thereafter. Generalized additive model analysis showed that increasing parenteral carbohydrate supply with 1 g/kg/day was associated with a 1.6% increase in glucose concentration (P < .001). Hyperglycemia was associated with more than double the 28‐day mortality risk (P < .01). In a logistic regression model, insulin treatment was associated with lower 28‐ and 70‐day mortality when given to infants with hyperglycemia irrespective of the duration of the hyperglycemic episode (P < .05). Conclusions Hyperglycemia is common in extremely preterm infants throughout the first postnatal month. Glucose infusions seem to have only a minimal impact on glucose concentrations. In the EXPRESS cohort, insulin treatment was associated with lower mortality in infants with hyperglycemia. Current practices of hyperglycemia treatment in extremely preterm infants should be reevaluated and assessed in randomized controlled clinical trials.