Lower respiratory illness, recurrent wheezing, and day care attendance.

We prospectively assessed the relations between various characteristics of day care and lower respiratory illness (LRI) in a cohort of 1,268 Minnesotan children, born between October 1989 and January 1991 and followed to 2 yr of age. Information on LRI was abstracted from medical records and data on day care use, respiratory symptoms, and physician diagnosis of asthma were obtained from questionnaires. We identified a subgroup of 60 children with recurrent wheezing illnesses. The LRI rate ratio for day care attendance was 2.0 (95% confidence interval = 1.7, 2.2). Rate ratios were similar regardless of the day care setting, number of other children present, or the number of hours spent in day care. A parental history of asthma further increased the rate ratio for day care attendance. Day care attendance was associated with a threefold risk of having recurrent wheezing illnesses. We conclude that day care attendance is an important risk factor for LRI in young children, and for recurrent wheezing illnesses.

The indoor air and children's health study: methods and incidence rates.

The Indoor Air and Children's Health Study is a prospective cohort study of the relation between indoor air pollution and lower respiratory illness (LRI) during the first 2 years of life. Information on family and household characteristics was obtained from a health maintenance organization for 1,424 infants enrolled at birth. Data on LRI were abstracted from medical records. The incidence of all LRI was 48.4 per 100 child-years. Wheezing-associated respiratory illness (WARI)/asthma was the most common specific LRI, with an incidence of 11.5 per 100 child-years. Total LRI incidence was lowest during the first 6 months of life. Girls had lower incidence than boys [rate ratio (RR) = 0.8; 95% confidence interval (CI) = 0.7-0.8)]. With the exception of croup, all LRI were most common during February and March. These results are comparable with those of other prospective studies. Consistent with other studies, self-reported maternal smoking demonstrated an RR of 1.5 (95% CI = 1.2-1.8) for total LRI, but the association varied for specific LRIs from 2.3 (95% CI = 1.5-3.0) for WARI/asthma to 1.0 (95% CI = 0.7-1.6) for bronchitis.

Measuring exposure to environmental tobacco smoke in studies of acute health effects.

The relations among three methods of measuring exposure to environmental tobacco smoke, questionnaires, urinary cotinine, and a passive monitor for ambient nicotine, were investigated in a study of 48 children in Minnesota in 1989. Subjects were all under 2 years of age and did not attend day care. Passive nicotine monitors were placed in the activity room and the child's bedroom for 1 week, urine samples were collected at the beginning and end of the week for cotinine analysis, and a detailed questionnaire concerning cigarette smoking was administered at the end of the week. These same measures were obtained weekly for 8 weeks for 22 of the children. Among households with smokers, concentrations of ambient nicotine and urinary cotinine were lowest when the father smoked, intermediate when the mother smoked, and highest when both parents smoked. Activity room concentrations were highly correlated with both urinary cotinine (r = 0.81) and the total number of cigarettes smoked in the house (r = 0.86). Regression equations indicated that knowing who smoked in the house was a more important predictor of ambient nicotine than knowing the amount smoked. Both urinary cotinine and ambient nicotine demonstrated variability over time, although ambient nicotine was less variable. In addition, 100% of possible ambient nicotine samples were collected in contrast to 80% of urine samples. The results of the study suggest that both urinary cotinine and ambient nicotine provide better information about the exposure of young children to environmental tobacco smoke than questionnaire data alone, and that ambient nicotine may be the more useful in this population based on its greater stability and ease of collection.

Relationship of ergonomic stressors to birthweight and gestational age.

Women in many occupations are exposed to ergonomic stressors (eg, prolonged standing, physical exertion, and long work weeks). After a consideration of the major methodological problems encountered in studying effects of ergonomic stressors on birthweight and gestational age, epidemiologic studies that have addressed this issue are reviewed. No individual ergonomic stressor has been consistently associated with effects on gestational age. However, most studies which have attempted to look at the cumulative effect of several stressors report that women in the highest exposure category are at higher risk of giving birth prematurely. In contrast, data regarding an association with birthweight are more variable, and firm conclusions cannot be drawn. While future studies that assess exposure to ergonomic stressors with a more comprehensive and quantitative approach are needed, current evidence is sufficient to suggest that clinicians should take ergonomic stressors into account in the assessment of their patients' risk for preterm delivery.

Radon progeny exposure and lung cancer risk in New Mexico U miners: a case-control study.

A case-control study was conducted to describe lung cancer risk in a cohort of New Mexico underground U miners. The subjects included 65 cases and 230 age-matched controls, most with exposures below 3.50 J h m-3 (1000 WLM). The risk for lung cancer was increased for all cumulative exposures to Rn progeny of 0.35 J h m-3 (100 WLM) or greater. The odds ratios were unchanged with control for cigarette smoking. With exclusion of subjects with exposures above 3.50 J h m-3 (1000 WLM), the estimated excess relative risk was 0.3% per mJ h m-3 (1.1% per WLM). The risk was greater for younger subjects and the data were consistent with a multiplicative interaction between cigarette smoking and exposure to Rn progeny.

Minnesota highway maintenance worker cohort mortality study: methods and noncancer mortality.

In 1984, the Minnesota Department of Health (MDH) began a cohort mortality study of 4,849 workers to follow up concerns with the health and safety of highway maintenance workers (HMWs). A total of 1,530 deaths had occurred, resulting in a standardized mortality ratio (SMR) of 91 (p less than .01) and an all cancer SMR of 84 (p less than .01). There was a significant elevation in the SMR for chronic renal failure among long-term rural workers (SMR = 676, p less than .05). The SMR was also elevated for transportation injuries. The latter SMR was highest among short-term urban workers (SMR = 280, p less than .01). In addition, the SMR for transportation-related injury deaths tended to increase the later the decade of starting work. The SMRs were 137, 259, 502, and 2,145 for urban workers starting work in the decades 1945-1954, 1955-1964, 1965-1974, and 1975-1984, respectively. This study demonstrates the possible adverse health effects of highway maintenance work and the need to comprehensively evaluate injury mortality among selected occupational cohorts.

Minnesota Highway Maintenance Worker Study: cancer mortality.

Highway maintenance workers (HMWs) have been exposed to a broad range of potentially toxic substances, including diesel fuels and exhaust, asphalts and tars, herbicides, gasoline, polynuclear aromatic hydrocarbons, benzene, and lead. The number of current and former state, county, and municipal HMWs in the United States exceeds 500,000, yet the health risks of this occupation had never been studied. To fill this void and to respond to the public perception that Minnesota HMWs were at high risk of developing leukemia, an occupational cohort mortality study was conducted of Minnesota HMWs employed between 1945 and 1984. Leukemia mortality in HMWs with 30-39 years of work (standardized mortality ratio [SMR] = 425; 95% confidence interval [CI] = 171-876) and urologic cancer mortality in HMWs with 40-49 year latency (SMR = 292; CI = 117-602) were significantly elevated. The extent to which these and other findings were directly related to work exposures is unknown. Further investigations to resolve the significance of the risks associated with the HMW occupation are currently underway.

Health effects and sources of indoor air pollution. Part I.

Since the early 1970s, the health effects of indoor air pollution have been investigated with increasing intensity. Consequently, a large body of literature is now available on diverse aspects of indoor air pollution: sources, concentrations, health effects, engineering, and policy. This review begins with a review of the principal pollutants found in indoor environments and their sources. Subsequently, exposure to indoor air pollutants and health effects are considered, with an emphasis on those indoor air quality problems of greatest concern at present: passive exposure to tobacco smoke, nitrogen dioxide from gas-fueled cooking stoves, formaldehyde exposure, radon daughter exposure, and the diverse health problems encountered by workers in newer sealed office buildings. The review concludes by briefly addressing assessment of indoor air quality, control technology, research needs, and clinical implications.

Respiratory effects of indoor air pollution.

Since the early 1970s, the health effects of indoor air pollution have been investigated with increasing intensity. A large body of literature is now available on diverse aspects of indoor air pollution: sources, concentrations, health effects, engineering, and policy. This article provides a selective summary of this new information with an emphasis on health effects relevant to health care practitioners concerned primarily with immunologically mediated respiratory diseases. We address exposures associated with acute and chronic respiratory effects: tobacco smoke, nitrogen dioxide, wood smoke, and formaldehyde. The article also describes the diverse health problems experienced by workers in newer sealed office buildings. The importance of indoor concentrations in determining personal exposures to pollutants is emphasized.

Work and pregnancy.

Pregnancy outcomes of 7,155 women who worked between one and nine months of pregnancy were compared with outcomes of 4,018 women who were not employed. There were no differences in rates of prematurity, Apgar score, birthweight, perinatal death rate, or malformation prevalence. Working women were divided into those who left employment during the first eight months and those who worked all nine months. The latter had a lower rate of adverse outcome than the other working group and the nonworking group. This indicates that working to term in the absence of contraindications does not impose an added risk on mother or infant. After control of confounding by parity and other relevant factors, an increased risk of prolonged gestational age was seen among primiparous working women. There was an increased risk of fetal distress among those women leaving work prior to nine months who were having their third or subsequent child. A small decrease in birth weight was seen among women who left work prior to term but not among those who worked all nine months. Overall the results are reassuring that working during pregnancy is not in itself a risk factor for adverse outcome.

The association of alcohol consumption with outcome of pregnancy.

Patterns of alcohol consumption were assessed in 12,440 pregnant women interviewed at the time of delivery. Only 92 women (0.7 per cent) reported drinking 14 or more drinks per week, with most consuming fewer than 21 drinks per week. In the crude data, alcohol intake of 14 or more drinks per week was associated with a variety of adverse pregnancy outcomes, including low birthweight, gestational age under 37 weeks, stillbirth, and placenta abruptio. After use of logistic regression to control for confounding by demographic characteristics, smoking, parity and obstetric history, only the association of placenta abruptio with alcohol consumption of 14 or more drinks per week remained statistically significant. With the exception of placenta abruptio, alcohol intake of fewer than 14 drinks per week was not associated with and increased risk of any adverse outcome. No association was seen with congenital malformations at any level of alcohol intake.