Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID).

BACKGROUND: Prenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study's aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of selenium against mercury toxicity were also examined. METHODS: Participants (mean corrected age = 6.6 months) were part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), lead and mercury were measured in maternal blood during pregnancy, as well as in the cord blood. The Teller acuity card test (TAC) (n = 429) and the visual evoked potentials in a sub-group (n = 63) were used to estimate behavioural and electrophysiological visual acuity, respectively. Multivariable linear regression models were used to investigate the relationship between exposure to each contaminant and visual acuity measures, while controlling for potential confounders. Breastmilk selenium, which was available for about half of the TAC and VEP samples, was also taken into account in the mercury models as exploratory analyses. RESULTS: We observed no significant associations between exposure to any contaminants and TAC. Analyses revealed a negative trend (p values < 0.1) between cord blood lead and mercury and electrophysiological visual acuity, whereas PCB and PBDE showed no association. When adding breastmilk selenium concentration to the mercury models, this association became statistically significant for cord concentrations (ß = - 3.41, 95% CI = - 5.96,-0.86), but also for blood levels at 1st and 3rd trimesters of pregnancy (ß = - 3.29, 95% CI = - 5.69,-0.88). However, further regression models suggested that this change in estimates might not be due to adjustment for selenium, but instead to a change in the study sample. CONCLUSIONS: Our results suggest that subtle, but detectable alterations of infant electrophysiological visual acuity can be identified in a population prenatally exposed to low mercury concentrations. Compared to behavioural visual acuity testing, electrophysiological assessment may more sensitive in detecting visual neurotoxicity in relation with prenatal exposure to mercury.

A randomized trial of the effect of dust control on children's blood lead levels.

OBJECTIVE: Dust control is recommended as one of the cornerstones of controlling childhood lead exposure; however, the effectiveness of dust control has not been demonstrated for children who have low to mild elevations in blood lead (ie, less than 25 micrograms/dL). The objective of this study was to determine whether dust control, as performed by families, had an effect on children's blood lead levels and dust lead levels in children's homes. DESIGN: Randomized, controlled trial. SETTING: Community-based trial in Rochester, NY. PARTICIPANTS: One hundred four children, 12 to 31 months of age at baseline. INTERVENTION: Families and children were randomized to one of two groups. Families of children in the intervention group received cleaning supplies, information about cleaning areas that are often contaminated with lead, and a cleaning demonstration. Families in the control group received only a brochure about lead poisoning prevention. OUTCOME MEASURES: Baseline measurements of lead in blood, house dust, soil, water, and paint were taken from both groups. Seven months after enrollment, a second blood lead assay was obtained, and lead levels in household dust were measured. The main outcome measures were change in blood lead levels and dust lead levels by treatment group. RESULTS: The median blood lead level of children enrolled in the study was 6.7 micrograms/dL (range, 1.7 to 30.6 micrograms/dL). There was no significant difference in the change of children's blood lead levels or dust lead levels by treatment group. The median change in blood lead levels among children in the intervention group was -0.05 micrograms/dL compared with -0.60 micrograms/dL among those in the control group. There also was no significant difference in the change of dust lead by group assignment, although there was a trend toward a significant difference in the percentage of change in dust lead levels on noncarpeted floors, which was greater among houses in the intervention group. CONCLUSIONS: These data suggest that an intervention that consists only of providing cleaning supplies and a brief description of dust control is not effective at reducing blood lead levels among urban children with low to mild elevations in blood lead levels at a 7-month follow-up.

Primary prevention of childhood lead exposure: A randomized trial of dust control.

BACKGROUND: Dust control is recommended as one of the primary strategies to prevent or control children's exposure to residential lead hazards, but the effect of dust control on children's blood lead levels is poorly understood. OBJECTIVE: To determine the effectiveness of dust control in preventing children's exposure to lead, as measured by blood lead levels, during their peak age of susceptibility. DESIGN: A randomized, controlled trial. SETTING: Rochester, NY. PARTICIPANTS: A total of 275 urban children were randomized at 6 months of age, of whom 246 (90%) were available for the 24-month-old follow-up visit. INTERVENTIONS: Children and their families were randomly assigned to an intervention group (n = 140), which received cleaning equipment and up to eight visits by a dust control advisor, or a control group (n = 135). OUTCOME MEASURES: Geometric mean blood lead levels and prevalence of elevated blood lead levels (ie, >10 microg/dL, 15 microg/dL, and 20 microg/dL). RESULTS: At baseline, children's geometric mean blood lead levels were 2.9 microg/dL (95% confidence interval [CI] = 2.7, 3.1); there were no significant differences in characteristics or lead exposure by group assignment, with the exception of water lead levels. For children in the intervention group, the mean number of visits by a dust control advisor during the 18-month study period was 6.2; 51 (36%) had 4 to 7 visits, and 69 (49%) had 8 visits. At 24 months of age, the geometric mean blood lead was 7.3 microg/dL (95% CI = 6.6, 8.2) for the intervention group and 7.8 microg/dL (95% CI = 6.9, 8. 7) for the control group. The percentage of children with a 24-month blood lead >/=10 microg/dL, >/=15 microg/dL, and >/=20 microg/dL was 31% versus 36%, 12% versus 14%, and 5% versus 7% in the intervention and control groups, respectively. CONCLUSIONS: We conclude that dust control, as performed by families and in the absence of lead hazard controls to reduce ongoing contamination from lead-based paint, is not effective in the primary prevention of childhood lead exposure.

Physiologic stability of newborns during cup- and bottle-feeding.

BACKGROUND: To prevent breastfeeding problems, cup-feeding has been recommended as a method of providing medically necessary supplemental feedings to breastfed infants. OBJECTIVES: To compare amounts ingested, administration time, and infant physiologic stability during cup-, bottle-, and breastfeeding. DESIGN/METHODS: A total of 98 term, healthy newborns were randomized to either cup-feeding (n = 51) or bottle-feeding (n = 47). The heart (HR), respiratory (RR), and oxygen (O(2)) saturation rates were monitored on these infants and 25 breastfed newborns during 1 feeding. Differences in amounts ingested and administration times were evaluated with t tests and physiologic data with repeat measures analysis of variance. RESULTS: There were no significant differences in administration time, amounts ingested or overall HR, RR, and (O(2)) saturation rates, between cup and bottle groups. Breastfed infants had longer administration times and lower overall HR, RR, and higher O(2) saturation as compared with cup- and bottle-fed infants. CONCLUSIONS: Administration times, amounts ingested, and infant physiologic stability do not differ with cup- and bottle-feeding. Breastfeeding takes longer than cup- or bottle-feeding, but infants experience less physiologic variability. These data support cup-feeding as an alternative to bottle-feeding for supplying supplements to breastfed infants.

Risk factors for the early acquisition of human herpesvirus 6 and human herpesvirus 7 infections in children.

OBJECTIVE: Human herpesviruses 6 and 7 (HHV-6 and HHV-7) are common infections in children, but risk factors for their early acquisition have not been described. METHODS: Excess sera from children 12 to 31 months of age enrolled in a cross-sectional, random survey were tested for human herpesviruses 6 and 7 infection, as measured by using immuno-blot and immunofluorescence assays. RESULTS: Of 164 children 131 (80%) had antibody to HHV-6, and 79 (47%) of 167 had antibody to HHV-7. In logistic regression analysis low income [odds ratio (OR), 2.9; 95% confidence intervals (CI), 1.02 to 8.7] and having more than 1 sibling (OR=2.1, 95% CI=0.9 to 5.1) were risk factors for HHV-6 infection after adjusting for age, whereas month of test (OR=2.7, 95% CI=1.3 to 5.9) and Black race (OR=2.0, 95% CI=0.9, 4.6) were associated with a higher prevalence of HHV-7 infection. In contrast having ever been breast-fed appeared to protect against HHV-7 infection (OR=0.5, 95% CI=0.3 to 1.1). CONCLUSIONS: Despite studies linking both HHV-6 and HHV-7 with exanthem subitum, risk factors for the early acquisition of HHV-6 and HHV-7 are distinct. Subsequent studies investigating the transmission of HHV-6 should explore family size and other factors associated with poverty, whereas breast-feeding should be examined as a protective factor for HHV-7 infection.

Association of livebirths and the resurgence of measles.

BACKGROUND: The basis for the resurgence of measles in the US in 1989 and 1990 is not understood. This analysis was undertaken to test the hypothesis that an increase in the number of livebirths was associated with the resurgence of measles in the US. METHODS: We undertook an ecologic analysis of 20 cities/countries in the US with documented rates of immunization among 2-year-old children. RESULTS: Over the 6-year period 1985-1990, the numbers of livebirths and of susceptible preschool aged children increased by 18.5% and 17.7%, respectively. Livebirths, and the number and density of susceptible preschool-age children were significantly associated with the number and incidence of measles among preschool children (r = 0.83, P = 0.04). In a comparison between counties, numbers of livebirths were also significantly correlated with the mean number (r = 0.73, P = 0.0003) and incidence of measles cases (r = 0.51, P = 0.02). Mean immunization rates of 2-year-old children were also associated with the mean incidence of measles (r = -0.66, P = 0.0015, and r = -0.57, P = 0.009, respectively). In a logistic regression model, levels of immunization and susceptible density were independent predictors of measles epidemics among preschool children. CONCLUSIONS: These data suggest that the increase in livebirths, leading to an increase in the number and density of susceptible hosts, was associated with the resurgence of measles among preschool-age children.

Hepatitis C virus infection in healthcare workers: risk of exposure and infection.

OBJECTIVES: To determine the incidence of hepatitis C virus (HCV) infection among healthcare workers (HCWs) at a university hospital, the proportion of HCWs having non-A, non-B hepatitis (NANBH) who were anti-HCV positive, and the rate of HCV transmission following a HCV-positive needlestick injury. DESIGN: Longitudinal analysis of a dynamic (cohort) population. MEASUREMENTS: From 1980 through 1989, HCWs who had clinical NANBH were identified, and from 1987 through 1989, HCWs who reported a blood or body fluid exposure and the patients who were the source of the exposure were screened for antibodies to HCV. SETTING: A 732-bed, university hospital and outpatient clinics. RESULTS: Over the 10-year period, six cases of occupationally acquired NANBH were observed, for an incidence of 21 cases per 100,000 HCWs per year (standardized incidence ratio, 2.96; 95% confidence interval [CI95], 1.83 to 4.36). Four of the six cases were confirmed to be HCV infection. From 1987 through 1989, 176 (12.7%) of 1,387 patients who were the source of an exposure were anti-HCV positive. Exposures that occurred in the emergency department were more likely to be anti-HCV positive than were exposures from all other locations (relative risk [RR] = 1.7; P = 0.009). Of HCWs who had an HCV-positive needlestick injury and whose serum had been tested for anti-HCV at least 5 months after the exposure, 3 (6.0%) of 50 seroconverted. From 1987 through 1989, the incidence of HCV infection among HCWs was 54 cases per 100,000 HCWs per year. CONCLUSION: The incidence of clinical NANBH among HCWs in this study is approximately three times higher than that of non-HCWs. HCWs are at significant risk for exposure to and acquisition of HCV.

Screening for tuberculosis infection in urban children.

OBJECTIVES: To determine the proportion of children who are at high risk for tuberculosis (TB) as defined by the American Academy of Pediatrics (AAP) criteria, the rate of compliance with visits for tuberculin skin test (TST) interpretation, and the prevalence of TB infection. DESIGN: A cross-sectional study of 401 children, 12 months to 18 years of age, who attended a hospital-based, urban pediatric clinic for well-child visits was undertaken from April 13, 1994, through August 30, 1994. Respondents completed a self-administered questionnaire, an intradermal TST was applied, and an appointment was scheduled for skin test interpretation in 48 to 72 hours. SETTING: Hospital-based, pediatric primary care center in Rochester, NY, serving children of low to moderate income (67% were receiving Medicaid). RESULTS: Of the 401 children, 342 (85%) had at least 1 risk factor for TB identified: 96 (24%) reported contact with persons who were considered to be at high risk for TB; 170 (42%) had at least 1 parent who was born in a high prevalence country; and 269 (67%) reported a household income of less than $15,500. Of the 401 children, 300 returned for TST interpretation, 257 (64%) by 48 to 72 hours and an additional 43 (11%) by 96 hours. Four (1.3%) of the 300 children had a positive TST (ie, induration > or = 10 mm). All 4 of the children who were TST positive had at least 1 parent from a high-risk country and were identified using AAP-defined risk criteria. The mean age of children who were TST positive was 15.3 years (range 13-17 years) compared with 8.1 years for those who were TST negative (P < .01). The positive predictive value of the questionnaire, which included income as a risk factor for TB, was only 1.5 (95% confidence interval = 0.5-4.0); when household income was not considered a risk factor, the positive predictive value was 2.0 (95% confidence interval = 0.7, 5.5). The estimated cost per child who was TST positive ranged from $430 for those who had contact with an incarcerated adult to $855 per child who was TST positive identified by using AAP-defined criteria. CONCLUSIONS: The overall sensitivity of the AAP-defined criteria and having at least 1 parent from a TB-endemic country were high. However, because of the low prevalence of TB infection, the positive predictive value of these criteria was very low. These data support AAP recommendations only to skin test children who are at high risk for TB, but they also suggest that annual testing may not be cost-effective for many communities in the United States.

Program directors' perspectives on federally funded fellowship training in primary care research.

PURPOSE: To describe the organization, models of training, and institutional impact of National Research Service Award fellowship programs in primary care research. METHOD: Survey of 25 directors of currently-funded and former training sites. RESULTS: Twenty-four program directors (96%) completed the survey. Programs allocated 39% of fellows' time to course work leading to an advanced degree or other didactic instruction, and 40% of time to the conduct of research. Collaborations with other training programs within the institution occurred at 83% of sites. Programs commonly (54%) or exclusively (42%) relied on a research model of "early research independence" in which the fellow defined an area of research interest, rather than an "apprenticeship" model in which the fellow worked in a senior investigator's research area. These programs enriched the local academic environment, but required extensive financial subsidies. The high costs of training often had adverse impacts on recruitment and other components of the training process. CONCLUSION: Research training programs in primary care often substitute acquisition of advanced degrees for early immersion in research. The "early independence" model of research differs from fellowships in the medical specialties, and requires further study to assess its effectiveness. The need to subsidize training costs poses substantial problems for the institutions that host these fellowship programs.

Cognitive deficits associated with blood lead concentrations <10 microg/dL in US children and adolescents.

OBJECTIVE: Lead is a confirmed neurotoxicant, but the lowest blood lead concentration associated with deficits in cognitive functioning and academic achievement is poorly defined. The purpose of the present study was to examine the relationship of relatively low blood lead concentrations-especially concentrations <10 micrograms per deciliter (microg/dL)--with performance on tests of cognitive functioning in a representative sample of US children and adolescents. METHODS: The authors used data from the Third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 to 1994, to assess the relationship between blood lead concentration and performance on tests of arithmetic skills, reading skills, nonverbal reasoning, and short-term memory among 4,853 children ages 6-16 years. RESULTS: The geometric mean blood lead concentration for children n the study sample was 1.9 microg/dL; 172 (2.1%) had blood lead concentrations > or =10 microg/dL. After adjustment for gender, race/ethnicity, poverty, region of the country, parent or caregiver's educational level, parent or caregiver's marital status parent, serum ferritin level, and serum cotinine level, the data showed an inverse relationship between blood lead concentration and scores on four measures of cognitive functioning. For every 1 microg/dL increase in blood lead concentration, there was a 0.7-point decrement in mean arithmetic scores, an approximately 1-point decrement in mean reading scores, a 0.1-point decrement in mean scores on a measure of nonverbal reasoning, and a 0.5-point decrement in mean scores on a measure of short-term memory. An inverse relationship between blood lead concentration and arithmetic and reading scores was observed for children with blood lead concentrations lower than 5.0 microg/dL. CONCLUSION: Deficits in cognitive and academic skills associated with lead exposure occur at blood lead concentrations lower than 5 microg/dL.

Trends and patterns of playground injuries in United States children and adolescents.

OBJECTIVE: To determine the prevalence, trends, and severity of injuries attributable to playground falls relative to other common unintentional mechanisms that resulted in an emergency department (ED) visit in the United States. DESIGN AND SETTING: Data from the emergency subset of the National Hospital Ambulatory Medical Care Survey collected from 1992 to 1997 for children <20 years. METHODS: Injury rates and 95% confidence intervals (CIs) were estimated and injury severity scores were computed. RESULTS: There were 920551 (95% CI: 540803 to 1300299) ED visits over the 6-year study period by children and adolescents that were attributable to falls from playground equipment. The annual incidence of visits for playground injuries did not significantly decrease over the course of the study (187000 to 98000, P =.053). Injury visits for playground falls were twice as prevalent as pedestrian mechanisms, but they were less prevalent than visits for motor vehicle-- and bicycle-related injuries. A larger proportion of playground falls resulted in "moderate-to-severe" injury than did bicycle or motor vehicle injuries. Children aged 5 to 9 years had the highest number of playground falls (P =.0014). Playground falls were most likely to occur at school compared to home, public, and other locations (P =.0016). CONCLUSIONS: Playground injury emergency visits have not significantly declined and remain a common unintentional mechanism of injury. Injury visits for playground falls were proportionally more severe than injury visits attributable to other common unintentional mechanisms. Interventions targeting schools and 5- to 9-year-old children may have the greatest impact in reducing emergency visits for playground injuries.

Efficacy of informational letters on hepatitis B immunization rates in university students.

A randomized, controlled trial was conducted at a private university to determine whether students who received an informational letter (n = 366) would be more likely to receive a hepatitis B vaccination than students in a control group (n = 366). Surveys were conducted to determine the students' reasons for deciding to be vaccinated. Rates of hepatitis B immunization were significantly higher among students assigned to the intervention group (10.7%) than among the control group (1.9%). Vaccinated students were more likely than unvaccinated students to report having had 3 or more sexual partners in the past 6 months. Students at higher risk for hepatitis B infection were more likely than others to be vaccinated. Although the overall rate of immunization was low, informational letters about the hepatitis B virus and vaccine were found to be efficacious in increasing hepatitis B immunization rates among students in the setting of a concurrent educational campaign.

Biomarkers in paediatric research and practice.

Children's health is, to a large extent, a function of their environment. Infectious agents remain the leading cause of death and disability in the world. In contrast, many of the new morbidities--asthma, intellectual impairments, behavioural problems, and cancer--are linked with industrial pollutants or other environmental influences. Our understanding of the risk factors for many diseases is incomplete, but it is widely recognised that disability and death result largely from interactions of environmental factors, broadly defined, and host susceptibility.

Trends and patterns in the transmission of bloodborne pathogens to health care workers.

The key determinants of transmission of bloodborne pathogens are the dose and serum viral concentration of an exposure. This conclusion is supported by data showing that the rate of transmission of hepatitis B virus is elevated if the source patient's viral serum concentration is high and by a comparison of serum concentrations and rates of transmission for hepatitis B virus, HIV, and hepatitis C virus: As the mean serum viral concentration of each of these pathogens increases, the rate of transmission also increases. While there is evidence that the incidence of clinical hepatitis B has declined as a result of vaccine-induced immunity, the prevalence of hospital patients who are HBsAg-positive has actually increased. As the AIDS epidemic evolves and increasing numbers of patients with AIDS are hospitalized, the risk of exposure to HIV and hepatitis B virus can be expected to increase further. Thus, health care workers, many of whom work in an urban setting and are exposed to the blood and body fluids of patients, should be required to receive hepatitis B vaccine. Whereas hepatitis B virus transmission can be prevented by immunization of health care workers, controlling hepatitis C virus and HIV will require efforts to reduce the incidence and dosage of exposures to blood and body fluids. These strategies include the design and use of safe medical devices, targeted interventions based on occupation-specific hazards, the use of gloves and other barriers, and ongoing surveillance and analysis of exposures in the health care setting.

Deaths in custody in Shelby County, Tennessee, January 1970-July 1985.

The purpose of this study is to review retrospectively the deaths that have occurred in the Shelby County detention center from 1970 to 1985. The Shelby County data are compared and contrasted with other studies to discern significant and preventable causes of death in custody. This study confirmed natural causes as most prevalent; however, suicide accounted for greater than 20% of all deaths (15-50-fold greater than the general population). Suicide occurred by hanging in greater than 90% of cases. This is a preventable cause of death while in custody, and means of prevention are addressed.

Transmission and control of bloodborne viral hepatitis in health care workers.

Although the incidence of clinical HBV has declined as a result of infection control measures and vaccine-induced immunity, the prevalence of patients who are HBsAg-positive has increased. HCWs who are exposed to the blood and body fluids of patients should be required to receive hepatitis B vaccine. However, there is no vaccine against HCV, the most prevalent bloodborne pathogen in the health care setting. It therefore is critical for health care workers to encourage the development and assessment of effective preventive and control strategies, including the design and use of safe devices, targeted interventions based on occupation-specific hazards, and surveillance and analysis of exposures in the health care setting.