Graham V. Vimpani

Port Pirie Cohort Study: Environmental Exposure to Lead and Children's Abilities at the Age of Four Years

We studied the effect of environmental exposure to lead on childrens abilities at the age of four years in a cohort of 537 children born during 1979 to 1982 to women living in a community situated near a lead smelter. Samples for measuring blood lead levels were obtained from the mothers antenatally, at delivery from the mothers and umbilical cords, and at the ages of 6, 15, and 24 months and then annually from the children. Concurrently, the mothers were interviewed about personal, family, medical, and environmental factors. Maternal intelligence, the home environment, and the childrens mental development (as evaluated with use of the McCarthy Scales of Childrens Abilities) were formally assessed. The mean blood lead concentration varied from 0.44 mumol per liter in midpregnancy to a peak of 1.03 mumol per liter at the age of two years. The blood lead concentration at each age, particularly at two and three years, and the integrated postnatal average concentration were inversely related to development at the age of four. Multivariate analysis incorporating many factors in the childrens lives indicated that the subjects with an average postnatal blood lead concentration of 1.50 mumol per liter had a general cognitive score 7.2 points lower (95 percent confidence interval, 0.3 to 13.2; mean score, 107.1) than those with an average concentration of 0.50 mumol per liter. Similar deficits occurred in the perceptual-performance and memory scores. Within the range of exposure studied, no threshold dose for an effect of lead was evident. We conclude that postnatal blood lead concentration is inversely related to cognitive development in children, although one must be circumspect in making causal inferences from studies of this relation, because of the difficulties in defining and controlling confounding effects.

Asthma knowledge, attitudes, and quality of life in adolescents.

Adolescents with asthma, their peers, and their teachers were studied in order to establish the level of knowledge concerning asthma and its management, their attitudes towards asthma, and the degree quality of life impairment due to asthma. A community survey was conducted among year 8 high school students (n = 4161) and their teachers (n = 1104). There was a good response rate to the questionnaires from students (93%) and teachers (61%). Twenty three per cent of students had asthma and this caused mild to moderate quality of life impairment, particularly with strenuous exercise. Asthma was provoked by passive smoke exposure in 30% of asthmatic students and up to 51% of students avoided situations because of asthma triggers. Asthma knowledge was low in teachers (mean score 14.90 out of a possible 31), students without asthma (11.25) and students with asthma (14.50). Specific knowledge on the prevention and treatment of exercise induced asthma was poor. There was a moderate degree of tolerance towards asthma among all three groups. Most considered internal locus of control as important, although students without asthma also considered chance to be a determinant of outcomes for people with asthma. Asthma is a common cause of quality of life impairment among year 8 high school students. Although specific knowledge on asthma is low, students and teachers hold favourable attitudes towards asthma. There are opportunities to intervene and improve asthma management among adolescents.

Child and family outcomes of a long-term nurse home visitation programme: a randomised controlled trial

Objective To investigate the impact of a long-term nurse home visiting programme, embedded within a universal child health system, on the health, development and well-being of the child, mother and family. Design Randomised controlled trial. Setting/participants 208 (111 intervention, 97 comparison) eligible at-risk mothers living in a socioeconomically disadvantaged area in Sydney, booking into the local public hospital for confinement. Intervention A sustained and structured nurse home visiting antenatal and postnatal parenting education and support programme. Control Usual universal care. Main outcome measures The quality of the home environment for child development (12–24 months), parent–child interaction and child mental, psychomotor and behavioural development at 18 months. Results Mothers receiving the intervention were more emotionally and verbally responsive (HOME observation) during the first 2 years of their childs life than comparison group mothers (mean difference 0.5; 95% CI 0.1 to 0.9). Duration of breastfeeding was longer for intervention mothers than comparison mothers (mean difference 7.9 weeks; 95% CI 2.9 to 12.9). There was no significant difference in parent–child interaction between the intervention and comparison groups. There were no significant overall group differences in child mental, psychomotor or behavioural development. Mothers assessed antenatally as having psychosocial distress benefitted from the intervention across a number of areas. Conclusion This sustained nurse home visiting programme showed trends to enhanced outcomes in many, but not all, areas. Specifically, it resulted in clinically enhanced outcomes in breastfeeding duration and, for some subgroups of mothers, womens experience of motherhood and childrens mental development. Trial registration number ACTRN12608000473369.

Determinants of Blood Lead Concentrations to Age 5 Years in a Birth Cohort Study of Children Living in the Lead Smelting City of Port Pirie and Surrounding Areas

Sources of variation and some principal determinants of blood lead concentration (PbB) were investigated in a cohort of children, followed to age 5 y, who were born near a lead smelter in Port Pirie, South Australia. The childs age and place of residence were the two variables most strongly predictive of PbB. A sharp increase in PbB occurred between 6 and 15 mo of age and was followed by a peak concentration that occurred at approximately 2 y of age, after which PbB steadily and consistently declined. Irrespective of age, the PbBs in children who lived in Port Pirie were significantly higher than levels identified in children who resided outside the city. There was no significant difference in PbB between boys and girls. Elevated PbB at each specific age was associated mainly with increased lead concentrations in the topsoil of the local residential area, employment of the father in the lead industry, parental smoking, and behaviors likely to cause ingestion of dirt. Blood samples taken from children at certain ages and during the warmer months contained more lead than samples obtained during the cooler months. The effects of these determinants on PbB during early childhood were basically consistent in both single and multivariable analyses.

Port Pirie Cohort study: childhood blood lead and neuropsychological development at age two years.

The Port Pirie Cohort Study is an ongoing prospective study of the relationship between exposure to environmental lead within a lead smelter community, and neuropsychological development in early childhood. Over 600 children, originally recruited during antenatal life, underwent serial blood lead estimations up to two years of age. Systematic interview information was collected on a range of variables, and formal developmental assessment (Bayley Scales of Infant Development) was carried out at 24 months of age. Blood lead concentrations measured antenatally (maternal), at delivery (maternal and umbilical cord) and postnatally at 6, 15 and 24 months were negatively correlated (p less than 0.05) with mental development at 24 months of age. Geometric mean blood lead concentrations (microgram/dl) were 14.3, 20.8 and 21.2 at 6, 15 and 24 months of age respectively. When multiple covariates, including maternal IQ, were controlled for in multiple regression analysis, a statistically significant (p less than 0.01) inverse association was observed between blood lead concentration (PbB) measured at 6 months of age and mental development at 2 years of age. No such association was evident for psychomotor development. When the quality of the home environment (HOME Score) was added to the multiple regression model, the inverse association between blood lead concentration at 6 months of age and mental development at 2 years persisted, albeit less strongly (p = 0.07). From this analysis, it is estimated that a child with with PbB of 30 micrograms/dl at age 6 months will have a deficit of 3.3 points (approximately 3%) on the Bayley Mental Development Scale relative to a child with PbB of 10 micrograms/dl.

Sociodemographic factors modifying the effect of environmental lead on neuropsychological development in early childhood

A long-term prospective cohort study was conducted to examine the association between prenatal and postnatal exposure to environmental lead and childhood neuropsychological development. The possible interactive effects of blood lead and some covariates on early development were explored in this study. Our data suggest that gender of the child modifies the effect of lead on the neuropsychological development during early childhood. At the ages of 2 and 4 years, girls appear to be more sensitive than boys to the neuropsychological effects of lead. However, there is no significant modification of the effect of lead by some other covariates, such as parental smoking, socioeconomic status, home environment, birth weight, and the kind of infant feeding. Evidence of interactions between environmental lead exposure and other covariates in the causation of neuropsychological deficits in childhood underscores the desirability of considering both main effects and interactions in this area of research. Such effects, if confirmed, may have implications for public health intervention strategies.

Does breastfeeding at six months predict cognitive development

There is controversy over whether the method of feeding in infancy affects intellectual development. We investigated the relationship between breastfeeding status at 6 months of age and long‐term cognitive development in a cohort of 375 children born in Port Pirie, South Australia, between 1979 and 1982. Cognitive assessments were conducted at ages 2, 4, 7 and 11 to 13 years. After adjustment for sociodemographic, environmental and biomedical factors, a small, statistically non‐significant, beneficial effect of breastfeeding on cognitive functioning was observed. Compared with the bottle‐fed children, the breast‐fed children had a 3.4 (95% C1 ‐0.1 to 6.9), 1.3 (‐2.3 to 4.9), 1.2 (‐2.0 to 4.4) and 0.8 (‐1.9 to 3.5) point advantage on the Bayley Mental Developmental Index at age 2 years, the McCarthy General Cognitive Index at age 4 years and the Wechsler Full‐Scale IQ at ages 7 and 11 to 13 years, respectively. Our data suggest that any beneficial effect of breastfeeding on cognitive development is quite small in magnitude.

Lead in the placenta, membranes, and umbilical cord in relation to pregnancy outcome in a lead-smelter community

As part of a cohort study of the effects of chronic exposure to lead on pregnancy outcome and child development, lead concentrations in the umbilical cord and placental tissues (body and membranes) from 9 late fetal deaths, 23 preterm births, and 18 births associated with premature rupture of the amniotic membranes were compared with the lead concentrations in the tissues obtained at 22 normal births. Modest elevations in lead concentration were found in the placental body of late fetal deaths (stillbirths) and preterm births as well as in the cord tissue associated with preterm births and premature rupture of membranes. The geometric mean lead concentration in the membranes from late fetal deaths was 2.73 micrograms/g of dry tissue (95% confidence limits 0.69-10.8), which was 3.5 times higher than the mean found in normal births (0.78 micrograms/g, 95% confidence limits 0.61-1.00). The concentration in the membranes of preterm births was also significantly high, being 1.24 micrograms/G (0.91-1.67). Low correlations of membrane and antenatal blood lead concentrations suggest that other factors in addition to exposure to environmental lead may influence the amount of lead accumulated in the placental membranes.

The effects of early paternal depression on children's development

Objective: To examine the effects of paternal depression during childrens first year on their wellbeing at 4–5 years of age using a large, representative sample of Australian families.

Exposure to environmental lead and visual-motor integration at age 7 years: the Port Pirie Cohort Study.

Early childhood exposure to environmental lead may result in subtle deficits in neuropsychological development. Most studies, however, have reported global measures of development, and the findings have not been consistent. In this report, we examine the association between blood lead concentration and a specific aspect of neuropsychological development, visual-motor integration. Each child in a cohort of 494 children living in and around the lead smelting town of Port Pirie, South Australia, was followed for its first 7 years of life. Serial blood samples were collected at various ages to estimate the lifetime burden of each individual. At the time of each blood sampling, systematic information was obtained on a wide range of other variables relevant to child development. We evaluated visual-motor integration at age 7 with the Beery Developmental Test of Visual-Motor Integration (mean score: 13.4). There was an inverse relation between blood lead concentration and visual-motor performance. After adjustment for potential confounding factors, both prenatal and postnatal blood lead concentrations exhibited a dose-related inverse association with childrens visual-motor performance. For an increase in lifetime average blood lead concentration from 10 μag per dl (0.48 μmol per liter) to 30 μg per dl (1.45 μmol per liter), the estimated deficit in childrens visual-motor performance was 1.6 points (95% confidence interval = 0.3–2.9). The results indicate that visual-motor integration may be a more sensitive index than global measures of development, such as intelligence quotient, for the assessment of lead effects on child development.