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Biomedical subjects

P A Baghurst

Publications and source records attributed to P A Baghurst.

At least 55 records · Page 3Linked to original sources
PubMed1988

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 children's 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 children's mental development (as evaluated with use of the McCarthy Scales of Children's 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 children's 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.

Australia↗
PubMed1988

Blood pressure in schoolchildren measured under standardized conditions.

The blood pressures of 6346 children who were between the ages of seven and 17 years were measured under standardized conditions. Blood pressures were similar in prepubertal boys and girls. After puberty, the systolic blood pressures of the girls remained unchanged whereas those of the boys continued to rise. The difference between the fourth and fifth Korotkoff sounds was 2 mm at both the 50th and 95th percentiles. The systolic blood pressure was observed to fall over a 10-min period by 4-9 mmHg at the 50th percentile and 9-15 mmHg at the 95th percentile. Over the same period of time, the diastolic blood pressure was seen to fall by 2-3 mmHg and 3-6 mmHg at the 50th and 95th percentiles, respectively. There was no further fall in blood pressure after 10 min. The conditions and timing of measurement are important in blood-pressure evaluation and may explain the differences in blood pressure that have been reported for different populations.

Adolescent↗
PubMed1988

A population-based case-control study of diet and breast cancer in Australia.

The relation between diet and breast cancer was examined in a population-based case-control study conducted in Adelaide, South Australia, involving 451 case-control pairs aged 20-74 years. Cases were identified through the state cancer registry between April 1982 and July 1984; for each case, one age-matched control was selected from the electoral register. Dietary intake was measured by self-administered quantitative food frequency questionnaires. There was little variation in risk across levels of daily intake of energy, protein, and total fat; for energy, the relative risk of breast cancer at the uppermost fifth of intake, relative to a risk of unity for the lowest fifth, was 1.22 (95% confidence interval (CI) 0.80-1.86); for protein, the corresponding relative risk was 1.09 (95% CI 0.72-1.64), and for total fat, the relative risk was 0.90 (95% CI 0.59-1.38). Variation in risk in association with sugar and starch intake was also insubstantial, while for fiber, there was a nonuniform reduction in risk at the three uppermost fifths of intake. Risk varied little with level of retinol intake, but it decreased with increasing intake of beta-carotene, a trend that was statistically significant; the relative risk of breast cancer at the uppermost fifth of beta-carotene intake was 0.76 (95% CI 0.50-1.18). Multivariate adjustment for the effects of potentially confounding variables did not alter these patterns. The study does not support a role for dietary fat in the etiology of breast cancer.

Adult↗
PubMed1988

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.

Child Development↗
PubMed1987

Determinants of blood lead concentrations of pregnant women living in Port Pirie and surrounding areas.

In the context of a wider prospective investigation into the effects of cumulative exposure to lead, in utero and postnatally, on the outcome of pregnancy and growth and development in early childhood, 831 pregnant women who were living in Port Pirie, South Australia, the site of Australia's largest lead smelter, were recruited between May 1979 and May 1982, and the various factors that were likely to influence their blood lead concentration were examined. No significant difference in blood lead level was found among different stages of pregnancy. Higher concentrations of blood lead were measured in women who resided in areas of high soil lead content and in women who had resided in Port Pirie for three or more years. A low socioeconomic status, the use of water from the reticulated water supply rather than rainwater, an age of 21 years or less, a high body mass index, a low dietary intake of calcium, and cigarette smoking were all factors that were associated with a higher blood lead concentration. Lower blood lead concentrations were observed in women who took iron and folic acid to supplement their diet. Multiple regression analysis of average antenatal blood lead levels confirmed most of the univariate associations.

Adult↗
PubMed1987

Effect of calcium supplementation on forearm bone mineral content in postmenopausal women: a prospective, sequential controlled trial.

Three hundred ten normal postmenopausal volunteers were invited to enter a controlled trial of the effects of calcium supplementation on forearm mineral content (FMC); 269 entered the study and 210 completed it. Of those who completed the study, 158 were allocated to one of three calcium-supplemented treatment regimes and 52 were allocated to a control group. Twenty-two of the subjects allocated to the treatment group were unable to take supplementary calcium but agreed to remain in the study as additional controls. There were therefore 136 treated subjects, 52 strict controls and 74 controls altogether. During the initial observation period of 9 mo, there was a highly significant loss of bone in all groups (P less than 0.001). During the 9-mo period of treatment, there was a highly significant reduction in the rate of bone loss in the treated subjects (P less than 0.001), a just significant reduction in the strict controls (P less than 0.05) and a nonsignificant reduction in the rate of loss in all controls. The difference between the treated and strict controls in the second period was not significant but the difference between the treated and all controls in the second period was significant (P less than 0.025). When the analysis was applied only to women within 10 yr of menopause, the difference between the treated and strict control groups in period 2 was significant (P less than 0.025) and the difference between the treated and all controls was highly significant (P less than 0.001).

Bone and Bones↗
PubMed1986

The Port Pirie cohort study: maternal blood lead and pregnancy outcome.

During a three-year period, 831 pregnant women in and around Port Pirie, South Australia--a lead smelter community with longstanding lead pollution--were enrolled in a cohort study to examine prospectively the relation between body lead burden and pregnancy outcome. Three-quarters of the enrolled women were residents of the Port Pirie municipality; the other women lived in adjacent towns and countryside. At 14-20 weeks' gestation, the Port Pirie resident women had a mean blood lead concentration of 10.6 micrograms/dl, while the mean in the other (non-Port Pirie) women was 7.6 micrograms/dl. Similar differences were observed in maternal blood samples taken at 30-36 weeks, at delivery, and from the umbilical cord. These blood lead measures, in conjunction with information collected on other risk factors, were then examined in relation to pregnancy outcome. Among 749 pregnancies followed to completion, pre-term delivery was statistically significantly associated, in a dose-response manner, with maternal blood lead concentration at delivery. Mothers of late fetal deaths (stillbirths) had blood lead concentrations at 14-20 weeks' gestation similar to those of all the other women but had lower concentrations at delivery than the other women. Outcomes of pregnancy for which no association with blood lead was detected were spontaneous abortion, low birthweight (for births at term), intrauterine growth retardation, premature rupture of the membranes, and congenital anomalies.

Abortion, Spontaneous↗
PubMed1986

The effect of maternal thyroidectomy prior to conception on foetal brain development in sheep.

Merino ewes were surgically thyroidectomized, and mated 6 weeks later when their plasma thyroxine (T4) levels were negligible. Their foetuses were delivered by hysterotomy at 52, 71, 84, 98, 125, 140 days gestation or at term (150 days). Despite the very low levels of T4 in maternal plasma, the concentrations of T4 in foetal plasma were not significantly different after 71 days gestation from those of foetuses of sham-operated (control) ewes. Foetal brain and body weights, however, were reduced from 71 days compared to those of foetuses of sham-operated ewes. The foetal brain weights but not the body weights were restored to normal from 125 days to term. In addition to the weights, cell number (DNA) and cell size (protein:DNA ratio) appeared to be normal in the neonatal brain at parturition and this was confirmed by histological examination of the brains. Thus lack of maternal thyroid hormones in early pregnancy may cause a reduction in brain and body growth in the foetus which, in the case of the brain, appears to be restored to normal after the onset of foetal thyroid function.

Animals↗
PubMed1985

The Port Pirie cohort study. Blood lead concentrations in early childhood.

A cohort of over 600 children who were born between 1979 and 1982 and accounted for the great majority of all births in Port Pirie, South Australia, and its immediate environs, underwent capillary blood sampling at the ages of 6 months, 15 months, 2 years, and annually thereafter. The mean blood lead concentration (Pb-B) initially rose markedly, peaked at 2 years of age, and subsequently declined gradually at 3 and 4 years of age. No differences in Pb-B were observed between girls and boys. Secular trends in Pb-B at the age of 2 years that were observed in blood samples taken over the 1981-1984 period suggest that both the drought of 1982 and changes in community behaviour may have accounted for some of the age-related variation. The Pb-B was associated positively with surface soil lead concentrations, with a two-fold variation in mean Pb-B between residential zones within Port Pirie. Pb-B was higher in summer than in winter months at the ages of 6 and 15 months, but not at older ages. These findings suggest that lead in dust influences strongly blood lead concentrations in early childhood.

Age Factors↗
PubMed1984

Diet, alcohol, and relative weight in gall stone disease: a case-control study.

A case control study of gall stone disease in relation to diet, alcohol, and relative weight was undertaken. The study population comprised 267 hospital patients with newly diagnosed gall stone disease, 241 individually matched controls selected from the community, and 359 controls who were patients in hospital. Dietary intake was estimated with a quantitative food frequency questionnaire. Multiple logistic regression analysis was used to estimate the net association between individual nutrients and the risk of formation of gall stones. Variations in risk with sex and age were examined in the light of prior evidence of influences of sex hormones and age on hepatobiliary metabolism. In both sexes increased intake of alcohol was associated with a decreased risk of developing gall stones; increased intake of simple sugars in drinks and sweets was associated with an increased risk; and increased intake of energy or fat was associated with an increased risk in young subjects. Obesity was associated with an increased risk only in young women.

Adult↗
PubMed1984

Congenital malformations and maternal drinking water supply in rural South Australia: a case-control study.

A case-control study, carried out in the Mount Gambier region of South Australia, investigated the relationship between mothers' antenatal drinking water source and malformations in offspring. It was prompted by earlier descriptive findings of a statistically significant, and localized, increase in the perinatal mortality rate in Mount Gambier, due principally to congenital malformations affecting the central nervous system and multiple organ systems. Available for statistical analysis were 218 case-control pairs, from the period 1951-1979, individually matched by hospital, maternal age (+/- 2 years), parity and date of birth (+/- 1 month). Compared with women who drank only rainwater during their pregnancy (relative risk (RR) = 1.0), women who consumed principally groundwater had a statistically significant increase in risk of bearing a malformed child (RR = 2.8). Statistically significant risk increases occurred specifically for malformations of the central nervous system and musculoskeletal system. Reanalysis of the data by estimated water nitrate concentration demonstrated a nearly threefold increase in risk for women who drank water containing 5-15 ppm of nitrate, and a fourfold increase in risk for those consuming greater than 15 ppm of nitrate. A seasonal gradient in risk was evident among groundwater consumers, ranging from 0.9 for babies conceived in winter, 3.0 in autumn, to 7.0 and 6.3 for spring and summer conceptions, respectively. Linear logistic regression analysis, controlling for risk factors not accounted for in the study design, showed that maternal water supply, infant's sex, and mother's area of residence all contributed significantly to the risk of malformation. These results are discussed in relation to previous experimental and human descriptive studies, suggesting a plausible mechanism for nitrate-induced teratogenesis.

Abnormalities, Drug-Induced↗
PubMed1984

Australian 10-year-olds' perceptions of food. III. The influence of obesity status.

Two studies were conducted which examined the relationships between 10-year-olds' body fat status and their perceptions of foods. The first study of 453 children showed that obese boys linked high-energy foods more to positive consequences, such as growth and satiation, than did slim boys. They also rated bread and potatoes as more fattening than did slim boys. In the second study, one-quarter randomized samples of 40 foods were presented to 500 children, on each of two forms on which the children rated the foods on eight attributes. Results of multivariate analyses showed that obese, average and slim children perceived foods differently along two general themes: (a) properties related to energy, and (b) tastiness-preference. The results are discussed in relation to possible social and physiological causes.

Child↗
PubMed1983

Maternal alcohol, tobacco and cannabis consumption and the outcome of pregnancy.

In a prospective study of 7,301 births, associations were sought between maternal alcohol, tobacco and cannabis use and several adverse outcomes of pregnancy. Apparent effects of alcohol use on prematurity, intrauterine growth retardation, congenital abnormalities and low Apgar score were consistent with previously reported work, but were not statistically significant. Infants born to smokers had lower birthweights and were more prone to intrauterine growth retardation, but they did not appear to have an increased risk of prematurity or perinatal death. Only 36 women reported using cannabis 2 or more times a week, not merely as smokers of marijuana but also as users of the more potent resin forms of cannabis. Subsequently 25% of these women gave birth to premature infants.

Adolescent↗
PubMed1983

Maternal exposure to environmental chemicals and the aetiology of teratogenesis.

Data on exposure of 10,879 pregnant women to various household and agricultural chemicals were obtained by interview; 6,267 of these women were seen both antenatally and postnatally, enabling a genuine prospective study of the association between chemical exposure and congenital abnormalities in the infant. The remaining 4,612 women were privately booked and were first seen postnatally. Statistical analysis of the 2 groups revealed a strong association of malformations with chemical exposure in both groups, even after other known risk factors were taken into account.

Abnormalities, Drug-Induced↗