Environmental contaminants and children's health: Cause for concern, time for action.

The present paper provides an outline of the developmental and behavioural characteristics that make children, especially the fetus and young child, more vulnerable to contaminants than adults. The major categories of contaminants are briefly described. The evidence for their possible effects on neurobehavioural development; immune, endocrine and respiratory systems; childhood cancer based on research studies with animals; children exposed to catastrophic 'accidents' involving overdose exposures; and pregnant women and children from communities with high 'background' levels of contamination who participated in studies is reviewed. While the data are worrisome, especially for children living in northern and certain urban communities, much remains to be learned about possible subtle effects and the potential for long term effects of the current background contamination experienced by the majority of Canadian children before its significance to their health can be fully evaluated. The present regulatory processes, which are based on risk assessment, are so cumbersome and costly that the great majority of chemicals in use have not been fully evaluated, and the ingenuity of new chemical production continually exceeds the capacity to test the new chemicals. Moreover, despite past insistence on scientific proof of adverse effects and safety, unanticipated effects have occurred that will threaten the sustainability of human life unless more effective control measures are taken to limit the release of toxic substances and persistent chemicals into the environment. Therefore, the shortcomings of risk assessment are discussed, and the precautionary principle, which is used in some countries and is proposed for use internationally as an alternative measure that may offer improved control for the future, is outlined. Finally, opportunities for physician action are suggested.

Children are different: environmental contaminants and children's health.

Although the impact of environmental contaminants on human health has been widely studied, few reports in the Canadian literature have focussed on the specific vulnerability of children. Because of their rapid growth, physiologic and metabolic immaturity, the fetus and child are often at increased risk from toxic substances in their environments. Furthermore, greater air, food and fluid intakes relative to body weight compared with the adult, increase the child's potential for excessive exposures. The crawling stage of infancy, the play patterns and short stature of toddlers also serve to increase their exposure to dust and heavy and volatile substances which accumulate near the floor. This article provides an overview of some of the developmental physiologic, anatomic and behavioural features of the fetus, infant and child which increase their vulnerability to environmental contaminants in comparison with adults. Specific examples are given.

Breast-feeding policies and practices in Canadian hospitals providing maternity care.

OBJECTIVE: To determine the extent to which policies and practices of Canadian hospitals providing maternity care are consistent with the World Health Organization (WHO)/UNICEF 10 Steps to Successful Breastfeeding, the WHO International Code of Marketing of Breast-Milk Substitutes and the WHO/UNICEF Baby Friendly Hospital Initiative. DESIGN: Cross-sectional mailed survey. SETTING: Canada. PARTICIPANTS: Representatives of 572 hospitals providing maternity care across Canada were sent a questionnaire in the spring and summer of 1993, 523 (91.4%) responded. OUTCOME MEASURES: Self-reported implementation of policies and practices concerning infant feeding; hospitals were grouped according to location, size (number of live births per year) and university affiliation status. MAIN RESULTS: Although 58.4% (296/507) of the respondents reported that their hospital had a written policy on breast-feeding, only 4.6% (21/454) reported having one that complied with all of the WHO/UNICEF steps surveyed. This figure dropped to 1.3% (6/453) when compliance with the WHO code (distribution of free samples of formula to formula-feeding and breast-feeding mothers) was added. Hospitals in Quebec and the Prairie provinces were significantly more likely than those in Ontario to give free samples of formula to both breast-feeding (OR 2.39 [95% confidence interval (Cl) 1.39 to 4.09] and 20.22 [95% Cl 9.27 to 44.33] respectively) and formula-feeding mothers (OR 1.82 [95% Cl 1.07 to 3.11] and 8.03 [95% Cl 3.29 to 19.6] respectively), after adjustment for hospital size and university affiliation status. CONCLUSION: There are considerable variations in the implementation of individual WHO steps and provisions of the WHO code according to hospital location, size and university affiliation status. Very few Canadian hospitals meet all of the criteria that would enable them to be considered "baby friendly" according to the WHO/UNICEF definition.

Postnatal changes in serum retinol status in very low birth weight infants.

BACKGROUND: Retinol deficiency may contribute toward the development of chronic lung disease in very low birth weight (VLBW) infants. We examined the retinol status during early infancy in VLBW infants from birth to 6 weeks 'post-term'. METHODS: Concentrations of serum retinol (SR) and its carrier proteins, retinol-binding protein (RBP), and transthyretin (TTR), were determined at birth, then weekly for 8 weeks, and at 4-6 weeks 'post-term' in preterm infants of less than 34 weeks gestation. The SR values of umbilical cord blood at birth from the preterm infants were compared to the maternal SR levels as well as to cord SR levels of term infants. RESULTS: From 24 through 33 weeks gestation, umbilical cord SR at birth was significantly lower than, but did not correlate with, maternal SR (P < 0.01). The cord SR in term infants was also higher than that in preterm infants (262 +/- 68 vs. 183 +/- 67 micrograms/l, P < 0.01). Longitudinal profiles of SR in 18 VLBW infants showed that, despite regular retinol supplementation, there was a decline in SR after birth, reaching a nadir of 128 +/- 40 microgram/l at 5-7 weeks (P < 0.001), followed by an increase toward levels comparable to those seen in full term infants. At follow-up at the corrected age of 4-6 weeks 'post-term', SR levels in VLBW infant (222 +/- 74 micrograms/l) had returned to within the normal range for term cord SR values. The concentrations of RBP also showed a similar biphasic pattern. Transthyretin levels did not change for 8 weeks but increased significantly at 4-6 weeks 'post-term'. CONCLUSIONS: Current practices of retinol supplementation in VLBW infants fail to maintain adequate retinol status in those infants during the neonatal period. Further efforts to improve the retinol status in these infants should be explored.

Factors predictive of follow-up clinic attendance and developmental outcome in a regional cohort of very low birth weight infants.

This population-based, retrospective cohort study of very low birth weight infants was undertaken to: 1) identify factors associated with nonattendance for follow-up, 2) estimate the prevalence of cerebral palsy at age > or = 18 months, and 3) model the prognostic association between prenatal and perinatal risk markers and cerebral palsy. The sample included 496 surviving very low birth weight infants born in 32 hospitals in Southwest Ontario between January 1982 and December 1986. Multivariate analyses were performed using the proportional odds regression model. Loss to follow-up was more likely among those with mothers < 20 years of age, those with unmarried mothers, and those not born in a tertiary center. Loss to follow-up was less likely for those with neonatal anemia and those of lower birth weight. Motor development of the 369 children who were followed at least 18 months was classified into one of three categories: normal, suspect, or cerebral palsy. Multivariate analysis revealed that factors predictive of poorer outcome were intraventricular hemorrhage, unmarried mother, male sex, recurrent apnea, and hydrocephalus. The finding that unmarried status was associated with loss to follow-up and was also an important predictor of cerebral palsy suggests that it is important for follow-up clinics to identify ways of assisting this population to remain in contact with the clinic.

Is perinatal care in southwestern Ontario regionalized?

OBJECTIVE: To determine whether perinatal care in southwestern Ontario is regionalized, to identify trends over time in referral patterns, to quantify trends in perinatal death rates and to identify trends in perinatal death rates that give evidence of regionalization. DESIGN: Cohort study. SETTING: Thirty-two hospitals in southwestern Ontario (1 level III, 1 modified level III and 30 level II or I). PATIENTS: All pregnant women admitted to the hospitals and their infants. MAIN OUTCOME MEASURES: Antenatal and neonatal transfer status, live-born with discharge home alive from hospital of birth, stillborn, and live-born with death before discharge. RESULTS: Between 1982 and 1985 the antenatal transfer rate increased from 2.2% to 2.8% (p less than 0.003). The proportion of births of infants weighing 500 to 1499 g increased from 49% to 69% at the level III hospital. The neonatal transfer rate increased from 26.2% to 47.9% (p less than 0.05) for infants in this birth-weight category and decreased from 10.2% to 7.1% (p less than 0.03) for infants weighing 1500 to 2499 g. The death rate among infants of low birth weight was lowest among those born at the level III centre and decreased at all centres between 1982 and 1985. CONCLUSIONS: Perinatal care in southwestern Ontario is regionalized and not centralized; regionalization in southwestern Ontario increased between 1982 and 1985.

Amikacin pharmacokinetics and suggested dosage modifications for the preterm infant.

The pharmacokinetics of amikacin administered intravenously at currently recommended doses (7.5 mg/kg every 12 h for infants with less than 7 days of life; 7.5 mg/kg every 8 h for infants with greater than 7 days of life) were studied in 28 preterm infants weighing less than 2,500 g (mean +/- standard deviation, 1.38 +/- 0.47 kg; postconceptional age, 30.50 +/- 2.86 weeks). The medication was infused over 45 min. Trough and peak serum samples as well as two additional samples were taken at steady state. The results showed a statistically significant inverse relationship between half-life (8.42 +/- 2.55 h) and postconceptional age (P = 0.002) and a direct correlation between total body clearance (0.84 +/- 0.28 ml/min per kg) and postconceptional age (P = 0.02). These pharmacokinetic data were used to calculate a new dosage schedule for preterm infants. The derived intravenous dosage of amikacin for infants of less than 30 weeks of postconceptional age was 9 mg/kg every 18 h. For infants of greater than 30 weeks of postconceptional age, the dosage was 9 mg/kg every 12 h. Peak and trough levels of amikacin in serum that fell within the therapeutic range were compared by using the currently recommended dosage schedule and the dosage schedule derived from our pharmacokinetic data. There was a reduction in the number of peak and trough levels that fell outside the accepted therapeutic range which was not statistically significant. Extension of the dosing interval and a further increase in the dosage may result in further improvement. Based on these data, the current recommendations are inadequate for the preterm infant. Our derived dosage schedule improved but did not eliminate high trough and low peak levels of amikacin in all infants. The current recommendations should be adjusted for the preterm infant. Ongoing therapeutic drug monitoring is essential to tailor the amikacin dosage to the individual patient.

Placental weight in diabetic pregnancies.

The placenta from 30 women with diabetes mellitus were examined and weighed at delivery. Nineteen of these were from women with overt and eleven from women with gestational diabetes. Eleven placentae from normal pregnancies served as controls. There was no difference between the mean +/- s.d. placental weight for the diabetic group and the control group (609 +/- 148 versus 591 +/- 93 g, NS). The mean placental weight ratios for the diabetic group and the control group were also similar (0.98 +/- 0.23 versus 0.89 +/- 0.15, NS). Moreover, there was no difference between the weights and weight ratios of placentae from women with overt (622 +/- 173 g, 1.02 +/- 0.27) and those with gestational diabetes (586 +/- 90 g, versus 0.90 +/- 0.13). Placental weights correlated with birthweights (r = 0.70, P less than 0.01) and with skinfold thickness measurements fo the infants (r = 0.40, P less than 0.05), but neither with gestational ages (r = 0.15, NS) nor with maternal glycosylated haemoglobin levels in the third trimester (r = 0.24, NS). Among the women with overt diabetes, placental weights were greater in those in White's class B and C than those in class D and R (689 +/- 143 versus 530 +/- 177 g; P less than 0.05). In general, placentae from well controlled diabetic patients were not heavier than those from normal pregnant women, although there was an increase in placental weight in White's class B and C, as compared with those in class D and R.

Neonatal intensive care and cost effectiveness.

During the past decade the rate of death among newborns weighing less than 1500 g at birth has decreased by approximately half. This dramatic reduction has resulted from the application of research findings and technologic advances, but it has proved expensive. Perhaps as a consequence of articles demonstrating the costs as well as the recognition that the overall prevalence of disabilities in infants is relatively unchanged, neonatal intensive care has recently been viewed as a possible area for cost containment. We reviewed the literature on the cost of neonatal intensive care and the limited information on other expensive medical programs and found that the cost of neonatal intensive care compared favourably, especially for infants whose birth weight was 1000 to 1500 g. Better information on the outcome of infants of very low birth weight and comparable rigorous studies of the cost effectiveness of other expensive medical programs are required, and other less easily quantified factors must be considered before decisions are made to limit neonatal intensive care on the basis of gestational age or birth weight.

Predictors of one-year developmental status in low birth weight infants.

The purpose of the present study was to describe the relations among various perinatal, environmental, and demographic measures in a sample of low birth weight infants and to relate those measures to 1-year developmental status. Perinatal variables included birth weight, gestational age, Apgar scores, and summary measures of respiratory distress and morbidity. Home visits provided ratings of the infants' environment at 7 and 12 months corrected age. The Bayley Scales of Infant Development were given at the 12-month home visit. A principal components factor analysis revealed four factors. The first factor was labeled an immaturity-illness factor, since it was primarily composed of gestational age, birth weight, and the respiratory distress and morbidity summary scores. Ratings of the infant's home environment loaded on the second factor, the demographic variables on the third factor, and the 1- and 5-minute Apgar scores comprised the fourth factor. The four factor scores together with the number of delays on the Denver Developmental Screening Test, given at 7 months corrected age, were entered as independent variables in four multiple regression analyses with the corrected and uncorrected mental development index index (MDI) and psychomotor development index (PDI) Bayley scores as the dependent variables. These regression analyses indicated that 1-year developmental status is a reflection of the infant's immaturity and neonatal morbidity, the quality of his or her home environment, and freedom from sensorimotor delays.

Neonatal resuscitation in Canadian hospitals.

A survey of Canadian hospitals providing obstetric care was undertaken to assess preparation, protocols, training and staff availability for neonatal resuscitation. Of the 721 hospitals contacted 577 (80%) responded. The reported availability of written guidelines for resuscitation varied greatly, depending on hospital size and proximity to a tertiary care centre. Many hospitals, especially those with 300 births or fewer annually, reported that they depend on family physicians or nurses to start and to continue neonatal resuscitation. Approximately one third of the hospitals had written guidelines for summoning personnel for additional help, and one third used a list of maternal or fetal indications for the presence of a physician specifically for the care of the infant at birth. Of 200 hospitals 138 (69%) had to summon additional medical help from outside the institution, 60% at all times. A neonatal resuscitation team in which members' roles were defined was established in 22% of the hospitals. Few hospitals held rehearsals for resuscitation. Nurses were permitted to perform intubation in 21 hospitals (4%), 7 of them in Alberta. National professional bodies should develop guidelines for training and skill maintenance, and hospitals should develop protocols for maintaining equipment and for neonatal resuscitation team activities, including regular practice. Training should be improved in family practice and obstetrics programs, and consideration should be given to training senior obstetric nurses and respiratory therapists in intubation of neonates.

Randomized controlled trial of very early continuous distending pressure in the management of preterm infants.

Application of continuous distending pressure at birth (very early CDP) should stabilize the immature airways and reduce the severity of respiratory distress syndrome (RDS) in preterm infants. Eighty-two preterm infants of less than 32 weeks gestation were randomly assigned at birth to early treatment group (TG), in which CDP of 6 cm water pressure was applied at birth by the nasopharyngeal route (NP-CDP), or to control group (CG), in which CDP was applied when indicated for established criteria (pO2 less than 50 mmHg in FiO2 greater than 0.5). Characteristics of the infants in the two groups were comparable. No statistically significant difference between the two groups was found in the incidence of RDS. The course of RDS, and oxygen and ventilatory requirements also did not appear to be changed. In blood gas parameters of most of the time frames, no significant difference was found between the two groups when the results were analyzed according to the assigned group. When the results were analyzed separately for the infants who developed RDS, infants in TG appear to have fared worse from the therapy in terms of oxygenation, as indicated by significantly higher FiO2 (P less than 0.01) and lower a/A (P less than 0.01) values on the third day of the course of RDS, as compared to infants in CG. The incidence of complications was comparable in the two groups. Four infants from TG (9.3%) and one from CG (2.6%) died (P = NS). We conclude that VECDP by nasopharyngeal route does not reduce the incidence of RDS and does not appear to improve the outcome and may worsen the severity of RDS when compared to application of CDP for established criteria.