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Biomedical subjects

W J Rogan

Publications and source records attributed to W J Rogan.

At least 55 records · Page 3Linked to original sources
PubMed1985

Study of human lactation for effects of environmental contaminants: the North Carolina Breast Milk and Formula Project and some other ideas.

The presence of environmental contaminant chemicals in human milk, their demonstrated toxicity, and the lack of data in human beings led to the North Carolina Breast Milk and Formula project, a three-center prospective birth cohort study of 856 children. In this study, we measure polychlorinated biphenyls (PCBs) and DDE in milk and other fluids, follow the course of lactation, and note growth, morbidity and development in the children. Lactation is hormonally complicated and has parts that are plausibly interfered with by contaminant chemicals, and certain kinds of morbidity that occur in breastfed children might also represent the result of chemical contamination of milk. Preliminary data analysis confirms the widespread presence of chemicals in milk; women with higher DDE levels do not breast-feed as long, but this is not true for women with higher PCBs. Besides this study, several case-control or survey-type studies, such as studies of failure to thrive, certain rashes, or short-term breast-feeding would be helpful. Laboratory studies of enzyme induction are now feasible in children and might be a very sensitive if not totally specific endpoint for study of PCBs in milk.

Breast Feeding↗
PubMed1985

Potential reproductive and postnatal morbidity from exposure to polychlorinated biphenyls: epidemiologic considerations.

There is both laboratory and epidemiologic evidence that PCBs are toxic to several phases of reproduction. Workplace exposure is an important but small part of the exposure to these compounds, since most of the population has detectable levels in blood or fat. Studies in the general population on PCBs and reproduction have not been done. Some studies in workers are under way, and in epidemic PCB poisonings, small babies with a distinct clinical syndrome are seen. We review some of the laboratory and epidemiologic data and the methods available for study of reproduction in humans; study of any highly exposed group should be done and studies of spontaneous abortion, birth weight and certain congenital anomalies should look for an effect of PCBs.

Abnormalities, Drug-Induced↗
PubMed1983

Chromatographic evidence of polychlorinated biphenyl exposure from a spill.

Women who were part of a study in which polychlorinated biphenyls (PCBs) were measured in breast milk were exposed accidentally to a PCB spill. While the overall level of PCBs found in their milk was not different from background levels, the chromatograms showed unusual peaks that indicate the presence of heavily chlorinated PCBs of the kind that were spilled.

Aroclors↗
PubMed1979

Misclassification and the design of environmental studies.

Many authors have documented the existence of effects due to misclassification. This paper examines the size of these effects in the context of environmental studies. Misclassification occurs because of the use of surrogate measures of exposure. Misclassification causes relative risks to appear smaller than they are, with larger relative risks being seriously affected. The power of statistical tests is reduced, but not as seriously.

Adipose Tissue↗
PubMed1979

Some fundamental aspects of epidemiology: a guide for laboratory scientists.

Epidemiologic methods used to study human diseases are often unfamiliar to the laboratory scientist. This paper outlines the standard method by which epidemiologic studies are classified, explains the methodologic strengths and weaknesses of different kinds of studies, and notes the kinds of inferences that can be drawn from each. Surveys on populations are treated first, followed by sample surveys. Prospective (follow-up) studies, in which groups of subjects are followed in time, are a basic epidemiologic method. Alternatives to these studies that do not require similar time commitments but may allow similar inferences are record studies. Retrospective, or case-control studies, are often the only feasible method for studying rare diseases. However, diseases with long latency periods and problems in control selection can make these studies difficult to analyze and interpret.

Disease Outbreaks↗
PubMed1978

Estimating prevalence from the results of a screening test.

This paper deals with some basis properties of screening tests. Such tests purport to separate people with disease from people without. Minimal criteria for such a process to be a test are discussed. Various ways of judging the goodness of a test are examined. A common use of tests is to estimate prevalence of disease; frequency of positive tests is shown to be a bad estimate, and the necessary adjustmants are given.

Epidemiologic Methods↗
PubMedDate not supplied

Polychlorinated biphenyls and the developing nervous system: cross-species comparisons.

Polychlorinated biphenyls are stable, lipophilic industrial compounds that are present in residue levels in human tissue, wildlife, and freshwater sediment. They are toxic, and are known to cross the placenta and intoxicate the fetus. Two large outbreaks of PCB poisoning have occurred in Asia; women pregnant at or after the exposures had children who were developmentally impaired. Laboratory experiments in rhesus monkeys and rodents, designed to assess neural or developmental effects, show altered activity levels, impaired learning, and delayed ontogeny of reflexes. Children exposed transplacentally to levels considered to be background in the U.S. have hypotonia and hyporeflexia at birth, delay in psychomotor development at 6 and 12 months, and poorer visual recognition memory at 7 months. Allowing for differences in testing, effects are roughly similar across species, but current methods used to calculate allowable or reference doses give results up to 4 orders of magnitude apart, with the lowest level based on the neurotoxicology level coming from the human data.

Animals↗
PubMedDate not supplied

In utero PCB/PCDF exposure: relation of developmental delay to dysmorphology and dose.

In 1979, there was an outbreak of food poisoning in central Taiwan due to cooking oil contaminated with polychlorinated biphenyls and their thermal degradation products. Starting in 1985, we studied 128 children born to exposed women after the oil was removed from the market; the exposure of these children was transplacental or through breast milk. We also studied matched controls. The exposed children exhibited developmental delays as measured by parental report, by neurologic examination, and by standard cognitive tests; delay was seen at all ages and persisted over time. Delay was greater in children who were smaller in size and in children who had exhibited neonatal symptoms of intoxication. Children with a history of nail deformity also were delayed. However, there was little relationship between other physical findings or measures of maternal exposure and developmental delay. There was some indication that the child's prenatal exposure was more important to developmental delay than was exposure through breast milk.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Aflatoxin and Reye's syndrome: a study of livers from deceased cases.

In order to reinvestigate a strong reported association, we attempted to identify aflatoxin in the livers of 12 children who presumably died of Reye's Syndrome and in the liver of one child who died accidentally. Aflatoxins were detected, but not confirmed in only one of the liver specimens (limits of detection 20 ppt). In addition, the microscopic appearance of the livers was reviewed. Although most of the cases fit the clinical definition of Reye's Syndrome, the microscopic appearance of the liver was varied. We conclude that aflatoxin is not regularly recoverable from cases of Reye's Syndrome at a high rate, and question the proposed etiologic relationship. We confirm the varied appearance of the liver late in the course of Reye's Syndrome; however, microvesicular fat was present in most cases.

Aflatoxins↗
PubMedDate not supplied

Urinary porphyrins in children exposed transplacentally to polyhalogenated aromatics in Taiwan.

In 1979, there was a large (greater than 2,000 cases) outbreak of poisoning due to contaminated rice oil in central Taiwan. The causal agent was a mixture of thermally degraded polychlorinated biphenyls (PCBs), polychlorinated quaterphenyls, and polychlorinated dibenzofurans, which had become mixed with the oil during processing. Patients remained symptomatic for several years afterward, and the chemicals persisted in their tissue. Women who became pregnant had children with high perinatal mortality and a dysmorphic syndrome. We examined urines from 75 children born to exposed mothers after the oil was confiscated, 74 controls, and 12 sibs of the exposed children. Four of the transplacentally exposed children, 2 controls, and 1 sib had a type B hepatic porphyria (i.e., uroporphyrin greater than coproporphyrin); total porphyrin excretion was elevated in the exposed children as a group (95 vs. 81 micrograms/L); and 8 of the 75 exposed children and 2 controls had total urinary porphyrin concentrations of greater than 200 micrograms/L.

Albuminuria↗
PubMedDate not supplied

Breastfeeding in the workplace.

There is potential for damage to lactation or to the nursling from a variety of agents that might be encountered in the workplace.

Breast Feeding↗