Warning: Childhood Can Be Hazardous to Your Health
Whether because of media attention, political postulating, or personal experience, most people are at least somewhat aware of the many environmental threats to their health. What they may be less aware of, however, is the particular harm these threats may pose to their children. The first Focus article examines the physiological, developmental, and behavioral differences of children that make them especially sensitive to environmental insults from substances such as lead, air pollution, pesticides, and radiation.
Planetary Prescription
Environmental medicine has long been viewed by many as a sort of stepchild of traditional medicine. With greater awareness of the very real environmental health hazards communities and individuals face in modern society, however, new regard is being given to environmental and occupational medicine as necessary components of medical care, and new emphasis is being given to training tomorrow's doctors to heal environmental harm.
Dye in the Soup
Innovations explores an exciting alternative to malathion for killing fruitflies. Baits laced with phototoxic dyes that become lethal when they interact with sunlight in a fly's transparent gut may provide a safer solution than spraying to a problem that plagues the world's fruit growers.
Urban Pollution Causes DNA Breaks in Human Nasal Cells
DNA damage assessed by single-strand breaks in nasal epithelial cells was compared between residents in Mexico City with highlevels of ozone pollution and residents of a relatively unpolluted coastal area. Calderón-Garcidueñas et al. report that the adults and children living in the city had significantly greater numbers of DNA-damaged cells than those living in the coastal area. Individuals newly arrived to Mexico City experienced a doubling in the rate of single- strand DNA breaks after 1 week in the city. In spite of further continuous exposure, the toxic response remained stable, suggesting that a threshold for DNA damage had been reached. DNA strand break analyses in nasal epithelial cells could serve as a sensitive biomarker for air pollution and would be a useful adjunct to studies of ozone toxicity.
Ozone Toxicity at Summer Camp
Analyses of data reported in three earlier studies from six summer camps were reevaluated to assess the potential effects of ozone on lung function in children. Kinney et al. used an analytical model to examine the relationship between lung function and ozone for each of the six studies and for all the studies combined. Negative lung function in the children was significantly associated with increased ozone concentrations for five out of six studies, with an average loss of 0.5 ml forced expiratory volume per ppb ozone, a magnitude of response that is readily demonstrable in controlled laboratory studies.
Stable Isotope Dilution Model for Human Lead Bioavailability
Graziano et al. used a highly sensitive method of lead analysis to determine the bioavailability of lead leached from lead-crystal storage decanters. The analytical assay relies upon a measurable rate of decay of the four stable isotopes of lead. Ingestion of 100 ml of decanter-stored sherry containing 14.2
mol/l lead by six adult men and women induced a rise in blood lead from 0.10 to 0.18
mol/l, with an average of 70% absorption of the ingested lead dose. The authors showed that lead from lead-crystal glass is highly bioavailable and demonstrated the utility of the stable isotope dilution method for studying lead bioavailability in other matrices like soil.
Lead and Iron Affect Cognitive Development in Children
Children between 18 and 30 months age were enrolled in an intervention treatment that included EDTA chelation to lower blood lead, home intervention to remove the lead source, and any necessary iron supplementation. Blood lead levels in the children ranged between 25 and 55
g/dl, and 20 of 42 children were iron deficient, with ferritin levels <16 ng/ml. Cognitive functioning was measured at enrollment and 6 months after intervention. Ruff et al. report that a decline in blood lead in iron-sufficient children and improvement in hematologic indices in iron-deficient children were associated with positive changes in cognitive development.
Ecotoxicity in an Argentine River Basin
Herkovits et al. used an amphibian developmental toxicity test with Bufo arenarum, a local species, to evaluate the condition of the Reconquista River, one of the supercritical river basins in Argentina. More than 3 million inhabitants and 12,000 industries are located in the basin. In most of the river extension, amphibian larval toxicity indicated that contamination was higher than the allowable magnitude for whole industrial effluent toxicity recommended by the U.S. EPA. One stream, the Arroyo Moron, exhibited degradation of water quality that was 10 times more toxic than the criteria maximum concentration recommended, a level which resulted in the complete elimination of macroorganisms. The use of local species can provide early and sensitive biomarkers for monitoring and restoration of polluted ecosystems.
Pesticide Toxicity to Human Mammary Cells
A large number of halogenated hydrocarbon pesticides, PCBs, and PBBs were examined by Kang et al. for their ability to interrupt normal cellular communication in an in vitro test using human breast epithelial cells. Toxic inhibition was exhibited by DDT, dieldrin, and toxaphene, as well as by several PCB and PBB congeners. At concentrations where individual chemicals were without effects, toxic inhibition occurred with mixtures of DDT and PCBs, with dieldrin and PCBs, and with dieldrin and PBBs. The data were consistent with current hypotheses that attribute tumor-promoting potential to halogenated hydrocarbon contaminants in human breast tissue.
Dietary Exposure to Metals and Pesticides
MacIntosh et al. estimated the average daily dietary exposures of 120,000 U.S. adults to arsenic, cadmium, lead, mercury, and three common organophosphate and four common organochlorine pesticides. The estimates were calculated by combining data from a food frequency questionnaire with FDA contaminant residue data for table-ready foods. Estimates of dietary contaminant exposure spanned two to three orders of magnitude among individuals, although a substantial fraction of the population was estimated to have dietary intakes of arsenic and dieldrin in excess of health-based standards established by the EPA. Fish, and in particular canned tuna, contributed to arsenic and heavy metal exposure, and wheat-based products and beef contributed to pesticide exposure. Further monitoring with more sensitive study designs is necessary before such data can be used for risk assessment or epidemiologic purposes.
Last Update: May 13, 1997