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Biomedical subjects

J O Nriagu

Publications and source records attributed to J O Nriagu.

15 recordsLinked to original sources
PubMed2000

Emissions of lead and zinc from candles with metal-core wicks.

We measured the amount of lead released from 14 different brands of candles with metal-core wicks sold in Michigan. The emissions of lead were found to range from 0.5 to 66 microg/h, and the rates for zinc were from 1.2 to 124 microg/h. It is estimated that burning four of the candles bought in Michigan for 2 h can result in airborne lead concentrations that can pose a threat to human health. In addition to inhalation of lead in the air, children get exposed to lead in candle fumes deposited on the floor, furniture and walls through their hand-to-mouth activity. Burning candles with leaded-core wick may be an important exposure route for lead that has generally been ignored.

Air Pollution, Indoor↗
PubMed1998

Saturation of ecosystems with toxic metals in Sudbury basin, Ontario, Canada.

Mining and resource recovery activities have not been kind to ecosystems in the Sudbury basin, Ontario. The combination of logging, smelting, fires and erosion resulted in an unusual anthropogenic ecosystem of denuded barren land with lifeless lakes, or a micro-desert. Since the 1970s, however, the concerted efforts made to reduce the emissions and rehabilitate parts of the degraded ecosystem have resulted in improvements in water quality, and recoveries in phytoplankton, zooplankton, zoobenthos and fish communities but have had little impact on toxic metal concentrations in many lakes. We show that most of the catchments in the Sudbury basin have become saturated with Cu and Ni, and some with Zn and Pb. It is estimated that mobilization of metals stored in soils and glacial overburden by surface runoff, groundwater drainage and wind re-working of tailings can sustain the high concentrations of Cu and Ni in many lakes for well over 1000 years. Strategies to immobilize the pollutant metals in the watershed rather than further emission controls may be required for dealing with high levels of toxic metals in surface waters of the saturated ecosystems.

Copper↗
PubMed1998

Lead poisoning of children in Africa, IV: Exposure to dust lead in primary schools in south-central Durban, South Africa.

Twenty primary schools in three areas (Merebank, Austerville and Bluff) of south-central Durban, South Africa were studied to determine if dust lead loading (microgram/m2) is high enough to constitute a risk to children. Atmospheric lead fallout rates in the schools varied from 9 to 264 micrograms/m2 per day and were higher than the values now being reported in the developed countries. Mean outside dust lead loadings were 425 micrograms/m2 in Merebank, 771 micrograms/m2 in Austerville and 1174 micrograms/m2 in Bluff areas, and 25% of the primary schools were found to have mean outside dust lead loading above 1000 micrograms/m2. Mean dust lead loadings inside classrooms were 2-4 times lower than the outside rates, and showed no significant difference among schools in the three areas. Dust lead loadings were correlated with lead concentrations in dust but not with distance from the highway or with atmospheric lead deposition rates. Exposure to dust lead in classrooms and in the school yard is considered to be an important contributor to blood lead levels in, and hence a potential health hazard to, children in many urban areas of the city.

Africa↗
PubMed1998

Clair Patterson and Robert Kehoe's paradigm of "show me the data" on environmental lead poisoning.

In 1925, Robert A. Kehoe enunciated a paradigm predicated upon categorical distinction between expectations and conjecture ("show me the data" mentality) from hard scientific facts on exposure outcomes. It led to a precedent-setting system of voluntary self-regulation by lead industry as a model for environmental control and implicitly signaled the level of industrial responsibility for lead pollution. It combined a cascading uncertainty rule (there is always uncertainty to be found in a world of imperfect information) with a highly skewed cost-benefit concept (immediate benefits of tetraethyl lead additives must be weighed against possible future health hazards). Many studies were funded by the lead industry to develop a theoretical framework for the paradigm which served as a strong defensive strategy against lead critics. It resulted in an unfettered growth in automotive lead pollution to over 270,000 tons per year in the United States and 350,000 tons per year worldwide during the early 1970s. Clair Patterson is credited with being the first person to mount an effective challenge against the Kehoe paradigm, and with his success came an upsurge of activity and attention to the risks of environmental lead pollution on public health.

Chemical Industry↗
PubMed1996

Childhood lead poisoning in Africa: a growing public health problem.

Gasoline sold in most African countries contain 0.5-0.8 g/l lead. In urban and rural areas and near mining centers, average lead concentrations reach 0.5-3.0 mu g/m3 in the atmosphere and > 1000 mu g/g in dust and soils. In addition to automotive and industrial sources, cottage industries and the burning of paper products, discarded rubber, battery casings and painted woods for cooking and heating represent additional hazards to individual households. Lead paint, lead solder and lead cosmetics are unregulated in some countries. Although African children are particularly predisposed to environmental lead exposure, because of their lifestyle and socioecological factors, a true picture of childhood lead poisoning in the continent remains undefined. Recent prevalence studies show that over 90% of the children in urban and rural communities of the Cape Province, South Africa have blood lead levels > or = 10 mu g/dl. Studies in other countries likewise suggest that childhood lead poisoning is a widespread urban health problem throughout the continent.

Africa↗
PubMed1992

Toxic metal pollution in Africa.

The available information suggests that the concentrations of toxic metals in many ecosystems of Africa are reaching unprecedented levels. Because of the heavy load of contaminated dusts in the air of the overcrowded cities, the ambient concentrations of toxic metals are now among the highest being reported anywhere. Lead pollution from the increasing number of automobiles and cottage industries represents a major health hazard, and it is estimated that 15-30% of the infants in some urban areas may already be suffering from lead poisoning. The cultural and lifestyle determinants of lead exposure and the greater susceptibility of African populations to environmental metal poisoning are highlighted. The suggestion is made that the environmental health criteria for toxic metals in the developed countries may not provide adequate protection for many African communities.

Africa↗
PubMed1988

A silent epidemic of environmental metal poisoning?

The main objective of this paper is to provoke and stimulate debate on the health effects of long-term, low-level exposure of human populations to toxic metals. Over one billion (10(9)) human guinea pigs are now being exposed to elevated levels of toxic metals and metalloids in the environment. The number of persons suffering from subclinical metal poisoning is believed to be several million. A large portion of the cases are in developed countries but the urban areas of developing countries have become 'hot-spots' of metal pollution, and the populations of such countries are particularly susceptible to environmental toxins. As a global problem, the potential health effects of metallic hazards should be a matter of public health concern, especially if the emissions of toxic metals into the environment continue at the current rate.

Journal Article↗
PubMed1987

Response of lake sediments to changes in trace metal emission from the smelters at Sudbury, Ontario.

Historical records preserved in sediments show that the lakes are extremely sensitive to metal emissions from the smelters in the Sudbury basin. From the observed quick response, a strong capacity for rapid recovery (deacidification) of acid-stressed lakes in the area is deduced. The study thus emphasises the need for curtailing the emissions of acidic and acidifying substances as a critical step in reducing lake acidification as well as in rehabilitating many of the afflicted lakes.

Journal Article↗
PubMed1983

Occupational exposure to lead in ancient times.

The uses and regional production of lead in ancient times are summarized. Since there is no evidence to suggest that any deliberate attempts were made to curtail personal exposure to the mine dusts or the emissions from the forges and crucibles, it is surmised that many of the ancient artisans who worked with lead probably contracted plumbism. The number of workers so exposed is estimated to be over 140,000 per year during the Roman Empire. The ancient literary records of work-related plumbism, however, are surprisingly sparse.

Greece, Ancient↗
PubMed1979

Global inventory of natural and anthropogenic emissions of trace metals to the atmosphere.

FEW (if any) recent studies on the atmospheric cycle of trace metals have considered the flux of the metals into the atmosphere on a global scale. Information on worldwide emissions is needed to assess the transboundary movement of pollutant metals and to validate models of the global atmospheric circulation patterns. The worldwide inventories of the natural and anthropogenic sources and emissions of airborne cadmium, copper, lead, nickel and zinc are presented here. The data summarised here are taken from very detailed studies published elsehwere(1-5).

Journal Article↗