Persistence of lead

There are several additional issues concerning lead markets that shall be discussed in this section. It is obvious that not only the term but also the reasoning of lead markets is related to Eric von Hippel s lead user theory. In this section I will discuss the important differences between lead users and lead markets. Second, I will address the relationship between pioneer advantages and lead markets. Thiid, there is the question of the persistence of lead markets. Does the lead market role shift from country to country over time and why Hitherto I have discussed lead markets as countries. One could ask, whether regions within countries or transnational regions can be lead markets as well. 

Lead-induced neurobehavioural deficit has been found to be persistent in several animal species, if exposure occurs during the early stages of brain maturation (Winneke, 1986 Lilienthal et al, 1986). Little evidence exists, however, to show that this holds true for children as well. Follow-up studies provide a means to test this possibility. Few such studies have been performed so far Otto and co-workers, using event-related brain potentials as the endpoint, found some persistence of lead-related alteration upon re-testing of the same children after 2 years (Otto et al, 1982) but not after 5 years (Otto et al (1985). Likewise Schroeder et al (1985) were unable to replicate exposure-related IQ deficit in a 5-year follow-up study. In both studies blood lead (PbB) values had declined during the test-retest interval from markedly... 

The present study represents another effort to test the hypothesis of the persistence of lead-related neurobehavioural deficit by retesting a group of children after an interval of 3 years, using a broad spectrum of neuropsychological and neurophysiological end-point measures. The results of the initial testing at age 6 have been published elsewhere (Winneke et al, 1985 Ewert et al, 1986). 

The practical importance of the higher sulfanes relates to their formation in sour-gas wells from sulfur and hydrogen sulfide under pressure and their subsequent decomposition which causes well plugging (134). The formation of high sulfanes in the recovery of sulfur by the Claus process also may lead to persistance of traces of hydrogen sulfide in the sulfur thus produced (100). Quantitative deteanination of H2S and H2S in Claus process sulfur requires the use of a catalyst, eg, PbS, to accelerate the breakdown of H2S (135). 

Resource pessimists counter that this process cannot proceed forever because the eternal persistence of demand for any given commodity that is destroyed by use must inevitably lead to its depletion. I lowever, the eternal persistence assumption is not necessarily correct. The life of a solar system apparently is long but finite. Energy sources such as nuclear fusion and solar energy in time could replace more limited resources such as oil and natural gas. Already, oil, gas, nuclear power, and coal from better sources have displaced traditional sources of coal in, for example, Britain, Germany, Japan, and France. 

Perchlorotriphenyl methyl radicals are particularly persistent . Among the factors contributing to the exceptional persistency of this kind of radicals the steric shielding of the a-(tricovalent) carbon is predominant. Only hydrogen or electron can reach the carbon radical. Thus, when perchloro radicals are formed in a DMSO-alkaline hydroxide solution an electron transfer occurs, leading to the perchlorocarbanions. It is assumed that the donor is the DMSO carbanion. 

Personality disorders are inflexible and maladaptive patterns of behavior that deviate markedly from expectations of society. These patterns are stable over time, pervasive and rigid, and lead to distress or impairment in the individual s life. Onset is in adolescence or early adulthood.1 Personality disorders and bipolar disorder may be comorbid, and patients with personality disorders may have mood symptoms. The two diagnoses are distinguished, however, by the predominance of mood symptoms and the episodic course of bipolar disorder, in contrast to the stability and persistence of the behavioral patterns of personality disorders. 

Landrigan PJ Mount Sinai School of Medicine of CUNY, New York, NY Lead and organochlorines in New York City study the current urban sources, environmental distribution and toxic effects on human health of lead and persistent chlorinated hydrocarbons—in particular PCBs and DDT National Institute of Environmental Health Sciences... 

Bushnell PJ, Bowman RE. 1979b. Persistence of impaired reversal learning in young monkeys exposed to low levels of dietary lead. J Toxicol Environ Health 5 1015-1023. 

Plants readily accumulate lead from soils of low pH or low organic content however, uptake is significantly reduced after the application of lime or phosphate, which converts lead to hydroxides, carbonates, or phosphates of relatively low solubility (Demayo et al. 1982). Lead persists for lengthy periods in forest litter the estimated Tb 1/2 is 220 years (Turner et al. 1985). High levels of lead persisted for at least 6 years in litter, soil, amphibians, and mammals after zinc smelting was discontinued in Palmerton, Pennsylvania (Storm et al. 1994). Lead seems to be tightly bound by... 

Laidlaw, M.A. Filippelli, G.M. 2008. Resuspension of urban soils as a persistent source of lead poisoning in children A review and new directions. Applied Geochemistry. 2008, 23, 2021-2039. 

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