Lead levels

A technique is any chemical or physical principle that can be used to study an analyte. Many techniques have been used to determine lead levels. For example, in graphite furnace atomic absorption spectroscopy lead is atomized, and the ability of the free atoms to absorb light is measured thus, both a chemical principle (atomization) and a physical principle (absorption of light) are used in this technique. Chapters 8-13 of this text cover techniques commonly used to analyze samples. 

Finally, analytical methods can be compared in terms of their need for equipment, the time required to complete an analysis, and the cost per sample. Methods relying on instrumentation are equipment-intensive and may require significant operator training. For example, the graphite furnace atomic absorption spectroscopic method for determining lead levels in water requires a significant capital investment in the instrument and an experienced operator to obtain reliable results. Other methods, such as titrimetry, require only simple equipment and reagents and can be learned quickly. 

Preventive Measures. The intake uptake biokinetic model (lUBK) projects the impact of lead in the environment on blood lead. This model assumes conservatively high levels of intake and cannot account for chemical speciation, thus over-predictions of blood lead levels often occur. Nonetheless, because of the allegations of the impact of blood lead and neurobehavioral development, blood lead levels in children are being reduced adrninistratively to below 10 //g/dL. In order to do so, soil leads are being reduced to a level of between 500—1000 ppm where remediation is required. 

The different forms of lead have different bioavailabiUty and this ultimately impacts cleanup levels. Mine tailings, slag, and other such residues have limited impact on blood lead levels because these materials contain lead in the form of lead sulfide, which has limited biological reactivity and uptake. 

In addition to limits on airborne lead, an OSHA regulation provides for biological monitoring and places limits on blood lead levels in workers of... 

Reviews on the occurrence, biochemical basis, and treatment of lead toxicity in children (11) and workers (3,12,13) have been pubhshed. Approximately 17% of all preschool children in the United States have blood lead levels >10 //g/dL. In inner city, low income minority children the prevalence of blood lead levels >10 //g/dL is 68%. It has been estimated that over two million American workers are at risk of exposure to lead as a result of their work. PubHc health surveillance data document that each year thousands of American workers occupationally exposed to lead develop signs and symptoms indicative of... 

Lead-induced anemia results from impairment of heme biosynthesis and acceleration of red blood cell destmction (10,13). Lead-induced inhibition of heme biosynthesis is caused by inhibition of S-aminolevulinic acid dehydratase and ferrochelatase which starts to occur at blood lead levels of 10 to 20 pu gjdL and 25 to 30 //g/dL, respectively (10,13). Anemia, however, is not manifested until higher levels are reached. 

Human toxicity, aquatic toxicity, and the environmental impact of engine coolants and deicing fluids ate typically measured on the fresh fluid only. Spent fluids contain varied contaminants that can drastically affect the toxicity and environmental impact of the fluid. Most pronounced is the impact of heavy-metal contaminants in spent antifreeze. Data on spent and recycled antifreeze, compiled by the ASTM Committee on Engine Coolants, show an average lead level 11 ppm, as weU as various other metal contaminants (iron, copper, zinc) (18). The presence of these contaminants in a used fluid may require special disposal techniques for the fluids. 

Lead is a poisonous metal that especially affects children because they retain a larger fraction of lead than adults da Lead levels of0.250 ppm in a child cause delayed cognitive development How many moles of lead present in 1.00 g of a child s blood would 0.250 ppm represent ... 

Lead Levels in Blood of Children Around Smelter Sites in Dallas... 

Table I indicates the sample size and population estimates of preschoolers by study area and stratum. Though all strata for the Dixie site are shown, at the Dixie site the configuration and location of the major traffic artery in relation to the smelter site did not allow analysis of the contribution of vehicular traffic to soil lead. The contribution of the smelter to soil lead levels was possible at the RSR site and the reference site.

Dust Lead. Table III, IV, and V show the levels of lead in household dust inside the households in this study. These lead levels were markedly below what is normally found in household dust. Because the levels are inexplicably low, the resulting lead levels in the dust are not considered in the analysis. 

Table III. Distribution of Mean Dust Lead Levels by Study Area...

Table X shows the percent of preschoolers having various blood-lead levels at the three sites.

Table X. Percentage Distribution of Blood-Lead Levels In Preschool Children...

Table XII shows the population estimate, sample size by stratum, and mean blood lead levels among black children In the reference area of 13.2 and 14.6 pg/dl In the low and high traffic density areas, respectively.

There are no children In the reference area who had lead toxicity or whose blood lead level exceeded 29 pg/dl (Table XIII). The term "lead toxicity" Is defined here as a child with a blood-lead level > 30 pg/dl and an EP pg/dl. The term "lead toxicity" Is not used In a toxicological sense. 

Table XVI shows that 17 percent of the black children living near the RSR site, were found to have a blood-lead level > 30 pg/dl In the high traffic density area and 8.3 percent In the low traffic density area. Only 1.6 percent of black children living beyond the 0.5 mile...

Table XII. Mean Blood Lead Levels by Race in Reference Area ...

Traffic Population Size Sample Size Lead Level ( g/dl) ... 

Table XVI. Distribution of Lead Levels In Blood by Race and Distance from RSR Site...

The mean blood lead level of black children at the Dixie site was found to be only slightly higher (15.8 g/dl) for those living within 0.5 mile of the smelter as compared to those living within 0.5 - 1 mile (14.9 g/dl). The three non-black children whose blood-lead levels were 30 g/dl were siblings in a family where a parent worked at Dixie Metals (Tables XVIII and XIX). 

Table XVIII. Mean Blood-Lead Level by Race, Traffic, and Distance from Dixie Site...

---