Blood lead level background

Background measurements, soil samples, 119-20 Blood-lead levels In preschool... 

Vi. Dosage and method of administration for lead poisoning (adults and children). Note Administration of EDTA should never be a substitute for removal from lead exposure. In adults, the federal OSHA lead standard requires removal from occupational lead exposure of any worker with a single blood lead concentration in excess of 60 mcg/dL or an average of three successive values in excess of 50 mog/dL. (However, recent declines in background lead levels and concern over adverse health effects of lower-level exposure support removal at even lower levels). Prophylactic chelation, defined as the routine use of chelation to prevent elevated blood lead concentrations or to lower blood lead levels below the standard In asymptomatic workers, is not permitted. Consult the local or state health department or OSHA (see Table IV-3, p 525) for more detailed information. 

In the analysis of two studies, for 40%-45% of confirmed cases of elevated blood lead levels in children, a possible source of lead paint hazard could not be located [73]. However, that should not weaken the role of lead-based paint as a major source of lead for children. The background contribution of lead from other sources is still not known even for children whose potential lead-paint hazard has been identified, making a discrimination of the lead proportion from either source impossible. 

Another important issue relates to the reliability of the test. That is, how reproducible or consistent are the test results across multiple administrations Inadequate reliability almost guarantees that a subtle toxicant effect will not be detected against a background of scores of broad individual variability that will be present in any normal population. An issue that has not received adequate attention is the sensitivity of these tests to detect toxicant effects, a factor that is of particular importance if the test results are used in the context of setting exposure standards. If a particular test indicates effects of lead, for example, at a blood lead concentration of 40 pg dl one may wonder whether this represents the bottom limits of sensitivity of the test or the actual blood lead value at which such effects occur. In other words, could the test have detected effects at even lower levels of exposure if it had been more sensitive A deficiency in test sensitivity could mean that exposure standards will be set at levels that are too high and will not protect the exposed populations. 

These observations are important because the effects were detected at blood lead concentrations lower than the current 10 pg dl level of concern for lead in children (CDC, 1991, 2002 WHQ, 1995 AAP, 2005) and approaching current background concentrations. Thus, no threshold lead exposure has been established below which no effects can be expected on cognitive function and academic performance in children (CDC 1991 WHO 1995). 

The administrator s selection of a numerical value for the Pb NAAQS was determined by a number of health-based factors (1) an adverse health effect, hemoglobin reduction (2) the protective statistic, virtually all children not exposed to lead with blood levels >15 p,g/dl (3) a background blood Pb level not based on air Pb, 12 p.g/dl (4) a blood lead air lead ratio of 2 units and (5) selection as the standard which provided an air-based PbB increment of no more than 3 PbB units. 

To deal with this problem the EPA invested in the development and validation of a pharmacokinetic model that is capable of relating intake of lead to blood level. The model also allows the risk assessor to develop blood level estimates that integrate all sources of exposure. Using this model, it becomes possible to determine whether a specific source, such as our suspect water supply, is leading to exposures in excess of the target for all sources combined (this assumes that other sources do not contain levels of lead greater than normal, background... 

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