Concentrates, lead INDEX

As noted in Chapters 1 and 2, the committee specifically sought health-effects data on blood lead levels (BLLs) under 40 pg/dL because the current standard of the Occupational Safety and Health Administration (OSHA) aims to maintain BLLs below that concentration. Evidence on health effects at a corresponding estimated cumulative blood lead index (CBLl) of 1,600 pg-years/dL (that is, 40 years at 40 pg/dL) and tibia lead levels of 40-80 pg/g were also specifically sought. 

The committee also considered studies that reported an association between cumulative lead dose, as assessed by cumirlative blood lead index (CBLI) or bone lead concentration, and adverse health outcomes. Associations of health outcomes with CBLI or tibia lead concentrations are probably representative of longer-latency, chronic health effects of cumulative dose. In considering CBLI and bone lead data, the committee used the following assumptions a BLL of 40 pg/dL over a 40-y working lifetime would be equivalent to a CBLI of 1,600 pg-years/dL, and this CBLI is roughly equivalent to a bone lead concentration of 40-80 pg/g (on the basis of the pubhshed relation that tibia lead can be estimated as 2.5-5% of the CBLI) (Hu et al. 2007 Healey et al. 2008). Thus, the committee examined evidence that suggested whether a CBLI of imder 1,600 pg-years/dL or a bone lead concentration of imder 40-80 pg/g may be associated with adverse health effects of lead exposure. 

The minimum polydispersity index from a free-radical polymerization is 1.5 if termination is by combination, or 2.0 if chains ate terminated by disproportionation and/or transfer. Changes in concentrations and temperature during the reaction can lead to much greater polydispersities, however. These concepts of polymerization reaction engineering have been introduced in more detail elsewhere (6). 

Polytetrafluoroethylene decomposition products thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentration should be minimal. (Trade names Algoflon, Fluon, Teflon, Tetran.)... 

Effects on Other Neurological End Points in Adults. Recent studies have provided evidence that exposure to lead affects postural balance. For example, Chia et al. (1996b) evaluated the possible association between postural sway parameters and current PbB concentration, cumulative PbB at different years of exposure, and an index of total cumulative exposure to lead in a group of 60 workers ... 

Mclnnes G. 1988. Airborne lead concentrations and the effect of reductions in the lead content of petrol. Govt Reports Announcements Index (GRA I). NTIS/PB88-151345, Issue 09. 

A global sensitivity analysis was performed for the lead concentration in the arterial blood model (Fig. 7) over the simulation period for each parameter. Parameters considered for the sensitivity analysis are listed in Table 8 (Annex 1). The magnitude of sensitivity is shown by relative sensitivity index. It was observed that the most influential parameter is the porosity of the sediment of the river (phi sed)... 

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