The document Air Quality Criteria for Lead (1986) [51] states that “it is
clear from the wealth of available literature. . that there exists a continuum of biological
effects associated with lead across a broad range of exposure.” At low levels
of exposure, biochemical changes begin to occur which affect enzyme activities
involved in biosynthesis which has importance in the normal physiological functioning
of the organs in the body. At higher levels, it begins to affect the nervous
system and can disrupt reproductive functions and impair immunological functions.
In cases of high exposure, disruptions of the nervous system and immunological
functions can result in lead poisoning, permanent mental retardation, and
even death. The severity of the effect has generally been, related primarily to the
concentration of lead in the blood stream. The national ambient air quality stan-