Occupational lead poisoning in the United States: clinical and biochemical findings related to blood lead levels.

Abstract

Dose-response relationships between blood lead levels and toxic effects have been evaluated in 160 lead workers in two smelters and a chemicals plant. Blood lead levels ranged from 0.77 to 13.51 mumol/litre (16-280 microgram/dl). Clinical evidence of toxic exposure was found in 70 workers (44%), including colic in 33, wrist or ankle extensor muscle weakness in 12, anaemia (Hgb less than 8.69 mumol/litre (Hb/4) or 14.0 gm/dl) in 27, elevated blood urea nitrogen (greater than or equal to 7.14 mmol/litre or 20 mg/dl) in 28, and possible encephalopathy in two. No toxicity was detected at blood lead levels below 1.93 mumol/litre (40 microgram/dl). However, 13% of workers with blood lead levels of 1.93 to 3.81 mumol/litre (40-79 microgram/dl) had extensor muscle weakness or gastrointestinal symptoms. Anaemia was found in 5% of workers with lead levels of 1.93-2.85 mumol/litre (40-59 microgram/dl), in 14% with levels of 2.90 to 3.81 mumol/litre (60-79 microgram/dl), and in 36% with levels greater than or equal to 3.86 mumol/litre (80 microgram/dl). Elevated blood urea nitrogen occurred in long-term lead workers. All but three workers with increased blood urea nitrogen had at least four years occupational lead exposure, and nine had received oral chelation; eight of this group had reduced creatinine clearance, and eight had decreased renal concentrating ability. These data support the establishment of a permissible biological limit for blood lead at a level between 1.93 and 2.90 mumol/litre (40-60 microgram/dl).

An epidemiological re-appraisal of the association between blood pressure and blood lead: a meta-analysis

“…Two studies reported only on young children (Ͻ10 years), 25,37 two studies were case reports, 45,48 one 66 recruited less than 50 persons, in one 54 owing to missing information the analysis was performed in less than 50 subjects, five estimated exposure from other measurements than the blood lead concentration, 30,77,78,81,88 and 11 did not provide enough information to compute the association size. 17,19,22,26,27,36,39,62,63,67,86 …”

Epidemiologic approaches to persons with exposures to waste chemicals.

“…Doll and Hill found that the death rate from lung cancer among British physicians was significantly higher in smokers than in nonsmokers and that the rate increased sharply the more tobacco was consumed (13,14). Likewise, in studies of persons exposed to lead, the prevalence of anemia was found to be higher in exposed than in unexposed persons, and further, the concentration of hemoglobin in the blood of exposed persons was found to be rather precisely correlated with their blood lead levels; persons with higher blood lead levels had lower hemoglobin concentrations (15).…”

Strategies for epidemiologic studies of lead in bone in occupationally exposed populations.

“…In one of the earliest of these studies, Hanninen et reported an increased prevalence offatigue and short-term memory loss in smelter workers exposed to lead; the prevalence of these abnormalities increased with blood lead levels (9).…”

“…The severity and prevalence of this anemia are correlated directly with the blood lead level (9). The anemia of lead is produced by two mechanisms: impairment of heme biosynthesis and acceleration of red blood cell destruction.…”

“…The blood lead level is, however, seriously deficient as an index of chronic lead exposure. Thus, it is of only limited value for assessing exposure-response relationships for such long-term consequences of exposure to lead as renal disease, hypertension, or chronic impairment of the central nervous system (9). For evaluation of the natural history and dose-response relationships of these effects, a measure of chronic lead exposure will be essential.…”