title: 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).
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis; D000740:Anemia / Q000139:chemically induced; D001806:Blood Urea Nitrogen; D002617:Chemical Industry; D004305:Dose-Response Relationship, Drug; D005767:Gastrointestinal Diseases / Q000139:chemically induced; D006801:Humans; D007677:Kidney Function Tests; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000097:blood* / Q000453:epidemiology; D008452:Maximum Allowable Concentration; D008669:Metallurgy; D009468:Neuromuscular Diseases / Q000139:chemically induced; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology; D014481:United States
chemical_list: D000395:Air Pollutants, Occupational; D007854:Lead