["Terzo fuoco", lead poisoning and chronic renal failure]

In ceramics, "Terzo fuoco" (Third fire) means a third firing of clay to fix colors on tiles or pottery. The low firing temperatures (800-900 degrees C) and the use of a spray gun are risk factors for lead poisoning. Because of their small size, handicraft companies often fail to implement the preventive measures that are utilized efficiently in large tile factories. We report a case of chronic lead poisoning with special emphasis on diagnostic tools and treatment goals.

A 38-year-old woman was hospitalized in 2005 because of grade 3 chronic renal failure (serum creatinine 1.69 mg%, Cockroft-Gault glomerular filtration rate [GFR] 45 mL/min), hypertension and elevated serum uric acid (13.4 mg%) without gout. She had been previously hospitalized elsewhere and diagnosed as suffering from hypertensive nephropathy. Her occupational history included acute lead poisoning 12 years before, which was treated with a short leave from work. She subsequently continued her job, using a spray gun for decorative drawing in a small tile company until 2004. Because of a low GFR she underwent a 3-day chelation test with 750 mg CaNaEDTA i.v., and excreted 1056 microg Pb (n.v < 600 microg) -- (PbU/EDTA ratio 1.41; n.v < 0.6). A renal biopsy showed chronic interstitial nephropathy with severe arteriolosclerosis. The patient was treated with 5 courses of EDTA, resulting in a final Pb excretion of 517 microg/72 h (PbU/EDTA 0.69). Her serum creatinine fell to 1.32 mg% (CFR 58 mL/min). A further course of chelation therapy is planned.

The EDTA chelation test allows to determine the lead body burden (PbBB) and to titrate subsequent chelation therapy. Recent papers have shown that PbBB is a major factor in the progression of chronic renal failure besides pressure control, and have indicated a PbBB safety level of less than 100 microg/test (PbU/EDTA < 0.1). In order to prevent the development of chronic renal failure, it is important that not only occupational but also environmental lead exposure be identified and adequately treated.