Status of Serum Calcium, Vitamin D and Parathyroid Hormone and Hematological Indices Among Lead Exposed Jewelry Workers in Dhaka, Bangladesh

Abstract

Jewelry utilizes lead either directly or as a base metal. Costume jewelry requires lead before molding and plating the product with valuable metals. Therefore, such ornaments have a great potential to release heavy metals having health hazards. Also, jewelry makers engaged in preparing German silver, an alloy, apply lead in smelting, alloying, rolling and milling silver wires and pieces. The metal is taken up by blood, soft tissues and bone. The biological effects of lead are dependent upon the level and duration of exposure. Lead inhibits three enzymes of heme biosynthesis-d-amino-levulinic-acid dehydratase (ALAD), coproporphyrin oxidase, and ferrochelatase, impairing heme synthesis and depressing serum level of erythropoietin resulting in decreased hemoglobin synthesis. Lead exposure also affects calcium metabolism and impair the synthesis of Calcitriol. In the present study, jewelry makers from Dhaka, Bangladesh, were shown to have significantly high levels of lead, protein, albumin, and parathormone in their blood, and significantly high amount of zinc-protoporphyrin and d-amino-levulinic-acid in their urine. The control group, on the other hand showed significantly higher amounts of calcium (both total and ionized form) Vitamin D 3 and non-activated erythrocyte ALAD in their blood, along with hemoglobin. It might be due to inhibition of 1-a-hydroxylase enzyme in renal tubules. Lead causes nephro-toxicity and inhibits 1-a-hydroxylase enzyme leading to decreased calcitriol synthesis resulting in impaired calcium absorption across gastro-intestinal tract and renal tubules. Low Vitamin D 3 and significantly increased Parathyroid hormone (PTH) in study group has been found.

Potential Antioxidant Activity of Calcium and Selected Oxidative Stress Markers in Lead- and Cadmium-Exposed Workers

“…The ZPP concentration has been commonly used in clinical diagnosis of chronic occupational lead exposure [ 52 – 54 ]. Mazumdar et al [ 55 ] showed that ZPP levels are negatively correlated with serum calcium concentration in jewelry makers (PbB: 69 μ g/dl). Our observation suggests that low calcium levels may enhance the negative impact of lead on heme biosynthesis.…”

Lead Affects Vitamin D Metabolism in Rats

“…This was further confirmed with the strong negative association between BPbLs and serum 25(OH)D levels (PND21; β = −0.64, R 2 = 0.47, p < 0.0001 and PND30; β = −0.78, R 2 = 0.25, p < 0.01) in all rat pups of the same age ( n = 31) irrespective of Pb exposure group. Few epidemiological studies have reported similar significant negative associations between Pb and serum 25(OH)D among women [ 49 ], Pb-exposed workers [ 20 , 21 ] and children [ 22 , 25 ]. Kersey et al [ 50 ] have found negative but statistically insignificant, association between BPbls and serum 25(OH)D levels in healthy toddlers and children under 6 years of age.…”

“…It has been suggested that high Pb exposure is one of the potential risk factor of VDD [ 20 , 21 ]. Studies of children with high Pb exposure demonstrated a significant negative association between 1,25-dihydroxyvitamin D [1,25(OH) 2 D] concentration and blood Pb level (BPbL) [ 22 , 23 , 24 , 25 ].…”

Urinary calcium: a promising predictive biomarker for early recognition of environmental lead exposure in children

“…6 Serum calcium level is maintained under tight homeostatic control and directly and indirectly involves the influence of diverse roles played by parathyroid hormone (PTH), vitamin D and phosphate. 7 Magnesium (Mg), may also be added to the group because it remotely plays a fundamental role in the release and action of PTH and controls many calcium channels, making it indispensable in Ca metabolism. 8 The close and complex association between Pb and Ca metabolism has been recognized for years.…”