Decreased total and ionized calcium levels and haematological indices in occupational lead exposure as evidence of the endocrine disruptive effect of lead

Abstract

The multisystem and prime environmental and occupational toxin, lead (Pb) is seldom included in the list of endocrine disruptors group like bisphenols A, B and F, nonylphenol, benzoquine, equiline etc. One hundred and thirty-seven subjects consisting of 86 lead workers and 51 unexposed individuals (as controls) participated in the study. Dietary intake including dairy products and micronutrients as assessed by 24-hour dietary recall was similar between lead workers and controls. Calcium homeostasis and haematological indices were evaluated in all subjects. Blood lead level was significantly higher in the lead workers than in controls (P<0.001). Total and ionized calcium levels were in contrast significantly decreased in lead workers compared with controls (P<0.01, P<0.001 respectively). Inorganic phosphate level though slightly raised compared to controls did not reach statistical significance (P>0.05). The haematological indices, haemoglobin, haematocrit, and mean cell haemoglobin concentration like calcium levels were all significantly reduced (P<0.001) in all cases. Semi-quantitative assessment of erythrocyte protoporphyrin was trace (±) in both lead workers and controls (i.e. similar). Serum copper level was significantly higher in Pb workers than in controls (P<0.005). These decreases are consistent with a repression of the endocrine systems regulating both erythropoiesis and calcium homeostasis resident in the proximal convoluted tubule(PCT) of the kidney; the most vulnerable site to Pb damage. Our findings therefore, appear to provide evidence or a reminder that Pb satifies the conditions defining EDCs and should be recognized as one, especially in developing countries where high environmental Pb and malnutrition co-exist and may magnify this effect.

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

“…This decreased calcium levels confirms earlier experimental and clinical reports and reflects disturbance of calcium metabolism due to lead [20]. Lead is a biochemical analogue of calcium, thus it interferes with calcium in several metabolic pathways.…”

Biochemical Effects of Lead Exposure on Battery Manufacture Workers with Reference to Blood Pressure, Calcium Metabolism and Bone Mineral Density

“…In this study increased blood lead may decrease calcitriol concentration resulting in hypocalcaemia and hypophosphatemia [27,28]. This decreased calcium level confirms earlier experimental and clinical reports and reflects perturbation of calcium metabolism due to lead [10,29,30]. Lead is a biochemical analogue of calcium, thus it interferes with calcium in several metabolic pathways.…”

“…The mechanism of the reduction of ionized calcium is still not clearly understood. It can be speculated that parathyroid hormone (PTH) which has a more direct effect on ionized calcium is also perturbed by the elevated lead level [10]. It indicates that lead is an endocrine modulator and thus a candidate for the endocrine disruptors group.…”

“…All these effects decrease mineralization of bone leading to decrease bone mineral density and increase the risk of osteoporosis in occupational lead exposed population. Lead also affects on cardiovascular system and increases systolic and diastolic blood pressure [8][9][10][11][12][13].…”

Assessment of Renal Biomarkers of Renal Function in Commercial Automobile Workers in Benin City, Edo State, Nigeria

“…An occupational disease is any chronic ailment that occurs as a result of work or occupational activity. It is an aspect of occupational safety and health, typically identified when the disease is more prevalent in a given group of workers compared with the general population or with other groups of workers [1] [2]. The assessment of occupational diseases therefore provides models for understanding environmental diseases.…”