Comparison of lead bioavailability in F344 rats fed lead acetate, lead oxide, lead sulfide, or lead ore concentrate from Skagway, Alaska

Abstract

An animal model using rats was developed to initiate investigations on the bioavailability of different sources of environmental lead. Lead must be absorbed and transported to target organs like brain, liver, kidney, and bone, before susceptible cells can be harmed. The bioavailability and therefore the toxicity of lead are dependent upon the route of exposure, dose, chemical structure, solubility, particle size, matrix incorporation, and other physiological and physicochemical factors. In the present study male F344 rats were fed < or = 38 microns size particles of lead sulfide, lead oxide, lead acetate, and a lead ore concentrate from Skagway, Alaska, mixed into the diet at doses of 0, 10, 30, and 100 ppm as lead for 30 d. No mortality or overt symptoms of lead toxicity were observed during the course of the study. Maximum blood lead concentrations attained in the 100 ppm groups were approximately 80 micrograms/dl in rats fed lead acetate and lead oxide, and were approximately 10 micrograms/dl in those fed lead sulfide and lead ore concentrate. Maximum bone lead levels in rats fed soluble lead oxide and lead acetate were much higher (approximately 200 micrograms/g) than those seen in rats fed the less soluble lead sulfide and lead ore (approximately 10 micrograms); kidney lead concentrations were also about 10-fold greater in rats fed the more soluble compared to the less soluble lead compounds. However, strong correlations between dose and tissue lead concentrations were observed in rats fed each of the four different lead compounds. Kidney lesions graded as minimal occurred in 7/10 rats fed 30 ppm and in 10/10 rats fed 100 ppm lead acetate, but not at lower doses or from other lead compounds. Similarly, urinary aminolevulinic acid excretion, a biomarker for lead toxicity, was increased in rats fed 100 ppm lead acetate or lead oxide, but was unaffected at lower doses or by the less soluble lead compounds. Although the histological and biochemical responses to lead toxicity were restricted to the more soluble lead compounds in this study, lead from Skagway lead ore concentrate and lead sulfide was also bioavailable, and accumulated in proportion to dose in vulnerable target organs such as bone and kidney. Longer-term studies with different mining materials are being conducted to determine if tissue lead continues to increase, and whether the levels attained are toxic. Data from such studies can be used to compare the toxicity and bioavailability of lead from different sources in the environment.

Lead Speciation in Artificial Human Digestive Fluid

“…The different lead salts and lead concentration levels in the OECD medium did not clearly show distinct behavior for both the ISE and the DPASV experiments, although differences in lead absorption between different lead salts in in vivo experiments have been observed by others (Barltrop and Meek 1975;Dieter et al 1993;Freeman et al 1996). Comparable to the in vivo experiments both well-soluble (Pb(CH 3 COO) 2 , Pb(NO 3 ) 2 , and PbCl 2 ) and sparingly soluble lead salts (PbSO 4 ) were investigated.…”

“…It is well known that intestinal absorption in in vivo experiments is affected by the form in which lead is added, i.e., lead administered as different salts, in a soil matrix, or in food (Barltrop and Meek 1975;Rabinowitz et al 1980;Dieter et al 1993;Freeman et al 1996). For example, a 12-fold relative difference in absorption in rat was found for seven different lead salts that were added to the diet at approximately equal concentrations (Barltrop and Meek 1975).…”

Characterizing Golden Eagle Risk to Lead and Anticoagulant Rodenticide Exposure: A Review

“…In rats, proximal tubular injury involves the convoluted and straight portions of the tubule (Aviv et al 1980;Dieter et al 1993;Khalil-Manesh et al 1992a, 1992bVyskocil et al 1989), with greater severity, at least initially, in the straight (S3) segment Murakami et al 1983). Typical histological features include, in the acute phase, the formation of intranuclear inclusion bodies in proximal tubule cells (see below for further discussion); abnormal morphology (e.g., swelling and budding) of proximal tubular mitochondria Goyer and Krall 1969); karyomegaly and cytomegaly; and cellular necrosis, at sufficiently high dosage.…”

Lead from mining and mineral processing activities to the community via the air-dust pathway: An example from Mount Isa city using human health risk assessment approach

“…Some parent minerals, such as bulk galena (PbS) and other metal sulfides, have limited bioavailability (Chaney et al, 2008, Dieter et al, 1993, Steele et al, 1990. Exposure to oxygen and moisture promotes oxidation of sulfide minerals and leads to mineral dissolution, metal mobilisation, and precipitation of secondary minerals (Parker and Robertson, 1999).…”

“…Bioaccessibility of soil contaminants depends on soil type and contaminant (Ellickson et al, 2001, U.S. EPA, 2007b, Ruby et al, 1999, Steele et al, 1990. Certain types of lead minerals are well-absorbed (e.g., cerussite, manganese lead oxide), while other forms are poorly absorbed (e.g., galena, anglesite) (U.S. EPA, 2007b, Dieter et al, 1993). …”