European Journal of Scientific Research - EuroJournals

354 E.A. Moses, J.C. Akan, V.O. Ogugbuaja and P.A. Onyeyili
Table 1: The Half-lives and Elimination rate constants of Chromium in Various Tissues of Goats Treated
Intratracheally and Intravenously with a Single Dose (50mg/kg) of Dusts.
Intratracheal route Intravenous route
Tissue Half-lives (days)
Elimination rate constant.
(Per day)
Half-life (days)
Elimination rate constant.
(Per day)
Lung 173.2 0.004 69.3 0.01
Liver 69.3 0.01 69.3 0.01
Heart 23.1 0.03 17.3 0.04
Kidney 69.3 0.01 34.3 0.02
Serum 3.3 0.21 3.6 0.19
Table 2: The Half-lives and Elimination rate Constants of Zinc in Various Tissues of Goats Treated
Intratracheally and Intravenously with a Single Dose (50mg/kg) of Dusts.
Intratracheal route Intravenous route
Tissue Half-lives (days)
Elimination rate constant.
(Per day)
Half-life (days)
Elimination rate constant.
(Per day)
Lung 115.5 0.006 69.3 0.01
Liver 173.2 0.004 34.7 0.02
Heart 3.6 0.10 23.1 0.03
Kidney 69.3 0.01 69.3 0.01
Serum 3.0 0.23 3.3 0.21
Discussion
The results of the serum kinetics study showed that the elements present in the dust were readily
absorbed following intratracheal and intravenous administration and distributed to various organs. The
presence of chromium and zinc in blood following dust administration may be an indication of the
blood protein binding of these elements and or movement of the element from the peripheral
compartments to central compartment for elimination (Onyeyili et al, 2001).
High concentrations of zinc were found in the lung, liver kidney and heart of animals treated
both intravenously and intratracheally with the dust. The high amounts present in these tissues may be
due to increased uptake of zinc by organs and tissues involved. The high concentration of these
elements in the tissues may also be due to the levels of these elements in the dust sample. The low
levels of chromium found in the various tissues following both routes of administration may be an
indication of their low concentrations in the dust.
Lung elemental accumulation from intratracheal dust exposure mode, as expected, are markedly
higher than those from intravenous dust instillation. However, the accumulation from the dust
introduced into the lung displayed by other studied tissues, although low; demonstrate the anticipated
transportation (absorption) of the dust from the lung into the rest of the goat system.
This study has shown that the liver acted as the main accumulator of the elements of interest.
Indications of the observed high liver accumulations are probably related to their effective absorption
from the respiratory tract and the ability of the liver to store them. Other studies have reported
capabilities of most organs, notably liver and kidney, to store large quantities of elements in the
biological systems. The mechanism entails interactions between these elements with the intrinsic
proteins in the organs (King, 1999). Large amounts of some of the detected elements in the liver can
therefore be accounted for.
The half-lives of the elements found in the dust samples was an indication of the length of time
each of these elements will be present in a particular organ or tissue. The higher the half-life of an
element, the longer the persistence of that element in a particular tissue (Renwick, 1996). Slow
elimination of the elements from the lungs is substantiated by the fact that the half-life of elimination
ranged between 115.5 to 173.2 hours after intratracheal administration. The higher half-lives of
elements in lungs following intratracheal administration of dusts compared to intravenous