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Change in decay rates of dioxin-like compounds in Yusho patients

View Article: PubMed Central - PubMed

ABSTRACT

Background: Once ingested, dioxins and dioxin-like compounds are excreted extremely slowly. Excretion can be evaluated by its half-life. Half-lives estimated from observed concentrations are affected by excretion and ongoing exposure. We investigated the change in apparent half-life using a theoretical model based on exposure to dioxin and dioxin-like compounds.

Methods: We carried out longitudinal measurements of the blood concentration of dioxins and dioxin-like compounds in a Yusho cohort during 2002 to 2010. We estimated the change in decay rates of 2,3,4,7,8-PeCDF and octachlorodibenzodioxin (OCDD) using a second-order equation.

Results: We found that the decay rate of OCDD increased, whereas the decay rate of 2,3,4,7,8-PeCDF of patients with a relatively high concentration of 2,3,4,7,8-PeCDF decreased. OCDD results were in accordance with decreasing levels of dioxin and dioxin-like compounds in the environment. The decay rate of OCDD in the body was affected by the decay rate of OCDD in the environment by ingestion because it was near the steady-state. In contrast, the decay rate of 2,3,4,7,8-PeCDF in the body was affected less by ingestion from the environment because it was far higher than in the steady-state.

Conclusion: We demonstrated that the level of 2,3,4,7,8-PeCDF in the environment is decreasing. The excretion half-life is longer than the environmental half-life, thus the excretion half-life in a Yusho patient is increased.

No MeSH data available.


Change in body burden in the constant-intake model
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Fig2: Change in body burden in the constant-intake model

Mentions: Figure 2 shows the time progression of body burden with a constant intake of dioxins for initially high and low concentrations, governed by Eq. (5). The dashed line corresponds to the steady-state of the body burden being equal to the integration constant, Q(t) = Q0. In a patient who underwent accidental exposure to a high level of dioxins, the body burden will decay exponentially as the first derivative is negative. In a patient who has a lower body burden than the steady-state level, the body burden will approach the steady-state level in an exponential fashion; i.e., the first derivative is positive and the second derivative is negative. Bartell evaluated how intake affects half-life if intake is constant [14].Fig. 2


Change in decay rates of dioxin-like compounds in Yusho patients
Change in body burden in the constant-intake model
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5015216&req=5

Fig2: Change in body burden in the constant-intake model
Mentions: Figure 2 shows the time progression of body burden with a constant intake of dioxins for initially high and low concentrations, governed by Eq. (5). The dashed line corresponds to the steady-state of the body burden being equal to the integration constant, Q(t) = Q0. In a patient who underwent accidental exposure to a high level of dioxins, the body burden will decay exponentially as the first derivative is negative. In a patient who has a lower body burden than the steady-state level, the body burden will approach the steady-state level in an exponential fashion; i.e., the first derivative is positive and the second derivative is negative. Bartell evaluated how intake affects half-life if intake is constant [14].Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Once ingested, dioxins and dioxin-like compounds are excreted extremely slowly. Excretion can be evaluated by its half-life. Half-lives estimated from observed concentrations are affected by excretion and ongoing exposure. We investigated the change in apparent half-life using a theoretical model based on exposure to dioxin and dioxin-like compounds.

Methods: We carried out longitudinal measurements of the blood concentration of dioxins and dioxin-like compounds in a Yusho cohort during 2002 to 2010. We estimated the change in decay rates of 2,3,4,7,8-PeCDF and octachlorodibenzodioxin (OCDD) using a second-order equation.

Results: We found that the decay rate of OCDD increased, whereas the decay rate of 2,3,4,7,8-PeCDF of patients with a relatively high concentration of 2,3,4,7,8-PeCDF decreased. OCDD results were in accordance with decreasing levels of dioxin and dioxin-like compounds in the environment. The decay rate of OCDD in the body was affected by the decay rate of OCDD in the environment by ingestion because it was near the steady-state. In contrast, the decay rate of 2,3,4,7,8-PeCDF in the body was affected less by ingestion from the environment because it was far higher than in the steady-state.

Conclusion: We demonstrated that the level of 2,3,4,7,8-PeCDF in the environment is decreasing. The excretion half-life is longer than the environmental half-life, thus the excretion half-life in a Yusho patient is increased.

No MeSH data available.