Exposure of hematopoietic stem cells to ethylene oxide during processing represents a potential carcinogenic risk for transplant recipients.

Stem cells for transplantation are obtained from bone marrow, umbilical cord blood, and peripheral blood. A rare complication of hematopoietic stem cell transplantation is donor cell-derived leukemia (DCL). The donors remain cancer free and the causes of these DCL are unknown.

A mechanism-based cancer risk assessment for 1,4-dichlorobenzene.

1,4-Dichlorobenzene (DCB) induced liver cancer in male and female B6C3F(1) mice in a gavage bioassay and in male and female BDF(1) mice in an inhalation bioassay. The weight of the evidence convincingly indicates that the mouse liver tumors induced by 1,4-DCB were via a nongenotoxic-mitogenic/promotional mode of action by forcing the growth of spontaneous precancerous lesions. Doses insufficient to exhibit mitogenic or promotional activity would not be expected to increase the risk of cancer.

A classification framework and practical guidance for establishing a mode of action for chemical carcinogens.

The recently released U.S. Environmental Protection Agency (U.

Contamination is a frequent confounding factor in toxicology studies with anthraquinone and related compounds.

Anthraquinone (AQ) (9,10-anthracenedione) is an important compound in commerce. Many structurally related AQ derivatives are medicinal natural plant products. Examples include 1-hydroxyanthraquinone (1-OH-AQ) and 2-hydroxyanthraquinone (2-OH-AQ), which are also metabolites of AQ.

Pathogen inactivation of RBCs: PEN110 reproductive toxicology studies.

Background: The novel PEN110 chemistry (INACTINE, V.I. Technologies) process for the purification of blood for transfusions involves treating WBC-reduced RBCs with PEN110 to inactivate a wide spectrum of pathogens.

Biologically motivated computational modeling of chloroform cytolethality and regenerative cellular proliferation.

Chloroform is a nongenotoxic-cytotoxic carcinogen in rodents. As such, events related to cytotoxicity are the driving force for cancer induction. In this paper we extended an existing physiologically based pharmacokinetic (PBPK) model for chloroform to describe a plausible mechanism linking the hepatic metabolism of chloroform to hepatocellular killing and regenerative proliferation.

Male mice deficient in microsomal epoxide hydrolase are not susceptible to benzene-induced toxicity.

Enzymes involved in benzene metabolism are likely genetic determinants of benzene-induced toxicity. Polymorphisms in human microsomal epoxide hydrolase (mEH) are associated with an increased risk of developing leukemia, specifically those associated with benzene. This study was designed to investigate the importance of mEH in benzene-induced toxicity.

Genetic susceptibility to benzene-induced toxicity: role of NADPH: quinone oxidoreductase-1.

Enzymes that activate and detoxify benzene are likely genetic determinants of benzene-induced toxicity.NAD(P)H: quinone oxidoreductase-1 (NQO1) detoxifies benzoquinones, proposed toxic metabolites of benzene. NQO1 deficiency in humans is associated with an increased risk of leukemia, specifically acute myelogenous leukemia, and benzene poisoning.

Chloroform inhalation exposure conditions necessary to initiate liver toxicity in female B6C3F1 mice.

Chloroform is a nongenotoxic-cytotoxic carcinogen in rodent liver and kidney, including the female B6C3F1 mouse liver. Because tumors are secondary to events associated with cytolethality and regenerative cell proliferation, these end points are valid surrogates for tumor formation in cancer risk assessments. The purpose of the experiments presented here was to more clearly define the combinations of atmospheric concentration and duration of exposure necessary to induce cytolethality and regenerative cell proliferation in the sensitive female B6C3F1 mouse liver.