The goal of this contract is to provide support of National Toxicology Program (NTP) hazard identification activities targeted toward the prevention of diseases or adverse effects caused by environmental exposure to chemical or physical agents. Toxicity testing is an important aspect of public health research in that it serves to identify chemicals that are hazardous to human health. Proper chemical analyses are required to ensure that, in toxicity studies, the test species are exposed to the prescribed chemicals at the specified dose concentrations. This contract contributes to the ability of toxicity studies to provide evidence of heightened cancer risk along with other toxicological outcomes, by providing characterization of the chemicals studied, confirmation of the dose levels administered, and internal dose determinations. This information is critical to evaluation of toxicity tests and development of sound, scientific conclusions about the potential toxicity of the study chemical in the test species and ultimately supports the risk assessment efforts of National Toxicology Program and other federal agencies. With internal dose information provided by this contract, extrapolations to humans can be made so that the public can be adequately informed about risk factors arising from exposure to studied chemicals. During FY08, more than 138 tasks were begun, performed, and/or completed in support of NTP and DIR research and testing protocols. As part of a Phase 1 High Throughput Screening initiative 257 chemicals were prepared as 10 mg aliquots and screened for purity in preparation for shipment to the NIH Chemical Genomics repository housed at Biofocus DPI. Of those 257 chemicals, 106 have so far met purity acceptability requirements set by the repository and were sent to Biofocus DPI. A gas chromatography rapid purity screen was developed to assess purity of chemicals sent to Biofocus as part of the high throughput screening initiative. Training sets of chemicals used in the high-throughput screen were used to develop DMSO solubility predictors based on physical properties of the chemicals (i.e., Log P value). The predictor is now being tested against a different set of chemicals for which the DMSO solubility is known. Work was begun on an analytical method to assess the speciation of chromium in tissue samples collected from the sodium dichromate and chromium picolinate 2-year bioassays. Whole samples from a perinatal toxicology study were analyzed for 3,3',4,4'-tetrachloroazobenzene using a previously validated method. In support of the National Toxicology Program's dietary zinc study the contract characterized the Zn concentrations in the 3 components of a commercial zinc-free AIN diet (casein-based diet, mineral and vitamin additives) along with the animal bedding to be used in the study. Using an ICP-OES method, Zn concentrations were found to be less than 5 ug/g in the mineral additive, < 1 ug/g in the vitamin additive, and 1.2 ug/g in the unformulated diet. This would result in a Zn concentration of ~1.3 ug/g in the formulated diet. The average Zn concentration found in the Sani-Chips(R) bedding was 3.4 ug/g. The chemistry support contractor prepared and analyzed dose formulations of nelfinavir, a drug used in AIDS prevention and treatment in support of an NTP immunotoxicology study. To support studies of butter flavored food additives diacetyl, acetoin, and 2,3-pentanedione were characterized and the stability of dose formulations was determined. It was found that atomizing the material for delivery in an inhalation chamber resulted in build up of residue on the generator and aerosol formation in the chamber. The residue was analyzed to determine if it was a trace impurity or perhaps the result of polymerization of the test article. Preliminary results indicate that the residue is structurally similar to the test article and is likely to be a mixture of the dimmer and trimer. To support an NTP study of the dietary supplement resveratrol, thought to be important in cancer prevention, probable metabolites of the parent compound were synthesized so that a method could be developed to analyze for them in biosamples to be received from the study, and in anticipation of a toxicokinetic study of resveratrol that will be conducted during FY09. A toxicokinetic study of ephedrine was completed. This study looked at plasma concentrations of ephedrine, pseudoephedrine and caffeine following exposure to ephedrine or ephedrine plus caffeine, or to the dietary supplement ma huang or ma huang plus caffeine. Since the ephedrine + caffeine combination is known to cause heart arrhythmias heart samples from the study were also analyzed for tropinin concentrations. High tropinin concentration is an indicator of heart disease or damage. A collaboration was established with Dr. Freya Kamel at NIEHS to analyze > 450 samples for lead and a suite of other heavy metals including arsenic. These samples are part of a study of amyotrophic lateral sclerosis (ALS) in veterans. Another in-house collaboration was established with Dr. Jean Harry to support a study of mercury exposure resulting from immunization. Samples from mice exposed to mercury or thimerosal were analyzed for total mercury and inorganic mercury. A separate collaboration with the National Cancer Institute, New England Bladder Cancer study and the Environmental Protection agency was begun to extract potentially mutagenic substances from human urine samples and test the resulting extracts for mutagenicity using an assay developed by the EPA.
