Comparative carcinogenicity in Sprague-Dawley rats of the polychlorinated biphenyl mixtures Aroclors 1016, 1242, 1254, and 1260.

A comprehensive chronic toxicity and carcinogenicity study was conducted on a series of Aroclors (1016, 1242, 1254, and 1260). Each Aroclor was assessed at multiple dietary concentrations, ranging from 25 to 200 ppm, for 24 months in male and female Sprague-Dawley rats. Liver toxicity was indicated by elevated serum enzyme activity (AST, ALT, and GGT), elevated serum cholesterol concentration, decreases in hematologic parameters (RBC, Hb, and Hct), hepatocellular hypertrophy, an increased incidence of altered hepatocellular foci, and an increased incidence of hepatocellular neoplasms (primarily adenomas). Liver toxicity was distinctly more severe in females than in males. The incidence of hepatocellular neoplasms was highly sex-dependent (females >> males), differed between Aroclor mixtures and, for females, increased with dose and followed the general incidence pattern of Aroclor 1254 > Aroclor 1260 approximately Aroclor 1242 > Aroclor 1016. A significant response (p < 0.05) in males was seen only for the high dose of Aroclor 1260. A small increase in the incidence of thyroid gland follicular cell adenomas was noted in males for Aroclors 1242, 1254, and 1260, with the incidence being uniform across dose groups and Aroclor mixtures. For females, increased survival relative to controls was observed for all Aroclor treatment groups. A significantly decreased trend in the incidence of mammary gland neoplasms compared to control was also noted for females receiving Aroclors 1242, 1254, and 1260.

Evaluation of enzyme-linked immunosorbent assay for the determination of polycyclic aromatic hydrocarbons in house dust and residential soil.

Two commercially available enzyme-linked immunosorbent assays (ELISA) for total polycyclic aromatic hydrocarbon (PAH) and carcinogenic PAH (C-PAH) were evaluated. The testing procedures were refined for application to screening PAH and C-PAH in house dust and soil samples for human exposure studies. The overall method precision expressed as percent relative standard deviation (%RSD) of triplicate real world dust and soil samples was within +/- 29% (12-29%) for PAH ELISA and +/- 21% (5.9-21%) for C-PAH ELISA. Spike recoveries from real world dust/soil samples were 114 +/- 30% for phenanthrene from PAH ELISA and 120 +/- 8.2% for benzo[a]pyrene from C-PAH ELISA. The overall method accuracy for PAH and C-PAH assays cannot be assessed for multiple PAH components in dust/soil samples (which represent real-world samples), because of the assays' cross reactivities with other PAH components. Over 100 dust/soil samples from 13 North Carolina homes and 22 Arizona homes were analyzed by PAH and C-PAH assays, as well as by the conventional gas chromatography/mass spectrometry (GC/MS) method. Statistical analysis showed that dust/soil PAH data from ELISA and GC/MS methods are significantly different. In general PAH ELISA responses were higher than PAH GC/MS responses. The regression analysis showed that the linear relationship between ELISA and GC/MS measurements is not strong in the combined data. The relationship became stronger for the data from the same type of dust/soil samples. The screening performance of ELISA was evaluated based on the frequency distribution of ELISA and GC/MS data. The results indicated that the ELISA PAH and C-PAH assays cannot be used as a quantitative analytical tool for determining PAH in real-world dust/soil samples. However, the ELISA is an effective screening tool for ranking PAH concentrations in similar types of real world dust/soil samples.

Neuromuscular effects of low level exposures to Sarin, pyridostigmine, DEET, and chlorpyrifos.

A study is being initiated to investigate subtle neurobehavioral effects and neuropathology in rats due to exposure to combinations of low levels of Sarin (GB), N,N-diethyl-m-toluamide (DEET), chlorpyrifos (CPF), and pyridostigmine bromide (PB). A similar study is being initiated in rhesus monkeys to investigate neurophysiologic effects and neuromuscular pathology due to exposure to a combination of GB, DEET, CPF, and PB, along with vaccination with botulinum toxoid. A description of these studies is presented.

Procedure for assessing myeloperoxidase and inflammatory mediator responses in hairless mouse skin.

A preparation procedure for making multiple inflammatory biomarker measurements from the same skin tissue was assessed. The backs of euthymic hairless mice were exposed to sulfur mustard (HD) vapor for 6 min. Animals were euthanized 24 h following exposure, dorsal skin tissue was excised and 12-mm, full-thickness biopsy punches of the exposed skin sites were taken. Specimens were snap-frozen, crushed to a powder using a biopulverizer unit, solubilized in buffer and centrifuged. Supernatant was assayed for pro-inflammatory cytokines and the acute-phase reactive protein, serum amyloid P (SAP). Myeloperoxidase (MPX), which is indicative of neutrophil infiltration into the skin, was associated with the pellet fraction. Results indicate an elevation of interleukin-6, SAP and MPX in mouse skin tissue specimens 24h following HD vapor exposure. The tissue preparation procedure allows the use of a single skin specimen to make multiple inflammatory endpoint measurements requiring different preparation processes, and it will be used in subsequent studies to characterize further the inflammatory nature of HD-exposed skin tissue.

Protection against botulinum toxins provided by passive immunization with botulinum human immune globulin: evaluation using an inhalation model.

Pentavalent botulinum toxoid adsorbed (ABCDE) vaccine is intended to protect military personnel from battlefield exposures to botulinum serotypes A-E. To determine the neutralizing antibody levels in serum that are indicative of protection against aerosolized botulinum toxins, a guinea pig model of passive antibody transfer was developed. Botulinum immune globulin (BIG), derived from plasma of vaccinated volunteers, was administered to guinea pigs by intraperitoneal injection to attain neutralizing antibody levels in serum of ca. 0.25 U ml(-1). Control groups were treated with vaccinia immune globulin (VIG), with dosages normalized to antibody content. Neutralizing antibody levels were determined by a mouse bioassay. Twenty-four hours after BIG treatment, animals were challenged with lethal levels (target of 25 x LCt(50)) of botulinum toxins by an inhalation route. Protection was defined as 80% or greater survival for BIG-treated animals. If protective, additional groups were treated with progressively smaller BIG dosages (75% decreases per iteration) and challenged with 25 x LCt(50) until protection was no longer afforded. Greater than 80% survival was observed at target levels of 0.25 U ml(-1) for all five serotypes. Breakthrough mortality (>20%) was observed at test levels of 0.05, 0. 004, 0.015, 0.014 and 0.003 U ml(-1) for serotypes A-E, respectively. These results, along with neutralizing antibody measurements from clinical trials, can be used to predict human efficacy following vaccination with pentavalent botulinum toxoid adsorbed (ABCDE) vaccine.

Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products.

Vesication and skin irritation studies were conducted in hairless guinea-pigs to determine the vesicant and skin irritation potential of chemically-neutralized Chemical Agent Identification Sets (CAIS). The CAIS are training items that contain chemical warfare-related material--sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)--and were declared obsolete in 1971. Animals were dosed topically with 'test article'--neat HD, 10% agent/chloroform solutions or product solutions (waste-streams) from neutralized CAIS--and evaluated for skin-damaging effects (gross and microscopic). Product solutions from the chemical neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solutions) sites manifested microblisters as well as other histopathological lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity associated with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chemical neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS containing agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS containing neat sulfur mustard.