Toxicity of emerging energetic soil contaminant CL-20 to potworm Enchytraeus crypticus in freshly amended or weathered and aged treatments

We investigated the toxicity of an emerging polynitramine energetic material hexanitrohexaazaisowurtzitane (CL-20) to the soil invertebrate species Enchytraeus crypticus by adapting then using the Enchytraeid Reproduction Test (ISO/16387:2003). Studies were designed to develop ecotoxicological benchmark values for ecological risk assessment of the potential impacts of accidental release of this compound into the environment. Tests were conducted in Sassafras Sandy Loam soil, which supports relatively high bioavailability of CL-20. Weathering and aging procedures for CL-20 amended into test soil were incorporated into the study design to produce toxicity data that better reflect soil exposure conditions in the field compared with the toxicity in freshly amended soils. Concentration-response relationships for measurement endpoints were determined using nonlinear regressions. Definitive tests showed that toxicities for E. crypticus adult survival and juvenile production were significantly increased in weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. The median effect concentration (EC50) and EC20 values for juvenile production were 0.3 and 0.1 mg kg-1, respectively, for CL-20 freshly amended into soil, and 0.1 and 0.035 mg kg-1, respectively, for weathered and aged CL-20 soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged CL-20 soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of emerging energetic contaminants in soil.

Inhalation toxicity of Cyclosarin (GF) vapor in rats as a function of exposure concentration and duration: potency comparison to sarin (GB)

The inhalation toxicity of cyclohexyl methylphosphonofluoridate (GF) was examined in male and female Sprague-Dawley rats exposed by whole body in a dynamic 750-L chamber. The objectives of this study were to (1) generate GF vapor in a dynamic inhalation chamber system, starting in the lethal to near-lethal concentration range, (2) examine dose-response effects of inhaled GF vapor and analyze the relationship between concentration (C) and exposure duration (T) in determining probability of lethality, and (3) establish a lethal potency ratio between GF and the more volatile agent Sarin (GB). Using a syringe pump, GF vapor concentrations were generated for exposure times of 10, 60, and 240 min. Dose-response curves with associated slopes were determined for each exposure duration by the Bliss probit method. GF vapor exposures were associated with sublethal clinical signs such as tremors, convulsions, salivation, and miosis. Concentration-exposure time values for lethality in 50% of the exposed population (LCT(50)) were calculated for 24-h and 14-day postexposure periods for 10-, 60-, and 240-min exposures. In general, LCT(50) values were lower in female rats than males and increased with exposure duration; that is, CT was not constant over time. The GF LCT(50) values for female rats were 253 mg min/m(3) at 10 min, 334 mg min/m(3) at 60 min, and 533 mg min/m(3) at 240 min, while the values for males were 371, 396, and 585 mg min/m(3), respectively. The GB LCT(50) values for female rats were 235 mg min/m(3) at 10 min, 355 mg min/m(3) at 60 min, and 840 mg min/m(3) at 240 min, while the values for males were 316, 433, and 1296 mg min/m(3), respectively. At longer exposure durations, the LCT(50) for GF was less than that found for GB but at shorter exposure durations, the LCT(50) for GF was more than that found for GB. Empirical models, consisting of the toxic load model plus higher order terms, were developed and successfully fit to the data.

Chemical and toxicological evaluation of pyrotechnically disseminated terephthalic acid smoke

The terephthalic acid (TPA) smoke obscurants (M-83 grenade and M-8 smoke pot) were developed by the U.S. Army for training purposes to replace the more toxic hexachloroethane (HC) smoke. Inhalation toxicity testing and chemical characterization of pyrotechnically generated TPA was conducted to assess the health hazard potential of TPA and its combustion products. Fisher 344 rats were subjected to acute and repeated exposures to TPA smoke generated from the M-83 grenade. Acute exposure levels ranged from 150-1,900 mg/m3 for 30 minutes and repeated dose exposures ranged from 128-1,965 mg/m3 for 30 min/day for 5 days. Exposed and control rats were evaluated for toxic signs, and histopathologic changes. During exposure, the rats exhibited slight to moderate lacrimation, rhinorrhea, lethargy and dyspnea, which reversed within 1-hr post-exposure. No deaths occurred, even at the highest smoke concentrations. Histopathological changes were confined to exposure related nasal necrosis and inflammation in both the acute and repeated dose exposures at levels above 900 mg/m3. Chemical characterization of the M-83 grenade and the M-8 smoke pot showed that formaldehyde, benzene and carbon monoxide were the major organic vapor by-products formed. These by-products were above their respective ACGIH threshold limit values at various concentrations, but should not pose a hazard if the smoke is deployed in an open area. Overall, TPA is a safer training smoke to replace the HC smoke.

Abnormalities in pulmonary function after brief exposure to toxic metal fumes

A 26-year-old welder became ill after exposure to zinc and cadmium fumes at work. His initial clinical course was consistent with that of metal fume fever, but persistence of symptoms and signs beyond the usual duration in this condition led to suspicion of a toxic pulmonary reaction to cadmium. The finding of high percentages of both metals in the urine confirmed this diagnosis. Pulmonary function tests showed restriction of lung volumes, with increased elastic recoil and reduced diffusion, but no evidence of airways obstruction. Chest roentgenograms indicated central pulmonary edema, which cleared in 6 days. Follow-up assessment 2 years later showed incomplete improvement of the restrictive ventilatory defect.

Suctioning of the left bronchial tree in critically ill patients

When suctioning patients with either a tracheostomy or endotracheal tube, the incidence of entry into the left main stem bronchus was recored at the time of routine AP chest examinations in an ICU. The success rate was 8% with an endotracheal tube and 25% when a tracheostomy tube was present; this was lower than has been reported by others. It could reflect the small size of the series or a more accurate picture.