Paleogeochemical deposits in northern Chile are a rich source of naturally occurring sodium nitrate (Chile saltpeter). These ores are mined to isolate NaNO3 (16-0-0) for use as fertilizer. Coincidentally, these very same deposits are a natural source of perchlorate anion (ClO4-). At sufficiently high concentrations, perchlorate interferes with iodide uptake in the thyroid gland and has been used medicinally for this purpose. In 1997, perchlorate contamination was discovered in a number of US water supplies, including Lake Mead and the Colorado River. Subsequently, the Environmental Protection Agency added this species to the Contaminant Candidate List for drinking water and will begin assessing occurrence via the Unregulated Contaminants Monitoring Rule in 2001. Effective risk assessment requires characterizing possible sources, including fertilizer. Samples were analyzed by ion chromatography and confirmed by complexation electrospray ionization mass spectrometry. Within a lot, distribution of perchlorate is nearly homogeneous, presumably due to the manufacturing process. Two different lots we analyzed differed by 15%, containing an average of either 1.5 or 1.8 mg g-1. Inadequate sample size can lead to incorrect estimations; 100-g samples gave sufficiently consistent and reproducible results. At present, information on natural attenuation, plant uptake, use/application, and dilution is too limited to evaluate the significance of these findings, and further research is needed in these areas.

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Perchlorate has been added to the U.S. Environmental Protection Agency's Drinking Water Contaminant Candidate List (CCL). The present work describes the analysis of perchlorate in water by liquid-liquid extraction followed by flow injection electrospray mass spectrometry (ESI/MS). Cationic surfactants, mostly alkyltrimethyl-ammonium salts, are used to ion-pair aqueous perchlorate, forming extractable ion pairs. The cationic surfactant associates with the perchlorate ion to form a complex detectable by ESI/MS. The selectivity of the extraction and the mass spectrometric detection increases confidence in the identification of perchlorate. The method detection limit for perchlorate based on 3.14 sigma n-1 of seven replicate injections was 100 ng L-1 (parts per trillion). Standard addition was used to quantitate perchlorate in a drinking water sample from a contaminated source, and the concentration determined agreed within experimental error with the concentration determined by ion chromatography.

Stachybotrys chartarum is a toxigenic fungus that has been associated with human health concerns, including pulmonary hemorrhage and hemosiderosis. This fungus produces a hemolysin, stachylysin, which in its apparent monomeric form has a molecular mass of 11,920 Da as determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry. However, it appears to form polydispersed aggregates, which confounds understanding of the actual hemolytically active form. Exhaustive dialysis or heat treatment at 60°C for 30 min inactivated stachylysin. Stachylysin is composed of about 40% nonpolar amino acids and contains two cysteine residues. Purified stachylysin required more than 6 h to begin lysing sheep erythrocytes, but by 48 h, lysis was complete. Stachylysin also formed pores in sheep erythrocyte membranes.Hemolysins are molecules that are designated as such because they have the ability to lyse erythrocytes (RBCs). It is now recognized that the biological significance of these toxins goes beyond their lysis of RBCs to their more general ability to form pores in many cells (4). Today, the consensus is that the majority of relevant bacterial pathogens produce pore-forming proteins (4). Hemolysins have been isolated and purified from many bacterial pathogens, and they are generally important virulence factors (3-45, 13, 17, 18, 22, 25).It is often thought that bacterial cytolysins act primarily by killing host cells, but nonlethal reactions in other cells, including endothelial and immune cells, occur as a result of exposure to these toxins (4, 6). Many bacterial hemolysins create pores not only in RBCs, but also in the membranes of nucleated cells (e.g., neutrophils, monocytes, and endothelial cells) (2,10,20), and can affect the aggregation of platelets (12). These hemolysin-mediated responses affect the pathophysiology of the host.A number of fungal pathogens produce hemolysins (11,19,26). Recently, production of a hemolysin by the toxigenic fungus Stachybotrys chartarum was described (23). S. chartarum is a toxigenic fungus that has been associated with human health concerns, including pulmonary hemorrhage and hemosiderosis (PH) in infants in Cleveland, Ohio (7). In this paper, we describe the isolation, purification, and characterization of a poreforming hemolysin, stachylysin, produced by S. chartarum. MATERIALS AND METHODSPurification of hemolysin. S. chartarum conidia of strain 58-06 were produced after 5 weeks of growth on sterile wall board, as previously described (23). Approximately 10 5 conidia in a 100-l suspension were used to inoculate 500 ml of tryptic soy broth (TSB) (Becton Dickinson, Sparks, Md.) in a 1-liter flask placed on an incubator shaker (LabLine, Inc. Melrose Park, Ill.) set at 36 Ϯ 1°C and mixed at 200 rpm/min. After 7 days of incubation, the cells and debris were removed from the culture by centrifugation for 15 min at 5,000 ϫ g in an RC5centrifuge (Dupont Instruments, Newton, Conn.), and the supernatant was recovered. The supernatant was centrifuged in a Millipore C...

The volume of water ingested by swimmers while swimming is of great interest to individuals who develop risk assessments using quantitative microbial risk assessment or epidemiological approaches. We have used chloroisocyanurate disinfected swimming pool waters to determine the amount of water swallowed by swimmers during swimming activity. The chloroisocyanurate, which is in equilibrium with chlorine and cyanuric acid in the pool water, provides a biomarker, cyanuric acid, that once swallowed passes through the body into the urine unchanged. The concentration of cyanuric acid in a 24 hour urine specimen and the concentration in pool water can be used to calculate the amount of water swallowed. Our study population of 549 participants, which was about evenly divided by gender, and young and adult swimmers, indicated that swimmers ingest about 32 mL per hour (arithmetic mean) and that children swallowed about four times as much water as adults during swimming activities. It was also observed that males had a tendency to swallow more water than females during swimming activity and that children spent about twice as much time in the water than adults.