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Biomedical subjects

S E Hrudey

Publications and source records attributed to S E Hrudey.

12 recordsLinked to original sources
PubMed2005

The design and use of the Personal Environmental Sampling Backpack (PESB II) for activity-specific exposure monitoring of career pig barn workers.

Career pig barn workers in large confinement barns are exposed to airborne contaminants that need to be quantified. Monitoring instrumentation had to be sanitized to satisfy the biosecurity entrance requirements for pig barns. We satisfied this requirement with the development of a portable Personal Environmental Sampling Backpack (PESB). A pilot study was conducted with the original PESB after which modifications were made to construct the PESB II. The objective of the present study was to modify the PESB to create a monitoring system that is acceptable to workers, accurate, able to collect and store data reliably, and transferable from one animal confinement operation to another. A CO2 sensor with a higher detection range was incorporated into the new instrumentation, H2S monitoring capability was added, and improvements were made to the amount of data the new PESB II instrumentation could store. Compared to the original PESB, the PESB II has a lower mass and volume (reduced by 46% and 70%, respectively), a wider range of CO2 measurement capability, an H2S sensor, a data logger with more data capacity for 11.5 h of real-time monitoring, and a high level of worker acceptability. Apart from revealing a problem with H2S cross-reacting with the NH3 sensor, the PESB II system measured all other parameters reliably and accurately while allowing disinfection to meet stringent biosecurity protocols.

Agricultural Workers' Diseases↗
PubMed2004

Urinary excretion half life of trichloroacetic acid as a biomarker of exposure to chlorinated drinking water disinfection by-products.

AIMS: To measure accurately urinary elimination half life of trichloroacetic acid (TCAA). METHODS: A longitudinal pilot exposure/intervention study measured the elimination half life of TCAA in urine. Beverage consumption was limited to a public water supply and bottled water of known TCAA concentration, and ingestion volume was managed. The five participants limited fluid consumption to only the water provided. Consumption journals were kept by each participant and their daily first morning urine (FMU) samples were analysed for TCAA and creatinine. TCAA elimination half life curves were generated from a two week washout period using TCAA-free bottled water. RESULTS: Individual elimination half lives ranged from 2.1 to 6.3 days, for single compartment exponential decay, the model which fit the data. CONCLUSION: Urinary TCAA is persistent enough to be viable as a biomarker of medium term (days) exposure to drinking water TCAA ingestion within a range of realistic concentrations.

Adult↗
PubMed2003

A fatal waterborne disease epidemic in Walkerton, Ontario: comparison with other waterborne outbreaks in the developed world.

An estimated 2,300 people became seriously ill and seven died from exposure to microbially contaminated drinking water in the town of Walkerton, Ontario, Canada in May 2000. The severity of this drinking water disaster resulted in the Government of Ontario calling a public inquiry by Mr. Justice Dennis O'Connor to address the cause of the outbreak, the role (if any) of government policies in contributing to this outbreak and, ultimately, the implications of this experience on the safety of drinking water across the Province of Ontario. The circumstances surrounding the Walkerton tragedy are an important reference source for those concerned with providing safe drinking water. Although some circumstances are obviously specific to this epidemic, others are uncomfortably reminiscent of waterborne outbreaks that have occurred elsewhere. These recurring themes suggested the need for attention to broad issues of drinking water security and they present the challenge for how drinking water safety can be managed to prevent such tragedies in the future.

Campylobacter jejuni↗
PubMed2001

Socioeconomic determinants of health- and food safety-related risk perceptions.

Individual and societal perceptions of food-related health risks are multidimensional and complex. Social, political, psychological, and economic factors interact with technological factors and affect perceptions in complex ways. Previous research found that the significant determinants of risk perceptions include socioeconomic and behavioral variables. Most of these past results are based on two-way comparisons and factor analysis. The objective of this study was to analyze the significance of socioeconomic determinants of risk perceptions concerning health and food safety. A multivariate approach was used and the results were compared with earlier bivariate results to determine which socioeconomic predictors were robust across methods. There were two major findings in this study. The first was that the results in the multivariate models were generally consistent with earlier bivariate analysis. That is, variables such as household income, number of children, gender, age, and voting preferences were strong predictors of an individual's risk perceptions. The second result was that the gender of the respondent was the only variable found to be robust across all three classes of health and food safety issues across two time periods.

Female↗
PubMed2000

Detection of microcystins using electrospray ionization high-field asymmetric waveform ion mobility mass spectrometry/mass spectrometry.

A combination of electrospray ionization, high-field asymmetric waveform ion mobility spectrometry, and mass spectrometry (ESI-FAIMS/MS) was used to analyze standard solutions of microcystins-LR, -RR, and -YR. The ability of FAIMS to separate ions in the gas phase reduced the amount of background in the mass spectrum without compromising the absolute signal for these microcystins. This reduction in background resulted in a ten-fold improvement in the signal-to-background ratio over conventional ESI-MS. Detection limits, using direct infusion, were determined to be 4, 2, and 1 nM for microcystins-LR, -RR, and -YR, respectively.

Bacterial Toxins↗
PubMed1998

Workshop report. Health risks of drinking water chlorination by-products: report of an expert working group.

Studies of water chlorination by-products have suggested a possible increased risk of bladder and colon cancers, as well as adverse reproductive and developmental effects such as increased spontaneous abortion rates and fetal anomalies. A workshop for an expert working group was convened to advise Health Canada on the need for further action. Participants were given background papers and a set of key questions to review prior to the meeting. At the workshop, experts presented an overview of what was known to date on water chlorination by-products from toxicologic studies, epidemiologic studies of cancer and adverse reproductive/developmental effects, and risk assessment. This paper summarizes the information provided in the background papers and presentations, describes the consensus arrived at regarding assessment of evidence for level of risk and presents a number of suggestions for future research.

Abnormalities, Drug-Induced↗
PubMed1997

Toxicity and mutagenicity of component classes of oils isolated from soils at petroleum- and creosote-contaminated sites.

Microtox and Ames bioassays were employed to assess acute toxicity and mutagenicity of water soluble components of class-fractionated oils extracted from one creosote- and four petroleum-contaminated soils. Microtox results revealed that potential acute toxicity resides mainly in the polar class fractions at three sites and indicated potential synergistic and antagonistic effects between compounds in the total extracts at two sites. Ames Salmonella/microsome testing indicated that the polyaromatic fractions at two sites exhibit weak mutagenicity with enzymatic activation, while the polar fractions at two sites are weakly mutagenic without enzyme activation. Further chemical characterization of the polar and polyaromatic fractions is required to fully assess the potential of health and ecological risks at the creosote-and petroleum-contaminated sites exhibiting these toxic responses.

Animals↗
PubMed1996

Hepatic and renal pathology of intraperitoneally administered microcystin-LR in rainbow trout (Oncorhynchus mykiss).

In 26 hr laboratory trials a dose of 1000 micrograms/kg microcystin-LR (MC-LR) caused 100% mortality in rainbow trout, while no mortality was observed at doses of 400 micrograms/kg or less. The liver to body mass ratio increased in fish exposed to the toxin which was likely due to water retention in the liver. In contrast to mammalian studies, hemorrhage of the liver was rare in fish. Exposure to MC-LR caused widespread hepatocellular swelling and lysis of hepatocyte plasma membranes, resulting in liquifactive necrosis (organelles floating in a milieux of cellular debris). Kidney lesions in the fish consisted of coagulative tubular necrosis with a dilation of Bowman's space. Lesions observed in the liver and kidney of fish exposed to MC-LR were considerably different than those previously reported for mammals.

Animals↗
PubMed1990

CO(2) Incorporation and 4-Hydroxy-2-Methylbenzoic Acid Formation during Anaerobic Metabolism of m-Cresol by a Methanogenic Consortium.

The metabolism of m-cresol by methanogenic cultures enriched from domestic sewage sludge was investigated. In the initial studies, bromoethanesulfonic acid was used to inhibit methane production. This led to the accumulation of 4.0 +/- 0.8 mol of acetate per mol of m-cresol metabolized. These results suggested that CO(2) incorporation occurred because each molecule of m-cresol contained seven carbon atoms, whereas four molecules of acetate product contained a total of eight carbon atoms. To verify this, [C]bicarbonate was added to bromoethanesulfonic acid-inhibited cultures, and those cultures yielded [C]acetate. Of the label recovered as acetate, 89% was found in the carboxyl position. Similar cultures fed [methyl-C]m-cresol yielded methyl-labeled acetate. A C-labeled transient intermediate was detected in cultures given either m-cresol and [C]bicarbonate or bicarbonate and [methyl-C]m-cresol. The intermediate was identified as 4-hydroxy-2-methylbenzoic acid. In addition, another metabolite was detected and identified as 2-methylbenzoic acid. This compound appeared to be produced only sporadically, and it accumulated in the medium, suggesting that the dehydroxylation of 4-hydroxy-2-methylbenzoic acid led to an apparent dead-end product.

Journal Article↗
PubMed1989

Uptake and biotransformation of 6,7-dimethylquinoline and 6,8-dimethylquinoline by rainbow trout (Salmo gairdneri).

1. 6,7-Dimethylquinoline (6,7-DMQ) is readily taken up by rainbow trout and bioconcentrated in tissue after exposure to ca 1 mg/l for 7.5 h. Mean bioconcentration factors (from water) were 21, 18, 6 and 14 for bile, liver, muscle and carcass respectively. Mean tissue concentrations after 69-96 h depuration were ND, ND, 0.54 and 0.48 micrograms/g for bile, liver, muscle and carcass respectively. 2. Major metabolites, following exposure to 6,7-DMQ, were conjugates (glucuronide or sulphate) of 7-hydroxymethyl-6-methylquinoline and 6-hydroxymethyl-7-methylquinoline. Mean concentration of metabolites in the bile were 500 micrograms/g after 7.5 h exposure to ca 1 mg/l and 1367 micrograms/g after 9.5 h exposure to ca 1 mg/l and 69 h depuration. 3. 6,8-Dimethylquinoline (6,8-DMQ) is also readily bioconcentrated in fish tissue after exposure to ca 1 mg/l. Mean bioconcentration factors (from water) were 23, 20, 13 and 25 for bile, liver, muscle and carcass respectively. Mean tissue concentrations after 7 h exposure to ca 1 mg/l and 63 h depuration were 4.0, 0.67, 0.49, and 3.2 micrograms/g respectively for bile, liver, muscle and carcass. 4. Major metabolites, following exposure to 6,8-DMQ were conjugates (glucuronide or sulphate) of 6,8-dimethyl-5-hydroxyquinoline, 6,8-dimethyl-7-hydroxyquinoline, 6,8-dimethyl-3-hydroxyquinoline and 6-hydroxymethyl-8-methylquinoline. Mean concentration of metabolites in the bile were 1278 micrograms/g after exposure to ca 1 mg/l for 8 h and 1031 micrograms/g after exposure to ca 1 mg/l for 7 h and 63 h depuration.

Acetylation↗
PubMed1988

Determination of polycyclic aromatic compounds in fish tissue.

A method is presented for the analysis of polycyclic aromatic hydrocarbons (PAHs), polycyclic aromatic sulfur heterocycles (PASHs), and basic polycyclic aromatic nitrogen heterocycles (PANHs) in fish. The analytical procedure includes Soxhlet extraction of prepared fish tissue with methylene chloride followed by gel permeation chromatography (GPC) using Bio-beads SX-3. For PAHs/PASHs, further cleanup is performed using adsorption chromatography on Florisil (5% water deactivated) and elution with hexane. For basic PANHs further cleanup of the fish extracts after GPC is achieved using liquid-liquid partitioning with 6 M hydrochloric acid and chloroform and then basifying the aqueous phase and extracting it with chloroform. Analysis of fortified fish samples was performed using capillary gas chromatography with flame ionization detection and capillary gas chromatography-mass spectrometry. Good agreement was observed for both methods of analysis when applied to fish samples fortified with PAHs, PASHs and basic PANHs at 0.1 to 1 microgram/g, suggesting that the method is effective at removing interfering biogenic compounds prior to analysis. Average recovery of PAHs/PASHs from fortified fish tissue was 87% and 70% for fish tissue fortified at 0.24-1.1 and 0.024-0.11 microgram/g, respectively. Average recovery for basic PANHs was 97% for fish fortified at 1.2-1.4 micrograms/g.

Animals↗