Biomedical subjects

Bruce Thomson

Publications and source records attributed to Bruce Thomson.

6 recordsLinked to original sources

PubMed2005

Occurrence of antibiotics in hospital, residential, and dairy effluent, municipal wastewater, and the Rio Grande in New Mexico.

This study had three objectives: 1) determine occurrence of antibiotics in effluent from hospitals, residential facilities, and dairies, and in municipal wastewater 2) determine antibiotic removal at a large wastewater treatment plant (WWTP) in Albuquerque, NM, and 3) determine concentrations of antibiotics in the Rio Grande, which receives wastewater from the Albuquerque WWTP. Twenty-three samples of wastewater and 3 samples of Rio Grande water were analyzed for the presence of 11 antibiotics. Fifty-eight percent of samples had at least one antibiotic present while 25% had three or more. Hospital effluent had detections of sulfamethoxazole, trimethoprim, ciprofloxacin, ofloxacin, lincomycin, and penicillin G, with 4 of 5 hospital samples having at least one antibiotic detected and 3 having four or more. At the residential sampling sites, ofloxacin was found in effluent from assisted living and retirement facilities, while the student dormitory had no detects. Only lincomycin was detected in dairy effluent (in 2 of 8 samples, at 700 and 6600 ng/L). Municipal wastewater had detections of sulfamethoxazole, trimethoprim, ciprofloxacin, and ofloxacin, with 4 of 6 samples having at least one antibiotic present and 3 having 3 or more. The relatively high concentrations (up to 35,500 ng/L) of ofloxacin found in hospital and residential effluent may be of concern due to potential genotoxic effects and development of antibiotic resistance. At the Albuquerque WWTP, both raw wastewater and treated effluent had detections of sulfamethoxazole, trimethoprim, and ofloxacin, at concentrations ranging from 110 to 470 ng/L. However, concentrations in treated effluent were reduced by 20% to 77%. No antibiotics were detected in the Rio Grande upstream of the Albuquerque WWTP discharge, and only one antibiotic, sulfamethoxazole, was detected in the Rio Grande (300 ng/L) below the WWTP.

Anti-Bacterial Agents↗

PubMed2004

Solid-phase microextraction combined with surface-enhanced laser desorption/ionization introduction for ion mobility spectrometry and mass spectrometry using polypyrrole coatings.

The successful application of polypyrrole (PPY) solid-phase microextraction (SPME) coatings as both an extraction phase and a surface to enhance laser desorption/ionization (SELDI) of analytes is reported. This SPME/SELDI fiber integrates sample preparation and sample introduction on the tip of a coated optical fiber, as well as acting as the transmission medium for the UV laser light. Using ion mobility spectrometry (IMS) detection, the signal intensity was examined as a function of extraction surface area and concentration of analyte. The linear relationship between concentration and signal intensity shows potential applicability of this detection method for quantitative analysis. Extraction time profiles for the fiber, using tetraoctylammonium bromide as test analyte, illustrated that equilibrium can be reached in less than one minute. To investigate the performance of the PPY coating, the laser desorption profile was studied. The fiber was also tested using a quadrupole time-of-flight (Q-TOF) mass spectrometer with leucine enkephalin as test analyte. Since no matrix was used, mass spectra free from matrix background were obtained. This novel SPME/SELDI fiber is easy to manufacture, and is suitable for studying low-mass analytes because of the intrinsic low background. These findings suggest that other types of conductive polymers could also be used as an extraction phase and surface to enhance laser desorption/ionization in mass spectrometry.

Journal Article↗

PubMed2004

Temporal variation in daily concentrations of ozone and acid-related substances at Saturna Island, British Columbia.

A multiple linear regression model was used to investigate seasonal and long-term trends in concentrations of ozone (O3) and acid-related substances at the Saturna Island monitoring station in southwestern British Columbia from 1991 to 2000. Statistically significant primary (dominant) cycles with a period of 1 yr were found for O3, sulfur dioxide (SO2), nitric acid (HNO3), and aerosol concentrations of sulfate (SO4(2-)), calcium (Ca2+) and chloride (Cl-). Of these, peak median concentrations occurred during the spring for O3 and Ca2+, during the warmer, drier months (April-September) for SO4(2-) and HNO3, and during the cooler, wetter months (October-March) for SO2 and Cl-. Statistically significant secondary cycles of 6 months duration were seen for concentrations of O3, SO4(2-), HNO3, Ca2+, and Cl-. Daily maximum O3 concentrations exhibited a statistically significant increase over the period of record of 0.33 +/- 0.26 ppb/yr. Statistically significant declines were found for concentrations of SO2, SO4(2-), HNO3, Ca2+, and potassium, ranging from 20 to 36% from levels at the start of the sampling period. Declines in ambient concentrations of SO2, SO4(2-), and HNO3 reflect local declines in anthropogenic emissions of the primary precursors SO2 and NOx over the past decade. Trends in Ca2+ and potassium ion concentrations are in line with a broader North American declining trend in acid-neutralizing cations.

Acid Rain↗

PubMed2003

Identifying US populations for the study of health effects related to drinking water arsenic.

The US Environmental Protection Agency recently set a new maximum contaminant level (MCL) for arsenic in drinking water of 10 micro g/l. In this paper, we review the completeness and accuracy of drinking water arsenic occurrence data in the United States and identify populations exposed to elevated arsenic concentrations that would be suitable for epidemiological studies of arsenic health effects. Using existing data from the Environmental Protection Agency Arsenic Occurrence and Exposure Database and additional data from state health and environment departments and water utilities, we identified 33 counties in 11 states with an estimated mean drinking water arsenic concentration of 10 micro g/l or greater. A total of 11 of these 'confirmed' counties had an estimated mean arsenic concentration of 20 micro g/l or more and two had an estimated mean arsenic concentration 50 micro g/l or more. Based on census data, between 1950 and 1999 there were approximately 51.1 million person-years of exposure to drinking water arsenic at levels of 10 micro g/l or more, 8.2 million at levels of 20 micro g/l or more arsenic and 0.9 million at levels of 50 micro g/l or more. Mortality and incidence of diseases known to be associated with arsenic exposure can and should be examined in these counties as part of a comprehensive assessment of arsenic health effects in US populations.

Arsenic↗

PubMed2002

Solid phase microextraction with matrix assisted laser desorption/ionization introduction to mass spectrometry and ion mobility spectrometry.

Solid phase microextraction (SPME) with matrix assisted laser desorption/ionization (MALDI) introduction was coupled to mass spectrometry and ion mobility spectrometry. Nicotine and myoglobin in matrix 2,5-dihydroxybenzonic acid (DHB), enkephalin and substance P in alpha-cyano-4-hydroxy cinnaminic acid were investigated as the target compounds. The tip of an optical fiber was silanized for extraction of the analytes of interest from solution. The optical fiber thus served as the sample extraction surface, the support for the sample plus matrix, and the optical pipe to transfer the laser energy from the laser to the sample. The MALDI worked under atmospheric pressure, and both an ion mobility spectrometer and a quadrupole/time-of-flight mass spectrometer were used for the detection of the SPME/MALDI signal. The spectra obtained demonstrate the feasibility of the SPME with MALDI introduction to mass spectrometry instrumentation.

Enkephalins↗

PubMed2002

Physical injury risks associated with drinking water arsenic treatment.

We estimated the number of transportation deaths that would be associated with water treatment in Albuquerque to meet the EPA's recently proposed revisions of the Maximum Contaminant Level (MCL) for arsenic. Vehicle mileage was estimated for ion exchange, activated alumina, and iron coagulation/microfiltration water treatment processes to meet an MCL of 0.020 mg/L, 0.010 mg/L, 0.005 mg/L, and 0.003 mg/L. Local crash, injury, and death rates per million vehicle miles were used to estimate the number of injuries and deaths. Depending on the water treatment options chosen, we estimate that meeting an arsenic MCL of 0.005 mg/L will result in 143 to 237 crashes, 58 to 98 injuries, and 0.6 to 2.6 deaths in Albuquerque over a 70-year period, resulting in 26 to 113 years of life lost. The anticipated health benefits for Albuquerque residents from a 0.005 mg/L arsenic MCL, estimated using either a multistage Weibull or Poisson model, ranged from 3 to 80 arsenic-related bladder and lung cancer deaths prevented over a 70-year period, adding between 43 and 1,123 years of life. Whether a revised arsenic MCL increases or reduces overall loss of life in Albuquerque depends on the accuracy of EPA's cancer risk assessment. If the multistage Weibull model accurately estimates the benefits, the years of life added is comparable or lower than the anticipated years lost due to transportation associated with the delivery of chemicals, disposal of treatment waste, and operation of the water treatment system. Coagulation/microfiltration treatment will result in substantially fewer transportation deaths than either ion exchange or activated alumina.

Accidents, Traffic↗