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J D Tessari

Publications and source records attributed to J D Tessari.

29 records · Page 2Linked to original sources
PubMed1980

Gas-liquid chromatographic determination of organochlorine pesticides and polychlorinated biphenyls in human milk.

A method for the detection of organochlorine pesticides and polychlorinated biphenyls (PCBs) in human milk is described. The method involves quantitative extraction of human milk with acetone and hexane. The pesticide and PCB residues are extracted from the milk fat with acetonitrile (ACN) and then partitioned back into hexane by aqueous dilution of the ACN extract. The ACN partitioning is followed by cleanup with Florisil column chromatography, eluting with 6 and 15% mixtures of ethyl ether-hexane. The 6% eluate is concentrated and transferred to a silicic acid column for separation of PCBs from pesticide residues. Compounds are quantitated by gas-liquid chromatography. Recovery studies demonstrated that the procedure provides 68-103% recovery for pesticides and PCBs.

Chromatography, Gas↗
PubMedDate not supplied

Two-stage evaluation of exposure to mercury and biomarkers of neurotoxicity at a hazardous waste site.

Communities surrounding the Rocky Mountain Arsenal (RMA), a Superfund site in Colorado, were studied in order to determine whether exposures to mercury were greater among persons who resided there than among residents of a comparison area 12-15 miles distant. From a census-based stratified random sample, 469 persons were interviewed and urine samples were obtained for biomonitoring. Mercury was detected in urine from 32 (6.8%) of the 469 persons sample at a detection limit of 5 ppb. Trace levels of mercury (detectable, but nonquantifiable) were found in 80 (17.1%) of the persons sampled. Neither the frequency of detection, the arithmetic mean, nor the geometric mean value for urine mercury was found to be statistically different when persons living near the site were compared to persons from the more distant comparison area. The risk of mercury exposure associated with demographic variables, residence, occupation, hobbies, dietary habits, water supply, housing, and activity patterns was evaluated. In the second stage of the evaluation, the Neurobehavioral Core Test Battery (NCTB) is being used to assess individual functional deficits and nervous system disorders associated with exposure to mercury and other neurotoxic chemicals.

Adolescent↗
PubMedDate not supplied

Field evaluation of a portable photoionization detector for assessing exposure to solvent mixtures.

To evaluate a portable photoionization detector for assessing personal exposure to solvent mixtures, a set of 26 side-by-side, time-weighted average (TWA) personal breathing zone samples were collected during various construction painting tasks by two different sampling methods: (1) standard charcoal sorbent tubes analyzed by gas chromatography (CST/GC), and (2) a direct-reading photoionization detector coupled with an extended data-logger (PID). The TWA concentrations of the hydrocarbons detected by CST/GC analysis were summed for comparison with the TWA concentration obtained from the direct-reading PID. Based on linear regression between the log TWA concentrations of the two sampling methods, the data were highly correlated (r2 = 0.95). Since the solvents had effects that may be considered additive, threshold limit values (TLVs) for mixtures were developed using American Conference of Governmental Industrial Hygienists formulas to evaluate solvent exposure. The logs of the TLV mixture data from the sampling methods were highly correlated (r2 = 0.94). Based on the linear regression analyses, the response of the portable PID was highly correlated to the CST/GC results for hydrocarbon mixtures encountered during various painting tasks. Due to the short duration of tasks, highly fluctuating exposures, and complexity of the mixtures, the PID may provide the most cost-effective, detailed exposure assessment for solvent mixtures.

Air Pollutants, Occupational↗
PubMedDate not supplied

1995 STP Young Investigator Award recipient. Increased rate of apoptosis correlates with hepatocellular proliferation in Fischer-344 rats following long-term exposure to a mixture of groundwater contaminants.

Apoptosis was evaluated in the livers of Fischer-344 rats following observations of increased hepatocellular proliferation from exposures, at low parts per million (ppm) levels, to a drinking water mixture of 7 groundwater contaminants during a 6-mo time-course study. The 7 chemicals used are among the most frequently detected contaminants associated with hazardous waste sites: arsenic, benzene, chloroform, chromium, lead, phenol, and trichloroethylene. Significant increases in 5-bromo-2'-deoxyuridine hepatocellular labeling were present in a unique pattern surrounding large hepatic veins (0.5-2.0 mm). This did not appear to be a regenerative response due to cytotoxicity, as assessed by the absence of increased plasma enzyme activity and the absence of hepatocellular lesions. Immunohistochemical staining for apoptosis, using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method showed patterns of labeling in treated animals that directly correlated to areas of increased hepatocyte proliferation. Apoptotic activity was maximum at the 1-mo exposure time point, whereas proliferating hepatocytes reached a maximum rate at the 10-day time point. This may have been triggered as a compensatory response to the increased cell proliferation or as a protective response to remove cells with altered DNA due to chemical mixture exposure. The principal findings of this paper are that (a) apoptosis directly correlated with changes in cell proliferation: (b) observed effects were produced by repeated exposures to a relatively low-level chemical mixture; and (c) the TUNEL method detected apoptotic cells at very early and late stages, potentially increasing the observable time period for apoptosis.

Animals↗
PubMedDate not supplied

Canine exposure to herbicide-treated lawns and urinary excretion of 2,4-dichlorophenoxyacetic acid.

A recent study by Hayes et al. (J. Natl. Cancer. Inst., 83: 1226-1231, 1991) found an increased risk of malignant lymphoma associated with exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) in pet dogs. We conducted a study to determine the extent to which dogs absorb and excrete 2,4-D in urine after contact with treated lawns under natural conditions. Among 44 dogs potentially exposed to 2,4-D-treated lawns an average of 10.9 days after application, 2,4-D concentrations greater than or equal to 10.0 micrograms/l were found in 33 dogs (75%) and concentrations of > or = 50 micrograms/l were found in 17 (39%). Among 15 dogs with no known exposure to a 2,4-D-treated lawn in the previous 42 days, 4 (27%) had evidence of 2,4-D in urine, 1 at a concentration of > or = 50 micrograms/l. The odds ratio for the association between exposure to a 2,4-D-treated lawn and the detection of > or = 50 micrograms/l 2,4-D in urine was 8.8 (95% confidence interval, 1.4-56.2). Dogs exposed to lawns treated within 7 days before urine collection were more than 50 times as likely to have 2,4-D at concentrations > or = 50 micrograms/l than dogs with exposure to a lawn treated more than 1 week previously (odds ratio = 56.0; 95% confidence interval, 10.0-312.2). The highest mean concentration of 2,4-D in urine (21.3 mg/l) was found in dogs sampled within 2 days after application of the herbicide.(ABSTRACT TRUNCATED AT 250 WORDS)

2,4-Dichlorophenoxyacetic Acid↗