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At least 469 records · Page 26Linked to original sources
PubMed2005

Using U.S. Poison Control Center records to identify bystander pesticide exposures: a one-year surveillance of four southeastern states.

The extent to which bystanders are exposed to pesticide applications is unknown. Systematic monitoring around spray areas is not routine. Quantifying exposures is extremely difficult. Persons inadvertently exposed to pesticides often do not know the chemical or quantity, and persons living near areas of frequent field spraying may receive multiple exposures. In the U.S., concerns about health consequences from these exposures may prompt calls to poison control centers. The goal of this study was to determine what surveillance poison control centers can provide on environmental pesticide exposures to bystanders. We searched the American Association of Poison Control Centers' 2001 electronic medical records for exposure reports involving persons from 129 agriculturally intensive counties in Kentucky, Tennessee, Louisiana, and Arkansas that implicated at least one of 54 generic classifications of agricultural chemicals. We abstracted 980 pesticide-related records. Narrative sections were reviewed to determine bystander status of the exposed person. Forty-six bystander exposures were identified from 32 events. Bystander ages ranged from 2 to 81 (median: 45; 16 females, 13 males). All pertinent information for bystander classification came from narrative sections of the record. 28% identified aircraft crop dusters as the pesticide source. The most implicated substance was malathion (30.4%), while 19.6% did not know the exposure substance. 73.9% of cases were symptomatic; 65.2% of the exposed persons were seen in or referred to a healthcare facility. No hospitalizations or deaths were reported. Although they may underestimate the true numbers, U.S. poison control center data can provide valuable information about bystander environmental pesticide exposures.

Adolescent↗
PubMedDate not supplied

The impact of work related trauma on the psychological health of nursing staff: a cross sectional study.

This study aims to investigate the effects of work-related trauma exposure on the health of nursing staff in hospitals. The survey was conducted using a randomised sample of 314 nurses. Half (52.2%, n = 189) of staff surveyed had multiple exposures to different kinds of trauma. Results on the General Health Questionnaire (GHQ) and Beck's Depression Inventory--Revised (BDI-R) suggested that nearly 40% of staff experienced poor health, while nearly 10% experienced moderate to severe depression. Results of the logistic analyses, after adjusting for confounders, suggested that high and long term trauma exposure is detrimental to the mental health of nurses. These findings indicate that hospital nursing staff, in particular those who have high exposure to trauma, are in urgent need of support services such as debriefing and counselling.

Accidents, Occupational↗
PubMed2005

Welder's lung associated with pneumothorax.

A 23-year-old male working in welding for 8 years was admitted to the hospital with chest pain. A large right pneumothorax with complete lung collapse was seen radiographically and a tube thoracostomy performed. At high-resolution computed tomography, multiple bilateral well-marginated nodules with surrounding ground-glass opacity were seen. Welder's lung was considered in this patient because of his work in welding for 8 years with iron dust exposure, multiple nodules with ground-glass opacity were seen on HRCT, and serum ferritin and ferritin levels in bronchoalveolar lavage fluid were elevated. The granules in alveolar macrophages obtained from parenchymal biopsy and bronchoalveolar lavage stained strongly with iron dyes. Following avoiding exposure to welding fumes, the lung lesions disappeared without additional therapeutic interventions after a 3-week period. Welder's lung with associated lung lesions has been described, although complicating pneumothorax is unique to the case presented herein.

Adult↗
PubMed1998

Photocarcinogenicity of drugs.

A number of commonly used medications including quinolone antibiotics, psoralens and various tetracycline derivatives are photosensitizers. These chemicals enhance the erythema response to sunlight. The effect of such exposures on cancer risk has only been quantified in humans for oral psoralen photochemotherapy (PUVA). The experience of a cohort of 1380 patients followed for more than 20 years who received PUVA therapy for the treatment of psoriasis documents that long-term high dose exposure to PUVA greatly increases the risk of squamous cell carcinoma. After 15 years, the risk of melanoma is also increased among high dose patients. With PUVA therapy, an agent which is immunosuppressive in the skin, induces psoralen DNA adducts, is genotoxic and mutagenic. Substantially increased risk is only observed after many purposeful exposures to ultraviolet and this drug. These data suggest that at least some photosensitizing chemicals can substantially increase the risk of skin cancer in humans, but long-term multiple exposures appear to be necessary for a clinical meaningful increase of risk.

Follow-Up Studies↗
PubMed1990

Representational guidance of action production in observational learning: a causal analysis.

This experiment tested the hypothesis that the number of model presentations and verbal coding of modeled actions affect reproduction accuracy through their effect on cognitive representation. Subjects viewed a complex action pattern either two or eight times with or without verbal coding to highlight the dynamic structure of the component actions and their temporal sequencing. They then received, in order, a recognition test and a pictorial-arrangement test to assess the accuracy of their cognitive representations of the modeled actions. Subsequently, all subjects were tested for their ability to reproduce the action pattern from memory. Results showed that increased exposure to modeled actions enhanced the accuracy of both the cognitive representation and the behavioral reproduction. Verbal coding also increased cognitive and reproduction accuracy, but only when combined with multiple opportunities to observe the modeled actions. A causal analysis confirmed that the effects of multiple exposures and verbal coding were entirely mediated by changes produced in the accuracy of cognitive representation.

Journal Article↗
PubMed1994

Alzheimer's disease and cumulative exposure to anesthesia: a case-control study.

OBJECTIVE: To evaluate prior exposure to general anesthesia as a potential risk factor for Alzheimer's disease (AD). DESIGN: A retrospective, population-based, case-control study. SETTING: The Rochester Epidemiology Resource. PATIENTS: Cases were all incident cases of AD from 1975 to 1984 who resided for 40 years or more in Olmsted County prior to the onset of their dementia (n = 252). One age- and gender-matched control for each case was selected from all registrations for care at Mayo Clinic during the year of onset in the incident case. The case and control groups each had 252 individuals. Of these, 208 cases and 199 controls had at least one exposure to general anesthesia prior to the year of onset of dementia in the matched AD patient. MEASUREMENTS: The cumulative duration of anesthesia and the total number of general anesthetic exposures prior to the age of onset of dementia and the corresponding year in each matched control were ascertained. RESULTS: There was no significant difference in mean cumulative exposure (in minutes) to general anesthesia (patients vs controls: 188.4 vs 170.5 minutes, ns). Neither exposure to six or more episodes of general anesthesia (OR = 1.44; 95% CI: 0.77-2.71) nor cumulative exposure to 600 minutes or more of general anesthesia (OR = 1.63; 95% CI: 0.53-5.04) were associated with a significantly increased risk of AD. CONCLUSION: It is unlikely that multiple exposures to general anesthesia increase the risk of AD.

Aged↗
PubMed1978

Discoloration of permanent front teeth in 3,157 Norwegian children due to tetracyclines and other factors.

During routine orthodontic screening in Oslo, Norway, of 3,157 children, aged 1--11 years and born in 1963/64, 36 cases (1.14%) with cosmetically marring discoloration of permanent front teeth were registered. Thirty-four of them arrived for a more exhaustive examination, which in 24 of the children revealed positive tetracycline fluorescence on exposure to ultraviolet light. In 13 (0.4%) of the children, the discolorations were diagnosed to be tetracycline-induced. Enamel hypoplasia was frequently found in teeth with positive fluorescence. Multiple exposures to various tetracyclines were reported in all children who exhibited positive fluorescence.

Child↗
PubMed1984

Biologic activity of epsilon-caprolactam.

In general, this literature review indicates that epsilon-caprolactam has a relatively low toxicity to humans. This low-degree of toxicity is attributable in part to its rapid elimination as demonstrated by experimental studies on animals. Human studies are mostly those based on workers in Russian factories. Although reporting physicians attributed such symptoms as general weakness, irritability, headaches, and insomnia, and such diagnoses as neurosis, neurasthenia, rapid mood shifts as well as others to excessive caprolactam exposures, the widely recognized Russian national scourge of alcoholism, particularly among working populations was not considered as a possible factor. Some of the reports recognized the complicating existence of multiple exposures in the factories such as excessively high temperatures and humidity, high noise levels, and other chemicals - including mixtures of diphenyl and diphenyl oxide, cyclohexane, benzene, and others, but most reports gave scant or no consideration to them.

Amino Acids↗
PubMed1994

Protein databases for compacted eight-cell and blastocyst-stage mouse embryos.

High-resolution two-dimensional sodium dodecyl sulfate-polyacrylamide (2D-SDS) gel electrophoresis combined with computerized analysis of gel images was used to construct and analyze protein data-bases for two stages of preimplantation mouse embryogenesis, the compacted eight-cell stage and the fully expanded blastocyst stage. These stages were chosen for their ease in identification of multiple synchronous embryos. Synchronous cohorts of 30-50 embryos were labelled with L-[35S]methionine for 2 hr. The embryos were then lysed in 30 microliters hot SDS sample buffer, and the lysates were stored at -80 degrees C until the gels were run. Five replicates were run for eight-cell embryos, and four for blastocyst-stage embryos. The samples were processed for 2D gel electrophoresis and fluorography; multiple exposures were made. Gel images were analyzed using the PDQUEST system, and databases were constructed. Analysis of the databases for both developmental stages showed high reproducibility of protein spots in multiple gel images. Of 1,674 total spots in eight-cell embryo standards, > 79% of spots had a percentage error (S.E.M./average) < 50%, and > 45% had a percentage error < 30%. Similarly, of 1,653 total spots in blastocyst-stage embryo standards, 74% of spots had a percentage error < 50%, and approximately 47% of spots had a percentage error < 30%. Forty-three spots (approximately 3% of the total spots) were found to be detected only in the eight-cell stage, while 75 spots were detected solely in the blastocyst stage. Sixty-nine proteins showed a greater than threefold increase in isotope incorporation from the eight-cell to the blastocyst stage, with a percentage error < 50% in both the eight-cell and the blastocyst stages. In contrast, 41 of the proteins showed a decrease during this period. Analysis of the protein databases described in this study has allowed us to document the overall quantitative changes in proteins from the compacted eight-cell stage to the blastocyst stage of mouse preimplantation development. These data-bases provide a valuable tool for further detailed quantitative analysis of specific proteins associated with developmental events. In addition they will permit analysis of the effects of environmental factors, such as growth factors, on early embryo development.

Animals↗
PubMed1973

Studies on heterologous immunity in schistosomiasis. 7. Observations on the development of acquired homologous and heterologous immunity to Schistosoma mansoni in baboons.

Observations were made on the development of immunity to Schistosoma mansoni in baboons using both homologous and heterologous systems. The baboons were immunized by either (a) a single exposure to cercariae of the homologous species S. mansoni, or (b) 1-2 exposures to cercariae of either a S. rodhaini/S. mansoni hybrid or a S. mattheei/S. haematobium hybrid, or (c) repeated exposure to the cercariae of S. rodhaini or S. bovis. Baboons immunized with 500 cercariae of the homologous parasite developed partial immunity to reinfection, as did the baboons immunized with multiple exposures to the heterologous cercariae of S. rodhaini and S. bovis, although these parasites produced neither adult worms nor eggs in the baboons. The hybrids gave rise to well-established adult worm infections, but produced less immunity, even though the S. rodhaini/S. mansoni hybrid was genetically very similar to S. mansoni. These results indicate that adult worms are not essential to produce a considerable degree of immunity to reinfection, which can be engendered by the earlier stages of the parasites. However, none of the immune responses prevented egg deposition in the tissues, and considerable pathological changes resulted from the challenge infection. These observations suggest that although heterologous infections show some promise as immunizing agents, further studies are needed of the pathological changes resulting from their use.

Animals↗
PubMed1985

Comparative changes in rat liver cytosolic proteins by mirex, diethylnitrosamine, and dimethylnitrosamine exposure.

Using a newborn rat model for carcinogenesis, changes in liver cytosolic proteins at three stages of tumorigenesis, on Days 21, 97, and 120, by mirex (dodecachloropentacyclo-1,3,4-metheno-2H-cyclobuta[cd] pentalene), and diethyl- and dimethylnitrosamines (DEN and DMN) were studied. Following multiple exposure to the hepatocarcinogens, groups of weanling rats were given dietary phenobarbital (PB) up to 120 days. SDS-PAGE separation of cytosolic proteins showed that at 21 days, prior to PB, two proteins of 26K and 23K mol wt were significantly induced by mirex and DMN while a high mol wt 63K protein was induced only by DEN and DMN. During the period of PB treatment up to 97 days, these proteins were well sustained at a higher level. A marked increase in 21K protein band was also observed at this point. In tumor tissues obtained from DEN and DMN rats continued on PB diet for 120 days, the high level of 63K protein was seen only in DEN and not in DMN tumor. The tumors also showed a significant reduction in 25K protein compared to 21- and 97-day groups. The presence of even lower mol wt proteins of 14-21K was seen in tumors. The early detection and further characterization of these low mol wt proteins may provide clues as to whether they are preneoplastic markers or oncogene products as speculated by other investigators. Moreover, certain similarities in the induction of cytosolic proteins by "epigenetic" and "genotoxic" carcinogens raise more interesting questions regarding the mechanisms of action of these distinct classes of carcinogens.

Animals↗
PubMed1995

Respiratory dysfunction in swine production facility workers: dose-response relationships of environmental exposures and pulmonary function.

Human respiratory health hazards for people working in livestock confinement buildings have been recognized since 1974. However, before comprehensive control programs can be implemented, more knowledge is needed of specific hazardous substances present in the air of these buildings, and at what concentrations they are harmful. Therefore, a medical epidemiological and exposure-response study was conducted on 207 swine producers using intensive housing systems (108 farms). Dose-response relationships between pulmonary function and exposures are reported here. Positive correlations were seen between change in pulmonary function over a work period and exposure to total dust, respirable dust, ammonia, respirable endotoxin, and the interactions of age-of-producer and dust exposure and years-of-working-in-the-facility and dust exposure. Relationships between baseline pulmonary function and exposures were not strong and therefore, not pursued in this study. The correlations between exposure and response were stronger after 6 years of exposure. Multiple regression models were used to identify total dust and ammonia as the two primary environmental predictors of pulmonary function decrements over a work period. The regression models were then used to determine exposure concentrations related to pulmonary function decrements suggestive of a health hazard. Total dust concentrations > or = 2.8 mg/m3 were predictive of a work period decrement of > or = 10% in FEV1. Ammonia concentrations of > or = 7.5 ppm were predictive of a > or = 3% work period decrement in FEV1. These predictive concentrations were similar to a previous dose-response study, which suggested 2.5 mg/m3 of total dust and 7 ppm of NH3 were associated with significant work period decrements. Therefore, dust > or = 2.8 mg/m3 and ammonia > or = 7.5 ppm should be considered reasonable evidence for guidelines regarding hazardous exposure concentrations in this work environment.

Adult↗
PubMed1973

Jaundice after multiple halothane anaesthetics administered during the treatment of carcinoma of the uterus.

Halothane is thought to cause hepatitis after multiple exposures in certain susceptible patients. Patients undergoing repeated anaesthetics for insertion of radioactive implants for gynaecological neoplasia appear to be particularly at risk. We are reporting three cases in which hepatitis has followed multiple halothane anaesthetics, and discuss them with reference to our present knowledge of this complication.

Aged↗
PubMed2000

Government laboratory worker with lung cancer: comparing risks from beryllium, asbestos, and tobacco smoke.

Occupational medicine physicians are frequently asked to establish cancer causation in patients with both workplace and non-workplace exposures. This is especially difficult in cases involving beryllium for which the data on human carcinogenicity are limited and controversial. In this report we present the case of a 73-year-old former technician at a government research facility who was recently diagnosed with lung cancer. The patient is a former smoker who has worked with both beryllium and asbestos. He was referred to the University of California, San Francisco, Occupational and Environmental Medicine Clinic at San Francisco General Hospital for an evaluation of whether past workplace exposures may have contributed to his current disease. The goal of this paper is to provide an example of the use of data-based risk estimates to determine causation in patients with multiple exposures. To do this, we review the current knowledge of lung cancer risks in former smokers and asbestos workers, and evaluate the controversies surrounding the epidemiologic data linking beryllium and cancer. Based on this information, we estimated that the patient's risk of lung cancer from asbestos was less than his risk from tobacco smoke, whereas his risk from beryllium was approximately equal to his risk from smoking. Based on these estimates, the patient's workplace was considered a probable contributing factor to his development of lung cancer.

Aged↗
PubMed1993

Probability-summation model of multiple laser-exposure effects.

A probability-summation model is introduced to provide quantitative criteria for discriminating independent from interactive effects of multiple laser exposures on biological tissue. Data that differ statistically from predictions of the probability-summation model indicate the action of sensitizing (synergistic/positive) or desensitizing (hardening/negative) biophysical interactions. Interactions are indicated when response probabilities vary with changes in the spatial or temporal separation of exposures. In the absence of interactions, probability-summation parsimoniously accounts for "cumulative" effects. Data analyzed using the probability-summation model show instances of both sensitization and desensitization of retinal tissue by laser exposures. Other results are shown to be consistent with probability-summation. The relevance of the probability-summation model to previous laser-bioeffects studies, models, and safety standards is discussed and an appeal is made for improved empirical estimates of response probabilities for single exposures.

Humans↗
PubMedDate not supplied

Correlation of chemopreventive efficacy data from the human epidermal cell assay with in vivo data.

Continuous exposure to low doses of potentially mutagenic and carcinogenic chemicals over the human lifetime makes the identification of agents, which could reduce the ensuing risk of cancer, beneficial. The Human Epidermal Cell (HEC) Assay includes multiple exposures to low, non-toxic doses of propane sultone, which increases cellular growth and inhibits differentiation, and co-exposure to potential chemopreventive agents to determine their ability to inhibit the increased growth or increase differentiation. Original data are presented on the efficacy of twenty potential cancer chemopreventive agents were screened for efficacy in the HEC Assay. Efficacy was determined by the ability of agents, at nontoxic concentrations, to reverse either of the propane sultone-induced biomarkers, enhanced growth and reduced involucrin expression. Based on the number of positive concentrations and the lack of toxicity, 1,2-dithiol-3-thione, oltipraz, and a synthetic retinoid, Ro 16-9100, were the most active. Eleven of seventeen positive agents were active for both endpoints. S-Allylcysteine was only active for the growth inhibition endpoint, and DFMO, Iycopene, perillyl alcohol, ursodiol, and black tea polyphenols were only active for the involucrin endpoint. The three agents that have been shown to be negative in animal models, diphenhydramine, d-mannitol, and nordihydroguaiaretic acid, were correctly identified as negative by the assay. When the data from previous studies (Elmore et al, Anticancer Res, 19: 909-918, 1999) are included, a positive response in one or more endpoints of the HEC Assay correlates 100% (26/26) with a positive response in one or more of the animal cancer prevention models (8). The available data suggest that the HEC Assay response is highly predictive of efficacy in animals in vivo with an overall accuracy of 90%. Future studies will include data with additional negative agents. The correlation of the HEC Assay data with data from in vivo studies in animal models, which utilize multiple carcinogens and multiple target organs, would suggest that this in vitro assay has the ability to identify agents with the potential to prevent carcinogen-induced cancer. While our ultimate goal is to identify agents with potential efficacy for preventing human cancer, sufficient human data are not yet available to make this correlation.

Anticarcinogenic Agents↗
PubMedDate not supplied

The detection of DNA-protein cross-links in rat tracheal implants exposed in vivo to benzo[a]pyrene and formaldehyde.

The DNA damage associated with benzo(a)pyrene (B[a]P) and formaldehyde (HCHO) exposure in rat tracheal implants was determined by alkaline filter elution adapted to measure DNA-protein cross-links (DPC) in vivo. In addition, histopathological responses of the tracheal epithelium were quantitated after multiple exposures to 20 micrograms B[a]P and 0.2% HCHO. Compared to either agent alone, combined exposure for 1-4 weeks caused an increase in cellular atypia and greater thickness of hyperplastic and metaplastic lesions. HCHO exposure resulted in a dose-dependent increase in DPC with a maximal response of 85% DNA filter retention at 0.2% HCHO, which were mostly removed by 72 h. B[a]P did not cause DPC, but when tracheas were pre-exposed to 20 micrograms B[a]P followed by 0.05% HCHO there was a 15% decrease in HCHO-induced DPC. This competition between B[a]P and HCHO for sites presumably on DNA does not offer a clear explanation for their markedly enhanced cocarcinogenicity observed in previous studies, but does demonstrate the interaction between the two agents in tracheal epithelium.

Animals↗
PubMed1994

Survey of construction workers repeatedly exposed to chlorine over a three to six month period in a pulpmill: II. Follow up of affected workers by questionnaire, spirometry, and assessment of bronchial responsiveness 18 to 24 months after exposure ended.

OBJECTIVE: The aim was to determine the prevalence of persistent respiratory symptoms and bronchial hyper-responsiveness due to reactive airways dysfunction syndrome in a population of construction workers at moderate to high risk of developing the syndrome, at an interval of 18 to 24 months after multiple exposures to chlorine gas during renovations to a pulp and paper mill. DESIGN AND PARTICIPANTS: 71 of 289 exposed workers (25%) were identified on the basis of an exposure and the onset of respiratory symptoms shortly after this event (moderate to high risk). A standardised respiratory questionnaire was first presented, followed by spirometry and a methacholine inhalation test on those whose questionnaire suggested the persistence of respiratory symptoms. RESULTS: 64 of 71 (90%) subjects completed the respiratory questionnaire at the time of the follow up. The questionnaire suggested a persistence of respiratory symptoms in 58 of the 64 workers (91%). Of the 58 subjects, 51 underwent spirometry and assessment of bronchial responsiveness. All of them used bronchodilators as required (not regularly) and four required inhaled anti-inflammatory preparations. Sixteen had bronchial obstruction (forced expiratory volume in one second) (FEV1 < 80% predicted) and 29 showed significant bronchial hyper-responsiveness. CONCLUSION: Of the subjects (n = 71) who were at moderate to high risk of developing reactive airways dysfunction syndrome after being exposed to chlorine and were seen 18 to 24 months after exposure ended, 58 (82%) still had respiratory symptoms, 16 (23%) had evidence of bronchial obstruction, and 29 (41%) had bronchial hyper-responsiveness.

Adult↗