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Abstract
Perchloroethylene is a solvent that is widely used for dry cleaning. There has been considerable interest in the toxicity of this chemical because of the potential for low-level exposure among a large portion of the US population. Although substantial epidemiologic literature exists on high-level occupational exposure to perchloroethylene, there are relatively few studies dealing with lower-level residential exposure. In the current paper, the author reviews this limited residential literature, with special emphasis on strengths, limitations, and consistency. Reviewed studies primarily address neurobehavioral, cancer, and reproductive endpoints. Most studies used an ecological or cross-sectional design, with exposure defined by either drinking-water contamination or proximity to dry cleaning. In general, reviewed studies were highly exploratory, with inconsistencies and potential for bias that detract from interpretation of study findings. The magnitudes of reported effects are frequently incompatible with the effects reported from much higher occupational and human-chamber exposures. Overall, few reliable conclusions can be drawn from this sparse and highly limited body of literature.
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Abstract
Industry and government institutions need a credible approach for evaluating and responding to emerging public health issues. Representatives of industry, government, and academia met under the auspices of the International Life Sciences Institute's Health and Environmental Sciences Institute (HESI) to develop successful strategies for dealing with emerging issues based on historical case studies. The case studies chosen for evaluation were (1) tampon use and toxic shock syndrome; (2) hazardous waste and childhood cancer risk in Toms River, New Jersey; (3) fenfluramine and phentermine use and valvular heart disease; (4) silicone breast implants and cancer and auto-immune disease; and (5) progestational drugs and birth defects. We identified eight lessons from these case studies. Foremost, we recommend that public and private institutions not defer action until an issue is scientifically resolved and stress that cooperation among issue stakeholders is critical for effective issue resolution. We suggest establishing a research program as an effective way to assure that good science is included in resolution of the issue. We further recommend frequent and timely communication with all stakeholders, and the development of research approaches to fill gaps when the scientific data on an issue are limited.
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Hygiene Hypothesis: A Review of Chronic Diseases Beyond Allergies and Asthma. Am J Epidemiol 2006. [DOI: 10.1093/aje/163.suppl_11.s15-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Association between air pollution and adverse pregnancy outcomes in Vancouver. ENVIRONMENTAL HEALTH PERSPECTIVES 2004; 112:A792-A794. [PMID: 15471710 PMCID: PMC1247591 DOI: 10.1289/ehp.112-a792a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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5
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Abstract
The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that the threshold limit value (TLV) for mineral oil mists be dramatically lowered, based on epidemiological evidence of respiratory health effects among machinists exposed to various metalworking fluid mists. A review of the literature regarding respiratory health effects from either metalworking or non-metalworking fluids suggest that machinists may have experienced slightly higher prevalence of common respiratory symptoms and mild and reversible cross-shift changes in some measures of pulmonary function. However, the inconsistency and potential for both random and systematic error in this body of literature argue against drawing definitive conclusions. There is also no substantive evidence that any of these effects led to permanent disease or impairment. The most likely causal agents for respiratory effects in these workers are microbial contaminants in water-based metalworking fluids, not straight mineral oils. This is consistent with the epidemic outbreaks of hypersensitivity pneumonitis, bronchitis, and asthma reported at some work sites using water-based metalworking fluids. This highlights the importance of frequent cleaning and fluid changes for metalworking fluid reservoirs, as part of a systematic approach to managing metalworking fluid aerosol exposures. A dramatic drop in the TLV for mineral oil mists would not resolve this problem.
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Practical implications of nonlinear effects in risk-assessment harmonization. NONLINEARITY IN BIOLOGY, TOXICOLOGY, MEDICINE 2004; 2:3-10. [PMID: 19330103 PMCID: PMC2647819 DOI: 10.1080/15401420490426927] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cancer and noncancer health effects have traditionally been handled differently in quantitative risk assessment. A threshold (i.e., safe exposure) has been assumed for noncancer health effects, and low-dose linearity without a threshold has been assumed for cancer. "Harmonization" attempts to reconcile these contrasting assumptions under one paradigm. Recent regulatory initiatives suggest that the U.S. Environmental Protection Agency may be leaning toward a harmonized, probabilistic/linear approach for noncancer health effects. Proponents of this approach cite variability in human susceptibility as an argument against thresholds (i.e., some individuals may be exquisitely sensitive at exposures well below threshold levels). They also cite the results of epidemiological models that suggest low-dose linearity for noncancer health effects. We will discuss the implications of these arguments and compare them to what is known about human biological variability in general. We will also touch on the regulatory implications of hormesis within this framework.
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An analysis of the risk of B-lymphocyte malignancies in industrial cohorts. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2003; 66:581-597. [PMID: 12751389 DOI: 10.1080/15287390309353768] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Among numerous studies of occupational groups with varied chemical exposures (e.g., farmers, petroleum workers, and rubber workers), some have reported excess risk for non-Hodgkin's lymphoma (NHL), multiple myeloma, and other cancers of the B-lymphocyte cell line. While not conclusive, these studies raise questions about the effects of chemical exposures on the lymphocytic versus myeloid cell lines. Almost 70 occupational cohort studies were identified that addressed B-cell cancer risks in 9 major industrial categories, in order to look for common patterns across industries. This effort was substantially limited by the inconsistent nature of lymphohematopoietic (LH) classification schemes across studies and over time, and the relative paucity of B-cell-specific results in studies for any given industry. Taking these limitations into consideration, a descriptive, graphical analysis suggested a pattern of B-cell cancer elevations in the rubber and "general chemical" industries, but no consistent patterns in petroleum production/distribution or petrochemical production. The limited data sources, which lack detail about differences in hazard and exposure for different types of products/chemicals, did not allow a comprehensive look at possible common exposures associated with B-cell cancer elevations across industries. This study suggests that evaluation of possible associations between specific chemical exposures and B-cell malignancies would require additional studies with clear and common definitions of B-cell outcomes. The article concludes by giving an example of a possible common framework for categorizing NHL, the diseases for which most classification issues arise.
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MESH Headings
- Butadienes/toxicity
- Case-Control Studies
- Cohort Studies
- Hazardous Substances/toxicity
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/chemically induced
- Leukemia, Lymphocytic, Chronic, B-Cell/classification
- Leukemia, Lymphocytic, Chronic, B-Cell/epidemiology
- Lymphoma, B-Cell/chemically induced
- Lymphoma, B-Cell/classification
- Lymphoma, B-Cell/epidemiology
- Multiple Myeloma/chemically induced
- Multiple Myeloma/classification
- Multiple Myeloma/epidemiology
- Occupational Diseases/chemically induced
- Occupational Diseases/classification
- Occupational Diseases/epidemiology
- Occupational Exposure/adverse effects
- Occupations/statistics & numerical data
- Petroleum/toxicity
- Population Surveillance
- Risk Factors
- Rubber/toxicity
- Styrene/toxicity
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Is the hygiene hypothesis an example of hormesis? NONLINEARITY IN BIOLOGY, TOXICOLOGY, MEDICINE 2003; 1:155-166. [PMID: 19330119 PMCID: PMC2651604 DOI: 10.1080/15401420391434306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
UNLABELLED The "hygiene hypothesis" has been suggested to explain the rising incidence of allergic disorders in developed countries. The postulated mechanism is that infectious and/or microbial agents stimulate the immune system toward Th1 (allergy fighting) rather than Th2 (allergy promoting) response. This paper reviews the evidence related to early life infectious/microbial exposures and subsequent atopic disorders and evaluates whether these data suggest a hormetic effect. Our review indicates an insufficient and contradictory association for bacterial/viral infections, with protective effects being either absent or specific to certain infections and/or populations. Chronic, heavy parasitic burdens appear to confer protection against atopic disorders, but are associated with considerable pathology. Moreover, light parasitic burden may increase allergic responses (i.e., no "low dose" beneficial effect). In contrast, there is consistent evidence that general microbial exposures, particularly gut commensals, may be protective against allergy development, which is consistent with a hormetic effect (i.e., potentially beneficial effects at low doses and detrimental effects at high levels). CONCLUSION General microbial exposures in relation to the "hygiene hypothesis" may represent a hormetic effect, although further research with more rigorous study methods (i.e., prospective designs and measurement of exposure timing, dose, route, etc.) are needed.
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Using epidemiological studies to check the consistency of the cancer risks predicted by high-dose animal experiments: a methodological review. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2001; 21:601-611. [PMID: 11726015 DOI: 10.1111/0272-4332.214138] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Epidemiological studies have been cited in the literature as evidence both for and against the human cancer risks predicted by high-exposure rodent studies. However, there has been little overall consistency in the ways that these animal-to-human comparisons have been made. This review examines some examples of these types of comparisons and describes the methods and techniques used by different investigators. Eleven "key decision areas" that need to be addressed are identified and recommendations for consistent, logical, and statistically appropriate approaches that might be taken to standardize the process are provided. In general, it is suggested that investigators provide the most useful information when they use logical, transparent, and statistically valid comparisons to pursue limited and focused objectives, such as directly testing the validity of an existing regulatory guidance value. Other recommendations include selecting biologically plausible extrapolative models that fit the data and drawing conclusions that are consistent with the study results and objectives.
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Abstract
This review examines the epidemiological evidence for adverse reproductive outcomes from those occupational studies that present toluene-specific findings. Clinical investigations of the reproductive effects of toluene abuse are also examined. Six occupational studies reported associations between toluene and spontaneous abortion, two between toluene and congenital malformation, and three between toluene and reduced fertility. The spontaneous abortion studies provided the most suggestive evidence for an association with toluene. However, the potential for bias in some of these studies, the relatively homogeneous nature of the populations examined (e.g., four of the six studies evaluated similar groups of Finnish workers), and the multiple chemicals to which most workers were simultaneously exposed suggest cautious interpretation of these findings. Also, spontaneous abortion has generally not been observed as a major problem among highly exposed women who abuse toluene during pregnancy. The results of the occupational studies should be considered "hypothesis generating". Truly prospective studies with individually monitored data on toluene exposure and early fetal loss are needed to more definitively investigate this issue.
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On Joseph Mangano's response to "Critical assessment of opposing views on trends in childhood cancer". INTERNATIONAL JOURNAL OF HEALTH SERVICES 2001; 31:203-4; discussion 204-5. [PMID: 11271645 DOI: 10.2190/qj79-5601-mhjr-x2y2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Critical assessment of opposing views on trends in childhood cancer. INTERNATIONAL JOURNAL OF HEALTH SERVICES 2000; 30:373-7; discussion 379-86. [PMID: 10862381 DOI: 10.2190/qqff-86cm-8uvx-qmjw] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two articles reaching opposite conclusions on the current trends in childhood cancer have recently appeared in the literature. One concluded that pediatric cancers have increased dramatically, suggesting an effect from environmental hazards; the other concluded that rates for the major pediatric cancers have remained fairly stable, except for modest increases due to improvements in diagnosis or reporting. This review discusses the reasons for this discrepancy, including differences in the populations, age groups, and time periods analyzed. The arguments in favor of an increase are examined and shown to provide no convincing evidence that environmental pollutants have increased pediatric cancer rates over the past 20 to 30 years. Any suggested increase appears to be the result of non-causal factors, such as selective analysis and reporting, residual confounding by age, random variation, and stepwise improvements in diagnosis and classification.
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Hormesis and health: a little of what you fancy may be good for you. South Med J 2000; 93:371-4. [PMID: 10798504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The term hormesis refers to beneficial effects from low doses of potentially harmful substances. Although there are many laboratory examples of this phenomenon, it remains controversial and has never become widely accepted by the health community. This review goes beyond the laboratory and describes many clinical and common sense, real-world examples of hormesis that often go unrecognized. Many vitamins and minerals are essential for life at low doses but toxic at higher ones. Similarly, exercise, caloric restriction, and alcohol consumption are examples of processes that are harmful in the extreme but beneficial in moderation. This review also highlights possible reasons why acceptance of the hormetic paradigm has lagged. These include high-dose toxicologic testing that precludes the demonstration of low-level effects and the threat posed by hormesis to the currently accepted precautionary principle, which assumes that any dose of a chemical is potentially harmful.
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Environmental causes for sinonasal cancers in pet dogs, and their usefulness as sentinels of indoor cancer risk. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 1998; 54:579-591. [PMID: 9726781 DOI: 10.1080/009841098158719] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A case-control study was conducted to investigate the environmental causes of sinonasal cancers among pet dogs. Sinonasal cancer (SNC) cases and digestive cancer controls from the years 1989 through 1993 were obtained from a veterinary histopathology database. Owners were mailed a self-administered survey requesting information on canine factors, owner demographics, household exposures (including environmental tobacco smoke), and local pollution. A total of 129 case owners and 176 control owners returned completed surveys: a response rate of approximately 72%. Only household exposures were associated with increased SNC risk. Use of indoor coal or kerosene heaters represented the strongest risk factors, with significant adjusted odds ratios of 4.2 and 2.2 respectively. Environmental tobacco smoke exposure was not a risk factor and was suggestive of a nonsignificant, mildly protective effect at the lower exposure levels. Increasing nasal length was a significant risk factor, and there was effect modification between nasal length and coal or kerosene combustion. No self-reported measures of local pollution, such as urban status or residence within 1 mile of a factory, were associated with SNC risk. These results suggest that canine SNC has a strong environmental component and highlight the importance of indoor exposures, especially from fossil fuel combustion products. These results also suggest that pet dogs represent excellent sentinels for indoor cancer risk and that canine SNC cases can be used as early markers of household exposure to carcinogenic combustion products.
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An alternative approach for investigating the carcinogenicity of indoor air pollution: pets as sentinels of environmental cancer risk. ENVIRONMENTAL HEALTH PERSPECTIVES 1997; 105:1312-9. [PMID: 9405322 PMCID: PMC1470413 DOI: 10.1289/ehp.971051312] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Traditionally, the cancer risks associated with radon,environmental tobacco smoke (ETS), and similar indoor residential exposures have been evaluated through either laboratory experiments in rodents or epidemiology studies in people. Laboratory studies have the advantage of being controlled experiments, but their utility as estimators of human risk is limited by the uncertainties of extrapolating from rodents to people and from high doses to those typically experienced in the home. These experiments also subject animals to noxious exposures, causing suffering that may be considered cruel. Traditional epidemiology studies evaluate human risk directly, at the exposure levels present in residences; however, these studies are limited by their potential for misclassification, biased recall, and uncontrolled confounding. The long time intervals involved between exposure and disease (often 30 years or more) make accurate recall particularly problematic. In this paper we discuss the limitations of these traditional approaches, especially as they relate to residential studies of radon and ETS. The problems associated with the maximum tolerated dose in rodent bioassays and exposure misclassification in traditional epidemiology are particularly examined. A third approach that supplements the traditional approaches and overcomes some of their limitations is suggested. This approach, dubbed pet epidemiology, estimates residential cancer risk by examining the exposure experience of pet dogs with naturally occurring cancers. The history of pet epidemiology is reviewed and its strengths and limitations are examined.
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Comparison of adverse drug reaction reporting in veterinary and human medicine. J Am Vet Med Assoc 1996; 209:40-5. [PMID: 8926206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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17
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Need training for application of insecticides. J Am Vet Med Assoc 1996; 208:1227-8. [PMID: 8635960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Reevaluating the evidence on pesticide safety. Am J Public Health 1995; 85:1586-7. [PMID: 7485679 PMCID: PMC1615703 DOI: 10.2105/ajph.85.11.1586-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Simulated Air Levels of Volatile Organic Compounds following Different Methods of Indoor Insecticide Application. ENVIRONMENTAL SCIENCE & TECHNOLOGY 1995; 29:673-676. [PMID: 22200275 DOI: 10.1021/es00003a014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Evaluation of the utility of a standard history questionnaire in assessing the neurological effects of solvents. Am J Ind Med 1992; 22:337-45. [PMID: 1519618 DOI: 10.1002/ajim.4700220307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Using a standard battery of medical surveillance questions, a study was undertaken to determine if an increase in reported neurologic symptoms was resulting from solvent exposure at a pharmaceutical research, development, and manufacturing site. The prevalence of positive responses to 13 interval history questions pertaining to neurological symptoms was compared between those enrolled in exposed surveillance programs (n = 840) and those enrolled in other, non-solvent exposed surveillance programs (n = 1,042). The ratio of positive responders between the exposed and unexposed groups was used to generate a relative prevalence ratio (RPR). No significantly elevated RPRs were seen when the analysis was adjusted for the confounding factors of age, sex, smoking, alcohol use, noise exposure, and number of interval histories. These results suggest that workplace solvent exposures in the employees studied did not appear to result in obvious neurologic symptoms. However, low-level neurotoxic exposures can cause asymptomatic or sub-clinical disorders. Therefore, more sensitive neurotoxic surveillance systems need to be developed.
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Biological markers in chromium exposure assessment: confounding variables. ARCHIVES OF ENVIRONMENTAL HEALTH 1991; 46:230-6. [PMID: 2069432 DOI: 10.1080/00039896.1991.9937454] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
An estimated two million tons of chromate production waste pollution has caused a major environmental and public health concern in Hudson County, New Jersey. As part of an occupational exposure assessment, urinary and red blood cell (RBC) chromium measurements were performed on 52 state employees who worked either near a contaminated site or elsewhere. Samples were collected so as to minimize contamination, and they were analyzed using sensitive techniques. These workers also completed a questionnaire that addressed potentially important third variables. Individual analyses suggested that exercise, drinking beer, past employment in chromium-related occupations, and diabetic status had an important effect on urinary chromium levels. These variables were entered into a regression model and were all found to be significant predictors of urinary chromium level (p less than .10). Some variables were also examined for their influence on RBC chromium level, but none had a measurable effect.
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Flea control a serious matter. J Am Vet Med Assoc 1987; 191:1351. [PMID: 3692974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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