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Exposure History (exposure + history)
Selected AbstractsChanging risk factors for fluorosis among South Australian childrenCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 3 2008A. John Spencer Abstract,,, Background:, Research in the last decade has shown changing exposure patterns to discretionary fluorides and declining prevalence of fluorosis among South Australian children, raising the question of how risk factors for fluorosis have changed. Objective:, To examine and compare risk factors for fluorosis among representative samples of South Australian children in 1992/1993 and 2002/2003. Methods:, Similar sampling strategies and data collection methods were employed in the Child Fluoride Study (CFS) Marks 1 (1992/1993) and 2 (2002/2003). Participants in each CFS round were examined for fluorosis using the Thylstrup and Fejerskov (TF) Index. Exposure history was collected for fluoride in water, toothpaste, fluoride supplements and infant formula, allowing for a fluorosis risk assessment analysis. Data were re-weighted to represent the child population at each time. Changes in prevalence of fluorosis, defined as having a TF score of 1+ on maxillary central incisors, fluoride exposure and risk factors between the two rounds were evaluated. Result:, A total of 375 and 677 children participated in the 1992/1993 and 2002/2003 rounds respectively. Prevalence of fluorosis declined significantly from 45.3% to 25.9%. Reduced use of fluoride supplements and increased use of 400,550-ppm children F toothpaste were the most substantial fluoride exposure changes. Early toothpaste use, residence in fluoridated areas and fluoride supplement use were the risk factors in 1992/1993. Early toothpaste use and fluoride supplement use were not risk factors, leaving fluoridated water as the only risk factor among the common variables in 2002/2003. In an analysis stratified by the type of fluoridated toothpaste in 2002/2003, the large amount of toothpaste used was a risk factor in those who used 1000-ppm fluoridated toothpaste, and eating/licking toothpaste when toothpaste use started was a risk factor among children who used either 1000-ppm or 400,550-ppm fluoridated toothpaste. Conclusion:, Introduction of the 400,550-ppm F toothpaste and use of smaller amount of toothpaste restricted risk associated with early toothpaste use. Less use and possibly a stricter fluoride supplements regimen also restricted fluorosis risk. Periodic monitoring of risk of fluorosis is required to adjust guidelines for fluoride use in caries prevention. [source] Malignant mesothelioma in Australia, 1945,2000,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 3 2002James Leigh MB Abstract Background Australia has maintained a total national malignant mesothelioma case register since 1980. There has been a marked increase in the incidence of mesothelioma in the last 20 years. Currently 450,600 cases are notified annually in a population of 20 million. While the history of the Wittenoom (Western Australia) crocidolite mine and its aftermath is well known, these cases comprise only 5% of the total. This study describes the incidence of mesothelioma in Australia from 1945 to 2000. Methods Using register data, time trends in mesothelioma incidence were calculated. Analyses of incidence are reported by age, sex, anatomical site, and state of notification. Associations with occupational and environmental asbestos exposure histories are described. Lung fiber content measurements were made on a subset of cases. Results Australia has had 6,329 cases of mesothelioma from 1 January 1945 to 31 December 2000. (A further 620 cases were notified in the period from 1 January 2001 to 31 October 2001.) Annual incidence rates for Australia per million population ,,20 years (1997) were: male, 59.8; female, 10.9; total, 35.4. Incidence rates have been continually increasing and are the highest reported national rates in the world. While Western Australia has the highest rate (1997 total rate, 52.8), most cases arise from the two most populous eastern states, New South Wales and Victoria. In 88% (male 90%, female 61%) of cases, a history of asbestos exposure was obtained. Exposures occurred in a wide variety of occupational and environmental circumstances. In 80% of cases with no history of exposure, TEM lung asbestos fiber counts >,200,000 fibers >,2 ,m length per gm dry lung were obtained, suggesting unrecognized exposure. Conclusions Australia's high incidence of mesothelioma is related to high past asbestos use, of all fiber types, in a wide variety of occupational and environmental settings. The number of cases in total is expected to be about 18,000 by 2020, with about 11,000 yet to appear. Am. J. Ind. Med. 41:188,201, 2002. © 2002 Wiley-Liss, Inc. [source] The exposure-time-response relationship between occupational asbestos exposure and lung cancer in two German case-control studies,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2002Michael Hauptmann PhD Abstract Background Numerous studies have been carried out to evaluate the association between lung cancer and occupational asbestos exposure. However, the effects of timing of exposure have not been analyzed thoroughly. Methods Two German case-control studies with data on occupational asbestos exposure histories have been pooled. Duration of work in potentially asbestos exposed jobs and two derived weighted exposure measures are analyzed together with time since last exposure. A spline function is used to model the effect of time since exposure. Results The odds ratios (OR) and corresponding 95% confidence intervals were 1.8 (1.2, 2.7) and 2.4 (1.7, 3.4) for subjects having worked for 3 to 7 years and 8 or more years, respectively, in a job with potential asbestos exposure compared to never-exposed. Based on an evaluation of time since last exposure, the OR decreased significantly to about one-half after more than 20 years since exposure ceased. Using a spline function, applied to workers' complete exposure histories, the effect of an increment of exposure is greatest 10,15 years after that exposure was received. Conclusions In contrast to previous indications, the risk of lung cancer increases soon after asbestos exposure, with its maximum effect from 10 to 15 years after the exposure was received. Am. J. Ind. Med. 41:89,97, 2002. Published 2002 Wiley-Liss, Inc. [source] Sesquiterpene lactone dermatitis in the young: is atopy a risk factor?CONTACT DERMATITIS, Issue 1 2008Evy Paulsen Screening for Compositae contact allergy has documented fairly high prevalence in adults, and recent studies indicate that the allergy may be more common in children than previously believed. However, detailed information on sensitization in this age group is sparse. The objective of this study was to present another 2 cases in children and review the literature. Screening with sesquiterpene lactone (SL) mix has shown prevalence of 0.5% and 1.8% in 2 studies, while screening with 2 different Compositae mixes detected 4.2% and 2.6% positives among children and adolescents. All individual case reports describe sensitization in atopic children, and the largest screening study showed a prevalence of Compositae mix sensitization that was significantly higher in children with atopic dermatitis compared with non-atopics. Compositae sensitization should be considered in children with a family or personal history of atopy, summer-related, or -exacerbated dermatitis of any kind, and a history of plant exposure. Screening with SL mix is recommended but should be supplemented with plant extracts based on exposure history. Compositae weeds, especially dandelions, seem to be important sensitizers in children. [source] Hair dye contact allergy: quantitative exposure assessment of selected products and clinical casesCONTACT DERMATITIS, Issue 6 2004Heidi SØsted Colouring of hair can cause severe allergic contact dermatitis. The most frequently reported hair dye allergens are p -phenylenediamine (PPD) and toluene-2,5-diamine, which are included in, respectively, the patch test standard series and the hairdressers series. The aim of the present study was to identify dye precursors and couplers in hair dyeing products causing clinical hair dye dermatitis and to compare the data with the contents of these compounds in a randomly selected set of similar products. The patient material comprised 9 cases of characteristic clinical allergic hair dye reaction, where exposure history and patch testing had identified a specific hair dye product as the cause of the reaction. The 9 products used by the patients were subjected to chemical analysis. 8 hair dye products contained toluene-2,5-diamine (0.18 to 0.98%). PPD (0.27%) was found in 1 product, and m -aminophenol (0.015 to 0.38%) and p -aminophenol (0.16 to 2.1%) were found in 3 products. The concentration levels were similar in the patient's products compared to a random sample of 16 hair dye products. The concentration present of toluene-2,5-diamine elicited allergic reactions in concentrations that were 10-fold lower than the legal EU limit of 10%. Hair dye allergy may cause severe clinical reactions, and the current regulation is insufficient in protection of the users. A preventive strategy is needed. [source] Characteristics of skin aging in Korean men and womenINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005J. H. Chung Introduction Korea is located between Japan and Mainland China. The people of these three countries have similar appearances and it is difficult to differentiate between them. Although the population of Asia is more than half of the total population of the Earth, the inherent characteristics of Asian skin have not been well investigated. Commercial markets for cosmetics and drugs for photoaged skin are rapidly expanding in many Asian countries. Therefore, many investigators in the field of dermatology and cosmetology have become interested in brown Asian skin. Clinical characteristics of skin aging and photoaging in Asians Skin aging can be divided into two basic processes: intrinsic aging and photoaging [1]. Intrinsic aging is characterized by smooth, dry, pale, and finely wrinkled skin, whereas photoaging, which indicates premature skin aging in chronically photodamaged skin, is characterized by severe wrinkling and irregular pigmentation. The pattern of wrinkling in Asians seems to differ from that in Caucasians. Asians have coarser, thicker and deep wrinkles, particularly in the forehead, perioral and Crow's foot areas. In contrast, Caucasians usually have relatively fine cheek and Crow's foot wrinkles. The reasons for these differences are not known and need further investigation. There are racial, ethnic and genetic differences, and differences of skin structure and function, between the brown skin of Asians and the white skin of Caucasians. As Asian skin is more pigmented, acute and chronic cutaneous responses to UV irradiation differ from those in white skin. Many people believe, based on clinical impressions, that the main process of photoaging in Asians involves pigmentary changes, rather than wrinkling. However, no study has been performed to confirm this belief. Risk factors for skin wrinkles and their relative risks in Korean skin [2] Various factors such as age, sun-exposure, and smoking are known to be important risk factors for wrinkles. However, the relative risks of each factor on wrinkles in the brown skin of Asians have not been investigated, and they could differ from those in Caucasians. An evaluation system for skin wrinkling is necessary for Asian skin [3]. Thus, we developed an eight-point photographic scale for assessing wrinkles in both Korean genders [2]. This scale can probably be applied to the populations of other Asian countries, at least to the Japanese and Chinese. The pattern of wrinkles in both genders appears to be similar. Age Age is an important risk factor for wrinkling in Asians, as in Caucasians. Korean subjects in their 60s showed a 12-fold increased risk of wrinkling, while subjects in their 70s have a 56-fold increased risk compared with young age group. UV light It is well known that the UV component in sunlight can cause and accelerate photoaging. The pigmented skin of Asian may better protect skin from acute and chronic UV damage. However, we found a strong association between sun-exposure and the development of wrinkling in Koreans. It was found that sun exposure of more than 5 h per day was associated with a 4.8-fold increased risk in wrinkling versus less than 2 h of sun-exposure in Koreans. Estrogen deficiency Korean females have more wrinkles than men, after controlling for age, sun exposure, and smoking, it was found that they have a 3.6-fold increased risk of developing wrinkles than their male counterparts [2]. It has also been reported, that the relative risk for wrinkling in women is higher than in men as for in white Caucasians [4]. The reason why women show more wrinkles remains to be determined. It is possible that a reduction in skin collagen because of estrogen deficiency in postmenopausal woman may aggravate wrinkling severity. Korean women with more than 10 years since menopause showed a 3.9-fold higher risk of wrinkling than the women 5 years of beyond menopause [5]. We demonstrated that women with a history of HRT have a significantly lower risk, more specifically, one fifth of the risk of facial wrinkling relative to those who had no history of HRT. Interestingly, we found that wrinkle severity significantly increased with an increasing number of full term pregnancies. The relative risk for severe wrinkling is increased by approximately 1.8-fold per full term pregnancy. Smoking It is known that smoking causes skin wrinkling in Caucasians, and that it plays no role in Blacks [6, 7]. Koreans with have a smoking history of more than 30 pack years showed a more than 2.8-fold increased risk of wrinkles [2]. The relative risks of wrinkles associated with a 30,50 pack-years history of smoking were 2.8- and 5.5-fold, respectively. Dyspigmentation in Asian skin To follow pigmentary changes, six photographic standards for both genders were developed for Korean skin, to produce a 6-point scale [2, 8]. Hyperpigmented spots, mostly lentigines, were prominent among women, while seborrheic keratosis tended to be more prominent in men. Seborrheic keratosis in Korean men Seborrheic keratoses (SKs) are benign cutaneous tumors. They have diverse clinical and histopathological appearances and are very common in the elderly (over 50 years old). The etiology of SKs is not well understood, although patients with a great number of lesionsshow a familial trait with an autosomal dominant pattern, and human papilloma virus has been suggested as possible cause because of verrucous appearance of the lesions. Exposure to sunlight has been suggested to be a risk factor for SKs. However, there is still some debate in terms of the role of sunlight. Recently, we have investigated the clinical characteristics of SKs and relationship between SKs and sunlight exposure in Korean males [9]. The prevalence of SKs in Koreans increases with age; it rose from 78.9% at 40 years, to 93.9% at 50 years and 98.7% in those over 60 years. Exposed areas, i.e. the face, neck and dorsum of the hands, demonstrate a significant increase in the prevalence of SKs by decade, whereas partly exposed areas, although SKs tended to increase in prevalence with age, this trend was not significant. When the estimated body surface area (BSA) is taken into account, the number of SKs on both the face and dorsum of the hands (0.51 ± 0.08 per 1% BSA) was over-represented compared with the trunk. SKs were also concentrated on the neck (0.38 ± 0.07 per 1% BSA) and in the V-area (0.47 ± 0.09 per 1% BSA). Outer forearms also showed 3-fold more SKs per unit area than neighboring arms and inner forearms, which are classified as partly exposed area (0.09 ± 0.02, 0.03 ± 0.01, respectively). The total area covered by SKs on exposed area also became significantly larger with aging than on intermittently exposed areas. These results indicate that exposure to sunlight might be related to SK growth. Our results indicated that excessive sun exposure is an independent risk factor of SKs. After controlling for age, smoking, and skin type, subjects with a sun exposure history of more than 6 hours per day showed a 2.28-fold increased risk of having severe SKs (n , 6) compared with those exposed for less that 3 h per day. These findings indicated that sun-exposure may play an important role in SK development. In summary, SKs are very common in Korean males and represent one of the major pigmentary problems. SKs concentrate on exposed skin, especially on the face and dorsum of the hands. Both age and lifetime cumulative sunlight exposure are important contributing factors and may work in a synergistic manner. Conclusion Many people tend to believe that wrinkles are not a prominent feature of Asian photoaged skin, and that dyspigmentation is a major manifestation in Asian skin. Contrary to this impression, wrinkling is also a major problem in the photoaged skin of Asians, and Korean people showing severe pigmentary changes usually tend to have severe wrinkles. In conclusion, the wrinkling patterns and pigmentary changes of photoaged skin in East Asians differ from those of Caucasians, and the relative risks of aggravating factors may be different from those of Caucasian skin. References 1.,Gilchrest, B.A. Skin aging and photoaging: an overview. J. Am. Acad. Dermatol. 21, 610,613 (1989). 2.,Chung, J.H. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 3.,Griffiths, C.E. et al. A photonumeric scale for the assessment of cutaneous photodamage. Arch. Dermatol. 128, 347,351 (1992). 4.,Ernster, V.L. et al. Facial wrinkling in men and women, by smoking status. Am. J. Public Health. 85, 78,82 (1995). 5.,Youn, C.S. et al. Effect of pregnancy and menopause on facial wrinkling in women. Acta Derm. Venereol. 83, 419,424 (2003). 6.,Kadunce, D.P. et al. Cigarette smoking: risk factor for premature facial wrinkling. Ann. Intern. Med. 114, 840,844 (1991). 7.,Allen, H.B., Johnson, B.L. and Diamond, S.M. Smoker's wrinkles? JAMA. 225, 1067,1069 (1973). 8.,Chung, J.H. Photoaging in Asians. Photodermatol. Photoimmunol. Photomed. 19, 109,121 (2003). 9.,Kwon, O.S. et al. Seborrheic keratosis in the Korean males: causative role of sunlight. Photodermatol. Photoimmunol. Photomed. 19, 73,80 (2003). [source] Influence of tetracycline exposure on tetracycline resistance and the carriage of tetracycline resistance genes within commensal Escherichia coli populationsJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2003D.P. Blake Abstract Aims: To assess the influence of incremental tetracycline exposure on the genetic basis of tetracycline resistance within faecal Escherichia coli. Methods and Results: Through the adoption of a novel combination of multiple breakpoint selection, phenotypic characterization and the application of a polymerase chain reaction based gene identification system it proved possible to monitor the influence of antibiotic exposure on resistance gene possession. Using tetracycline as a case study a clear hierarchy was revealed between tet genes, strongly influenced by host antimicrobial exposure history. Conclusions: The antimicrobial exposure regime under which an animal is produced affects both the identity and magnitude of resistance gene possession of a selected bacterial population within its enteric microflora. Among the ramifications associated with such resistance gene selection is the degree of resistance conferred and the carriage of linked resistance determinants. This selection is applied by exposure to antibiotic concentrations well below recognized minimum inhibitory tetracycline concentration breakpoints widely adopted to characterize bacterial ,susceptibility'. Significance and Impact of the Study: This study confirms the ability of minimal antibiotic exposure to select for the continued persistence of resistance genes within the enteric microflora. It is clearly demonstrated that different antimicrobial regimes select for different resistance genes, the implications of which are discussed. [source] Is susceptibility to tuberculosis acquired or inherited?JOURNAL OF INTERNAL MEDICINE, Issue 2 2007E. Schurr Abstract. Tuberculosis is an ongoing major public health problem on a global scale. One of the striking features of the disease is that only an estimated 10% of immunocompetent persons infected by the causative pathogen Mycobacterium tuberculosis will develop clinical signs of disease. This well-established epidemiological observation has prompted an intense search for the factors that trigger advancement of infection to disease in the small proportion of susceptible individuals. Central to this search is the questions if tuberculosis patients are inherently susceptible to the disease or if disease development is promoted by specific environmental factors. It is known that genetic and non-genetic factors of both the bacterium and the host have impact on the host response to M. tuberculosis. Yet, little is known about the interaction of these different factors and the resulting impact on disease development. Recent work suggests that in addition to common host susceptibility genes a second group of susceptibility loci exists the action of which strongly depends on the individual's clinical and exposure history. The latter genes may have a very strong effect on promoting advancement from infection to disease only in specific epidemiological settings. These findings suggest that a more detailed knowledge of gene,environment interactions in tuberculosis is necessary to understand why a small proportion of individuals are susceptible to the disease whilst the majority of humans are naturally resistant to tuberculosis. [source] Effects of Surface Chemistry on the Nanomechanical Properties of Commercial Float GlassJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2010Pavan V. Kolluru Nanoindentation was used to evaluate the mechanical properties of commercial float glass surfaces that were subjected to various surface cleaning treatments and other short-term corrosion conditions. The changes in the plane strain elastic modulus, where ,s and Es are the Poisson ratio and Young modulus of the specimen, respectively) and hardness after exposure to dilute hydrochloric acid (pH 0.9), reverse osmosis water (pH 7.1), and commercial cleaning solutions (pH 9.5) were found to be 0.5%,9% and 2%,35%, respectively. Similarly, weathering in a humid atmosphere and leaching in hot deionized water also had a distinct effect on the measured properties of the float glass surfaces. Moreover, both the surface cleaning treatments and the short-term corrosion exposures affected the tin side of the float glass differently than the air side. This work suggests that many of the discrepancies in the literature on the effect of tin concentration on the nanomechanical properties of float glass surfaces are likely due to variability in the surface cleaning and exposure history of the samples and calibration glasses that have been used. [source] Physical properties of Martian meteorites: Porosity and density measurementsMETEORITICS & PLANETARY SCIENCE, Issue 12 2007Ian M. COULSON These samples represent igneous rocks, much like basalt. As such, many laboratory techniques designed for the study of Earth materials have been applied to these meteorites. Despite numerous studies of Martian meteorites, little data exists on their basic structural characteristics, such as porosity or density, information that is important in interpreting their origin, shock modification, and cosmic ray exposure history. Analysis of these meteorites provides both insight into the various lithologies present as well as the impact history of the planet's surface. We present new data relating to the physical characteristics of twelve Martian meteorites. Porosity was determined via a combination of scanning electron microscope (SEM) imagery/image analysis and helium pycnometry, coupled with a modified Archimedean method for bulk density measurements. Our results show a range in porosity and density values and that porosity tends to increase toward the edge of the sample. Preliminary interpretation of the data demonstrates good agreement between porosity measured at 100× and 300× magnification for the shergottite group, while others exhibit more variability. In comparison with the limited existing data for Martian meteorites we find fairly good agreement, although our porosity values typically lie at the low end of published values. Surprisingly, despite the increased data set, there is little by way of correlation between either porosity or density with parameters such as shock effect or terrestrial residency. Further data collection on additional meteorite samples is required before more definitive statements can be made concerning the validity of these observations. [source] Airways obstruction among older construction and trade workers at Department of Energy nuclear sitesAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 3 2010John M. Dement PhD Abstract Background A study of chronic obstructive pulmonary disease (COPD) among 7,579 current and former workers participating in medical screening programs at Department of Energy (DOE) nuclear weapons facilities through September 2008 was undertaken. Methods Participants provided a detailed work and exposure history and underwent a respiratory examination that included a respiratory history, respiratory symptoms, a posterior,anterior (P,A) chest radiograph classified by International Labour Office (ILO) criteria, and spirometry. Statistical models were developed to generate group-level exposure estimates that were used in multivariate logistic regression analyses to explore the risk of COPD in relation to exposures to asbestos, silica, cement dust, welding, paints, solvents, and dusts/fumes from paint removal. Risk for COPD in the study population was compared to risk for COPD in the general US population as determined in National Health and Nutrition Examination Survey (NHANES III). Results The age-standardized prevalence ratio of COPD among DOE workers compared to all NHANES III data was 1.3. Internal analyses found the odds ratio of COPD to range from 1.6 to 3.1 by trade after adjustment for age, race, sex, smoking, and duration of DOE employment. Statistically significant associations were observed for COPD and exposures to asbestos, silica, welding, cement dusts, and some tasks associated with exposures to paints, solvents, and removal of paints. Conclusions Our study of construction workers employed at DOE sites demonstrated increased COPD risk due to occupational exposures and was able to identify specific exposures increasing risk. This study provides additional support for prevention of both smoking and occupational exposures to reduce the burden of COPD among construction workers. Am. J. Ind. Med. 53:224,240, 2010. © 2009 Wiley-Liss, Inc. [source] Antithetical effect of tumor necrosis factor-,gene polymorphism on coal workers' pneumoconiosis (CWP),AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2005Xin-Tao Wang MD Abstract Background Inter-individual variation in the severity of pneumoconiosis has been described, even with the same environmental exposure. We hypothesized that TNF-, promoter polymorphisms associate with lung responses to environmental exposure in coal worker's pneumoconiosis (CWP) patients. Methods We examined polymorphisms at ,238, ,308, and ,376 in 124 patients with CWP who had similar dust exposure history and in 122 non-exposed controls. CWP patients were divided into two groups: (1) nodular CWP (n,=,84); (2) progressive massive fibrosis (PMF) (n,=,44). Results The ,308 A allele frequency was higher in patients with CWP compared to controls (6.35% and 2.05%, P,<,0.01). It was also higher in patients with nodular CWP compared to PMF (P,<,0.05). Logistic regression analysis revealed that patients with the ,308 A allele were 3.8 times (P,=,0.036) and those with smoking habit were 2.3 times (P,<,0.002) more likely to have nodular CWP than PMF. Conclusion TNF-,-308 A allele might interact with smoking to enhance susceptibility to nodular CWP. Am. J. Ind. Med. 48:24,29, 2005. © 2005 Wiley-Liss, Inc. [source] | ||||||||||