Long-term occupational exposures on disability-free survival and mortality in older adults.

BACKGROUND: The impact of long-term occupational exposures on health in older adults is increasingly relevant as populations age. To date, no studies have reported their impact on survival free of disability in older adults. AIMS: We aimed to investigate the association between long-term occupational exposure and disability-free survival (DFS), all-cause mortality and cause-specific mortality in initially healthy older adults. METHODS: We analysed data from 12 215 healthy participants in the ASPirin in Reducing Events in the Elderly (ASPREE) study whose mean age was 75 years. Their work history was collated with the 'ALOHA-plus JEM' (Job Exposure Matrix) to assign occupational exposures. The primary endpoint, DFS, was a composite measure of death, dementia or persistent physical disability. The secondary endpoint, mortality, was classified according to the underlying cause. Cox proportional hazard models were used to calculate hazard ratios and 95% confidence intervals, adjusted for confounders. RESULTS: A total of 1835 individuals reached the DFS endpoint during the median 4.7 years follow-up period. Both ever-high and cumulative exposure to all dusts and all pesticides during a person's working years were associated with reduced DFS. Compared to no exposure, men with high exposure to dusts and pesticides had a reduced DFS. Neither of these exposures were significantly associated with all-cause mortality. Men with high occupational exposure to solvents and women exposed to dusts experienced higher all-cause and cancer-related mortality. CONCLUSIONS: Long-term occupational exposure to all dusts and pesticides was associated with a reduced DFS and increased mortality in community-dwelling healthy older adults.

Wireless phone use in childhood and adolescence and neuroepithelial brain tumours: Results from the international MOBI-Kids study.

In recent decades, the possibility that use of mobile communicating devices, particularly wireless (mobile and cordless) phones, may increase brain tumour risk, has been a concern, particularly given the considerable increase in their use by young people. MOBI-Kids, a 14-country (Australia, Austria, Canada, France, Germany, Greece, India, Israel, Italy, Japan, Korea, the Netherlands, New Zealand, Spain) case-control study, was conducted to evaluate whether wireless phone use (and particularly resulting exposure to radiofrequency (RF) and extremely low frequency (ELF) electromagnetic fields (EMF)) increases risk of brain tumours in young people. Between 2010 and 2015, the study recruited 899 people with brain tumours aged 10 to 24 years old and 1,910 controls (operated for appendicitis) matched to the cases on date of diagnosis, study region and age. Participation rates were 72% for cases and 54% for controls. The mean ages of cases and controls were 16.5 and 16.6 years, respectively; 57% were males. The vast majority of study participants were wireless phones users, even in the youngest age group, and the study included substantial numbers of long-term (over 10 years) users: 22% overall, 51% in the 20-24-year-olds. Most tumours were of the neuroepithelial type (NBT; n = 671), mainly glioma. The odds ratios (OR) of NBT appeared to decrease with increasing time since start of use of wireless phones, cumulative number of calls and cumulative call time, particularly in the 15-19 years old age group. A decreasing trend in ORs was also observed with increasing estimated cumulative RF specific energy and ELF induced current density at the location of the tumour. Further analyses suggest that the large number of ORs below 1 in this study is unlikely to represent an unknown causal preventive effect of mobile phone exposure: they can be at least partially explained by differential recall by proxies and prodromal symptoms affecting phone use before diagnosis of the cases. We cannot rule out, however, residual confounding from sources we did not measure. Overall, our study provides no evidence of a causal association between wireless phone use and brain tumours in young people. However, the sources of bias summarised above prevent us from ruling out a small increased risk.

Suicide in Australian pesticide-exposed workers.

BACKGROUND: Epidemiological research has observed that workers with exposure to anticholinesterase pesticides, and particularly those with a history of acute overexposure, may be at increased risk of depression. However, there is little published research about the risk of suicide in relation to pesticide exposure. AIMS: To investigate risk of suicide in relation to metrics of pesticide exposure and type of work. METHODS: A nested case-control study was performed within a retrospective cohort study of pesticide-exposed workers from various industries. Ninety male suicide deaths and 270 male controls were matched by age bands, state of residence and live status. Cholinesterase inhibition was determined using subject-specific biomonitoring records collected at the time of exposure. RESULTS: Suicide risk was not significantly elevated in relation to exposure to any particular pesticide classes nor in relation to pesticide overexposure, confirmed by blood test. While the risk of suicide associated with a history of cholinesterase inhibition was raised, this was not significant (odds ratio = 1.90, 95% confidence interval = 0.73-4.93). CONCLUSIONS: This study did not find an elevated suicide risk associated with use of any major class of pesticide and there was little evidence that overexposure was associated with increased risk of suicide. A non-significant association between overexposure to anticholinesterase pesticides may be consistent with previous research showing increased depression in workers with a history of cholinesterase inhibition and warrants further investigation.

Healthy hire effect, job selection and inhalation exposure among young adults with asthma.

The aim of the present study was to assess whether asthma onset prior to entering the workforce influences whether a person holds a subsequent job with asthma-related inhalation exposures. The data of 19,784 adults from the European Community Respiratory Health Survey were analysed. For each respondent, a current or previously held job was linked to a job exposure matrix assigning high, low or no exposure to dust, gases or fumes. Jobs were also categorised according to the risk of exposures related to occupational asthma. Associations between asthma and subsequent occupational exposures were assessed using logistic regression models, with a random intercept for study centre and fixed adjustment for age, sex, type of study sample and smoking status. Of the respondents, 8% (n = 1,619) reported asthma with onset before completion of full-time education. This population was at decreased risk of having a job with high (odds ratio 0.79; 95% confidence interval 0.68-0.92) or low (0.91; 0.80-1.03) exposure to dust, gases or fumes. The associations were consistent across exposure types (dusts, gases or fumes) and for jobs with a high risk of occupational asthma. Adults with asthma onset prior to entering the workforce may be less likely to hold jobs involving inhalation exposures.

Use of mobile phones and changes in cognitive function in adolescents.

BACKGROUND: Several studies have investigated the impact of mobile phone exposure on cognitive function in adults. However, children and adolescents are of special interest due to their developing nervous systems. METHODS: Data were derived from the Australian Mobile Radiofrequency Phone Exposed Users' Study (MoRPhEUS) which comprised a baseline examination of year 7 students during 2005/2006 and a 1-year follow-up. Sociodemographic and exposure data were collected with a questionnaire. Cognitive functions were assessed with a computerised test battery and the Stroop Color-Word test. RESULTS: 236 students participated in both examinations. The proportion of mobile phone owners and the number of voice calls and short message services (SMS) per week increased from baseline to follow-up. Participants with more voice calls and SMS at baseline showed less reductions in response times over the 1-year period in various computerised tasks. Furthermore, those with increased voice calls and SMS exposure over the 1-year period showed changes in response time in a simple reaction and a working memory task. No associations were seen between mobile phone exposure and the Stroop test. CONCLUSIONS: We have observed that some changes in cognitive function, particularly in response time rather than accuracy, occurred with a latency period of 1 year and that some changes were associated with increased exposure. However, the increased exposure was mainly applied to those who had fewer voice calls and SMS at baseline, suggesting that these changes over time may relate to statistical regression to the mean, and not be the effect of mobile phone exposure.

Cancer incidence and mortality in a historical cohort of Australian pest control workers.

OBJECTIVES: To determine the rates of mortality and incident cancer in a historical cohort of pest control operators. METHODS: A retrospective cohort was assembled from former state government occupational health surveillance programmes. This cohort was linked to the Australian national registries of cancer and mortality and the results were compared with the general Australian population rates. RESULTS: 125 deaths and 89 incident cancers were found during the periods of observation (mortality 1983-2004 and cancer 1983-2002). Overall cancer incidence and mortality rates were not found to be significantly different from the general population. Among the specific causes of death, suicide (standardised mortality ratio; SMR 1.78; 95% CI 1.12 to 2.83) and unintentional falls (SMR 4.57; 95% CI 1.72 to 12.19) were significantly in excess, although the latter was based on only 4 deaths. Melanoma was the only specific incident cancer found significantly in excess (standardised incidence ratio 1.56; 95% CI 1.03 to 2.37). CONCLUSIONS: Pest control workers have overall mortality and cancer rates similar to the general population. Excess rates of incident melanoma and intentional self-poisoning mortality are of concern and warrant further investigation. Follow-up of this cohort as its members age, will provide more insight into these possible associations.

Mortality and cancer incidence in workers in two Australian prebake aluminium smelters.

BACKGROUND: Exposures in the aluminium production industry have been declining and this study aimed to investigate cancer and mortality in two Australian prebake aluminium smelters. METHODS: The cohort included 4396 males who had worked in a prebake smelter for at least 3 months. They were matched against the National Death Index and the National Cancer Statistics Clearing House to obtain cause of death and type of cancer. Standardised Mortality Ratios (SMRs) and Standardised Incidence Ratios (SIRs) were calculated for the whole cohort, for production or maintenance work categories and for duration of employment categories. RESULTS: The SMRs for all causes, circulatory, respiratory and injury deaths were at or below expected. Mesothelioma was the only significantly increased cause of death (SMR 3.52, 95% CI 1.47 to 8.46). Death from prostate cancer in production workers was elevated (SMR 2.39, 95% CI 1.29 to 4.44) and in those who had worked for more than 20 years in production or maintenance jobs (SMR 3.67, 95% CI 1.53 to 8.81). There were statistically significant excesses of incident stomach cancer, mesothelioma, and kidney cancer cases, while the SIR for melanoma was significantly reduced. There was no significant trend for duration of exposure for any type of incident cancer. CONCLUSIONS: This study found no overall excess of mortality or cancer, but incident mesothelioma and kidney cancer risks were elevated. The lack of excess risk for lung or bladder cancer or deaths from respiratory disease may be related to the different level and pattern of exposure between Søderberg and prebake smelters.

Relationships between alumina and bauxite dust exposure and cancer, respiratory and circulatory disease.

OBJECTIVES: To examine the associations between alumina and bauxite dust exposure and cancer incidence and circulatory and respiratory disease mortality among bauxite miners and alumina refinery workers. METHODS: This cohort of 5770 males has previously been linked to national mortality and national and state cancer incidence registries (1983-2002). In this paper, Poisson regression was used to undertake internal comparisons within the cohort based on subgroups of cumulative exposure to inhalable bauxite and alumina dust. Exposure was estimated using job histories and historical air monitoring data. RESULTS: There was no association between ever bauxite exposure and any of the outcomes. There was a borderline significant association between ever alumina exposure and cerebrovascular disease mortality (10 deaths, RR 3.8, 95% CI 1.1 to 13). There was some evidence of an exposure-response relationship between cumulative bauxite exposure and non-malignant respiratory disease mortality (seven deaths, trend p value: 0.01) and between cumulative alumina exposure and cerebrovascular disease mortality (trend p value: 0.04). These associations were based on very few cases and for non-malignant respiratory disease the deaths represented a heterogeneous mixture of causes. There was no evidence of an excess risk for any cancer type with bauxite or alumina exposure. CONCLUSIONS: These preliminary findings, based on very few cases, suggest that cumulative inhalable bauxite exposure may be associated with an excess risk of death from non-malignant respiratory disease and that cumulative inhalable alumina dust exposure may be associated with an excess risk of death from cerebrovascular disease. Neither exposure appears to increase the risk of incident cancers.

Use of hardware modified phones for exposure assessment in health studies in Australia: verification of compliance with standards.

Most epidemiological studies investigating health effects of mobile telephone use have been criticised for poor quality of exposure assessment. Most used questionnaires which have limited precision to assess exposure. Clearly more relevant and direct methods of exposure assessment are needed. We describe the calibration of hardware modified phones (HMPs) for exposure assessment and dosimetry and verified their compliance with Australian and international standards. Specific energy absorption rate (SAR) values at various tilts and rotations and their combinations were obtained for the HMPs using a 'DASY3' SAR measuring system. Calibration involved placing HMPs on human head phantoms and taking measurements at 900 and 1800 MHz bands on right and left sides of the phantom. At 900 MHz the maximum SAR obtained with HMPs at the touch position was 0.9 W/kg and 0.4 W/kg at 30 degrees tilt but at 1800 MHz, SAR at the touch and 30 degrees tilts were 1.1 W/kg and 1.3 W/kg respectively. Whilst tilt and rotation each had an effect on SAR at constant frequency, no interaction was observed with rotation and frequency, however one was observed between tilt and frequency. At 1800 MHz mean SAR at 30 degrees tilt was 0.22 W/kg higher (95% CI 0.15, 0.30) than at 0 degrees, whereas at 900 MHz mean SAR at 30 degrees tilt was 0.60 W/kg lower (95% CI 0.52, 0.67) than at 0 degrees. Our results indicated that tilts influence SAR more than rotations. SAR values obtained at both 900/1800 MHz for the HMPswere well below ICNIRP limits for the general public. The phones were compliant with both international and Australian standards.

Training and other predictors of personal protective equipment use in Australian grain farmers using pesticides.

OBJECTIVES: To investigate patterns of use of personal protective equipment (PPE) to reduce pesticide exposure in a sample of Australian farmers and also to assess the influence of possible predictive factors. METHODS: A cross-sectional survey of 1102 farmers recruited through the Victorian Farmers Federation (VFF) was conducted. A written questionnaire was filled out by participants at VFF meetings attended by a visiting research assistant. Participants answered questions about frequency of pesticide use and PPE items they usually used when doing two different pesticide-related tasks, mixing and application, of each of four classes of pesticides. They also answered questions about personal characteristics, farm characteristics, farming activities, career and health. RESULTS: Nearly all surveyed farmers had ever used pesticides, and over 87% had used Herbicides or Animal Health Products in the previous 12 months. Non-use of PPE was frequently reported, with up to 10-40% of farmers routinely using no PPE at all when using pesticides. Across all pesticide classes, PPE use was higher for pesticide mixing than for application. In multivariate analyses PPE use appeared to be most strongly associated with younger age and farm chemical training. CONCLUSIONS: PPE use across all pesticide classes was poor, indicating the possibility of clinically significant pesticide exposure in many farmers. Given that PPE use was found to be associated with farm chemical training, the authors suggest that training is likely to be an important intervention for reducing farmers' pesticide exposure. Poor uptake of farm chemical training by farmers and the aging farming workforce are causes for concern in the light of these findings.

Mobile phones and brain tumours: a review of epidemiological research.

There has been a great deal of public concern regarding the possibility that the use of mobile phone-related technologies might result in adverse health effects. Corresponding to this, there has been substantial epidemiological research designed to determine whether the use of mobile phones (MP) has any effect on health, and in particular whether it increases the risk of developing head and neck tumours. Such literature is particularly heterogeneous, which makes it difficult to pool in a meta-analysis. This paper thus reviews the epidemiological literature pertaining to the use of mobile phones and mobile phone-related technologies, and head and neck tumours, in an attempt to consolidate the various reports. Although there have been individual reports of associations between MP-use and tumours, this research is not consistent and on balance does not provide evidence of an association. There are reports of small associations between MP-use ipsilateral to the tumour for greater than 10 years, for both acoustic neuroma and glioma, but the present paper argues that these are especially prone to confounding by recall bias. The reported associations are in need of replication with methods designed to minimise such bias before they can be treated as more than suggestive.

Occupational exposure to power frequency magnetic fields and risk of non-Hodgkin lymphoma.

OBJECTIVES: To investigate the risk of non-Hodgkin lymphoma (NHL) using a job-exposure matrix (JEM) to assess exposure to occupational magnetic fields at the power frequencies of 50/60 Hz. METHODS: The study population consisted of 694 cases of NHL, first diagnosed between 1 January 2000 and 31 August 2001, and 694 controls from two regions in Australia, matched by age, sex and region of residence. A detailed occupational history was given by each subject. Exposure to power frequency magnetic fields was estimated using a population-based JEM which was specifically developed in the United States to assess occupational magnetic field exposure. The cumulative exposure distribution was divided into quartiles and adjusted odds ratios were calculated using the lowest quartile as the referent group. RESULTS: For the total work history, the odds ratio (OR) for workers in the upper quartile of exposure was 1.48 (95% CI 1.02 to 2.16) compared to the referent (p value for trend was 0.006). When the exposure was lagged by 5 years the OR was 1.59 (95% CI 1.07 to 2.36) (p value for trend was 0.003). Adjusting for other occupational exposures did not significantly alter the results. CONCLUSIONS: These findings provide weak support for the hypothesis that occupational exposure to 50/60 Hz magnetic fields increases the risk of NHL.

Retrospective assessment of occupational exposure to chemicals in community-based studies: validity and repeatability of industrial hygiene panel ratings.

BACKGROUND: Occupational hygiene panels are increasingly being used to rate retrospective occupational exposures to chemicals in community-based studies. This study aimed to assess the validity, reliability and feasibility of using such an expert panel in a brain tumour case-control study. METHODS: A panel of five experts was recruited to rate exposure to 21 chemicals for 298 job descriptions to investigate the level of agreement. Validity was assessed by comparing the ratings of the experts for 49 of the jobs with objective quantitative exposure data which existed for these jobs. Repeatability was assessed by comparing the results for 50 resubmissions. RESULTS: Specificity was high for reporting that exposure occurred (all above 90%), but sensitivity was variable with values between 48% and 79%. Weaker validity was found for rating exposure level and exposure frequency. The raters showed the greatest inter-rater agreement for exposure to three of the 21 chemicals considered (kappa = 0.64 for cutting fluids, kappa = 0.57 for welding fumes and kappa = 0.42 for lubricating oils). Intra-rater reliability, based on the 50 resubmitted jobs, was fair to good (kappa = 0.46, 0.73). CONCLUSIONS: The potential effect of exposure misclassification from using expert panels was quantified and found to be a significant source of bias. The optimum situation occurred where three of the five raters concurred, where an odds ratio of 2.2 was observed for a true odds ratio of 4.0. Future studies which plan to use expert panels should screen the experts for their suitability by validating their performance against jobs with known exposure data.

Brain chirps: spectrographic signatures of epileptic seizures.

OBJECTIVE: A chirp is a brief signal within which the frequency content changes rapidly. Spectrographic chirps are found in signals produced from many biological and physical phenomena. In radar and sonar engineering, signals with chirps are used to localize direction and range to the signal source. Although characteristic frequency changes during epileptic seizures have long been observed, the correlation with chirps and chirp technology seems never to have been made. METHODS: We analyzed 19404 s (1870 s of which were from 43 seizures) of intracranially (subdural and depth electrode) recorded digital EEG from 6 patients for the presence of spectral chirps. Matched filters were constructed from methods in routine use in non-medical signal processing applications. RESULTS: We found that chirps are very sensitive detectors of seizures (83%), and highly specific as markers (no false positive detections). The feasibility of using spectral chirps as matched filters was demonstrated. CONCLUSIONS: Chirps are highly specific and sensitive spectrographic signatures of epileptic seizure activity. In addition, chirps may serve as templates for matched filter design to detect seizures, and as such, can demonstrate localization and propagation of seizures from an epileptic focus.

Asthma and vaccination history in a young adult cohort.

BACKGROUND: It has been suggested that childhood vaccinations may be associated with the onset of asthma. We investigated the association between asthma, atopy and vaccination history in a cohort of young adults living in Melbourne, Australia. METHODS: Subjects were aged between 22 and 44 years and were surveyed by an interviewer-administered questionnaire. Questions were asked about vaccinations to measles, mumps and rubella (MMR), triple antigen (DTP), hepatitis B and Sabin polio vaccine (OPV). Atopy was assessed by skin prick testing to common aeroallergens. RESULTS: There was no significant association observed for subjects diagnosed with asthma who had received measles or MMR vaccinations compared with those who did not receive measles or MMR vaccinations (RR 1.33, 95% CI 0.98-1.80). Non-significant associations were also observed for OPV and hepatitis B vaccinations (RR 3.27, 95% CI 0.50-21.3 and RR 1.08, 95% CI 0.83-1.41, respectively). However, subjects reporting full immunisation were found to be at higher risk to asthma (RR 1.52, 95% CI 1.09-2.11) but not atopy. CONCLUSIONS: Our results show relatively weak support for the hypothesis that childhood vaccinations may lead to increased risk of asthma, but caution is advised due to possible recall bias.

Spinal anesthesia with meperidine: will epinephrine prolong its duration?

Meperidine (Demerol) has local anesthetic properties separate from its opioid receptor agonist effect. Unlike morphine, meperidine is structurally similar to local anesthetics. Therefore, it is not surprising that it possesses some characteristics of local anesthetics. If meperidine acts like a local anesthetic, binding to the same receptor sites and inhibiting nerve conduction, then drugs that alter the action and duration of local anesthetics may have a similar effect on it. This double-blinded investigation used low-dose meperidine as the sole intrathecal agent to determine the effect of epinephrine on the duration of sensory blockade. Thirty male ASA physical status I through III patients between the ages of 58-81 years who were scheduled for transurethral resection of the prostate or of bladder tumors were randomly assigned to receive meperidine with or without epinephrine. A continuous spinal technique was utilized, and meperidine 0.5 mg/kg was administered after ascertaining the proper position of the catheter. Fourteen of the patients received epinephrine, and 16 patients did not. There were no statistically significant differences between the two groups in terms of age, height, weight, and ASA physical status. No statistically significant prolongation of the sensory blockade was observed with the addition of epinephrine. There were no statistically significant differences between the two groups with regard to onset time or the incidence of complications. The occurrence of a full motor block in the group that did not receive epinephrine was statistically significant.

Growth factors and gene therapy: the prospects for treating limited cartilage defects.

The limited regenerative capacities of articular are well known. Among the many methods used to repair the joint surface, among the most innovative involve stimulating chondrocytes to grow and differentiate by local application of exogenous protein growth factors, and attempting to transfer the genes responsible for cell division and maturation. This article presents the current state of knowledge on the possibilities for the treatment of limited cartilage defects used these methods.

Methods for the isolation and culture of human articular chondrocytes.

The tissue engineering of cartilage implants may open new paths for the surgical treatment of joint surface defects. Autologous chondrocyte transplantation (ACT) has been gaining in clinical significance over the last several years. This study presents the methods used for isolation, monolayer culturing, multipication and assesment in transmission light microscopy of human chondrocytes. The tissue was gained from resected fragments of joint during total knee replacement.

The use of carbon fibers to restore cartilage defects in the knee.

Research on carbon biomaterials has Bern in progress at the Warsaw Orthopedic Clinic for more than 20 years. Recently these materials have also been used in clinical practice as matrix material for repairing tissue defects in the motor organs. In this article, a new method is presented using carbon fiber to treat cartilage defects in the knee. This study describes the authors experience with carbon fibers used as scaffolds in drilled cartilage lesions to enhance the in growth of regenerative tissue. The research involved 35 patients treated for cartilage defects from December 1993 to June 1997. The average age was 46 (range 19-68), and the average follow-up was 48 months (range 24-55 months). The results were assessed by applying the HSS knee scale, the Wallgren-Tegner activity score, the VAS (visual analogue scale of pain), and the patients subjective judgment of the surgery. Good or excellent outcomes were obtained in 25 of the 35 patients (71%). The most striking aspect of the outcome was good pain relief. Early follow-ups are necessary, but the results must be confirmed in long-term observations.

The diagnostic value of bone scintigraphy in patients with back pain.

Background. The aim of the study was retrospective evaluation of planar bone scintigraphy in the diagnostics of back pain syndrome.
Material and methods. The study included 252 patients referred to the Nuclear Medicine Department from the Rehabilitation and Spine Diseases Consulting Unit from January 2001 to June 2003. In all cases whole body radionuclide imaging was performed using Tc 99m -MDP.
Results. Of patients suffering from a back pain 14% had normal scans. Among the causes of abnormal results in our study dominated changes of degenerative background - osteoarthritis (68,5%). In 26 patients (10,3%) pathological uptake was typical for metastatic disease.
Conclusions. Bone scan offers the advantage of total body examination and images bone lesions earlier than other techniques. In selected cases, radionuclide imaging may explain the etiology of back pain syndrome and facilitate definite treatment.