The impact of AIDS and the dread of acquiring HIV infection from patients have led to the resurgence in infection-control practices among health care workers. Recent reports of blood-borne pathogen transmission in health care settings, including oral health, have caused considerable public health concern. Transmission has been reported from patient to patient, patient to health care workers, but rarely from health care worker to patient. The risks of dental clinicians acquiring serious infections have been well documented but the risk to dental assistants has received less attention, especially in South Africa. Aim: To assess infection-control practices of dental assistants and their level of adherence to universal precautions in public health care facilities in Limpopo Province. Objectives: To establish the prevalence and the type of occupational exposures among dental assistants working in public health care facilities in Limpopo Province. Methods: A cross-sectional survey was conducted among dental assistants in Limpopo Province in 2005. The study population comprised all 73 employees who performed the functions of a dental assistant in public dental facilities. A self-administered questionnaire was used to collect information regarding work experiences and training, infection-control practice and knowledge, and the nature, incidences and reporting of any occupational exposures they had experienced. A follow-up telephone call was made to these dental assistants, after they had received the questionnaire, to re-iterate the importance of the survey and to request them to complete and return the questionnaire in the prepaid envelope they had been given. The facilities were clustered according to the six districts in Limpopo Province. Ethical approval was given by the University of the Witwatersrand and the Department of Health and Welfare in Limpopo Province. Results: Fifty-nine dental assistants returned the completed questionnaire, giving a response rate of 80.8%. Epi Info Version 3.3.2 programme was used to analyze the data. The majority of respondents were female (95%), with a mean age of 40.2 years (age range 23-54). More than 90% of the respondents had no formal training for their occupation, half (49.1%) did not have any health training, 22% were auxiliary nurses, 18.6% were “correspondence-trained” assistants who had been trained via distance learning and had no practical clinical training and only 10.2% of the respondents had received training at a technikon or university . The majority of the dental facilities (57.6%) had one dental assistant working alone, followed by those with two or three assistants (39.5%). The number of respondents assisting more than two oral clinicians in a day was 93.3%. The mean number of clinicians assisted per day was 3.8. The total numbers of dental assistants who experienced occupational exposures while working at the various dental clinics were 26 (44.1%), with 11.5% experiencing multiple injuries within the preceding six months. Auxiliary nurses and trained assistants were significantly more likely than untrained assistants to be aware of universal precautions, their protective effects, needle stick protocols, and of the need for personal protective equipments to be worn for all procedures (p=0.001). Compliance with infection-control practices was low overall. More than twothirds of the assistants routinely wore gloves during procedures. The lowest compliance reported was the use of protective eye shields, whilst more than 62.7% were not vaccinated against hepatitis B virus. More than two-thirds of the assistants were injured in the process of removing and or cleaning instruments; 65.3% of the injuries were direct punctures. Twenty-three percent did not report the injury. The risk of injury for the untrained assistants was 9.9 times higher than that for auxiliary nurses, p=0.008. A small percentage (23.8%) of those with sharp injuries was placed on antiretroviral drugs. Surprisingly, a significant high percentage of respondents were given wound cleaning only as treatment of their occupational exposures (78.4%) and sharp injuries (83%). Conclusion and recommendation More than 90% of the respondents had no formal training for their occupation. Dental assistants were understaffed and had increased workload. The greatest incidence of injury was associated with the handling of sharp objects, and this included recapping used needles. Occupational exposures to infectious material were found to be relatively high whilst compliance to some basic infection-control guidelines was low among dental assistants. The training of dental assistants should be regulated. More suitably qualified dental assistants should be appointed and existing ones should be given inservice training on the importance of infection-control practices and compliance with universal precautions.

The objective of this thesis was to investigate firefighters’ exposures to carcinogens and mutagens. This thesis aimed to (1) characterize firefighters’ exposures during emergency fire suppression, (2) examine the use of silicone wristbands as passive samplers to assess firefighters’ exposures, and (3) assess the ability of post-fire decontamination protocols to reduce firefighters’ exposures. Chapter 1 provides a general introduction and background information on the concepts covered in this thesis. In Chapter 2, I examined air and surface contamination with polycyclic aromatic hydrocarbons (PAHs) and metals, both at fire stations and following emergency fire suppression activities. I also investigated the ability of current laundering methods to remove surficial PAHs and metals from firefighters’ personal protective equipment. In Chapter 3, I assessed the ability of silicone wristband passive samplers to measure firefighters’ exposures to PAHs during live fire training. In Chapter 4, I assessed the ability of three post-fire dermal decontamination methods to remove surface contamination and reduce internal dose. In Chapter 5, conclusions and implications for each chapter are summarized. Future directions for the field are described. The overall conclusions for this thesis were: i. firefighters experience significant occupational exposures to carcinogens during emergency fire suppression and live fire training; ii. the ability of silicone wristbands to properly sample PAHs is altered in a fire environment and correction factors must be determined to improve their utility for exposure assessment; iii. current post-fire dermal decontamination methods, which are intended to reduce firefighters’ exposures, do not reduce their internal dose of PAHs.

Occupational skin and respiratory symptoms, and disease, are common problems. Workers can develop new disease or aggravate existing disease as a result of exposures at work. Many workers are exposed to chemicals that can cause both respiratory and skin responses and there is evidence that some workers experience symptoms in both systems. There is also evidence that skin exposure may lead to sensitization and the development of respiratory disease. There is very little research that has examined both airborne and skin exposures together with lung and skin outcomes. The purpose of this thesis was to further investigate the relationships between occupational exposures, skin symptoms and disease, and respiratory symptoms and disease. Four studies were undertaken to improve our understanding of these complex relationships. Results from a study of clinical patch test data determined that seven of the ten most common occupational contact allergens are also capable of causing occupational asthma and that these common occupational exposures may not be recognized as sensitizers in common reference materials. Exposure-response relationships for skin symptoms were modeled in bakery workers and auto body shop workers using historical data; significant exposure-response relationships were found for auto body workers. In two separate studies of concurrent skin and respiratory symptoms, workers did report concurrent skin and respiratory symptoms. In predictive models, subjects reporting a history of eczema were more likely to report concurrent skin and respiratory symptoms. Overall, the results from this thesis provide more evidence that the skin and respiratory systems are associated. This body of work suggests that: (1) several common occupational exposures can cause disease in both the skin and respiratory system; (2) a portion of workers report both skin and respiratory symptoms; and (3) exposure-response relationships do exist for skin symptoms, both work-related and non-work-related. Future studies need to gather detailed information about exposure and response in both systems in order to better determine the role of exposure(s) in the development of skin and respiratory symptoms. Improved understanding of these relationships will allow for more targeted and effective exposure prevention strategies and will ultimately reduce the burden of occupational disease.

Occupational skin and respiratory symptoms, and disease, are common problems. Workers can develop new disease or aggravate existing disease as a result of exposures at work. Many workers are exposed to chemicals that can cause both respiratory and skin responses and there is evidence that some workers experience symptoms in both systems. There is also evidence that skin exposure may lead to sensitization and the development of respiratory disease. There is very little research that has examined both airborne and skin exposures together with lung and skin outcomes. The purpose of this thesis was to further investigate the relationships between occupational exposures, skin symptoms and disease, and respiratory symptoms and disease. Four studies were undertaken to improve our understanding of these complex relationships. Results from a study of clinical patch test data determined that seven of the ten most common occupational contact allergens are also capable of causing occupational asthma and that these common occupational exposures may not be recognized as sensitizers in common reference materials. Exposure-response relationships for skin symptoms were modeled in bakery workers and auto body shop workers using historical data; significant exposure-response relationships were found for auto body workers. In two separate studies of concurrent skin and respiratory symptoms, workers did report concurrent skin and respiratory symptoms. In predictive models, subjects reporting a history of eczema were more likely to report concurrent skin and respiratory symptoms. Overall, the results from this thesis provide more evidence that the skin and respiratory systems are associated. This body of work suggests that: (1) several common occupational exposures can cause disease in both the skin and respiratory system; (2) a portion of workers report both skin and respiratory symptoms; and (3) exposure-response relationships do exist for skin symptoms, both work-related and non-work-related. Future studies need to gather detailed information about exposure and response in both systems in order to better determine the role of exposure(s) in the development of skin and respiratory symptoms. Improved understanding of these relationships will allow for more targeted and effective exposure prevention strategies and will ultimately reduce the burden of occupational disease.

No description available.

No description available.

O atual modelo de desenvolvimento econômico, que tem como uma de suas bases a acentuada produção de bens de consumo, é responsável pelo aumento crescente de riscos ambientais que incidem nas questões de saúde das populações. Esse modelo é também responsável por um aumento na geração de resíduos sólidos, considerado um dos problemas ambientais emergentes com significativos impactos para a saúde humana. O crescimento na geração de resíduos vem sendo acompanhado por um aumento considerável no número de catadores de material reciclável, que encontram nessa atividade uma estratégia de sobrevivência. Esse grupo de trabalhadores encontra-se potencialmente exposto a maiores riscos no campo da saúde em função de sua ocupação. Na presente investigação, avaliaram-se os níveis de exposição aos metais cádmio (Cd), chumbo (Pb), mercúrio (Hg) e níquel (Ni) em catadores de material reciclável de quatro cooperativas na Região Metropolitana de São Paulo (RMSP) e os resultados foram comparados com estudos de biomonitoramento também realizados na RMSP .Foram coletadas amostras de sangue de 226 indivíduos (IC:95%, precisão 6%) e aplicados questionários para o levantamento de características associadas às concentrações de metais e à presença de valores acima dos Valores de Referência (VR) definidos por estudos de biomonitoramento. As concentrações médias de Cd (MA: 0,47 ug/L; MG: 0,34 ug/L) foram quase quatro vezes superiores às apontadas no estudo de referência e 24,3% dos indivíduos apresentaram concentrações de Cd acima dos VR. As concentrações médias de Pb (MA: 39,13 ug/L; MG: 34,11 ug/L) foram 1,4 vezes superiores às da população de referência e 10,6% dos indivíduos apresentaram concentrações de Pb acima do VR. As concentrações médias de Hg (MA: 1,46 ug/L; MG: 0,94 ug/L) não foram significativamente diferentes da população de referência, porém 4,9% dos indivíduos apresentaram concentrações de Hg acima do VR. As concentrações médias de níquel (Ni) (MA:3,3 ug/L; MG:1,89 ug/L) apresentaram grande variabilidade, não sendo possível realizar inferências sobre os níveis de exposição. Os resultados encontrados apontam para uma maior exposição ao Cd entre os catadores, possivelmente relacionada ao trabalho com a reciclagem, porém as fontes específicas não puderam ser determinadas por este estudo. Os resultados apontam também uma maior exposição ao Pb, porém de menor magnitude, o que pode estar relacionado com a condição socioeconômica e maior percentual de tabagistas na população do estudo e não necessariamente com a ocupação que exercem / The current model of economic development, which has as one of its bases a constant increase in production and consumption, is responsible for the intensification of environmental risks that can compromise a population\'s health. This model is also responsible for the continued growth in waste generation which is accompanied by a considerable increase in the number of recyclable materials collectors, who find in this activity a survival strategy. This population group that has for decades played an important role in solid waste management, now has greater exposures to health risks due to their daily activity. In the present study, the levels of exposure to the metals cadmium (Cd), lead (Pb), mercury (Hg) and nickel (Ni) were evaluated in recyclable materials collectors from four cooperatives in the Metropolitan Region of São Paulo (MRSP). Blood samples were collected from 226 individuals (CI: 95%, accuracy 6%) and the results were compared with other biomonitoring studies from MRSP. Questionnaires were applied to obtain information regarding variables that could influence the blood levels of the metals under study. The mean concentrations of Cd found (AM: 0.47 ug/L; GM: 0.34 ug/L) were almost four times that the ones found in the reference study and 24,3% of the individuals presented Cd concentrations above the Reference Values (RV). The mean concentrations of Pb in the collectors (AM: 39.13 ug/L; GM: 34.11 ug/L) were also significantly higher than the mean concentration in the reference study population (about 1.4 times) and 10,6% of the collectors presented Pb concentrations above the RV. The mean concentrations of mercury (AM: 1.46 ug/L; GM: 0.94 ug/L) were not significantly higher than the mean concentration found in the reference study. The concentration of Ni presented a large variability, so it was not possible to make inferences about the exposure to this metal. This study indicates that recyclable materials collectors have a greater exposure to Cd when compared with the general population, and this is possibly related to the work developed by these individuals, even though the sources could not be determined by this study. It also indicated that the collectors have a greater exposure to Pb, but the magnitude of the results might be explained by the socioeconomic characteristics and the larger amount of smokers among the sampled population

<p>Manganese (Mn) is an essential element and, at high doses, a neurotoxin that many workers are exposed to daily. Increased Mn body burden due to occupational exposures leads to a parkinsonian disorder that features symptoms such as mood disturbances, cognition deficits, and motor dysfunction. To understand exposed workers’ risk, biomarkers of exposure have been developed using blood, hair, bone, and toenails. None of these biomarkers take into account how much Mn is in the brain and instead rely on the assumption that Mn uptake in these materials is proportional and related to the levels in the brain. One way to measure Mn in the brain is through neuroimaging modalities, such as magnetic resonance imaging and positron emission tomography, however there remains a need to establish reliable neuroimaging biomarkers for Mn exposure and its toxicological effects. This thesis addresses this need.</p><p>First, we hypothesized that changes in Mn exposure would be reflected by changes in the MRI relaxation rate R1 and thalamic γ-aminobutyric acid (GABA). As part of a prospective cohort study, 17 welders were recruited and imaged on two separate occasions approximately two years apart. MRI relaxometry was used to assess changes of Mn accumulation in the brain. Additionally, GABA was measured using magnetic resonance spectroscopy (MRS) in the thalamic and striatal regions of the brain. Air Mn exposure ([Mn]air) and cumulative exposure indexes of Mn (Mn-CEI) for the past three months (Mn-CEI3M), past year (Mn-CEI12M), and lifetime (Mn-CEILife) were calculated using personal air sampling and a comprehensive work history, while toenails were collected for analysis of internal Mn body burden. Finally, welders’ motor function was examined using the Unified Parkinson’s Disease Rating Scale (UPDRS). Mn-CEI12M decreased significantly between the first and second scan (Wilcoxon Signed Rank, p = 0.02). ΔMn-CEI3M were correlated with R1 in the substantia nigra (spearman partial correlation, ρ = 0.50, p = 0.036) and thalamic GABA (ρ = 0.66, p = 0.001), but only GABA significantly decreased linearly with Mn-CEI3M (quantile regression, β = 15.22, p = 0.02). Finally, Mn-CEILife influences the change in R1 in the substantia nigra with Δ[Mn]Air, where higher Mn-CEILife lessened the ΔR1 per Δ[Mn]Air (F-test, p = 0.005). While R1 and GABA changed with Mn exposure, UPDRS was unaffected.</p><p>Secondly, we hypothesized that occupational exposure to Mn would lead to disturbances in dopamine release (DA), as measured with PET. Excess exposure to manganese (Mn) can lead to symptoms similar to Parkinson’s disease (PD). While symptoms of PD are due to loss of nigrostriatal dopaminergic neurons, there is no DA neuron loss with Mn toxicity. To assess how DA release may be affected by Mn exposure, 6 subjects (3 welders, 3 controls) were scanned with positron emission tomography and [11C]raclopride (a DA D2/D3 receptor antagonist displaceable by endogenous DA) at baseline and during an amphetamine challenge. There were no apparent differences in amphetamine-induced striatal DA release between groups. However, UPDRS motor scores were positively linearly related to [11C]raclopride binding potential (BPND) in the putamen, whereas Mn-CEILife was negatively related to baseline pre-commissural caudate and ventral striatum BPND. The pilot results suggest that [11C]raclopride PET might delineate the cause of mood and motor dysfunction in subjects exposed to Mn.</p><p>Third, we hypothesized that advanced data analysis techniques, such as machine learning, would increase our power in finding differences between groups of welders and controls based on exposure and biological outcomes. This study used data from previous studies in occupationally exposed welders and controls. Whole brain relaxometry using MRI measuring the relaxation rate R1 was acquired in 52 welders and 37 controls. Because measures of R1 in selected regions of the brain have been previously found to be proportional to Mn, we hypothesized that an advanced model taking into account the whole brain might be more predictive for Mn exposure. Additionally, because R1 is proportional to Mn in the region, we used a biokinetic model to estimate the amount of excess Mn in the brain from occupational exposures. Support vector machines (SVM) with a linear kernel were trained using leave-one-out cross-validation. Results indicated that models had recall and accuracy better than chance targeting air Mn exposure, years welding, age, and thalamic GABA. In comparison to all models, R1 appears to reliably predict thalamic GABA across all thresholds, which was previously shown to change with increased Mn exposure. This suggests that while R1 may be proportional to Mn, some Mn may not be free to contribute to signal, and instead thalamic GABA might better reflect the overall amount of free Mn in the brain. </p><p>Collectively, this thesis is a successful step towards establishing neuroimaging biomarkers of effect from occupational Mn exposure. The MRI relaxation rate R1, with adequate modeling, could eventually be used to measure total Mn brain burden while thalamic GABA might represent a better metric for measuring the neurochemical effects from recent exposures. However, future research should incorporate more endpoints, such as motor tests, mood assessments, and behavior assessments. </p><div><br></div><p><br></p>

Les expositions professionnelles représentent la 2nde étiologie de cancer du poumon. Parmi elles, les laines minérales (LM) utilisées comme substitut à l’amiante sont suspectées d’augmenter le risque de cancer du poumon en raison de leur structure proche de celle de l’amiante. Dans ce contexte, ce travail a pour objectif d'évaluer le rôle de l'histoire professionnelle et en particulier celui de l'exposition professionnelle aux LM dans la survenue de cancer du poumon en tenant compte des expositions à l'amiante, à la silice, autres substances très prévalentes dans le secteur de la construction. Une dernière partie a consisté à étudier le risque de cancer du poumon associé à l'exposition professionnelle aux poussières de ciment.Nous avons analysés les histoires professionnelles complètes des cas et témoins inclus dans l'étude cas-témoins en population générale ICARE, identifiés dans 10 départements français abritant un registre général de cancer. Au total, 2 276 cas de cancer du poumon chez les hommes et 2 780 témoins ont été inclus ainsi que 650 cas de cancers du poumon féminins et 775 témoins. Deux stratégies d'évaluation des expositions aux LM et à l'amiante ont été utilisées: une matrice emplois-expositions (MEE) et une matrice tâche-exposition élaborée par des hygiénistes industriels et tenant compte des données individuelles. Les expositions à la silice et au ciment ont toujours été évaluées par MEE. Nos résultats confirment le rôle important des expositions professionnelles comme déterminant du risque de cancer du poumon en mettant en évidence des associations avec de nombreuses professions et secteurs d'activité. L'hypothèse d'une association entre le risque de cancer du poumon et l'exposition professionnelle aux LM est suggérée sans toutefois pouvoir exclure une confusion résiduelle par l'amiante car ces deux expositions sont très corrélées. Par ailleurs, nos résultats confirment le rôle cancérogène de l'amiante et de la silice et suggèrent une association entre l'exposition aux poussières de ciment et le risque de cancer du poumon. / Occupational exposures are the second main risk factor of lung cancer. Asbestos has progressively been substituted by mineral wools (MW). Because of their similarity in shape with asbestos, they have been suspected of causing cancer of the respiratory system. In this context, the objectives of this work were to assess the role of occupational history in lung cancer risk; to investigate in details lung cancer risk associated with exposure to MW, carefully taking into account occupational exposures to asbestos and crystalline silica, two common potential carcinogenic exposure among construction workers; and to study the risk of lung cancer associated with occupational exposure to cement dusts.We analysed lifetime occupational history of cases and controls included in the ICARE study, a large multi-centre, population-based, case-control study. They were recruited in 10 French départements with a general cancer registry. The study included 6481 subjects (men: 2 276 lung cancer cases and 2 780 controls, women: 650 lung cancer cases and 775 controls). Two strategies of assessment of occupational exposure to MW and asbestos were used: a job-exposure matrix (JEM) and a task-exposure matrix constructed by trained hygienist and taking into account individual information. Occupational exposures to crystalline silica and cement dusts were both assessed using specific JEMs.Our results confirm the important role of occupational exposure as a determinant of lung cancer risk by showing associations between lung cancer risk and several occupations or industries. An association between MW exposure and lung cancer risk is suggested without being able to exclude a potential residual confounding by asbestos since these two exposures are deeply correlated. Our results also confirm asbestos and silica carcinogenicity and suggest an association between cement dusts and lung cancer risk.

<p>Aluminum (Al) is the third most abundant metal on the earth’s surface. An association of Al with Alzheimer’s disease has been suggested, but, given limited human evidence, is controversial. It is possible that exploration of long-term, or cumulative, exposure to Al will help clarify this debate. Therefore, our study hypothesis was that occupational exposure to Al, particularly long-term exposure, is associated with adverse cognitive and olfactory outcomes. </p><p>Biomarkers are important tools in epidemiologic research; however, the reliability and quality of various biomarkers may vary. Therefore, in Chapter 2, we reviewed current evidence on Al biomarkers with the goal to synthesize current understanding regarding their utility for use in research. Our review evaluated 78 papers which discussed various biomarkers of Al exposure. Limited evidence is currently available for Al in nails, hair, breastmilk, saliva and semen. Although they have more daily variation than other biomarkers, blood Al concentrations may differentiate between exposed and non-exposed groups. Unlike blood Al, Al concentrations in both urine and bone are not subject to daily fluctuations. Bone Al appears able to quantify long term Al exposure. Therefore, the use of <i>in vivo</i>neutron activation analysis (IVNAA), a novel bone biomarker, can potentially represent cumulative Al exposure. </p><p>In Chapter 3, we evaluated the hypothesis that the correlation between bone and CEI measurements will be higher than the correlation between bone with fingernail. A cross-sectional cohort of 61 ferroalloy and manufacturing factory workers from Zunyi, China were used in this secondary analysis. Correlations of bone Al with other Al measures (fingernail and cumulative exposure index (CEI)) were assessed for 43 of the factory workers who had bone Al samples. Fingernail samples were analyzed using inductively coupled plasma mass spectrometry. Bone measurements were taken with a compact IVNAA developed by our research team. CEI was calculated as CEI_i=, where C_iis estimated Al exposure based on job title (low/medium/high) and Y_iis the years employed. The CEI was calculated for the prior 5, 10, 15, 20 years and lifetime work history. Median Al values were: 34.4 mg/g (IQR=46) fingernail; 15 mg/g (IQR=28) bone; and 26 (IQR=21) total CEI. Adjusting for age and education, the linear regression model suggests that bone Al is reflective of 15 years of exposure based off the significant association between bone Al and 15-year CEI (b=0.91, <i>p</i><0.02). Other models with CEI were not statistically significant.</p><p>In Chapter 4, we evaluated the association between bone, CEI and fingernail Al measurements with olfactory and cognitive function. The relationship between cognitive and olfactory function was compared with bone Al (N=43), fingernail Al (FnAl) (N=56), 5 year Al CEI and lifetime Al CEI (N=61) measurements. Olfactory function was assessed with the University of Pennsylvania Smell Identification Test and cognitive function was assessed with the WHO/UCLA Auditory Verbal Learning Test (AVLT). Verbal fluency was assessed using Fruit Naming and Animal Naming. Additional variables were assessed via questionnaire. Linear regression models, adjusted for age, education, current alcohol consumption and current smoking status, showed a significant association between higher BnAl and higher recall on the AVLT interference list (b=0.04, 95% Confidence interval (CI)=0.01, 0.08) and higher 5-year CEI with higher recall on the fifth AVLT trial (b=-0.23, 95% CI=-0.45, -0.01). No significant association between FnAl and lifetime CEI with olfactory and cognitive function was observed. </p><p>In Chapter 5, we explored the potential for interactions of Al with another metal to impact the potential association of Al with cognitive and olfactory function. Interaction models used the natural log of fingernail Al with each of copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) for the 56 male workers. The linear regression models controlled for age, education current alcohol consumption, current smoking status, and all five fingernail metals. Higher ln(FnMn) was associated with lower recall for several AVLT trials. The interaction term for ln(FnAl) and ln(FnZn) was significantly associated with AVLT Trial 1 (β= 1.99, 95% CI=0.07, 3.93), AVLT Trial 5 (β= 2.71, 95% CI= 0.02, 5.41) and AVLT average (β=2.11, 95% CI=0.01, 4.21). </p>Overall, this research presents valuable information regarding noninvasive, <i>in vivo</i>assessment of BnAl and its relationship with other Al biomarkers and measures of cognitive function. To the best of our knowledge, this is the largest study to use INVAA BnAl measurements to quantify long-term aluminum exposures within an occupational population, the first to compare BnAl with an estimate of cumulative Al exposure. Additionally, we are not aware of prior studies which have examined the interaction of fingernail metals, including Al, with olfactory and cognitive tests. Our results suggest BnAl is significantly associated with the prior 15-years of Al exposure and that IVNAA to assess BnAl can be used in field epidemiology studies. For our study, there was limited evidence of an association of BnAl and 5-year CEI with cognitive function. Most comparisons did not show any evidence of an association of Al with cognitive or olfactory function, but a statistically significant interaction between Al and Zn with some measures of cognitive function was observed. It is recommended that our findings be confirmed with larger studies.