1
|
Hadrup N, Sørli JB, Jenssen BM, Vogel U, Sharma AK. Toxicity and biokinetics following pulmonary exposure to aluminium (aluminum): A review. Toxicology 2024; 506:153874. [PMID: 38955312 DOI: 10.1016/j.tox.2024.153874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Revised: 06/17/2024] [Accepted: 06/26/2024] [Indexed: 07/04/2024]
Abstract
During the manufacture and use of aluminium (aluminum), inhalation exposure may occur. We reviewed the pulmonary toxicity of this metal including its toxicokinetics. The normal serum/plasma level based on 17 studies was 5.7 ± 7.7µg Al/L (mean ± SD). The normal urine level based on 15 studies was 7.7 ± 5.3µg/L. Bodily fluid and tissue levels during occupational exposure are also provided, and the urine level was increased in aluminium welders (43 ± 33µg/L) based on 7 studies. Some studies demonstrated that aluminium from occupational exposure can remain in the body for years. Excretion pathways include urine and faeces. Toxicity studies were mostly on aluminium flakes, aluminium oxide and aluminium chlorohydrate as well as on mixed exposure, e.g. in aluminium smelters. Endpoints affected by pulmonary aluminium exposure include body weight, lung function, lung fibrosis, pulmonary inflammation and neurotoxicity. In men exposed to aluminium oxide particles (3.2µm) for two hours, lowest observed adverse effect concentration (LOAEC) was 4mg Al2O3/m3 (= 2.1mg Al/m3), based on increased neutrophils in sputum. With the note that a similar but not statistically significant increase was seen during control exposure. In animal studies LOAECs start at 0.3mg Al/m3. In intratracheal instillation studies, all done with aluminium oxide and mainly nanomaterials, lowest observed adverse effect levels (LOAELs) started at 1.3mg Al/kg body weight (bw) (except one study with a LOAEL of ~0.1mg Al/kg bw). The collected data provide information regarding hazard identification and characterisation of pulmonary exposure to aluminium.
Collapse
Affiliation(s)
- Niels Hadrup
- National Research Centre for the Working Environment, 105 Lersø Parkallé, Copenhagen Ø, Denmark; Research Group for Risk-Benefit, National Food Institute, Technical University of Denmark; Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
| | - Jorid B Sørli
- National Research Centre for the Working Environment, 105 Lersø Parkallé, Copenhagen Ø, Denmark.
| | - Bjørn M Jenssen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
| | - Ulla Vogel
- National Research Centre for the Working Environment, 105 Lersø Parkallé, Copenhagen Ø, Denmark; National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark.
| | - Anoop K Sharma
- Division for Risk Assessment and Nutrition, Group for Chemical Risk Assessment and GMO, National Food Institute, Technical University of Denmark, Kemitorvet, 201, 031, 2800 Kgs. Lyngby, Denmark.
| |
Collapse
|
2
|
Principi N, Esposito S. Do Vaccines Have a Role as a Cause of Autoimmune Neurological Syndromes? Front Public Health 2020; 8:361. [PMID: 32850592 PMCID: PMC7399175 DOI: 10.3389/fpubh.2020.00361] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/24/2020] [Indexed: 01/05/2023] Open
Abstract
Vaccines are the most important preventive measure against infectious diseases presently available. Although they have led to the eradication or the elimination of some infectious diseases, concerns about safety are among the main reasons for vaccine hesitancy. In some cases, the biological plausibility of a given damage in association with the temporal association between vaccine administration and disease development makes it difficult to define causality and can justify hesitancy. Only well-conducted epidemiological studies with adequate evaluation of results can clarify whether a true association between vaccines and adverse event development truly exists. Autoimmune neurological syndromes that follow vaccine use are among these. In this narrative review, the potential association between vaccines and the development of these syndromes are discussed. Literature analysis showed that most of the associations between vaccines and nervous system autoimmune syndromes that have been reported as severe adverse events following immunization are no longer evidenced when well-conducted epidemiological studies are carried out. Although the rarity of autoimmune diseases makes it difficult to strictly exclude that, albeit exceptionally, some vaccines may induce an autoimmune neurological disease, no definitive demonstration of a potential role of vaccines in causing autoimmune neurological syndromes is presently available. Consequently, the fear of neurological autoimmune disease cannot limit the use of the most important preventive measure presently available against infectious diseases.
Collapse
Affiliation(s)
| | - Susanna Esposito
- Pediatric Clinic, Department of Medicine and Surgery, Pietro Barilla Children's Hospital, University of Parma, Parma, Italy
| |
Collapse
|
3
|
Meng H, Wang S, Guo J, Zhao Y, Zhang S, Zhao Y, Niu Q. Cognitive impairment of workers in a large-scale aluminium factory in China: a cross-sectional study. BMJ Open 2019; 9:e027154. [PMID: 31209090 PMCID: PMC6589001 DOI: 10.1136/bmjopen-2018-027154] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 05/14/2019] [Accepted: 05/22/2019] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES To investigate the prevalence of mild cognitive impairment and the relationship with plasma aluminium among aluminium workers. DESIGN This was a cross-sectional case-control study in the SH Aluminium Factory, China. SETTING The university and affiliated hospital cooperated in the study. PARTICIPANTS There were 910 aluminium workers on duty, among whom 853 participated in our study. Participants, such as those with cerebral vascular disease, epilepsy, brain trauma, Parkinson's and mental diseases, aluminium-containing drug and mental drug use, and any family history of dementia in first-degree relatives were excluded. PRIMARY AND SECONDARY OUTCOME MEASURES Blood samples were collected, and plasma aluminium was measured by inductively coupled plasma-mass spectrometry. For each case, four age-matched controls were evaluated to determine the relationship between aluminium exposure and mild cognitive impairment. Conditional logistic regression was used to explore influential factors in mild cognitive impairment. RESULTS Among 910 workers, 93.74% participated in stage 1; 53 cases were finally diagnosed. The crude prevalence of mild cognitive impairment among aluminium workers on duty was 6.21%. There was a significant difference in plasma aluminium concentration between the two groups. In the multivariate analysis, we found that a higher level of plasma aluminium was associated with a high risk of cognitive impairment when compared with a lower aluminium level (AOR=2.24, 95% CI=1.17 to 4.26), and a high education level was a protective factor (AOR=0.36, 95% CI=0.18 to 0.70). No other factor was statistically significant. CONCLUSIONS Mild cognitive impairment is no longer a disease specific to elderly people. High plasma aluminium exposure might be associated with an increased risk of cognitive impairment, but a reduced risk was observed with a high education level. The cognitive function of aluminium workers on duty must be considered seriously.
Collapse
Affiliation(s)
- Huaxing Meng
- School of Public Health, Shanxi Medical University, Taiyuan, China
- Department of Neurology, First Hospital of Shanxi Medical University, Taiyuan, China
| | - Shanshan Wang
- School of Public Health, Shanxi Medical University, Taiyuan, China
| | - Junhong Guo
- Department of Neurology, First Hospital of Shanxi Medical University, Taiyuan, China
| | - Yarong Zhao
- Department of Neurology, First Hospital of Shanxi Medical University, Taiyuan, China
| | - Shuhui Zhang
- School of Public Health, Shanxi Medical University, Taiyuan, China
| | - Yuqing Zhao
- School of Public Health, Shanxi Medical University, Taiyuan, China
| | - Qiao Niu
- School of Public Health, Shanxi Medical University, Taiyuan, China
| |
Collapse
|
4
|
Xu L, Zhang W, Liu X, Zhang C, Wang P, Zhao X. Circulatory Levels of Toxic Metals (Aluminum, Cadmium, Mercury, Lead) in Patients with Alzheimer's Disease: A Quantitative Meta-Analysis and Systematic Review. J Alzheimers Dis 2019; 62:361-372. [PMID: 29439342 DOI: 10.3233/jad-170811] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Environmental exposure to toxic metals has been postulated to play a role in the pathophysiological processes of Alzheimer's disease (AD). However, the circulatory levels of toxic metals in AD patients are not consistent in previous studies. OBJECTIVE To systematically assess levels of toxic metals (aluminum, mercury, cadmium, lead) in the circulation (blood, serum/plasma) of AD patients and controls. METHODS PubMed, Web of Science, Science Direct, Cochrane Library, and the China National Knowledge Infrastructure (CNKI) were systematically searched to identify studies published up to January 1, 2017. Meta-analyses were performed using random-effects models and the pooled standardized mean difference (SMD) were reported with 95% confidence intervals (CI). RESULTS We identified 17, 7, 8, and 10 studies for aluminum, mercury, cadmium, and lead, respectively. Meta-analyses showed significantly elevated circulatory levels of aluminum (SMD = 1.08, 95% CI: 0.66, 1.50), mercury (SMD = 0.55, 95% CI, 0.15, 0.95), and cadmium (SMD = 0.62, 95% CI: 0.12, 1.11), whereas lower levels of lead (SMD = -0.23, 95% CI: -0.38, -0.07) in AD patients than in controls. Publication bias was only observed for aluminum studies, but the "trim and fill" analysis showed that the publication bias did not alter the direction of the effect. Sensitivity analyses showed no studies from the pooled analysis changed the results. CONCLUSION Compared to controls, circulatory levels of aluminum, mercury, and cadmium are significantly higher but the levels of lead were reduced in AD patients. These findings suggest that elevated aluminum, mercury, and cadmium in the circulation, especially in serum may play a role in the progression of AD.
Collapse
Affiliation(s)
- Lin Xu
- Department of Toxicology, School of Public Health, Shandong University, Jinan, China
| | - Wenchao Zhang
- Department of Epidemiology, School of Public Health, Shandong University, Jinan, China
| | - Xianchen Liu
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Cuili Zhang
- Department of Toxicology, School of Public Health, Shandong University, Jinan, China
| | - Pin Wang
- Department of Neurology, The Second Hospital of Shandong University, Jinan, China
| | - Xiulan Zhao
- Department of Toxicology, School of Public Health, Shandong University, Jinan, China
| |
Collapse
|
5
|
Occupational exposure to extremely low frequency magnetic fields and risk of Alzheimer disease: A systematic review and meta-analysis. Neurotoxicology 2018; 69:242-252. [DOI: 10.1016/j.neuro.2017.12.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 12/18/2017] [Accepted: 12/21/2017] [Indexed: 12/16/2022]
|
6
|
Aluminum in vaccines: Does it create a safety problem? Vaccine 2018; 36:5825-5831. [PMID: 30139653 DOI: 10.1016/j.vaccine.2018.08.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 08/03/2018] [Accepted: 08/15/2018] [Indexed: 12/21/2022]
Abstract
For almost a century, aluminum (Al) in the form of Al oxyhydroxide (a crystalline compound), Al hydroxyphosphate (an amorphous Al phosphate hydroxide), Al phosphate, and Al potassium sulfate has been used to improve the immunogenicity of vaccines. Al is currently included in vaccines against tetanus, hepatitis A, hepatitis B, human papillomavirus, Haemophilus influenzae type b, and infections due to Streptococcus pneumoniae and Neisseria meningitidis. Official health authorities consider the inclusion of Al in most of the presently recommended vaccines to be extremely effective and sufficiently safe. However, the inclusion of Al salts in vaccines has been debated for several years because of studies that seem to indicate that chronic Al exposure through vaccine administration can interfere with cellular and metabolic processes leading to severe neurologic diseases. Children, who in their first years of life receive several vaccine doses over a reduced period of time, would be most susceptible to any risk that might be associated with vaccines or vaccine components. The main aim of this paper was to discuss the data presently available regarding Al neurotoxicity and the risk for children receiving vaccines or other pharmaceutical preparations containing Al. Analysis of the literature showed that no apparent reason exists to support the elimination of Al from vaccines for fear of neurotoxicity. The only problem that deserves attention is the suggested relationship between Al oxyhydroxide-containing vaccines and macrophagic myofaciitis or myalgic encephalomyelitis/chronic fatigue syndrome. Currently, definitive conclusions cannot be drawn on these risks and further studies must be conducted. Until then, Al remains the best solution to improve vaccine efficacy.
Collapse
|
7
|
Becker LC, Boyer I, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler DC, Marks JG, Shank RC, Slaga TJ, Snyder PW, Andersen FA. Safety Assessment of Alumina and Aluminum Hydroxide as Used in Cosmetics. Int J Toxicol 2018; 35:16S-33S. [PMID: 27913785 DOI: 10.1177/1091581816677948] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This is a safety assessment of alumina and aluminum hydroxide as used in cosmetics. Alumina functions as an abrasive, absorbent, anticaking agent, bulking agent, and opacifying agent. Aluminum hydroxide functions as a buffering agent, corrosion inhibitor, and pH adjuster. The Food and Drug Administration (FDA) evaluated the safe use of alumina in several medical devices and aluminum hydroxide in over-the-counter drugs, which included a review of human and animal safety data. The Cosmetic Ingredient Review (CIR) Expert Panel considered the FDA evaluations as part of the basis for determining the safety of these ingredients as used in cosmetics. Alumina used in cosmetics is essentially the same as that used in medical devices. This safety assessment does not include metallic or elemental aluminum as a cosmetic ingredient. The CIR Expert Panel concluded that alumina and aluminum hydroxide are safe in the present practices of use and concentration described in this safety assessment.
Collapse
Affiliation(s)
- Lillian C Becker
- Cosmetic Ingredient Review Scientific Analyst/Writer, Washington, DC, USA
| | - Ivan Boyer
- Cosmetic Ingredient Review Toxicologist, Washington, DC, USA
| | - Wilma F Bergfeld
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Donald V Belsito
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Ronald A Hill
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | | | - Daniel C Liebler
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - James G Marks
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Ronald C Shank
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Thomas J Slaga
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - Paul W Snyder
- Cosmetic Ingredient Review Expert Panel Member, Washington, DC, USA
| | - F Alan Andersen
- Former Director, Cosmetic Ingredient Review, Washington, DC, USA
| |
Collapse
|
8
|
Klotz* K, Weistenhöfer* W, Neff F, Hartwig A, van Thriel C, Drexler H. The Health Effects of Aluminum Exposure. DEUTSCHES ARZTEBLATT INTERNATIONAL 2017; 114:653-659. [PMID: 29034866 PMCID: PMC5651828 DOI: 10.3238/arztebl.2017.0653] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 12/08/2016] [Accepted: 01/21/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND Aluminum is regularly taken up with the daily diet. It is also used in antiperspirants, as an adjuvant for vaccination, and in desensitization procedures. In this review, we present the scientifically documented harmful effects of aluminum on health and the threshold values associated with them. METHODS This review is based on publications retrieved by a selective search of the PubMed and SCOPUS databases on the topic of aluminum in connection with neurotoxicity, Alzheimer's disease, and breast cancer, as well as on the authors' personal experience in occupational and environmental medicine. RESULTS The reference values for the internal aluminum load (<15 μg/L in urine, <5 μg/L in serum) are especially likely to be exceeded in persons with occupational exposure. The biological tolerance value for occupational exposure is 50 μg of aluminum per gram of creatinine in the urine. For aluminum welders and workers in the aluminum industry, declining performance in neuropsychological tests (attention, learning, memory) has been found only with aluminum concentrations exceeding 100 μg/g creatinine in the urine; manifest encephalopathy with dementia was not found. Elevated aluminum content has been found in the brains of persons with Alzheimer's disease. It remains unclear whether this is a cause or an effect of the disease. There is conflicting evidence on carcinogenicity. The contention that the use of aluminum-containing antiperspirants promotes breast cancer is not supported by consistent scientific data. CONCLUSION The internal aluminum load is measured in terms of the concentration of aluminum in urine and blood. Keeping these concentrations below the tolerance values prevents the development of manifest and subclinical signs of aluminum toxicity. Large-scale epidemiologic studies of the relationship between aluminum-containing antiperspirants and the risk of breast cancer would be desirable.
Collapse
Affiliation(s)
- Katrin Klotz*
- * The two authors share first authorship
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine. University of Erlangen-Nuremberg
| | - Wobbeke Weistenhöfer*
- * The two authors share first authorship
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine. University of Erlangen-Nuremberg
| | - Frauke Neff
- Departments of Pathology at Städtische Kliniken München GmbH & Technische Universität München
| | - Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT)
| | - Christoph van Thriel
- Leibniz Research Centre for Working Environment and Human Factors at Technische Universität Dortmund
| | - Hans Drexler
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine. University of Erlangen-Nuremberg
| |
Collapse
|
9
|
Killin LOJ, Starr JM, Shiue IJ, Russ TC. Environmental risk factors for dementia: a systematic review. BMC Geriatr 2016; 16:175. [PMID: 27729011 PMCID: PMC5059894 DOI: 10.1186/s12877-016-0342-y] [Citation(s) in RCA: 204] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 09/19/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Dementia risk reduction is a major and growing public health priority. While certain modifiable risk factors for dementia have been identified, there remains a substantial proportion of unexplained risk. There is evidence that environmental risk factors may explain some of this risk. Thus, we present the first comprehensive systematic review of environmental risk factors for dementia. METHODS We searched the PubMed and Web of Science databases from their inception to January 2016, bibliographies of review articles, and articles related to publically available environmental data. Articles were included if they examined the association between an environmental risk factor and dementia. Studies with another outcome (for example, cognition), a physiological measure of the exposure, case studies, animal studies, and studies of nutrition were excluded. Data were extracted from individual studies which were, in turn, appraised for methodological quality. The strength and consistency of the overall evidence for each risk factor identified was assessed. RESULTS We screened 4784 studies and included 60 in the review. Risk factors were considered in six categories: air quality, toxic heavy metals, other metals, other trace elements, occupational-related exposures, and miscellaneous environmental factors. Few studies took a life course approach. There is at least moderate evidence implicating the following risk factors: air pollution; aluminium; silicon; selenium; pesticides; vitamin D deficiency; and electric and magnetic fields. CONCLUSIONS Studies varied widely in size and quality and therefore we must be circumspect in our conclusions. Nevertheless, this extensive review suggests that future research could focus on a short list of environmental risk factors for dementia. Furthermore, further robust, longitudinal studies with repeated measures of environmental exposures are required to confirm these associations.
Collapse
Affiliation(s)
- Lewis O. J. Killin
- Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK
- Centre for Cognitive Ageing & Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
- Scottish Dementia Clinical Research Network, NHS Scotland, Perth, UK
| | - John M. Starr
- Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK
- Centre for Cognitive Ageing & Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
| | - Ivy J. Shiue
- Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK
- Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, UK
| | - Tom C. Russ
- Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK
- Centre for Cognitive Ageing & Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
- Centre for Dementia Prevention, University of Edinburgh, Edinburgh, UK
- Division of Psychiatry, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
10
|
Virk SA, Eslick GD. Aluminum Levels in Brain, Serum, and Cerebrospinal Fluid are Higher in Alzheimer's Disease Cases than in Controls: A Series of Meta-Analyses. J Alzheimers Dis 2016; 47:629-38. [PMID: 26401698 DOI: 10.3233/jad-150193] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Aluminum is the most studied environmental agent linked with Alzheimer's disease (AD). However, it remains unclear whether levels are significantly elevated in AD sufferers. OBJECTIVE To systematically assess levels of aluminum in brain, serum, and cerebrospinal fluid (CSF) of AD cases and controls. METHODS Electronic searches of Medline, Embase, PubMed, and Cochrane Library were conducted up to June 2015. Studies reporting brain, serum, or CSF aluminum levels in individuals with AD and non-demented controls were included. Meta-analyses were performed using random-effects models and the pooled standardized mean difference (SMD) reported with 95% confidence intervals (CI). RESULTS Overall, 34 studies involving 1,208 participants and 613 AD cases met the criteria for inclusion. Aluminum was measured in brain tissue in 20 studies (n = 386), serum in 12 studies (n = 698), and CSF in 4 studies (n = 124). Compared to control subjects, AD sufferers had significantly higher levels of brain (SMD 0.88; 95% CI, 0.25-1.51), serum (SMD 0.28; 95% CI, 0.03-0.54), and CSF (SMD 0.48; 95% CI, 0.03-0.93) aluminum. Sensitivity analyses excluding studies without age-matched controls did not impact upon these results. CONCLUSIONS The findings of the present meta-analyses demonstrate that aluminum levels are significantly elevated in brain, serum, and CSF of patients with AD. These findings suggest that elevated aluminum levels, particularly in serum, may serve as an early marker of AD and/or play a role in the development of the disease. These results substantially clarify the existing evidence examining the link between chronic aluminum exposure and the development of AD.
Collapse
|
11
|
Brief Report: Meta-analysis of Antacid Use and Alzheimer's Disease: Implications for the Aluminum Hypothesis. Epidemiology 2016; 26:769-73. [PMID: 26098935 DOI: 10.1097/ede.0000000000000326] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Exposure to aluminum remains a controversial risk factor for Alzheimer's disease. Antacids are aluminum-rich medications that are widely used in substantial amounts, but their association with Alzheimer's disease has not been systematically quantified. METHODS We conducted electronic searches of PubMed, Embase, and Cochrane Library up to January 2015 for case-control and cohort studies published in any language. Summary risk estimates were derived using random-effects models. RESULTS Seven case-control studies (n = 5,468; 829 Alzheimer's disease cases) and two cohort studies (n = 842; 110 Alzheimer's disease cases) met the criteria for inclusion. Study quality was limited by imprecise characterization of the timing and duration of antacid use. Regular antacid use was not associated with Alzheimer's disease in either case-control (odds ratio = 1.0; 95% confidence interval = 0.8, 1.2) or cohort studies (relative risk = 0.8; 95% confidence interval = 0.4, 1.8). Sensitivity analysis including studies specifically examining aluminum-containing antacids did not reveal an association. CONCLUSIONS Although the findings of this meta-analysis do not support an association between aluminum intake and Alzheimer's disease, prospective studies with longer follow-up and more precise characterization of exposure are required to definitively exclude an etiologic role for aluminum.
Collapse
|
12
|
Wang Z, Wei X, Yang J, Suo J, Chen J, Liu X, Zhao X. Chronic exposure to aluminum and risk of Alzheimer’s disease: A meta-analysis. Neurosci Lett 2016; 610:200-6. [DOI: 10.1016/j.neulet.2015.11.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 02/06/2023]
|
13
|
Willhite CC, Karyakina NA, Yokel RA, Yenugadhati N, Wisniewski TM, Arnold IMF, Momoli F, Krewski D. Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts. Crit Rev Toxicol 2014; 44 Suppl 4:1-80. [PMID: 25233067 PMCID: PMC4997813 DOI: 10.3109/10408444.2014.934439] [Citation(s) in RCA: 239] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007) . Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of "total Al"assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al(+3) to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)(+2) and Al(H2O)6 (+3)] that after complexation with O2(•-), generate Al superoxides [Al(O2(•))](H2O5)](+2). Semireduced AlO2(•) radicals deplete mitochondrial Fe and promote generation of H2O2, O2 (•-) and OH(•). Thus, it is the Al(+3)-induced formation of oxygen radicals that accounts for the oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.
Collapse
Affiliation(s)
- Calvin C. Willhite
- Risk Sciences International, Ottawa, ON, Canada
- McLaughlin Centre for Population Health Risk Assessment, Ottawa, ON, Canada
| | | | - Robert A. Yokel
- Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, USA
| | | | - Thomas M. Wisniewski
- Departments of Neurology, Psychiatry and Pathology, New York University School of Medicine, New York City, New York, USA
| | - Ian M. F. Arnold
- Occupational Health Program, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Franco Momoli
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Daniel Krewski
- Risk Sciences International, Ottawa, ON, Canada
- McLaughlin Centre for Population Health Risk Assessment, Ottawa, ON, Canada
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| |
Collapse
|
14
|
Zawilla NH, Taha FM, Kishk NA, Farahat SA, Farghaly M, Hussein M. Occupational exposure to aluminum and its amyloidogenic link with cognitive functions. J Inorg Biochem 2014; 139:57-64. [PMID: 24973993 DOI: 10.1016/j.jinorgbio.2014.06.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/29/2014] [Accepted: 06/02/2014] [Indexed: 11/26/2022]
Abstract
As many other metals, aluminum is a widely recognized neurotoxicant and its link with neurodegenerative disorders has been the subject of scientific debate. One proposal focuses on amyloid β deposition (amyloidogenesis) as the key player in triggering neuronal dysfunction the so-called amyloid cascade hypothesis. We undertook this study first to investigate the cognition status of workers exposed to Al dust in an Al factory in Southern Cairo, second, to evaluate serum amyloid precursor protein (APP) and cathepsin D (CD) enzyme activity to study the possible role of Al in amyloidogenesis, and finally to explore the relation between these potential biomarkers and cognitive functions. The study was conducted on 54 exposed workers and 51 matched controls. They were subjected to questionnaire, neurological examination and a cognitive test battery, Addenbrooke's Cognitive Examination - Revised (ACE-R). Serum Al, APP and CD enzyme activity were measured. A significant increase of serum Al was found in the exposed workers with an associated increase in serum APP and decrement in CD activity. The exposed workers displayed poor performance on the ACE-R test. No significant correlation was detected between ACE-R test total score and either APP or CD activity. We concluded that occupational exposure to Al is associated with cognitive impairment. The effect of occupational Al exposure on the serum levels of APP and CD activity may be regarded as a possible mechanism of Al in amyloidogenesis. However, our findings do not support the utility of serum APP and CD activity as screening markers for early or preclinical cognitive impairment.
Collapse
Affiliation(s)
- N H Zawilla
- Department of Occupational & Environmental Medicine, Faculty of Medicine, Cairo University, Egypt
| | - F M Taha
- Department of Medical Biochemistry, Faculty of Medicine, Cairo University, Egypt.
| | - N A Kishk
- Department of Neurology, Faculty of Medicine, Cairo University, Egypt
| | - S A Farahat
- Department of Occupational & Environmental Medicine, Faculty of Medicine, Cairo University, Egypt
| | - M Farghaly
- Department of Neurology, Faculty of Medicine, Cairo University, Egypt
| | - M Hussein
- Department of Neurology, Faculty of Medicine, Bani-suef University, Egypt
| |
Collapse
|
15
|
Abstract
The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust.
Collapse
|
16
|
Davanipour Z, Tseng CC, Lee PJ, Markides KS, Sobel E. Severe Cognitive Dysfunction and Occupational Extremely Low Frequency Magnetic Field Exposure among Elderly Mexican Americans. ACTA ACUST UNITED AC 2013; 4:1641-1662. [PMID: 24839595 PMCID: PMC4020120 DOI: 10.9734/bjmmr/2014/7317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Aims This report is the first study of the possible relationship between extremely low frequency (50–60 Hz, ELF) magnetic field (MF) exposure and severe cognitive dysfunction. Earlier studies investigated the relationships between MF occupational exposure and Alzheimer’s disease (AD) or dementia. These studies had mixed results, depending upon whether the diagnosis of AD or dementia was performed by experts and upon the methodology used to classify MF exposure. Study Design Population-based case-control. Place and Duration of Study Neurology and Preventive Medicine, Keck School of Medicine, University of Southern California, 2 years. Methodology The study population consisted of 3050 Mexican Americans, aged 65+, enrolled in Phase 1 of the Hispanic Established Population for the Epidemiologic Study of the Elderly (H-EPESE) study. Mini-Mental State Exam (MMSE) results, primary occupational history, and other data were collected. Severe cognitive dysfunction was defined as an MMSE score below 10. The MF exposure methodology developed and used in earlier studies was used. Results Univariate odds ratios (OR) were 3.4 (P< .03; 95% CI: 1.3–8.9) for high and 1.7 (P=.27; 95% CI: 0.7–4.1) for medium or high (M/H) MF occupations. In multivariate main effects models, the results were similar. When interaction terms were allowed in the models, the interactions between M/H or high occupational MF exposure and smoking history or age group were statistically significant, depending upon whether two (65–74, 75+) or three (65–74, 75–84, 85+) age groups were considered, respectively. When the analyses were limited to subjects aged 75+, the interactions between M/H or high MF occupations and a positive smoking history were statistically significant. Conclusion The results of this study indicate that working in an occupation with high or M/H MF exposure may increase the risk of severe cognitive dysfunction. Smoking and older age may increase the deleterious effect of MF exposure.
Collapse
Affiliation(s)
- Zoreh Davanipour
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Chiu-Chen Tseng
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Pey-Jiuan Lee
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Kyriakos S Markides
- Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston, Texas 77555-1153, USA
| | - Eugene Sobel
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA ; Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| |
Collapse
|
17
|
Peters S, Reid A, Fritschi L, de Klerk N, Musk AWB. Long-term effects of aluminium dust inhalation. Occup Environ Med 2013; 70:864-8. [PMID: 24142983 DOI: 10.1136/oemed-2013-101487] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES During the 1950s and 1960s, aluminium dust inhalation was used as a potential prophylaxis against silicosis in underground miners, including in Australia. We investigated the association between aluminium dust inhalation and cardiovascular, cerebrovascular and Alzheimer's diseases in a cohort of Australian male underground gold miners. We additionally looked at pneumoconiosis mortality to estimate the effect of the aluminium therapy. METHODS SMRs and 95% CI were calculated to compare mortality of the cohort members with that of the Western Australian male population (1961-2009). Internal comparisons on duration of aluminium dust inhalation were examined using Cox regression. RESULTS Aluminium dust inhalation was reported for 647 out of 1894 underground gold miners. During 42 780 person-years of follow-up, 1577 deaths were observed. An indication of increased mortality of Alzheimer's disease among miners ever exposed to aluminium dust was found (SMR=1.38), although it was not statistically significant (95% CI 0.69 to 2.75). Rates for cardiovascular and cerebrovascular death were above population levels, but were similar for subjects with or without a history of aluminium dust inhalation. HRs suggested an increasing risk of cardiovascular disease with duration of aluminium dust inhalation (HR=1.02, 95% CI 1.00 to 1.04, per year of exposure). No difference in the association between duration of work underground and pneumoconiosis was observed between the groups with or without aluminium dust exposure. CONCLUSIONS No protective effect against silicosis was observed from aluminium dust inhalation. Conversely, exposure to aluminium dust may possibly increase the risk of cardiovascular disease and dementia of the Alzheimer's type.
Collapse
Affiliation(s)
- Susan Peters
- Western Australian Institute for Medical Research, University of Western Australia, Perth, Western Australia, Australia
| | | | | | | | | |
Collapse
|
18
|
Occupational Exposure to Extremely Low-Frequency Magnetic Fields and Neurodegenerative Disease. J Occup Environ Med 2013; 55:135-46. [DOI: 10.1097/jom.0b013e31827f37f8] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
19
|
Riihimäki V, Aitio A. Occupational exposure to aluminum and its biomonitoring in perspective. Crit Rev Toxicol 2012; 42:827-53. [DOI: 10.3109/10408444.2012.725027] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
20
|
Willhite CC, Ball GL, McLellan CJ. Total allowable concentrations of monomeric inorganic aluminum and hydrated aluminum silicates in drinking water. Crit Rev Toxicol 2012; 42:358-442. [DOI: 10.3109/10408444.2012.674101] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
21
|
Santibáñez M, Bolumar F, García AM. Occupational risk factors in Alzheimer's disease: a review assessing the quality of published epidemiological studies. Occup Environ Med 2007; 64:723-32. [PMID: 17525096 PMCID: PMC2078415 DOI: 10.1136/oem.2006.028209] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2007] [Indexed: 11/04/2022]
Abstract
Epidemiological evidence of an association between Alzheimer's disease (AD) and the most frequently studied occupational exposures--pesticides, solvents, electromagnetic fields (EMF), lead and aluminium--is inconsistent. Epidemiological studies published up to June of 2003 were systematically searched through PubMed and Toxline. Twenty-four studies (21 case-control and 3 cohort studies) were included. Median GQI was 36.6% (range 19.5-62.9%). Most of the case-control studies had a GQI of <50%. The study with the highest score was a cohort study. Likelihood of exposure misclassification bias affected 18 of the 24 studies. Opportunity for bias arising from the use of surrogate informants affected 17 studies, followed by disease misclassification (11 studies) and selection bias (10 studies). Eleven studies explored the relationship of AD with solvents, seven with EMF, six with pesticides, six with lead and three with aluminium. For pesticides, studies of greater quality and prospective design found increased and statistically significant associations. For the remaining occupational agents, the evidence of association is less consistent (for solvents and EMF) or absent (for lead and aluminium).
Collapse
Affiliation(s)
- Miguel Santibáñez
- Department of Preventive Medicine and Public Health, University Miguel Hernandez, Spain.
| | | | | |
Collapse
|
22
|
Berr C, Akbaraly TN, Nourashemi F, Andrieu S. Épidémiologie des démences. Presse Med 2007; 36:1431-41. [PMID: 17560760 DOI: 10.1016/j.lpm.2007.04.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 04/17/2007] [Indexed: 11/29/2022] Open
Abstract
Dementia is a major public health problem and its burden will increase in the 30 years to come. Prevalence increases with age and incidence is slightly higher in women than men, especially after the age of 80 years. Survival after the onset of dementia is approximately 5 years. Lifestyle and health habits are a keystone for dementia: risk factors include physical, intellectual and social activity and nutritional habits. Data from well-conducted intervention studies are necessary to show whether better care for hypertension, diabetes, and dyslipidemia might decrease the incidence of dementia.
Collapse
Affiliation(s)
- Claudine Berr
- Inserm, U888, Université Montpellier 1, Montpellier (34).
| | | | | | | |
Collapse
|
23
|
Kiesswetter E, Schäper M, Buchta M, Schaller KH, Rossbach B, Scherhag H, Zschiesche W, Letzel S. Longitudinal study on potential neurotoxic effects of aluminium: I. Assessment of exposure and neurobehavioural performance of Al welders in the train and truck construction industry over 4 years. Int Arch Occup Environ Health 2007; 81:41-67. [PMID: 17522885 DOI: 10.1007/s00420-007-0191-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Accepted: 03/01/2007] [Indexed: 11/24/2022]
Abstract
OBJECTIVES Previous cross sectional studies on potential neurotoxic effects of long-term aluminium exposures by aluminium welders lack clear interpretable results for methodological reasons. The present longitudinal study examined on the one hand the reliability and representativity of Al-biomonitoring as indicator of individual long-term exposure and on the other hand the long-term changes of neurobehavioural performance in Al welders in relation to Al exposure and neurobehavioural performance changes of a non-exposed control group. METHODS The longitudinal study compared repeatedly measured exposure data and neurobehavioural data of 20, initially 44, male Al welders in the train and truck construction industry with data of a control group of similar age on the basis of three investigations over a period of 4 years. The repeated measurements of exposure included total dust in air as well as Al in pre- and post-shift plasma and urine samples. Neurobehavioural methods comprised symptoms, verbal intelligence, logic thinking, psychomotor behaviour, memory, and attention. Computer-aided tests from the Motor Performance Series (MLS) and the European Neurobehavioural Evaluation System (EURO-NES) were used. The characteristics of the biomonitoring data and the relationship to neurobehavioural data were examined with methods of correlation and regression analysis. The courses of neurobehavioural changes were analysed with multivariate covariance-analytical methods (MANCOVA) considering the covariates age, indicators of 'a priori' intelligence differences (education or 'premorbid' intelligence), and alcohol consumption (carbohydrate-deficient transferrin in plasma, CDT). RESULTS The mean total dust load during welding, near to the routinely worn ventilated helmets, was in the range of 5-8 mg/m(3). The biomonitoring data of the welders (pre-shift: 88-140 microg Al/g creatinine in urine; 13-16 microg Al/l plasma) showed a high long-term stability but also sensitivity to acute shift dependent exposure changes. The Al welders who had been working in this profession at an average of 15 years showed no significantly increased symptom levels compared with the control group. Explorative regression and covariance analyses revealed neither a correlation between biomonitoring and performance variables nor a significant difference between Al-exposed and controls in the performance courses during the 4 years period. Explorative modelling indicated that the structure of neurobehavioural outcomes could be determined by possible indicators of intellectual 'a priori' (premorbid) differences between subjects but not by their exposure information. CONCLUSIONS Compared to studies in the literature this study is characterized by relatively high and non-confounded Al exposure of the welders, a repeated-measurement design, and multivariate analyses. However, the long-term stable interindividual differences of internal Al exposure were not related to interindividual differences in neurobehavioural performances. Additionally, the lack of processual changes of neurobehavioural performances during the observation phase and the insignificant group differences do not make it very probable that degenerative processes caused by Al had happened before study onset or stopped just at this time point.
Collapse
Affiliation(s)
- E Kiesswetter
- Institute for Occupational Physiology, University of Dortmund, Ardeystr. 67, 44139 Dortmund, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Krewski D, Yokel RA, Nieboer E, Borchelt D, Cohen J, Harry J, Kacew S, Lindsay J, Mahfouz AM, Rondeau V. Human health risk assessment for aluminium, aluminium oxide, and aluminium hydroxide. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2007; 10 Suppl 1:1-269. [PMID: 18085482 PMCID: PMC2782734 DOI: 10.1080/10937400701597766] [Citation(s) in RCA: 509] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Daniel Krewski
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Brown RC, Lockwood AH, Sonawane BR. Neurodegenerative diseases: an overview of environmental risk factors. ENVIRONMENTAL HEALTH PERSPECTIVES 2005; 113:1250-6. [PMID: 16140637 PMCID: PMC1280411 DOI: 10.1289/ehp.7567] [Citation(s) in RCA: 281] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The population of the United States is aging, and an ever-increasing number of Americans are afflicted with neurodegenerative diseases. Because the pathogenesis of many of these diseases remains unknown, we must consider that environmental factors may play a causal role. This review provides an overview of the epidemiologic evidence for environmental etiologies for neurodegenerative diseases such as Alzheimer disease, Parkinson disease, parkinsonian syndromes (multiple system atrophy and progressive supranuclear palsy), and amyotrophic lateral sclerosis. Epidemiologic evidence for an association between environmental agents' exposure and neurodegenerative diseases is not conclusive. However, there are indications that there may be causal links, and the need for more research is obvious.
Collapse
Affiliation(s)
- Rebecca C Brown
- Association of Schools of Public Health, National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC 20460, USA.
| | | | | |
Collapse
|
26
|
Caban-Holt A, Mattingly M, Cooper G, Schmitt FA. Neurodegenerative memory disorders: a potential role of environmental toxins. Neurol Clin 2005; 23:485-521. [PMID: 15757794 DOI: 10.1016/j.ncl.2004.12.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The hypothesis that neurotoxins may play a role in neurodegenerative disorders remains an elusive one, given that epidemiologic studies often provide conflicting results. Although these conflicting results may result from methodological differences within and between studies, the complexity of chemical disruption of the central nervous system cannot be ignored in attempts to evaluate this hypothesis in different neurodegenerative disorders. Spencer provides a detailed review of the complex processes involved in defining the neurotoxic potential of naturally occurring and synthetic agents. Even concepts such as exposure and dose, as often reported in studies attempting to evaluate the risk imparted by a potential compound, can be deceptive. For example, although dose reflects "that amount of chemical transferred to the exposed subject", factors such as time and concentration in the organism, the ability to access the central nervous system, and how a compound reaches the central nervous system (routes of administration) or secondarily affects other organ systems leading to central nervous system disruption are clearly important to the concept of neurotoxic risk in neurodegenerative disorders. These factors would appear to explain the observed disagreements between studies using animal or neuronal models of neurotoxicity and population-based studies in humans. The importance of these factors and how a potential neurotoxin is investigated are clearly seen in the data on AD and aluminum. In contrast, the impact of MTPT on the central nervous system is more direct and compelling. Added complexity in the study of neurotoxins in human neurodegeneration is derived from data showing that agents may have additive, potentiating, synergistic, or antagonistic effects. Therefore, data from studies evaluating EMF risks could be readily confounded by the presence or absence of heavy metals (eg, arc welding). Other factors that may conceal neurotoxic causes for a given disorder focus on additional features such as genetic predispositions, physiologic changes that occur in aging, and even nutritional status that can support or hinder the affect of a given agent on the central nervous system. Finally, many studies that investigate exposure risk do not readily incorporate the five criteria proposed by Schaumburg for establishing causation. For example, if we apply Schaumburg's first criterion, epidemiologic studies often determines the presence of an agent through history, yet they cannot readily confirm exposure based on environmental or clinical chemical analyses to fulfill this criterion for causation. Additional limitations in research design along with the populations and methods that are sued to study neurotoxins in human neurodegenerative disorders often fail to meet other criteria such as linking the severity and onset with duration and exposure level. Therefore, although studies of agents such as MTPT provide compelling models of neurotoxins and neurodegeneration in humans, disorders such as ALS, PD, and particularly AD will require additional effort if research is to determine the contribution (presence or absence) of neurotoxins to these neurologic disorders.
Collapse
Affiliation(s)
- Allison Caban-Holt
- Sanders-Brown Center on Aging, University of Kentucky Medical Center, Lexington, KY 40536, USA
| | | | | | | |
Collapse
|
27
|
|
28
|
Nelson LM, Tanner CM, Van Den Eeden SK, McGuire VM. Alzheimer’s Disease and Vascular Dementia. Neuroepidemiology 2004. [DOI: 10.1093/acprof:oso/9780195133790.003.05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
This chapter explores the frequency with which dementing illnesses occur in populations, their distributions by personal characteristics, and what is known about their causes and potential protective factors. The primary focus is on the most common forms of dementia: Alzheimer's disease and vascular dementia. The chapter summarizes clinical and pathologic features of Alzheimer's disease and vascular dementia, and highlights recent theories of how risk factors affect brain reserve. With the evolution of the epidemiology of dementia from case-control studies to prospective cohort studies has come a new set of methodological challenges. These include identification of representative populations, enhancing subject participation and retention in studies, the need to include institutionalized as well as community-dwelling populations, the non-standardized use of cognitive tests to screen for dementia, and the complexities of the diagnostic process itself. Finally, the chapter summarizes risk and protective factors for disease expression, including cardiovascular risk factors, lifestyle factors, and factors that affect brain reserve.
Collapse
|
29
|
Jing Y, Wang Z, Song Y. Quantitative study of aluminum-induced changes in synaptic ultrastructure in rats. Synapse 2004; 52:292-8. [PMID: 15103695 DOI: 10.1002/syn.20025] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Some evidence suggests that aluminum is one of the risk factors in Alzheimer's disease (AD); however, there is no study on the relationship between the synaptic configuration changes and aluminum uptake. In the present study, 40 rats were fed with water solution aluminum for 3 months and the effects of aluminum on the Gray's type I synapses in hippocampus and frontal cortex of rats were quantitatively investigated by electron microscopy. The effects of aluminum on the ability to learn and memorize were tested by a Morris water maze. Length of synaptic active zone, width of synaptic cleft, curvature of synapse, and thickness of postsynaptic density (PSD) were measured in the interface of synapses by the IBM-PC microimage processing system. The flat synapse, positive and negative curvature synapses, as well as the perforated synapse were classified and counted according to the type of the interfacial structure of a synapse. The amounts of aluminum deposited in brain were measured with an atomic absorption spectrophotometer. Our results show that the time and the distance taken by the rats to find the water maze increased after the rats were fed aluminum for 3 months. As compared with control, the synapses in aluminum-induced rats exhibited the following significant changes: decreased thickness of PSD (P < 0.01), increased width of synaptic cleft (P < 0.05), increased numbers of flat synapse, decreased numbers of positive curvature synapse and perforated synapse, and significantly increased aluminum deposits in hippocampus and frontal cortex (P < 0.01). Our study indicates that aluminum can decrease the ability of rats to learn and memorize and induce their synaptic configuration changes. These changes may be related to synaptic efficacy and may be one of the mechanisms for AL to induce AD.
Collapse
Affiliation(s)
- Yuhong Jing
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, P.R. China
| | | | | |
Collapse
|
30
|
Kim K. Perinatal exposure to aluminum alters neuronal nitric oxide synthase expression in the frontal cortex of rat offspring. Brain Res Bull 2003; 61:437-41. [PMID: 12909287 DOI: 10.1016/s0361-9230(03)00159-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Disturbance of the neuronal nitric oxide signaling pathway by chronic exposure to aluminum (Al) in drinking water may be a causal factor of neurological disorders in offspring. In order to investigate the relationship between Al administration and expression of neuronal nitric oxide synthase (nNOS), the numbers and distribution patterns of nNOS-immunoreactive neurons were examined in the frontal cortex of offspring after exposure to 0, 5, and 10 mM of Al in drinking water during prenatal and neonatal periods. At the bregma 0.20 level, the number of nNOS-positive neurons was significantly increased (10%) and decreased (17%) following exposure to 5 and 10 mM of Al in drinking water, respectively. The change was more severe in the upper layer than in deep layer of the cortex. In contrast, at the bregma -2.80 level, the number and distribution pattern was not significantly changed following exposure to Al. These data suggest that Al toxicity may be mediated through disturbances to the nitric oxide signaling pathway and exhibits a biphasic effect, especially in the frontal area of the cortex. In addition, the results suggest that impaired expression of nNOS plays an important role in the development of neurological syndrome caused by an exposure to Al during the early developmental stage.
Collapse
Affiliation(s)
- Kisok Kim
- Division of Neurotoxicology, National Institute of Toxicological Research, 5 Nokbun-dong, Eunpyung-ku, 122-704 Seoul, South Korea.
| |
Collapse
|
31
|
Polizzi S, Pira E, Ferrara M, Bugiani M, Papaleo A, Albera R, Palmi S. Neurotoxic effects of aluminium among foundry workers and Alzheimer's disease. Neurotoxicology 2002; 23:761-74. [PMID: 12520766 DOI: 10.1016/s0161-813x(02)00097-9] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND In a cross-sectional case-control study conducted in northern Italy, 64 former aluminium dust-exposed workers were compared with 32 unexposed controls from other companies matched for age, professional training, economic status, educational and clinical features. The findings lead the authors to suggest a possible role of the inhalation of aluminium dust in pre-clinical mild cognitive disorder which might prelude Alzheimer's disease (AD) or AD-like neurological deterioration. METHODS The investigation involved a standardised occupational and medical history with particular attention to exposure and symptoms, assessments of neurotoxic metals in serum: aluminium (Al-s), copper (Cu-s) and zinc (Zn-s), and in blood: manganese (Mn-b), lead (Pb-b) and iron (Fe-b). Cognitive functions were assessed by the Mini Mental State Examination (MMSE), the Clock Drawing Test (CDT) and auditory evoked Event-Related Potential (ERP-P300). To detect early signs of mild cognitive impairment (MCI), the time required to solve the MMSE (MMSE-time) and CDT (CDT-time) was also measured. RESULTS Significantly higher internal doses of Al-s and Fe-b were found in the ex-employees compared to the control group. The neuropsychological tests showed a significant difference in the latency of P300, MMSE score, MMSE-time, CDT score and CDT-time between the exposed and the control population. P300 latency was found to correlate positively with Al-s and MMSE-time. Al-s has significant effects on all tests: a negative relationship was observed between internal Al concentrations, MMSE score and CDT score; a positive relationship was found between internal Al concentrations, MMSE-time and CDT-time. All the potential confounders such as age, height, weight, blood pressure, schooling years, alcohol, coffee consumption and smoking habit were taken into account. CONCLUSIONS These findings suggest a role of aluminium in early neurotoxic effects that can be detected at a pre-clinical stage by P300, MMSE, MMSE-time, CDT-time and CDT score, considering a 10 micrograms/l cut-off level of serum aluminium, in aluminium foundry workers with concomitant high blood levels of iron. The authors raise the question whether pre-clinical detection of aluminium neurotoxicity and consequent early treatment might help to prevent or retard the onset of AD or AD-like pathologies.
Collapse
Affiliation(s)
- Salvatore Polizzi
- Dipartimento di Medicina del Lavoro dell'Università di Torino, Servizio di Medicina del Lavoro, ASL 8, 10044 Carignano, TO, Torino, Italy.
| | | | | | | | | | | | | |
Collapse
|
32
|
Roberts N, Zhu H, Kim J, Shin H, Kim J, Choi S. Further studies on the interrelationship of aluminum and silicon in patients receiving aluminum hydroxide therapy for dyspepsia and factors that relate to the solubilization of aluminum. ACTA ACUST UNITED AC 2002. [DOI: 10.1002/jtra.1054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
33
|
Abstract
BACKGROUND Microdermabrasion is a widely performed skin rejuvenation procedure. Few studies have examined its efficacy. OBJECTIVE To evaluate the clinical and histopathologic effects of microdermabrasion. METHODS Fourteen patients underwent microdermabrasion treatments over 12-14 weeks. Self-rated questionnaires were given before and after the treatment series and were evaluated by a paired t-test. Three of the 14 patients were treated for moderate to severe acne scarring. Acute histologic effects were assessed ex vivo on human abdominal skin. Chronic histopathologic effects were examined in three volunteers who underwent skin biopsies before and after a treatment series on the dorsal forearms. RESULTS By patient assessment, there was statistically significant improvement in roughness, mottled pigmentation, and overall improvement of skin appearance, but not in rhytides. Acne scarring sometimes improved, but required deeper ablation. Acutely the stratum corneum was homogenized and focally compacted. Chronically there was epidermal hyperplasia, decreased melanization, and some increase in elastin. CONCLUSION Microdermabrasion improves some aspects of photoaging and select cases of acne scarring.
Collapse
Affiliation(s)
- E K Shim
- Division of Dermatology and Cutaneous Surgery, Scripps Clinic and Research Foundation, La Jolla, CA, USA.
| | | | | | | |
Collapse
|
34
|
|
35
|
Abstract
Aluminium (Al) is clearly a powerful neurotoxicant. Considerable evidence exists that Al may play a role in the aetiology or pathogenesis of Alzheimer's disease (AD), but whether the link is causal is still open to debate. This paper reviews the epidemiological evidence linking Al and AD. Nine out of 13 published epidemiological studies of Al in drinking water and AD have shown statistically significant positive relations. Given the difficulty in producing high-quality data for the occurrence of AD and also for Al exposure, with the resulting unavoidable misclassification errors biasing any true association towards the null value, these studies are remarkably consistent. A major problem in their interpretation is that drinking water, even at high Al concentrations, only contributes a fraction of the total dietary intake of Al. In particular, regular consumers of antacids ingest gram amounts of Al daily, thousands of times the amounts taken in through drinking water, and epidemiological studies of antacid exposure and AD have been largely negative. However, Al is very poorly absorbed in the gastrointestinal tract, and the possibility that some Al fractions present in drinking water may be particularly bioavailable cannot be dismissed at present. The combined evidence linking Al and AD warrants substantial research efforts. Such efforts should focus on clarification of the cellular and molecular mechanisms in Al toxicity and of the basic metabolism and kinetics of Al in the human body, and on further epidemiological studies including diverse routes of Al exposure and also variables that are known or suspected to influence the individuals' susceptibility to AD, such as apolipoprotein E allele status and family history of AD.
Collapse
Affiliation(s)
- T P Flaten
- Department of Chemistry, Norwegian University of Science and Technology, Trondheim, Norway.
| |
Collapse
|
36
|
Abstract
The prevalence of dementia in subjects 65 years and older in North America is approximately 6%-10%, with Alzheimer's disease (AD) accounting for two-thirds of these cases. If milder cases are included, the prevalence rates double. Both causative and associative genes for AD have now been identified. The search for nongenetic risk factors has been less conclusive. Only age and family history of dementia are consistently associated with AD in all studies, but putative, protective agents such as estrogen, nonsteroidal anti-inflammatory agents (NSAIDs), and vitamin E are now undergoing clinical trials.
Collapse
Affiliation(s)
- H C Hendrie
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202-5111, USA
| |
Collapse
|
37
|
Varner JA, Jensen KF, Horvath W, Isaacson RL. Chronic administration of aluminum-fluoride or sodium-fluoride to rats in drinking water: alterations in neuronal and cerebrovascular integrity. Brain Res 1998; 784:284-98. [PMID: 9518651 DOI: 10.1016/s0006-8993(97)01336-x] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This study describes alterations in the nervous system resulting from chronic administration of the fluoroaluminum complex (AlF3) or equivalent levels of fluoride (F) in the form of sodium-fluoride (NaF). Twenty seven adult male Long-Evans rats were administered one of three treatments for 52 weeks: the control group was administered double distilled deionized drinking water (ddw). The aluminum-treated group received ddw with 0.5 ppm AlF3 and the NaF group received ddw with 2.1 ppm NaF containing the equivalent amount of F as in the AlF3 ddw. Tissue aluminum (Al) levels of brain, liver and kidney were assessed with the Direct Current Plasma (DCP) technique and its distribution assessed with Morin histochemistry. Histological sections of brain were stained with hematoxylin & eosin (H&E), Cresyl violet, Bielschowsky silver stain, or immunohistochemically for beta-amyloid, amyloid A, and IgM. No differences were found between the body weights of rats in the different treatment groups although more rats died in the AlF3 group than in the control group. The Al levels in samples of brain and kidney were higher in both the AlF3 and NaF groups relative to controls. The effects of the two treatments on cerebrovascular and neuronal integrity were qualitatively and quantitatively different. These alterations were greater in animals in the AlF3 group than in the NaF group and greater in the NaF group than in controls.
Collapse
Affiliation(s)
- J A Varner
- Psychology Department, Binghamton University, Binghamton, NY, USA
| | | | | | | |
Collapse
|
38
|
Abstract
This review explores the different areas of research that, over the past 35 years, have provided grounds for linking Alzheimer's disease and aluminium. However, in spite of the growing evidence, exposure to aluminium as a risk factor is yet to be confirmed. The evidence is discussed under four headings: evidence from brain aluminium studies; evidence from aluminium uptake studies; evidence from aluminium-related neurodegenerative conditions; and evidence from chronic aluminium exposure studies: aluminium in drinking water, and by occupational exposure.
Collapse
Affiliation(s)
- E Salib
- Consultant Psychiatrist, Winwick Hospital, Warrington
| |
Collapse
|