Characterization of bone aluminum, a potential biomarker of cumulative exposure, within an occupational population from Zunyi, China

Aluminum exposure and cognitive performance: A meta-analysis

BACKGROUND

Aluminum is increasingly used in various industrial processes due to its beneficial properties. Occupational exposure to aluminum, however, has been linked to several adverse health effects. The impact of occupational aluminum exposure on worker's cognitive performance and its contribution in developing neurodegenerative diseases is highly discussed with competing results.

METHOD

We conducted a literature search via online databases until June 2023. Applicable studies fulfilling inclusion criteria investigating the effects of occupational aluminum exposure on cognitive functions were gathered. Results were aggregated using random effects meta-analysis and the effect size g. We further explored types of publication biases, moderating variables and exposure-effect relationships using meta-regressions.

RESULTS

The final sample consisted of 18 studies with 87 effect sizes for seven cognitive functions. We found significant worse performances in workers occupationally exposed to aluminum regarding processing speed, working memory, attention, and reaction time after exclusion of outliers. Additionally, we found increased blood plasma aluminum significantly predicting decreased cognitive performance in exposed workers.

CONCLUSION

Our results show decreased performance levels in processing speed, working memory, attention and reaction time in workers occupationally exposed to aluminum compared to controls. Furthermore, we found that aluminum in blood plasma was the only biomarker as significant predictor of cognitive performance. We discuss recommendations for further research in relation to occupational health and safety. Finally, we extend the discourse between occupational aluminum exposure and development of neurodegenerative diseases like Alzheimer's disease.

Bone aluminum measured in miners exposed to McIntyre powder

A small pilot study was conducted to test whether the technique of in vivo neutron activation analysis could measure bone aluminum levels in 15 miners who had been exposed to McIntyre Powder over 40 years prior. All miners were over 60 years of age, had worked in mines that used McIntyre Powder, and were sufficiently healthy to travel from northern to southern Ontario for the measurements. Individual aluminum levels were found to be significantly greater than zero with 95% confidence (p < 0.05) in 7 out of the 15 miners. The inverse variance weighted mean of the 15 participants was 21.77 ± 2.27µgAl/gCa. This was significantly higher (p < 0.001) than in a group of 15 non-occupationally exposed subjects of a comparable age from Southern Ontario who had been measured in a previous study. The inverse variance weighted mean bone aluminum content in the non-occupationally exposed group was 3.51 ± 0.85µgAl/gCa. Since the use of McIntyre Powder ceased in 1979, these subjects had not been exposed for more than 40 years. Calculations of potential levels at the cessation of exposure in the 1970s, using a biological half-life of aluminum in bone of 10 to 20 years predicted levels of bone aluminum comparable with studies performed in dialysis patients in the 1970s and 1980s. This pilot study has shown that the neutron activation analysis technique can determine differences in bone aluminum between McIntyre Powder exposed and non-exposed populations even though 40 years have passed since exposure ceased. The technique has potential application as a biomarker of exposure in cross-sectional studies of the health consequences of exposure to McIntyre Powder.

Determination of aluminum concentrations in biological specimens: application in the clinical laboratory

Aluminum enters the body primarily through diet or occupational exposure, and is cleared through urine. However, this trace element may accumulate and cause toxicity in subjects with renal insufficiency, and even in dialysis patients. The mechanism of aluminum toxicity is related to increased oxidative and inflammatory stress, iron and calcium dyshomeostasis, or cholinergic dysregulation, among other. A review was conducted on the specimens and analytical methods used to determine aluminum in biological specimens and dialysis water. This paper describes the most relevant aspects related to quality assurance. This is a practical guideline for the development and implementation of a reliable method for determination of aluminum in the clinical laboratory. Serum aluminum is the main biomarker of toxicity. For cases of chronic exposure, urine testing is recommended. At present, inductively coupled plasma mass spectrometry (ICP-MS) is the gold-standard determination method, since it has been proven to have the best quantification limits, selectivity and robustness. Clear recommendations are provided in relation to the specimens used for aluminum determination. Relevant pre-analytical, analytical, and post-analytical considerations are also presented.

ROS-mediated mitophagy and apoptosis are involved in aluminum-induced femoral impairment in mice

The problem of excessive aluminum (Al) content in food is widespread. After Al enters the body, it can cause mineral metabolism imbalance and reactive oxygen species (ROS) overproduction, which ultimately leads to bone impairment. ROS is mainly produced in mitochondria and acts on mitochondria. Mitochondrial damage is closely related to mitophagy and apoptosis. In order to clarify whether ROS-mediated mitophagy and apoptosis are involved in Al-induced femoral impairment, forty-eight male C57BL/6 N mice were exposed to AlCl₃ (179.3 mg/kg) and/or NAC (100 mg/kg) for 90 days. Our results showed that NAC inhibited the mitophagy and apoptosis, and alleviated growth inhibition, mineral metabolism imbalance, structural damage, decreased bone mineral density and decreased bone formation factor expressions in the femora of Al-treated mice. These results suggest that ROS-mediated mitophagy and apoptosis are involved in Al-induced femoral impairment in mice, exogenous ROS clearance is a potential strategy for the treatment of Al-induced bone impairment.

In vivo neutron activation assembly design for quantification of trace elements using MCNP

BACKGROUND

Trace and essential elements both play a crucial role in maintaining normal cellular and organ functions in human, while abnormal exposure to some of them are also potentially related to diseases, e.g., manganism. To study the association between elemental intake and health outcomes, accurate assessment of elemental uptake and storage in the human body is essential.

OBJECTIVES

Neutron activation analysis based technology can be used for in vivo measurements of the trace elements given that the measurement system guarantees a low detection limit with an acceptable dose. This study aims to design and optimize a customized and portable deuterium-deuterium (DD) neutron generator-based irradiation assembly for neutron activation analysis of trace elements in vivo, using Monte Carlo simulations.

METHODS

The irradiation assembly includes a moderator, a fast neutron filter (FNF), reflector, and shielding. The human hand equivalent phantoms doped with manganese (Mn) and potassium (K) are used to determine the respective elements' system sensitivity and detection limit.

RESULTS

The calculated detection limit is 0.16 g Mn per gram dry bone (ppm) for Mn and 17 ppm for K, with an equivalent dose of 36 mSv to the hand for a 10 min irradiation.

CONCLUSION

This more sensitive in vivo neutron activation analysis system will detect trace elements in vivo.