External exposure levels and fluoride content in the urine of workers at aluminium electrolysis

Introduction. In the context of large-scale modernization and intensification of aluminium production, it becomes relevant to assess the actual fluoride loads and the main factors that determine the occupational exposure of workers to fluorides for health risk analysis. Materials and methods. Monitoring studies of the content of hydrofluoride and aerosols of fluoride salts in the air of electrolysis shops were carried out with traditional and modernized technologies for producing aluminium and fluorine in urine in 108 workers of the primary professions and 35 people in the control group. Determination of the concentration of fluorides was carried out by photometric methods, and fluorine in urine - by ionometric methods. Results. The total concentration of fluoride compounds in the air of the modernized shops was 1.4-2.1 times lower than the values in traditional shops. The fluoride content in the urine of workers in these workshops ranged from 0.8 to 4.7 mg/l, 1.1-6.7 times higher than the level of the control group and 1.1-2.3 times the limit value of the biological exposure index. The highest external and internal fluoride loads and associated health risks are found in workers who maintain electrolyzers and anodes. A closer, noticeable (r = 0.644) correlation was found between the content of fluoride in urine and the levels of gaseous hydrofluoride in the air, indicating its predominant effect on workers compared to other determinants (total concentration of fluorides, seniority and age). Conclusion. The studies’ results indicate a high additional informative value and reliability of biomonitoring of fluoride in urine, which, combined with analysis of air pollution with fluorides, provides a completely objective assessment of the risk of exposure to workers. The presence of high levels of hydrofluoride in the air of electrolysis shops creates a higher occupational health risk for workers.

Dental fluorosis among people and livestock living on Gihaya Island in Lake Kivu, Rwanda

Background Dental fluorosis is caused by prolonged exposure to excessive fluoride during the period of permanent tooth formation and is characterized by tooth discoloration, pitting, and loss of shape. Communities living near Lake Kivu in Western Rwanda exhibit a high prevalence of dental fluorosis; however, data on prevalence and risk factors are scarce. Methods This cross sectional, quantitative study used a One Health approach to investigate dental fluorosis prevalence among people and livestock and to measure fluoride content in the environment. In 2018, oral health examinations were conducted to assess the prevalence of fluorosis in children (aged 9 to 15 years), cattle and goats residing on Gihaya Island (Rwanda, East Africa). All children and cattle/goats meeting basic eligibility criteria (e.g., island residence) were invited to participate. Presence and severity of dental fluorosis was categorized according to the Dean’s Fluorosis Index. Samples of local foods, water, soil and grass were collected from communal sources and individual households and analyzed for fluoride content using standard laboratory techniques. Descriptive and binomial analyses (Fisher Exact Test) were used to assess this dataset. Results Overall, 186 children and 85 livestock owners (providing data of 125 livestock -23 cattle and 102 goats) participated. Dental fluorosis was recorded in 90.7% of children and 76% of livestock. Moderate to severe fluorosis was observed in 77% children while goats and cattle most often exhibited mild or absent/questionable severity, respectively. Water from Lake Kivu (used primarily for human cooking water and livestock drinking water) contained fluoride levels that were consistently higher than the maximum threshold (1.5 mg/L) recommended by the World Health Organization. Other sources (borehole and rainwater) were within safe limits. All food, soil and grass samples contained fluoride. The highest levels were observed in porridge (0.5 mg/g) and small fishes (1.05 mg/g). Conclusions Altogether, dental fluorosis was highly prevalent among children and goats on Gihaya Island with various food and water sources contributing a cumulative exposure to fluoride. An immediate and coordinated response across human, animal and water professionals is needed to reduce fluoride exposure within safe limits for island residents.

Analysis of Fluoride Concentration in Toothpastes in the United Arab Emirates: Closing the Gap between Local Regulation and Practice

Background: While there is much scientific evidence supporting the benefits of fluoride for oral health, the concentration of fluoride in over-the-counter fluoride toothpaste should meet United Arab Emirates (UAE) regulations of a fluoride concentration not exceeding 0.15%. Objectives: The current study examines the fluoridated toothpaste products available on the UAE market and aims to quantify their total fluoride content. Methods: A total of 50 toothpaste products were collected and analyzed in this study. Ion Chromatography (IC) conductivity analysis was performed to determine the total fluoride content. Results: Among the 50 products tested, 10 exceeded the recommended concentration of total fluoride of less than 0.15%, while 12 had a total fluoride concentration that was less than was declared on their labels. Moreover, this study has revealed that 22 of the sampled products had a total fluoride concentration below 1000 ppm fluoride. An increased risk of higher total fluoride content was observed in the toothpaste products with monofluorophosphate active ingredients than in products with potassium nitrate/sodium fluoride and sodium fluoride (p = 0.011). Conclusions: There is a need to reassess the effectiveness of current regulations in the UAE to ensure that all fluoridated toothpastes available on the market are safe and effective for the consumer. Specifically, appropriate guidelines should be established on the basis of the risks and benefits inherent in fluoride exposure. Moreover, fluoridated toothpastes need to be subject to stricter monitoring and control regarding their safety and quality through good manufacturing practices (GMPs), education, research, and adverse event reporting.

Analysis of aerosol pollution processes in the vicinity of the Irkutsk aluminum plant

The issues of assessing the pollution fields in the vicinity of industrial enterprises are discussed according to the monitoring studies of the snow cover. The formulations of problems of low-parameter reconstruction of concentration fields are considered on the basis of model descriptions of the processes of transport of impurities in the surface layer of the atmosphere. With regard to the Irkutsk aluminum plant, the results of studies of the pollution of its surroundings with aluminum are presented. Using the data of route observations, a numerical reconstruction of the fluoride content in the snow cover was carried out. The quality control of the results obtained is carried out by comparing the measured and calculated concentrations of impurities at the control points of observation.

A Case Study From Ramannapeta Mandal, Nalgonda, Telangana, India: Fluoride Contamination of Ground Water

The groundwater quality evaluation for fluoride element was studied in Ramannapeta Mandal, Nalgonda District, and Telangana State, India. The water samples were collected in pre and post monsoon seasons in the year of 2015-2016 from hand pumps bore wells or dug wells in the villages of Ramannapeta Mandal. The collected water samples were analyzed within a week. The Spatial distributions of fluoride maps were prepared with the help of the Remote Sensing Imaginary (RSI) and Geographical Information System (GIS) techniques. The range of fluoride in the study area varied from 0.6 to 5.6 ppm whereas the maximum permissible limit in drinking water is 1.5 ppm (As per Bureau of Indian Standard (BIS) guideline-IS: 10500: 1991). The high contamination 4.0-5.5 ppm of fluoride in drinking water was observed in Siripuram, Dubbaka villages. During the study, it was found that the most of villages in Ramannapeta Mandal are affected with high fluoride content in drinking water in the range of 1.5-3.0 ppm. Nalgonda district including Ramannapeta Mandal is underlain by different rocks such as granites (80%), gneisses, dolerite, dykes (10%), older metamorphic and intrusive (10%). The lock of freshwater exchange due to periodical drought conditions, the granitic rocks and the arid climate of the region are the factors for the higher incidence of fluoride in the groundwater resources. The constructions of rain water harvesting structures are proposed to minimize fluoride content in drinking water.

The Effect of Fluoride and Iron Content on the Clinkering of Alite-Ye’elimite-Ferrite (AYF) Cement Systems

Alite–ye’elimite–ferrite (AYF) cement is a more sustainable alternative to Portland cement (PC) that may offer improved mechanical, rheological, and chemical performance. Using traditional raw materials and conventional clinker processing conditions, alite (C3S) and ye’elimite (C4A3$), the major phases in PC and calcium sulfoaluminate (CSA) cements, respectively, cannot be coproduced. The typical formation temperature in the kiln for alite is >1350°C, but ye’elimite normally breaks down above 1300°C. However, with careful composition control and in the presence of fluoride, alite can be mineralized and formed at lower temperatures, thus enabling the production of AYF clinkers in a single stage. In this study, the production of AYF cement clinkers with different chemical compositions is attempted at 1250°C. The sensitivity of the fluoride content is initially assessed with a fixed target clinker composition to determine the optimal requirements. The effect of altering the target ferrite (C4AF) and alite (C3S) contents is also assessed followed by the effect of altering the target C4AF and C4A3$ contents. It is shown that AYF clinkers can be produced in a single stage through the careful control of the fluoride content in the mix; however, the formation/persistence of belite and mayenite could not be avoided under the conditions tested. It is also shown that ∼10 wt% ferrite in the target composition provides sufficient AYF clinker burnability and the amount of fluoride needs to be controlled to avoid stabilization of mayenite.

Assessment of Fluoride Content in Ground Water and its Impact on Wheat and Vegetables of Dausa District, Rajasthan, India

In the present investigation samples of ground water ( open well, hand pump), wheat and vegetables (spinach, potato and tomato) were collected from different areas of Dausa district of Rajasthan and analyzed to access the adverse effect on human health due to fluoride accumulation. The fluoride concentration varies between 5.1-14.9 mg/l in the collected water samples, where as in wheat samples it was found in the range of 3.42-14.25mg/l and in vegetables from 1.19-22.45mg/l. The fluoride accumulation was found to be much higher in leafy vegetable (spinach) than that of in other vegetables, where seeds or tubers are the main edible part (potato and tomato). Cereal crop ( wheat ) also estimated with more fluoride content then potato and tomato. The maximum concentration of fluoride in water, wheat and vegetables was 14.9mg/l (Bairwa Mohalla/Dausa ), 14.25 µg/g (Seengpura/Dausa) and 22.45 µg/g (Kalyanpura/ Dausa) respectively. It was observed that large number of people from Bairwa Mohalla/Dausa were suffering from Skeletal and Dental fluorosis.