Answer:
Hepato- and nephrotoxicity of fluoride have been demonstrated in animals, but few studies have examined potential effects in humans. This population-based study examines the relationship between chronic low-level fluoride exposure and kidney and liver function among United States (U.S.) adolescents. This study aimed to evaluate whether greater fluoride exposure is associated with altered kidney and liver parameters among U.S. youth.
This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2013–2016). We analyzed data from 1983 and 1742 adolescents who had plasma and water fluoride measures respectively and did not have kidney disease. Fluoride was measured in plasma and household tap water. Kidney parameters included estimated glomerular filtration rate (calculated by the original Schwartz formula), serum uric acid, and the urinary albumin to creatinine ratio. Liver parameters were assessed in serum and included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, gamma-glutamyl transferase, and albumin. Survey-weighted linear regression examined relationships between fluoride exposure and kidney and liver parameters after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons.
The average age of adolescents was 15.4 years. Median water and plasma fluoride concentrations were 0.48 mg/L and 0.33 μmol/L respectively. A 1 μmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73 m2 lower estimated glomerular filtration rate (95% CI: −17.50, −3.22; p = 0.05), a 0.29 mg/dL higher serum uric acid concentration (95% CI: 0.09, 0.50; p = 0.05), and a 1.29 mg/dL lower blood urea nitrogen concentration (95%CI: −1.87, −0.70; p < 0.001). A 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen concentration (95% CI: −1.44, −0.42; p = 0.007).
Fluoride exposure may contribute to complex changes in kidney and liver related parameters among U.S. adolescents. As the study is cross-sectional, reverse causality cannot be ruled out; therefore, altered kidney and/or liver function may impact bodily fluoride absorption and metabolic processes.
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Answer:
Microbial mats.
Explanation:
Microbes formed sheets that were able to capture layers of sediment is called microbial mats. These mats of microbes provide good fossil evidence to the researchers. These microbial mats consist of bacteria and archaea which is considered the earliest form of life on earth. These microbial mats grow on moist places as compared to dry environment. About 3,500 million years ago, these microbes are the most important members of earth and maintainers of the ecosystems.
The right answer is D.
Intermolecular forces lead to the assembly of microscopic systems. They are responsible for the cohesion of matter in most macroscopic phases. These are weak forces compared to covalent bond strengths. They do not modify the nature of the molecular species and only influence their mode of assembly. The most well-known intermolecular bonds are the Van der Waals bond and the hydrogen bond.
The greater the intermolecular forces, the more the aspect of the element will tend to be more condensed (gas <liquid <solid).
Answer:
The human skeleton performs six major functions: support, movement, protection, production of blood cells, storage of minerals, and endocrine regulation
Short term example forgetting where you parked your car
long term example is remembering work skills you learned in your first job
