“The most recent serum HCO3− levels measured in the NHANES population (which uses venous blood) was 25.3m milliequivalents per litre (mEq / L) (in 2019–2020), representing a ~ 7 per cent increase from 1999. Similarly, this has paralleled atmospheric CO2 over the same period. As stated above, the upper healthy limit for HCO3− in venous blood can be taken as 30 mEq / L, although this value requires further scrutiny particularly given that the high HCO3− condition would likely be perpetual in the future as atmospheric CO2 continues to increase,” it stated.
This trend, the scientists said, closely mirrors the rise in atmospheric CO2 that was recorded to be 428.62 ppm at the NOAA Mauna Loa Observatory, Hawaii from a baseline of 280 ppm in 1960.
The authors said this is because human physiology evolved during a long period of stable, low atmospheric CO2 (< 300 ppm) and our bodies may not be equipped to handle the rapid shift to current (420+ ppm) and future levels.
At the same time, the mean serum levels for calcium and phosphorus decreased by about 2 per cent and roughly 7 per cent respectively.
The study said that the total serum calcium levels for healthy adults are generally accepted to be between 2.1 and 2.6 millimoles per litre (mmol / L), with levels below this termed hypocalcemia. For phosphorus, the healthy range is 0.81 to 1.45 mmol / L, below which hypophosphatemia occurs.
Hypocalcemia causes numbness, muscle spasms, confusion, while hypophosphatemia can lead to respiratory alkalosis, diabetic ketoacidosis.
Assuming a linear relationship and a ~ 0.34 per cent increase rate per year, the healthy maximum HCO3− level of 30 mEq / L will be reached in the year 2076, scientists predicted. While the lower limit for calcium and phosphorus would be reached in 2099 and 2085 respectively.