Fly ash hemolysis as related to its alkalinity

Area of Science:

• Environmental Science
• Toxicology
• Materials Science

Background:

• Fly ash is a byproduct of coal combustion, posing potential environmental and health risks.
• Airborne particulate matter, including fly ash, can be inhaled and interact with biological systems.
• Understanding the biological activity of fly ash is crucial for risk assessment.

Purpose of the Study:

• To investigate the hemolytic activity of respirable coal fly ash particles.
• To elucidate the mechanisms underlying fly ash-induced red blood cell damage.
• To analyze the chemical composition of fly ash contributing to its hemolytic properties.

Main Methods:

• Collection of fly ash from a Hong Kong power plant precipitator.
• Hemolytic activity assay using rat red blood cells.
• Chemical characterization using scanning electron microscopy with energy dispersive X-ray microanalysis, inductively coupled plasma spectrophotometry, and X-ray powder diffractometry.

Main Results:

• Coal fly ash demonstrated significant hemolytic activity, independent of dose.
• Hemolysate color change from red to brownish-green indicated hemoglobin degradation.
• Surface analysis revealed a substantial coating of calcium salt on fly ash particles.
• High alkalinity of calcium salts was identified as the primary cause of red blood cell membrane damage and hemoglobin destruction.

Conclusions:

• Coal fly ash possesses potent hemolytic properties due to alkaline calcium salt coatings.
• The mechanism involves direct damage to red blood cell membranes and subsequent hemoglobin degradation.
• Accurate measurement of hemolytic activity requires careful consideration of hemoglobin remaining in the incubation medium.