Base excess in the other. A secondary (compensatory) process can be readily identified because it "opposes" the observed deviation in blood pH. For example, inadequate ventilation, a respiratory problem, causes a buildup of CO, hence respiratory acidosis; the kidneys then attempt to compensate for the low pH by raising blood bicarbonate. The kidneys only partially compensate, so the patient may still have a low blood pH, i.e. acidosis. In summary, the kidneys partially compensate for respiratory acidosis by raising blood bicarbonate. A high base excess, thus metabolic alkalosis, usually involves an excess of bicarbonate. It can be caused by A base deficit
Water purification leading to the leaching of lead into residential spigots. This can result in harmful exposure, including elevated blood lead levels. Lead is a known neurotoxin. Distillation removes all minerals from water, and the membrane methods of reverse osmosis and nanofiltration remove most to all minerals. This results in demineralized water which is not considered ideal drinking water. The World Health Organization has investigated the health effects of demineralized water since 1980. Experiments in humans found that demineralized water increased diuresis and the elimination of electrolytes, with decreased blood serum potassium concentration. Magnesium, calcium, and other minerals in water can help