The safety of a high pH depends entirely on the context. A pH above 7 is alkaline, and while some alkalinity is natural and even beneficial in certain situations, extremely high pH levels can be hazardous.
Understanding pH Levels and Their Impact
The pH scale measures how acidic or alkaline a substance is, ranging from 0 (highly acidic) to 14 (highly alkaline), with 7 being neutral. Many sources state that pH levels reaching or exceeding 12.5 are considered hazardous. This is consistent across several sources, including LeadLab. Contact with highly alkaline substances can cause harm to human health and the environment.
Examples of High pH Impacts:
- Human Health: High pH levels (above 12.5) can cause skin and eye irritation, burns, and other serious health problems. Even lower, but still high pH levels in drinking water (above 8.5) can impact taste and potentially contribute to mineral imbalances, per UCLA Health.
- Swimming Pools: While a slightly high pH in a swimming pool (e.g., around 8.4) might not be immediately dangerous, it can lead to discomfort like dry skin, eye irritation, and unpleasant smells. Reddit discussions on swimming pools confirm that while swimming is possible, a pH of 7.2-7.4 is ideal.
- Food Preservation: In food canning, a pH of 4.6 or below is considered safe for boiling water bath canning due to its high acidity. A pH above 4.7 indicates low acidity, potentially requiring different preservation methods. Food In Jars details this crucial aspect.
Specific Applications & Safety Considerations
The "safety" of a high pH is highly context-dependent. A pH of 9.5 in drinking water is generally not considered healthy, as noted in Reddit chemistry discussions. While a slightly high pH in a swimming pool might not cause immediate harm, it's less desirable than an ideal range.
