To jump right in, here’s my take on the highlights, along with some details and references.
- EPA’s max allowable lead level in water is 15 Parts Per Billion (sample taken from kitchen tap)
- Dangerous blood level for children: 5 µg/dL (that is, micrograms per deciliter. A measurement taken from a person’s blood. Consult your doctor, but this is a good starting magnitude. For adults, some sources say 10 to 25 µg/dL is acceptable).
- 15ppb = 1.5µg/dL, for water anyway… more on that below. Nonetheless, this is surprising and unresolved for me since because the CDC study below correlates dangerous water lead levels of 15ppm to 5 µg/dL blood levels. But alas, I needn’t resolve it, only play it safe. The safe path here is: do not go above 15ppb in water and monitor children (and adults) per doctor’s recommendation.
- Municipalities measure, record, and publish lead levels, e.g. https://www.niskayuna.org/sites/niskayunany/files/uploads/2014_annual_water_quality_report.pdf
- Private Wells: always test at regular intervals. Some sources sight once per year though your specific trends may lengthen that interval if you are well below limits.
- If you are worried about lead levels, you must test. Recourses outlined below.
Now, the details.
If you’re like me you’re wondering, why on Earth would you report Lead in Water in units of parts per billion, and separately, Lead in Blood in micrograms per deciliter? Or more to the point, why the two dangerous levels don’t equate? Perhaps your body gets rid of some lead naturally. It doesn’t much matter other than: don’t ingest any concentration above the max safe level of concentration.
Links and comments below are just a start on Lead and what to do about it. You must become informed further to respond appropriately to your particular situation.
EPA’s overview on the subject
Identifying lead sources in your home
Note, a lead pipe in your home is not necessarily cause for alarm. Although it sounds bad, you really have to test to know. Lead paint and a host of other sources may exist. Continue below on how cities deal with lead in main water lines.
Municipalities tend to add orthophosphates and other chemicals to drinking water to inhibit internal pipe corrosion and leaching
CDC often cited paper on the subject
“The findings in this report suggest that levels exceeding the EPA action level of 15 ppb can result in an increase in the percentage of BLLs >5 µg/dL.”
Diving into the Units of measure
EPA reports in ppb, the test lab I use reports lead in mg/l (that’s milli, not micro) which is equivalent to parts per million. Doctors report in µg/dL (there’s the micro symbol).
Now, the engineer / high-school chemistry student in you should be screaming… because mass per volume is not equatable to part ratio count. At least not without a conversion factor. Ahhh, that’s where water comes in. In first link below, the EPA nicely says “For water, 1ppm = approximately 1mg/L). The approximately part is actually very appropriate and accurate, but it’s nice to see I’m not crazy about the fact you can’t just mix units.