Dermal Uptake of Nitrates

Posted June 29th, 2019

Are Nitrates Taken in Through the Skin?

There is growing evidence that nitrates in water are a serious threat to human health, that nitrate levels in water supplies, both public and private, are steadily increasing, and that the longstanding 10 part per million regulatory allowable is way too lenient.

The bright side of the nitrate issue, though, is that home treatment for nitrates is relatively easy and inexpensive. Like many other problem contaminants, lead, arsenic, and PFAS, for example, nitrates are almost entirely an ingestion issue.  Nitrates are dangerous when swallowed, but of no great concern for other household exposures like bathing, washing clothing, or cleaning.

Here’s what the World Health Organization says:

Using a multiroute exposure assessment approach (Krishnan & Carrier, 2008), it was found, on the basis of the estimated skin permeability coefficients and the air to water concentration values, that dermal and inhalation exposures to nitrate or nitrite through showering or bathing were not significant (Health Canada, 2013).  WHO: Nitrate and Nitrite in Drinking Water.

Similarly, the US Environmental Protection Agency says:


Nitrates in water used for showering or bathing is not a health concern. Nitrates in drinking water above the federal standard (10mg/L) can be very harmful if ingested, so a treatment device on taps that dispense water primarily for drinking or cooking is recommended.


The Oregon State Health Authority says that high nitrate water should not be used for drinking or preparing food, but that it is safe for gardening, washing dishes, cleaning, and laundry.  Bathing?  “Nitrate does not easily enter the body through the skin. Bathing, swimming and showering with water that has levels of nitrate over 10 mg/L is safe as long as you avoid swallowing the water. Supervise small children when they are bathing and brushing teeth to ensure they do not swallow the water.”


The practical lesson from this is that point of use treatment for nitrates is the easy solution  An undersink reverse osmosis unit or a small undersink filter with a nitrate cartridge can provide high quality drinking water. Nitrate removal for water for the rest of the home is not essential.