Excessive nitrates in drinking water pose a human
health threat, especially to infants. Methemoglobinemia,
or blue-baby syndrome, is a potentially fatal condition
that inhibits the ability of red blood cells to bind and
transport oxygen. Nitrates/nitrites have also been linked
to such conditions as cancer, birth defects, and behavioral
and developmental abnormalities.
Nitrates are frequently found in wells in rural farming
areas because synthetic fertilizers (containing nitrates)
leach from the soil into the groundwater. The
Lower Umatilla Basin (LUB) in Morrow and Umatilla counties
of Oregon represents an intensively farmed and irrigated
area in which relatively high amounts of nitrates are present
in the groundwater and domestic well water.
This study investigated population demographics for
the rural Lower Umatilla Basin, comparing these data to
identified well-water nitrate levels for the purpose of
estimating nitrate exposures and potential risk of adverse
health effects in the survey area. Results of the investigation
revealed that 25 percent of the domestic-use wells
in the survey area had nitrate levels that were in excess
of the 10 ppm nN MCL for drinking water, as established by
the U.S. Environmental Protection Agency. From access to
these wells, 23 percent of the surveyed population was exposed
to nitrate concentrations in excess of the MCL standard.
However, resident infants were neither exposed to
well-water nitrates in excess of the standard, nor were
they exposed to illness that could have increased the risk
of methemoglobinemia.
The LUB survey population was generally older than the
populations from cities in the LUB or the combined populations
of rural areas of Morrow and Umatilla counties. The
population included few women of childbearing age, and it
was not subject to an appreciable increase in the proportion
of younger to older families. These factors reduced
the likelihood of a significant increase in the infant population,
which also minimized the risk of methemoglobinemia
to this population. Even though the risk of methemoglobinemia
to infants was low in the LUB area, it is recommended
that exposures to well-water nitrates be prevented, if possible
even for adults, to reduce the potential for chronic,
adverse health effects from excess nitrate ingestion.
Continued monitoring of private wells by state agencies
is recommended, with attention directed at domesticuse
wells with nitrate levels in excess of 10 ppm nN. This
information should be shared with local health departments
for follow-up, investigation, and educational efforts as
needed. Future studies by the Oregon DEQ, or other agencies
which seek to document the sources of well-water nitrate
contamination in the LUB, should include an investigation
of the influence of local sources of nitrate contamination. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36348 |
| Date | 04 May 1993 |
| Creators | Mitchell, Thomas J. |
| Contributors | Harding, Anna |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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