Pharmaceuticals and Endocrine Disrupting Chemicals

Pharmaceutically active compounds (PhACs) and personal care products (PPCPs), come from a variety of sources, such as human, agricultural, or veterinary usage of medications, fragrances, cosmetics, vitamins, and many other products. Many PhACs or PPCPs are also endocrine disrupting chemicals (EDCs), which are natural compounds and synthetic chemicals that mimic natural hormones.

Pharmaceuticals have become a source of increasing concern because they are released into the environment with little regulation, and they persist at low ppb to ppt concentrations, which may have an adverse effect on the ecosystem as well as groundwater and surface water systems. Studies have linked EDCs to adverse biological effects in animals, which suggests the potential for similar effects in humans. EDCs enter the groundwater table from point source discharges from industry, as well as from runoff in urban and agricultural areas.

Some adverse effects from the increased presence of pharmaceuticals and EDCs in the aquatic ecosystem include cancer, fertility problems, and organ-specific health effects. Concentrations of these compounds well below their accepted regulatory levels are associated with negative effects on human and wildlife health. More research needs to be completed to assess the results of low level exposure to these compounds, but it is already known that adverse affects exist, and measures must be taken in order to reduce the influx of these compounds into the environment.

One Word vs. Two

Perhaps you've heard, the USGS is now officially using "groundwater" as one word, instead of two. The change is in response to the widespread use of the term as one word, and is an attempt to create a single convention for the word. This move has been met with approval from some, and resistance from others.

In my introduction to groundwater at the USGS as a green hydrologic technician (two years ago), I learned that the debate between ground water and groundwater was an intense one. As an earth science student with mediocre training in hydrology, I was baffled by the debate. Whenever I was writing about ground water, I often had to ask my boss whether it should be two words or one (or hyphenated) so that the wrath of senior hydrologists would not be visited upon me later for making such a serious mistake.

I'm not sure that I understand the reason that some people find this to be such a heady issue, other than the fact that they have used ground water for most of their hydrological career. I am an unbiased party, having no particular attachment to one word or two, and as a person who prefers to have one common, standard way of reporting things, I am pleased that the USGS has come to the decision to standardize this word in a way that coincides with much of the rest of the hydrological world.

To Purge, or not to Purge

I was discussing a recent study in Bozeman with a student of groundwater hydrology where the local water quality district tested values of nitrates from wells that are purged before sampling versus nitrate levels from wells that were not purged. The results indicated that the difference in values between purged wells and water that had been sitting stagnant in the casing was subtle, but apparent.

I have not been able to find the study, as I don't think the results have been published, but this is an interesting topic since most of the groundwater in privately-owned wells is tested by untrained well owners who do not purge their wells. Thus, while the difference is not enough to be significant for owners who are just finding a baseline value for their drinking water, it is significant in terms of the data collected from owners throughout the state which is used to examine trends in groundwater by, say, the university.

When I worked for the USGS in California, we always sampled from purged wells to ensure that we sampled a representative portion of the groundwater, and not just stagnant water that hung around in the casing and did not represent the composition of the groundwater. We thus ensured an unbiased sample and that the results of our lab tests accurately reflected the actual groundwater below the well.

Nitrates

Nitrate (NO3) is a naturally-occuring compound made up of nitrogen and oxygen that is an essential nutrient for plants. It forms when ammonia or other sources of nitrogen combine with oxygen in water. Nitrate is found in plants, soil, animal manure, septic systems, sewage, fertilizers, and airborne components from industry that are deposited through precipitation or dry particles.

Nitrate is highly soluble in water and does not easily bind with other compounds, making it more likely to remain in the water cycle and thus move large distances and remain in solution in rivers, streams, or groundwater for long periods of time. This means that one could find nitrate in high concentrations miles from the original source, and years after the original source was gone.

Infants under 6 months are susceptible to methemoglobinemia, where the nitrates are converted to nitrites in their stomachs (due to bacteria in their stomachs) which then enter the bloodstream and subsequently interferes with the body's ability to carry oxygen to tissues. In children and adults, nitrates may be linked to birth defects and certain types of cancer.

So what does this mean? Long-term exposure to high levels of nitrate poses a health hazard, and therefore well owners should regularly test their groundwater for levels of nitrate above the MCL (maximum contaminant level), which is 10 mg/L for both Montana and California.

Image: American Falls at Idaho Falls, ID (July 2008)