Fish can tell us a lot about the water we drink

December 15, 2009

By Dallas Cross

Fish Journal

Our fresh water fish are not only interesting for those who value them for food or sport, but are also studied by naturalists, wildlife biologists, ecologists, public health professionals and even biochemists.We have a lot in common with fish. We intimately share the same water. They swim and breathe in it, and we drink it and bathe in it. Because we share water, fish become our aqueous mine canaries, signaling problems in the water that may adversely affect our own health.

Many municipalities get their water supply directly from rivers, reservoirs or from wells supplied by surface waters. They also treat their water waste or sewage to control disease by removing bacteria. But treatment plants are not designed to take out all the pollutants, especially toxic chemicals.

Downstream, treated water is collected by another town or city for domestic water. There, it accumulates additional chemical contaminants, is treated and after use is dumped back into the system. Also, surface run off water from city streets, industrial and agricultural areas add chemical contaminants, which accumulate in our water sources.

So, let’s examine some recent observations about the quality of our waters and the health of the fish that swim in them. Having been a biochemist, I focus on the contamination of water supply with estrogenic chemicals.

These are organic chemicals that affect the health of animals in ways similar to that of natural estrogen, a hormone responsible for development of female traits in animals. Thus, they are called estrogenic, because they biologically imitate estrogen.

Estrogenic chemicals polluting our water come from birth control pills containing synthetic estrogen, some insecticides, plastic used for food and drink containers, plastic water pipes, and many industrial and household products. A prominent estrogenic contaminant is bisphenol-A or BPA, a compound used to harden plastic. BPA leaches out of virtually all plastic, including polycarbonate food and drink containers.

So, what are fish telling us about these chemical additions to our shared water environment? Wildlife biologists report that the ability for salmon and trout to reproduce are adversely affected by the increase in estrogenic chemical pollutants in the Columbia River system. There appears to be a hormone-induced sex reversal of salmon males to females, with subsequent offspring becoming genetically abnormal males.

Levels of estrogenic chemicals have been measured to be increasing in Puget Sound and its tributary rivers and streams. Levels are high enough to not only change the reproductive ability of trout, but are cited as being able to affect frogs, river otters and other fish.

Some adverse effects of estrogenic compounds in humans are increased incidence of breast cancer and interference with natural sexual development. A recent report found that young girls who drank water from plastic bottles were more aggressive than those who did not. BPA is linked to these problems and is found to be retained in humans a long time after ingestion, in females more than males.

BPA contamination comes from many plastic items with which we have daily contact — plastic water bottles and food containers, and plastic liners in many major brand canned foods. It also leaches from plastic drinking water pipes and from liners in water storage tanks.

Water treatment experts tell us that sewage treatment removes a large percentage of the estrogenic compounds as solid waste. However, the waste sludge is often returned to the soil as fertilizer for crops, which again introduces toxic chemicals into our food and water supplies.

Studies show estrogenic chemicals in solid waste products do infiltrate into the ground, polluting underground water such that 30 percent of some surveyed municipal wells have been contaminated.

The new Brightwater treatment plant being built in Snohomish County to process King County sewage is designed to remove more of the estrogenic compounds than do current plants. So, the danger of pollution by chemicals such as BPA is being recognized by our local governments.

There is also a strong local movement, promoted by the Sno-King Watershed Council. Its objective is to control ground water run off from industrial, agricultural and residential sources that contaminate our streams and water supplies.

These are partial measures in the right direction to reduce the harmful chemical contaminants affecting us and the fish who are giving us an “early warning.” But we all need to help by limiting or avoiding the use of products responsible for such contamination.

A significant fact is that harmful chemicals in plastic containers are released in higher amounts into food and drink when heated. This is true for BPA and styrene, the latter is carcinogenic in animals and found in polystyrene or Styrofoam. Thus, microwaving or heating consumables in contact with such plastic is not a good idea.

Hearing the increasingly soprano song of our fish, I advise my friends and family to buy and keep their food and drink in metal or glass containers, especially baby bottles.

Reach Dallas Cross at View previous articles at Comment at

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