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Xenobiotic Danger in Recreational Water

“What’s In Your Water?”

By Robert W. Lowry year 2005

What in the world is “Xenobiotic” and why should I be worried about it?

This will be from the “You-heard-about-it-here-first” file. No, it isn’t some new kind of disease, bacteria, parasite or organism. It is a term that is used collectively or as a catch-all for a number of things. Xeno is Greek for “foreign” and biotic is from bios which means “life,” but means “biologically active.”

Household products such as window, counter top and floor cleaners, dishwashing and laundry compounds, and heavy-duty potent chemicals such as degreasers, drain cleaners and oven cleaners are now all going down the drain and through the sewer system. Septic tanks do not destroy these chemical wastes either and they cause local pollution. Newer cleaners with anti-microbial ingredients are also part of the household wastewater.

One of the concerns in providing high quality drinking water is that the source may be getting scarce or contaminated due to droughts, expanding population, well closings, pesticide contamination, MTBE, perchlorate, agricultural runoff and chemical manufacturing and industrial pollution to name a few.

Drinking water quality has gotten better over the past few decades in large part because of better analytical techniques. Things have been found in water we never knew were there. We identified them and then established standards and procedures to remove the harmful ones. Who would have heard about chemicals such as PCBs, (polychlorinated biphenyl) THMs (trihalomethanes), TCE (trichloroethylene) or MTBE (methyl t-butyl ether) or organisms like crypto (cryptosporidium parvum) or giardia (giardia lamblia) 25 years ago? Today, practically everyone in recreational water has heard of most of these.

This lack of fresh, uncontaminated source water has caused municipalities to consider and implement water recycling practices. It may be easier to remove the contaminants from household wastewater and recycle it rather than removing contaminants from industrial or agricultural polluted source or ground water.

This caused a shift in the water quality focus from natural elements and traditional waterborne pathogens (disease-causing organisms) to known individual synthetic chemicals and newer, harder-to-kill pathogens. We have only recently become concerned with the impact of phosphates and nitrates on recreational water quality.

There are no guidelines yet, but we will probably have to focus on THMs in recreational water soon. THMs are disinfectant by-products formed when chlorine or bromine react with certain natural organic matter in water. These halogenated organics are named as derivatives of methane and include suspected carcinogens. They are any of various derivatives CHX3 of methane (such as chloroform or bromoform) that have three halogen atoms per molecule. THMs are not allowed in drinking water. To comply with Federal regulations, water treatment methods changed at drinking water treatment facilities so THMs would not be produced.

The next shift of focus in water quality will probably be toward synthetic contaminants such as pharmaceuticals and “natural” contaminants such as hormones. These contaminants will

be in much lower concentrations than any other contaminants. They will also have biological effects that may occur at concentrations below the current detection levels.

Each time a new drinking water contaminant is identified and becomes a concern, recreational water concerns are not far behind. Then the new contaminant has to be added to some catch-all category or collective term that describes what it is. These are terms like pesticides, synthetic organics chemicals (SOCs), volatile organic chemicals (VOCs), inorganics, metals and radionuclides.

Xenobiotics include pharmaceutically active compounds (PhACs) and endocrine-disrupting chemicals (EDCs). Exogenous hormones (those hormones that are produced outside the body) and one’s own hormones are definitely biotic (caused or produced by living beings). Xenobiotics also include drugs both the legal kind that you get by prescription and the illegal type like cocaine, heroin, marijuana, meth, ice, speed and crank.

Perchlorate is an example of both a xenobiotic and an endocrine disruptor. It is a chemical used as the primary ingredient of solid rocket propellant and in munitions beginning in the 1950s. Perchlorate is also used in the production of explosives and fireworks. It adds the blue color to firework displays.

For disposal, perchlorate has often been dissolved in water and poured on the ground. Perchlorate dissolves easily and moves quickly in underground and surface water. It breaks down very slowly in the environment. Wastes from the manufacture and improper disposal of perchlorate-containing chemicals are increasingly being discovered in soil and water. Traces of perchlorate have been found in groundwater in virtually every state in the U.S. It has been detected in many rivers and low levels have been found in some lettuce samples and milk. The term perchlorate includes ammonium perchlorate, potassium perchlorate, sodium perchlorate, and perchloric acid.

Perchlorate interferes with iodide uptake into the thyroid gland. Because iodide is an essential component of thyroid hormones, perchlorate disrupts the function of the thyroid. The thyroid helps to regulate metabolism. In children, the thyroid also plays a major role in proper development. Impairment of thyroid function in expectant mothers may impact the fetus and newborn and result in effects including changes in behavior, delayed development and decreased learning capability. Changes in thyroid hormone levels may also result in thyroid gland tumors.

Although the range of health effects for these xenobiotics is broad, all of these compounds are foreign to the living organism in which the health effect is observed which makes them xenobiotic.

Pharmaceuticals (prescription medications) are formulated to be highly soluble and not readily degradable in the human digestive system. These properties make them persistent in water and not readily degraded by sunlight. Pharmaceutical residuals appear in urine and sweat as a product of their use and subsequent excretion. Other prescription preparations such as topical ointments and lotions that are used for dermal conditions are easily shed into the water upon immersion.

When they tested sewage for the top 50 different prescription medications in studies done recently in Australia, all 50 drugs were present.

A test published by the U.S. Geological Survey in March 2002, states that tiny amounts of everyday products such as soap and prescription drugs were found in 80 percent of the water

sources sampled. The study tested streams in 30 states. Streams showed 95 different chemicals from antibiotics to fragrance. Most of these chemicals were in the ppb (part per billion) range.

If municipalities are going to recycle sewage and mix it with source water to meet demands, they are going to have to consider monitoring and treating xenobiotics as part of their program.

Many of the PhACs are active in the micro-gram per liter to pico-gram per liter range. No one knows what the potential adverse health effects are of consuming xenobiotics in drinking water.

The ultimate recycling of water is a commercial recreational water facility (a public swimming pool, spa or hot tub). The water is sometimes used for years before draining or significant dilution.

In a study done by J. Alan Beech in 1981, it was determined that the amount of pollution per person entering the water leaves 200 mL (milliliters) of sweat and 50 mL of urine. No reliable studies have been made on which to base the amount of urine voided in the water by swimmers. Warren and Ridgeway from Water Research Laboratory, Marlow, England estimated it to be 25-50 mL per swimmer in 1978. Beech estimated it to be much higher for children under 10 years of age. He adopted a value of 50 mL per swimmer.

Kuno from C. C. Thomas in Springfield, IL reported that an active swimmer in water at 24° C (75°F), when the air temperature was 38° C (100° F) lost approximately 1 liter (1.06 quart) of sweat per hour. For his calculation he assumed 10 percent of the volume or 100 mL/hr. The average time spent in the pool is 2 hours. The EPA estimates that child swimmers aged 5-9 years spend 3 hours in pools at a time, teenagers spend 6 hours and adults 1 hour. Beech used an average of 2 hours which produced 200 mL of sweat.

We know that drugs appear in sewage. Therefore, it is not a quantum leap to understand that drugs (xenobiotics), household cleaners and personal care preparations are present in recreational water.

Here is a partial list of prescription drug residuals found in sewage in Australia:


Metformin (HCl)



Ranitidine (HCl)




Salicylic acid


























Clavulanic acid










Tiaprofenic acid






Of primary concern is the potential for adverse health effects. Drug residual concentrations reported in sewage to date are an order of magnitude (two or more times) below those at which an effective therapeutic dose would result from ingesting the water. [That is in sewage, not in recycled, recreational water that may be years old. The concentrations will be much higher in old recreational water.]

Multiple drugs in the water raises the possibility of drug interactions that may cause health effects not otherwise observed. [No one has ever put that many drugs into one body of water with continuous additions made over many months or even years and then exposed swimmers to it.]

Then there is the idea of continuous, multiple or repeated exposure to low levels of these drugs. [Swimming every day in a drug soup may have untold consequences. It could take one or many exposures over months or years for any symptoms or adverse health effects to appear. This could make finding xenobiotics in recreational water as the culprit nearly impossible. Doctors may not even be able to diagnose the problem much less the cause.]

Some evidence suggests that dose-response curves for some drugs are actually U-shaped, having an unexpected range of increased significance or beneficial effect at very low concentrations. [This is of such concern that there is even a program and advisory committee devoted to this. It is called BELLE – biological effects of low-level exposure and it has a multi-institutional Advisory Committee (

Because little is known about the potential environmental effects of these xenobiotics in drinking water, the U.S. EPA National Exposure Research Laboratory is planning further research into drinking water sources. One area of concern is the impact of natural and synthetic sex steroids on the endocrine system on aquatic life such as fish. The potential growth of antibiotic-resistant bacteria and other pathogens is another area of concern. They need more data to understand and determine the risks posed by xenobiotics in source water.

Human and environmental exposure to xenobiotics is of a concern when:

1. A small amount of sewage is recycled and mixed with source water for drinking

2. Small amounts of municipally-treated sewage is returned to the environment where it can contaminate source water

3. Septic tank wastewater is returned to the land through leach fields where it can run off and contaminate source water


Imagine if you will, what might be in swimming pool, spa, hot tub, whirlpool, waterslide, waterpark, lazy river or other recreational water. How much and what might be in the water of a recreational facility that has a daily bather load of 9,000 people and has used the same water for 100 days? What about the spa that has 25 people in it all day long and the water is a month old?

If you swallow some pool water are you ingesting some or all of the 50 prescription drugs listed above? It is estimated that 25-30 percent of all people over the age of 18 years have tried illegal drugs. You may be ingesting some pot, cocaine, heroin, methadone, crack or other drugs. You could be getting some extra hormones, amino acids, vitamins or minerals. You could even be getting some extra caffeine or nicotine. Maybe you never thought about it. Maybe you didn’t want to know. Maybe you will never go swimming in a public facility again. Maybe you will.

This xenobiotic material has been in the water since the very first pool was ever built. We have just recently been able to analyze it. We are just now talking about it. You may start to hear about from your patrons. You will soon be doing something about it.

There are test methods for drugs. They are the same ones used to test Olympic athletes, some felons and homicide victims for drugs. They are very expensive and very sophisticated. There are no easy tests for xenobiotics or drugs. They are insignificant on a TDS (total dissolved solids) test.

We also do not know what any common water sanitizers will do to xenobiotics. They may destroy them. They may do nothing to them. They may chlorinate them, brominate them or oxidize them to unknown byproducts that may be harmful or harmless.

At present for recreational water, the only defense we have against xenobiotics is draining. One draining method used in England and Europe is to drain 30 liters (about 8 gallons) of water per bather per day. This may also reduce the need to superchlorinate because of combined chlorine.

One recommendation is to use water from an approved potable municipal water treatment facility. This water must meet the requirements of the Safe Drinking Water Act. Some 100+ known contaminants are below the level determined safe and it has been tested. Do not use ground water, well water or surface water in a recreational water facility unless the water has been tested by the local health authority and approved for drinking. There is no way of knowing what is in that water without extensive and expensive testing.

Now you have another concern for the safety of your patrons or swimmers and you have a valid reason for keeping the water fresh. The fresher the water, the less chance there is for xenobiotics to be present or build up.

It is a hot topic in drinking water right now. It will not be long before recreational water comes under scrutiny. Will you be ready when your customers or patrons start asking about this?

About the author

Dr. Howard Dryden

Dr. Howard Dryden

Dr. Dryden has unique knowledge combination of biology, chemistry and technology and is the inventor of the activated, bio-resistant filter media AFM®. Dr. Dryden is one of the world`s leading experts in sustainable water treatment.

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