What in the world is a “xenobiotic,” and why should I be worried about it?
No, it isn’t some new kind of disease, bacteria, parasite or organism. It is a term that is used as a catch-all for a number of things. Xeno is Greek for “foreign” and “biotic” is from “bios,” which means “life,” but also means “biologically active.”
Common xenobiotics we encounter daily include household products such as window, countertop and floor cleaners; dishwashing and laundry compounds; and heavy-duty potent chemicals such as degreasers, drain cleaners and oven cleaners. They also include pharmaceutically-active compounds and endocrine-disrupting chemicals. Drugs, both legal and illegal, are also considered to be xenobiotics also.
There are many concerns when it comes to providing high-quality drinking water: scarce water sources, droughts, expanding population and well closings. You can add xenobiotics to the list as well. As xenobiotics go down the drain and through the sewer system, septic tanks do not destroy these chemical wastes, resulting in local pollution.
While drinking water quality has gotten better over the past few decades, the 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. However, recycling water poses another question in terms of the xenobiotics present in water and how they may build over time, an idea which plays a large role in the world of recreational water.
Take perchlorate, for example. An example of both a xenobiotic and an endocrine disruptor, perchlorate is the primary ingredient of solid rocket propellant and in munitions beginning since the 1950s. Perchlorate is also used in the production of explosives and fireworks — it adds the blue color to firework displays.
For disposal, perchlorate is often dissolved in water and poured on the ground. It breaks down very slowly in the environment, but it moves quickly through underground and surface water. Wastes from the manufacture and improper disposal of chemicals that contain perchlorate are increasingly 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.
How does it affect the body? First, 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, making them xenobiotic.
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 for dermal conditions are easily shed into the water upon immersion.
More importantly, these medications appear in sewage in water. When scientists recently tested sewage in Australia for the top 50 different prescription medications, all 50 drugs were present. And after testing streams in 30 states, a study published by the U.S. Geological Survey in March 2002 found trace amounts of everyday products such as soap and prescription drugs in 80 percent of the water sources sampled. Streams showed 95 different chemicals from antibiotics to fragrances.
The bottom line: If municipalities are going to recycle sewage and mix it with source water to meet demands, they have to consider the monitoring and treatment of xenobiotics as well.
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.
A study done by J. Alan Beech in 1981 found the amount of pollution per person who enters a pool is 200 mL (milliliters) of sweat and 50 mL of urine. No reliable studies have been done 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 two hours. The EPA estimates that child swimmers aged 5-9 years spend three hours in pools at a time, teenagers spend six hours and adults one hour. Beech used an average of two hours which produced 200 mL of sweat.
We know drugs appear in sewage. Therefore, it is not a quantum leap to understand that drugs, household cleaners and personal care preparations are present in recreational water.
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.
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.
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 commonly prescribed drugs? It is estimated that 25 to 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 extra hormones, amino acids, vitamins or minerals. You could even be getting some extra caffeine or nicotine.
Xenobiotic material has been in the water since the very first pool was ever built. We have just recently been able to analyze it, and we are just now talking about it. And unfortunately, there are no easy tests for xenobiotics or drugs, as they are insignificant on a 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.
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.
As I mentioned earlier, xenobiotics is a hot topic in drinking water right now, meaning it’ll naturally trickle down to the pool industry. It won’t be long before recreational water comes under scrutiny — will you be ready when your customers start asking about it?
