Sick of golf?

Golfers today have grown accustomed to playing on quality turf and are willing to pay higher greens fees to play on “tour-quality” greens. But are higher greens fees the only price golfers pay for their manicured courses? The press has recently made alarming claims that chemicals used in turf maintenance cause golfers a variety of health problems, including reduced sex drive, reduced fertility, cancer and even fatal allergic reactions.

Is it true that golf courses cause health problems and disease? If so, are all golfers affected or at risk? How significant are the risks? What can be done to reduce health risks to golfers?

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These are the types of questions that toxicologists try to answer so that regulatory agencies and the public can make informed decisions about using chemicals. Let's consider what is known and what is not known about chemicals used to maintain golf turf, and what can be done to better answer questions about health risks to golfers.

What we know

Many people misunderstand the terminology that toxicologists use, words such as toxic, risk and safe (for some definitions, see “Basic terminology,” below). All chemicals can be toxic to some organism at some dose. For this reason, the U.S. Environmental Protection Agency (EPA) requires toxicity testing and regulates the use of pesticides and other chemicals in agriculture and industry. Only chemicals that can be used safely are allowed in commerce in the United States. “Safely” in this context does not mean “no risk.” It means that when enough chemical is applied to have the intended effect — such as controlling insects — there will not be a significant risk of unintended effects — such as toxic injury to the people who apply the chemical or who come into contact with it after application.

All pesticides, and many other chemicals used as soil modifiers and fertilizers, are tested extensively for toxicity to various organs and tissues of the body, including the heart, liver, kidneys, lungs, nervous system and reproductive system, and for damage to DNA that could result in cancer. These toxicity tests are conducted on laboratory rodents and test-tube systems; from these data, we can estimate the levels of exposure that should be safe for humans.

We also have case reports and detailed information from accidental or intentional poisonings with pesticides. Such human experiences provide some information about the toxicological effects of short-term, high doses of pesticides. People who survive a single poisoning incident from common pesticides do not typically experience long-term health problems.

The EPA also considers epidemiological data when making decisions about the appropriate use of pesticides in the United States. Epidemiological studies evaluate the health status of human populations exposed to specific chemicals by virtue of some aspect of their lifestyle, occupation or geographical location. Epidemiological data provide insights as to whether health problems may occur more frequently in populations that are exposed to specific chemicals. To date, a few epidemiological studies have reported higher rates of some types of cancer in populations highly exposed to some herbicides. However, those studies were very preliminary in nature and do not indicate a particular cause of the cancers. Taken together, the results of all studies conducted to date do not show any clear pattern of disease in populations exposed to pesticides and do not indicate a significant health risk from the types of chemicals used to grow and maintain golf course turf.

In addition to toxicological and epidemiological studies, the EPA also considers information on potential exposure to workers and other individuals who may contact a chemical when it is used commercially. Exposure information is used to provide a rough estimate of dose when dosimetry studies are lacking. Exposure data includes the results of pesticide dislodgeability studies (how much pesticide is removed from plants by human contact with the plant), volatility studies (how much pesticide evaporates into the air during and after application) and run-off studies (how much is washed off with rain and irrigation). Because golfers are potentially exposed to pesticides that might be removed from turf during play, dislodgeability studies may be particularly relevant to evaluating health risks for golfers.

Dislodgeability studies and volatilization studies have been conducted for golf course turf (see the list of recommended reading, page Golf 16). Several pesticides were studied and various golf activities and re-entry times were simulated in these studies. The results indicated low risks to golfers under what are assumed to be normal playing conditions. However, they do suggest that observing label-specified re-entry times following pesticide application may be important to maintain safe exposure conditions for golfers.

Exposure and dosimetry studies have been conducted for occupations other than golf. Studies involving licensed pesticide applicators and agricultural workers measured contact (exposure) and internal doses of chemicals received during normal working activities (dosimetry). Such studies help to refine recommendations concerning protective clothing, equipment and work practices that should be employed when using various pesticides. The applicability of those studies to golfers is uncertain, but common sense suggests that pesticide applicators and farmers are more highly exposed than golfers. Because occupational studies have not shown adverse health impacts for these workers, one would not expect significant health risks to golfers.

To sum it up, when used according to the label directions, pesticides approved for use on golf course turf are believed to not pose a real health risk to either the workers who apply the chemicals or to others who may come into contact with the chemicals after application, including golfers.

What we don't know

An old adage says nothing is certain but death and taxes. Because toxicology studies are conducted using laboratory animals, they cannot determine with certainty how humans will respond to chemicals. Some animals respond very similarly to humans and are a reliable basis for toxicological assessment, but other animal tests may prove to be less relevant to humans. Human poisoning incidents provide only anecdotal information about chemical effects because they lack the controlled exposure conditions of a true experiment. Epidemiological studies are statistically controlled, but may not have sufficient resolving power to identify very rare adverse health effects in a human population. Despite numerous uncertainties, the data and procedures used to make regulatory decisions have yielded a safe and effective supply of medicines, antiseptics, pesticides and consumer products over several decades. As an added safeguard, toxicologists constantly strive to identify adverse effects that current tests might not detect.

With respect to golfer exposures, we have only rough estimates of the amounts of pesticides that might be contacted during play. Although carefully conducted studies have measured dislogdeable residues during some golfing activities, little data exist on the frequency with which golfers actually engage in these activities during a round. We also lack data regarding the variability of these behaviors among golfers. Perhaps more importantly, we have not systematically studied all of the potential golfer behaviors that would increase pesticide exposure during a round of golf. While it might seem that we can make reasonable predictions about the behaviors of golfers that would result in exposure, even the best predictions and assumptions are not substitutes for scientific data.

The largest information gap preventing accurate health-risk estimates for golfers is inadequate dosimetry data. Risk assessments that have been conducted on golfers must rely on several layers of assumptions about how much chemical might get from turf or soil into a golfer's bloodstream during a round of golf. In the absence of actual dosimetry studies for golfers, significant uncertainties will be present in any risk estimates regardless of the quality of the exposure data. However, dosimetry studies that have been conducted in occupational- and residential-exposure settings (not involving golf courses) have typically found that actual doses of pesticides received by people are hundreds of times lower than the estimates made using standard, protective assumptions, such as those used in estimating health risks for golfers.

How to better evaluate health risks to golfers

Without systematic studies that tell us which behaviors result in the greatest pesticide exposures, it is difficult to give advice on reducing or eliminating health risks to golfers. A few behavior modifications are obvious. For example, golfers should avoid nibbling on strands of grass or on wooden or plastic golf tees that have been stuck into the turf. They should also avoid placing cigars or cigarettes on turf while playing a shot. Avoiding such behaviors would reduce exposure not only to pesticides but also to bacteria and fungi in the soil or from animal feces that drop onto the turf. The latter may be more significant health risks than chemicals.

To be protective, courses should be closed for a sufficient time to ensure that reentry times are strictly observed and that golfer exposures are maintained at acceptable levels based on conservative exposure assumptions. More detailed dosimetry data are required to determine whether less stringent practices are equally protective.

Just as manufacturers have a responsibility to study the potential toxicity of chemicals they produce, it may be incumbent upon the golf industry to study chemical exposures that could be encountered by golfers. While the available data do not link golf with diseases or health problems, a more complete data set would provide scientific answers to alarmist claims made in the popular press about health risks from golf courses.

Dr. Christopher J. Borgert is a toxicologist with Applied Pharmacology and Toxicology Inc. (Alchua, Fla.); Raymond H. Snyder is a researcher and George H. Snyder is a professor, both at the University of Florida.

BASIC TERMINOLOGY

It's important to understand some terminology that toxicologists use: toxicity, dose, toxicological risk and exposure. Understanding these four terms can help you to avoid much of the confusion that often surrounds reporting of environmental health risks in the popular press.

  • Toxicity is the injury that a chemical (or drug) might cause if a person receives a sufficient dose of it. Toxicity may occur immediately (acute poisoning), as in a case of accidental poisoning or attempted suicide, or may be more insidious, occurring only after many years of (chronic) exposure.

  • Dose is the amount of the chemical or drug that enters the body or is received at the site of toxic action. Usually, we refer to the amount of chemical in the blood as the dose, but not always. For example, if a chemical affects the nasal passages, the dose of interest is the amount that enters the tissues of the nasal passages, not the amount in the blood.

  • Toxicological risk is the probability of injury caused by a chemical or drug. Toxicologists estimate risk by multiplying toxicity by dose because the greater the dose, the greater the probability that the chemical or drug will produce injury.

  • Exposure is the amount of chemical that contacts a person. It is important to remember that exposure is not dose. For example, drinking seawater can make a person extremely ill because the high salt content dehydrates body tissues. However, you do not become dehydrated and sick when you swim in the ocean because, although your exposure to seawater is immense, your dose of seawater is miniscule.

RECOMMENDED READING

  • Borgert, C. J., S. M. Roberts, R. D. Harbison, J. L. Cisar and G. H. Snyder. 1994. Assessing chemical hazards on golf courses. USGA Green Section Record, March/April.

  • Joyce, S. 1998. Why the grass isn't always greener. Environmental Health Perspectives 106: A378-385.

  • Murphy, K., R. Cooper and J. Clark. 1996b. Volatile and dislodgeable residues following triadimefon and MCPP application to turfgrass and implications for human exposure. Crop Sci. 36:1455-1461.

  • Sears, M., C. Bowhey, H. Bruan and G. Stephenson. 1987. Dislodgeable residues and persistence of diazinon, chlorpyrifos, and isophenphos following their application to turfgrass. Pest. Sci. 20:223-231.

  • Snyder, R. H., J. B. Sartain, J. L. Cisar and C. J. Borgert. 1999. Dislodgeable residues of fenamiphos applied to turfgrass and implications for golfer exposure. Soil and Crop Science Society of Florida Proceedings, vol 58:51-57.

  • Thompson, D. G., G. R. Stephenson, M. K. Sears. 1984. Persistence, distribution and dislodgeable residues of 2, 4-D following its application to turfgrass. Pest. Sci. 15:353-360.

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