They say a cat has nine lives. A decision before our Legislature about whether to update water protections has me reflecting on how many lives are already in my count.

For 27 years, I worked for the U.S. Centers for Disease Control and Prevention. When Mt. St. Helens erupted in 1980, I was ordered to go there and study the effects of the dust exposure to the loggers working on the ash-covered slopes of the volcano. The volcano could and did continue to erupt violently. Once, it erupted only two hours after I had left the danger zone. My wife thought I was dead. Instead, I was dead asleep on a red-eye flight home.

The incident, at the time, left me with no lasting impression about the risk I was taking. In 27 years of doing my job at the CDC, I once reckoned I had used 10 of my nine cat-lives. In my seventh decade of life, I’ve started to make sure I look both ways when crossing the street. All of this is just a way of acknowledging that life can be risky. We know that.

What we might not know or, perhaps, not understand is how best to judge that risk. As a scientist, I can give you a number. That number represents a risk: how likely something is to happen. That number is, to all but the most ardent of gamblers, an abstraction. It is like asking, “How small is small?” A number without some emotional context might be difficult to judge.

Consider a risk of 1 in 1 million. That would be the chance of something happening one time in every million tries. Seems like that’s a pretty small risk. The Legislature is currently considering what limits should be set for the risk you experience from someone dumping cancer-causing chemicals into the streams from which you eventually get the water you drink or the fish you eat. In 2015, the U.S. Environmental Protection Agency updated suggested chemical levels, which states may adopt, that are supposed to keep the risk to one extra cancer death per million people.

You might be tempted to think a one-in-a-million rate of occurrence should assure you that it won’t happen to you — unless you’ve recently bought a lottery ticket. In that case, you’ve decided that, even with a chance of more than 1 in 100 million, your chance of winning the lottery, might not be so unlikely.

Different circumstances can alter a person’s emotional context.

As an example of the emotional context behind risk, consider letting your children play in traffic. Sure, they can get run over, but what are the chances? Even if I could give you a number for that risk, would you advise your children to go play in traffic? Would you suggest to your child, if they had not been playing in traffic as much as normal, that they go outside and spend more time doing it? That’s emotional context.

Would you then recommend that your state raise the amount of cancer agents in your water to get to that one-in-a-million risk level, when the levels that were there before were lower and were ones industry was attaining? Would you do all that if you realized that your state was already one of the least healthy of all the states? If you knew that the EPA’s risk estimate of one in a million might not be based on how unhealthy you already are, would you allow yourself to be further exposed? If you’re standing on the edge of a cliff, do you really want someone pushing you?

If you don’t think closely about the risk — and I certainly didn’t when I was on the slopes of the volcano — it might seem acceptable. My wife would, obviously, disagree. The Senate Energy, Industry and Mining Committee decided that the risk is real and the less risky path might be the better. It selected new limits on the amount of chemicals discharged in the waterways that would put less risk on all the population of the state.

Could that have an effect on the pocketbooks of some? Possibly. Will it otherwise have an effect on decreasing the risk to the health of all? Unquestionably.

If you’re wondering about what the Legislature should do next, you might want to ask yourself, how many of your nine lives do you have left? How many does your family have?

Michael McCawley is an engineer

with a doctorate in environmental health and an associate professor at

the WVU School of Public Health.