I like to read bumper stickers. They’re much more interesting than vanity license plates. I also admit to having a few on my ancient Toyota Camry.

I recently saw one that shouted, “BAN FRACKING, ONLY YOU CAN PREVENT FAUCET FIRES!” These words were wrapped around a picture of Smokey Bear, the U.S. Forest Service icon I hadn’t seen in many years. Didn’t he retire?

Focusing on flames in the kitchen sink may seem to be an extreme way to express concerns about risks and impacts associated with hydraulic fracturing, aka fracking. As we should all know by now, fracking refers to the method being used in Pennsylvania, West Virginia and other states to coax natural gas and oil from shale layers deep below the surface.

If it takes bumper stickers and other messages bordering on alarmist to alert regulatory agencies, elected officials and the general public to the risks of this industrial activity to human health and the environment, I say, “So be it.”

But how to respond to the risks associated with fracking or numerous other human endeavors is not always clear. Decisions about how to protect human health and the environment, while noble goals, are often fraught with scientific uncertainty about cause and effect.

At times, it seems like the only thing certain about the protection of human health and the environment is uncertainty. Scientific uncertainty is a fact of life. But scientific knowledge, even when incomplete and imperfect, can provide important clues about risks that can be acted on to prevent as much harm as possible.

So I offer this strategy for surmounting these challenges and dealing with uncertainty about risk. I urge government agencies charged with protecting Maryland’s environment and public health to embrace and apply a decision-making tool that has ethical power and scientific rigor: the Precautionary Principle.

If you’re only vaguely familiar with this concept, here are three well-known descriptions.

≈ The Rio Earth Summit, which took place in 1992 emphasized precaution in Principle 15 of the Rio Declaration on Environment and Development: “When there are threats of serious and irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.”

≈ A few years later, the 1998 Wingspread Conference on the Precautionary Principle, convened by the Science and Human Health Network, produced this broader description: “When an activity raises threats to human health or the environment, precautionary measures should be taken even if some cause-and-effect relationships are not fully established scientifically.” The Wingspread Statement also added: “In this context the proponent of an activity, rather than the public, should bear the burden of proof.”

≈ More recently, in 2005, the World Commission on Ethics of Scientific Knowledge and Technology published this description of the Precautionary Principle: “When human activities lead to morally unacceptable harm that is scientifically plausible but uncertain, actions shall be taken to avoid or diminish that harm.”

All three descriptions are useful, but I prefer the Wingspread Statement.

In its most basic form, the Precautionary Principle is a strategy for dealing with scientific uncertainties in the assessment and management of risks. The principle speaks to the common sense idea that “it is better to be safe than sorry” and “look before you leap,” adages that our parents and teachers tried to pass along when we were children.

Think of caution in advance or caution practiced in the face of uncertainty. The Precautionary Principle also carries the sense of foresight and perspective, not merely caution. If regulatory agencies apply the Precautionary Principle when they review permit applications for human activities on the landscape that carry risks and then act accordingly, I’m convinced public health and the environment would be better protected.

Although the Precautionary Principle is not new, I rarely hear it mentioned.

The United States signed and ratified the 1992 Rio Declaration, one of the most important international expressions of the Precautionary Principle.

In some legal systems (e.g., the European Union), the application of the Precautionary Principle is a statutory requirement. While a few U.S. policies could be characterized as precautionary (e.g., The National Environmental Policy Act), the Precautionary Principle has not yet become the rule in U.S. environmental policy.

In my 40-plus years working with a range of environmental issues in several states — most recently in Maryland — I have observed only a few explicit applications of the Precautionary Principle.

In 2013, the European Commission acknowledged the uncertainty associated with the ecological risks of using a group of systemic agricultural insecticides called neonicotinoids. The commission banned three of them. There is growing scientific evidence that neonicotinoids may be one of the main causes of honey bee colony die-offs worldwide.

These chemicals are lethal to pollinating insects by blocking nerve endings, which paralyzes them. At a low dose of exposure, neonicotinoids can also reduce a bee’s immunity and render it more susceptible to common pathogens.

Bee declines in the nation are continuing at unprecedented rates, with some beekeepers losing half of their hives in recent years. These losses affect beekeepers’ livelihoods and could devastate the segment of the agricultural economy dependent on pollinators (e.g., almonds and fruits).

A 2012 Japanese study showed that neonicotinoids affected brain development in mammals. So these insecticides may also pose a risk to human health.

By banning the use of three neonicotinoids, the European Commission exercised the Precautionary Principle and essentially said, “We should not be using these chemicals until we understand more about them.” In contrast, the U.S. Department of Agriculture and EPA acknowledged that neonicotinoids are a “potential hazard,” but have so far decided that there isn’t enough scientific evidence to justify a ban on their use.

Last March, the EPA issued a moratorium on approving any new use permits for these kinds of systemic insecticides. But, in the context of this commentary, neither U.S. federal agency chose to exercise the Precautionary Principle.

In spite of all this, I’m still hopeful. During the last legislative session, the Maryland General Assembly passed a bill with veto-proof majorities in both the House of Delegates and Senate that established a two-year fracking moratorium. The bill became law and the moratorium will take effect Oct. 1. Permits cannot be issued to allow fracking in Western Maryland until October 2017.

This new law extends the “unofficial” moratorium put in place in early 2011 when then-Gov. Martin O’Malley issued an executive order, the Marcellus Shale Safe Drilling Initiative. During this unofficial moratorium, state funds were made available so studies could be conducted to gain knowledge about the risks and potential impacts of gas development on human health, water resources, biodiversity, infrastructure and the economy — plus develop best management practices, new regulations and monitoring strategies — all designed to reduce uncertainty. These two responsible governmental actions exercised the Precautionary Principle, even though they were never labeled as such.

I am optimistic that we are moving slowly in the right direction, at least here in Maryland. But we can do even better. Some would say that since the 1980s, the U.S. regulatory system has been subverted by industry, with the encouragement of some political leaders and even the courts.

The Precautionary Principle should emerge into full sunlight in the nation and be widely embraced. The Precautionary Principle should be one of the most used items in our bag of regulatory tools and become the basis for reforming environmental laws and regulations.

When uncertainty runs high about the possible impacts of a proposed action on human health or the environment, regulatory agencies must acknowledge that uncertainty and make cautionary decisions that always give the benefit of the doubt to protecting human health and the environment.

Even though risk can rarely be reduced to zero, actions should be taken that are proportional to the seriousness of the potential harm. Anything less would be irresponsible and not fulfill their regulatory responsibilities.

One of the controversial issues swirling around the Precautionary Principle in environmental law is the burden of proof. Some argue that the Precautionary Principle shifts the burden from the opponents of an activity or product to their proponents. Others claim that the principle does not change the traditional approach —the burden is on the public and regulatory agencies — while others say it does but only in certain areas.

There is a large body of literature on the Precautionary Principle, both supportive and critical, for anyone who wants to know more. For starters, I recommend the paper by Bob Constanza and Laura Cornwell (Constanza, R. and L. Cornwell. 1992. “The 4P approach in dealing with scientific uncertainty.” Environment 34(9):12-42). Their paper not only talks about the Precautionary Principle, but also expounds on the Polluter Pays Principle — another item that should be found in our regulatory tool bag and used regularly as needed.

In closing, be informed, be prudent, and look before you leap.