Are we all just guinea pigs?

One of the comments on my previous post on fluoride toxicity suggested we are all just guinea pigs in a fluoridation experiment. Is this true? Yes – but we are also guinea pigs for a lot more things. Is it a bad thing? Well, maybe it’s not ideal, but it’s inevitable and it isn’t going to end in the foreseeable future. We are exposed to countless chemicals for which we don’t have complete certainty about the effects, ranging from pharmaceuticals to industrial chemicals to the natural components of the food we eat.

Pharmaceuticals undergo rigorous testing protocols prior to being approved for human use, including metabolic studies, animal toxicity tests, and pilot studies in humans to demonstrate effectiveness and safety. However, no matter how much testing is done, rare effects or effects that are increased only a small amount over background rates may not be noticed purely because only a finite number of subjects (animal or human) can be included in any trial. Regulators have to look at the data the can be reasonably collected (current testing requirements result in a cost to get a drug approved on the order of 1 billion dollars, so substantial increases in testing requirements aren’t likely to be feasible until more cost-effective methods are developed), then make a decision about whether the benefits of a drug outweigh potential risks. Follow-up monitoring is then done once a wider population starts using the drug to ensure no unexpected adverse effects occur – if they do the drug’s approval may be revoked. Even this follow-up monitoring can’t necessarily detect all effects, particularly since it is often hard to establish a cause-effect relationship unless there is a very clear trend. However, effects that are rare enough to not be detected in this follow-up monitoring generally aren’t going to outweigh the benefits of the pharmaceutical in most cases.

Widespread exposure to industrial pollution started with the industrial revolution. In more recent times, as awareness of the potential adverse effects of exposure to pollution grew, limits were placed on industrial emissions and guidelines were set for maximum concentrations of various chemicals in air based on our understanding of potential health effects. In general these limits are set at levels where no significant effects are expected to occur, but again there are gaps in our knowledge of chemical toxicity, particularly for rare effects or for mixtures of several chemicals. The ideal (from a human health perspective) would be no exposure, but that isn’t feasible at present without shutting down a bunch of useful industries. Regulators base their decisions about whether to approve an application for an industrial facility on whether the benefits of the facility (to society as a whole) outweigh potential risks.

Similarly, we are all exposed to a wide range of chemicals in various consumer products – plastics, electronics, adhesives, paints, and more.  Many of these chemicals have not been properly studied – in most countries, when modern chemical testing regulations started to be developed, any chemicals already in use were basically “grandfathered” and assumed to be safe in the absence of convincing evidence to the contrary. It is only recently that programs such as Canada’s Chemicals Management Plan and Europe’s REACH program have started to look at many of these chemicals, and at least identify chemicals that might be of concern. Newer chemicals are tested more thoroughly before approval, but even still there are again the same limits for detecting rare effects, and the potential risks have to be weighed against potential benefits and the availability of other chemicals to fill the same roll.

Even if we eliminated all pharmaceuticals, all pollution, and all other man-made chemical exposures (which I certainly don’t advocate), we’d still be exposed to countless substances of unknown toxicity. Everything around us, including organic fruit and vegetables, is made of chemicals, and most of these haven’t been studied at all. There are known carcinogens that occur naturally in plants we eat, not even considering the products of combustion from fires (even naturally-caused fires).

So essentially without having complete understanding of the potential toxicity of every chemical around us, which we aren’t even remotely close to having, we will always be guinea pigs for the effects of chemical exposures. All we can do is balance benefits vs. risks as best we can, and continue to improve our knowledge of chemical toxicity. Overall we’re not doing a bad job in North America; life expectancy continues to increase, age-adjusted cancer rates are generally stable or decreasing, and our quality of life is generally pretty good compared to previous times. In general the benefits of our modern society have outweighed the adverse effects of the associated increases in chemical exposures. There’s certainly still room for improvement though, and it’s important to keep monitoring for trends in adverse health effects in the population, continue to study existing chemicals, and ensure proper testing of new chemicals.

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