First let me say that it is reasonable to be wary of virtually any claim (including "I think, therefore I am"). However, being wary of something and rejecting it are two different things.
The claim that "there are no long-term negative effects" is not falsifiable (i.e., it cannot be proven false). Long-term negative effects (or risk factors) are a possibility with the introduction of every new medicine, technology, and ideology. Science does not work with certainties nor does it make any guarantees. What it can do, is use induction to make predictions of possible risk factors, and predict the probability associated with them. When a new medicine is released, extensive testing has already been done determining the risk factors linked to the medicine since testing began. The future potential risk factors are hypothesized based on theory. We don't know that aspirin won't make all heads explode on January 1, 2020. But to consider that as a risk factor, we need to have a reason (or a theoretical framework) for why that might be. In the absence of such a reason, we don't need to consider an exploding head in the year 2020 a risk factor of aspirin. How about more reasonable long-term side effects such as cancer or heart attack? The same criteria are applied—what reason do we have to think this would be a risk factor? Without a reason, we have no risk factor.
There are many psychological reasons why people tend to overestimate the probability of potential long-term negative effects. Many of these reasons are related to cognitive biases. One evolutionary explanation has to do with the cost of being wrong versus the benefit of being right. We tend to have a negativity bias that results in a hypersensitivity of potentially harmful events. Our ancestors who were irrationally fearful more often than not, out survived those who irrationally confident more often than not. But in the age of science, we don't need play it safe with irrational intuitions and gut feelings; we can make informed and confident decisions often with a high a degree of probability.
As mentioned, science cannot provide any guarantees. Regardless, a science-based approach to predicting future possible negative effects is far superior to any other approach including one based on what one believes is one's own "common sense." Despite being a relatively low-risk product of science, we may find that the reward of a product is simply not great enough for the potential risk. Conversely, a personal benefit may be greater than a personal cost. On a personal level, I support this kind of thinking. For example, one may choose to consume organic food because they have the luxury of the expendable income to afford it. What I am strongly against, is someone ignoring the science and exaggerating the risk or reward, then demanding that it be made into a law that must be applied to everyone.
As I have explained, there are evolutionary reasons as to why we would tend to be wary of a recent scientific consensus because of unknown possible long-term effects. But we are not prisoners of our evolutionary tendencies—we can use our reasoning to overcome inaccurate intuitions (what we often call "common sense") and make better decisions. This is what science is all about.
Reason: Book I - A Critical Thinking-, Reason-, and Science-based Approach to Issues That Matter is based on the first two years of The Dr. Bo Show, where Bo takes a critical thinking-, reason-, and science-based approach to issues that matter with the goal of educating and entertaining. Every chapter in the book explores a different aspect of reason by using a real-world issue or example.
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