Professional Discipline
All professional disciplines have some standards of
performance, but how those standards are developed vary tremendously. Some professions, like engineering, have
obvious external measures of success. A
bridge must work like a bridge. Under those circumstances, the credentials an engineer
must have to practice their trade are themselves designed to insure, for
example, that the bridge will stand and cross the river. Yet, even when there are objective of
performance, there are examples where the credentialing process has proven to
be inadequate. For example, stock market
crashes often come about because standard accounting practices show one or more
failing businesses to be entirely solvent.
A profession with absolutely no objective measures of
performance isn’t providing much of a service.
So, there aren’t very many of those.
But, there are plenty of professions where the definition of successful
performance is not at all obvious even when there is a clear purpose. Examples can be found in medicine that cover
the entire range. Some treatments are
highly effective; and under those circumstances medicine is essentally biological engineering. If the treatment doesn’t work, then it is
likely that the doctor is at fault. But
there are also many other medical treatments where success is not so straightforwardly
defined. The treatment may not always
work, or it may only partially mitigate or cure a disease. In that case, the standard of performance
cannot be entirely dictated by the success of an outcome. Instead a doctor is likely to be judged as to
whether or not they followed the norms of the profession.
Academic Fiefdoms
Many academic disciplines correspond to professions, so
standards of academic practice will generally correspond to those of the
profession. However, because performance
in academia is less often tied directly to objective measures of professional
success, normative standards of behavior are more often what determines
acceptable practice. In other words, peer review. One might presume that the journal reviewers,
editors and study section members that essentially regulate a scientific discipline
all have some objective measures of success in mind, but maybe
they don’t. There is no written guarantee.
The other thing about academia is that there are many areas
of academic study that don’t correspond to a profession at all. For example, if you get a degree in
literature or art history, about the only thing you can do with it is teach literature
or art history. Since there are no objective
measures of performance, peer review is the only game in town. If the reviewers say the paper is good, it is. If they say it’s bad, then it is. Why? "Because
we say so".
In the realm of public health, there are plenty of tweeners. Ostensibly, public health is concerned with
the health of the entire population, rather than the health of individuals. You might think that would entail the same sense
of objective performance that is found in medicine, but the reality is that the
quantitative analyses that define success can be so nebulous that only a "properly qualified" expert can judge it. Sure, there are standards of practice,
but do those standards actually work? Is
“statistical significance” indicative of actual significance? Maybe
not. Do environmental epidemiologists
think it is their responsibility to sort out when an association can be
considered to be causal? Often, they don’t.
The other thing about a public health is that you can’t just
take your degree and hang out your shingle.
Outside of academia, the main employers are governments. Consequently, the norms of public health tend
to be very political. For example, if
you are a toxicologist, the quality of a scientific argument may be judged
by whether or not it advocates proper public policy. It also explains why, when push comes to
shove, the safety
assessment paradigm is preferred to the risk
assessment paradigm: It gives the profession of toxicology more control
over public policy. It can also add the
authority of the government to “because we say so”.
The Nutrition Paradigm
Some nutritionists work at a personal level, and they often have truly objective measures of performance (e.g. weight loss, energy). But, in public health the main game is setting standards. Like the standards in toxicology, there are a number of acronyms, including the older Recommended Dietary Allowance (RDA), which has been replaced by the RDI (Reference Daily Intake or Recommended Daily Intake, which lets decide whether you prefer to sound like the FDA or the EPA). The RDI is defined as
The daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of healthy individuals in every demographic in the United States.
But unlike the standards of toxicology, there is no regimented procedure for the creation of RDAs. On the hand, there is a "framework" (IOM, 2015). NOT having a prescriptive procedure allows every nutrient to be treated as a unique issue, so that can be a good thing. But here's the problem: when nutrients are also toxic, the standards of practice of toxicology and nutrition result in a cultural clash (Greger, 1998; Oilin, 1998). In particular, all of the following issues arise:
- Safety factors. This is the most obvious difference. In setting standards, toxicologists routinely apply safety factors, while nutritionists do not. While there are many nutrients where perhaps an extra factor of 10 could be applied “just to be safe”, there are many others where 10 times the RDA is toxic (e.g. iron, vitamin A). It is also not so clear that toxicologists really should be completely enamored with safety factors either, so let’s score this one in favor of the nutritionists.
- Burdens of Proof. Toxicologists tend to want to err on the side of safety, which often means using a worst-case analysis as the basis for setting standards. For example, the Benchmark Dose has come to be preferred to the No Observed Adverse Effect Level (NOAEL) because it reverses the burdens of proof. Although nutritionists tend to use human experiments (i.e. Randomized Clinical Trials - RCTs) to set standards, the generally use a standard of certainty (i.e. staitsically significant) akin to the NOAEL as the burden of proof. If you want to balance nutritional requirement vs toxicity, then neither one of these standard are really appropriate. Common sense dictates that what is really needed is a middle of the road as-likely-as-not standard (i.e. “preponderance of the evidence”). Let’s call this one even.
- Dose-Response. Toxicology has a long history of emphasizing the relationship between dose and response. The dose makes the poison. But, you just never hear “the dose makes the nutrient”. Obviously, there are underlying dose response relationships for nutritional effects. In general, it is presumed that while a certain amount is required, more is not necessary (Olin, 1988). (But then again, there is the Vitamin C debate). But somehow that fact doesn’t always get figured into the design of RCTs. For example, Hurtado et al (2015) reported the results of an RCT concerned with omega-3 supplementation during pregnancy. Yet the members of the study were all advised to consume fish 2-3 times, which follows guidelines that are partly justified by the fact that “fish and seafood also are sources of other important nutrients, including the long-chain polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA)” (IOM, 2015). Yet, the authors concluded that “Omega-3 LCPUFA supplementation had no neurodevelopment effects”. What’s wrong with that? Well, let’s suppose you were going to design a toxicology experiment. Would your control group be a population that had already been poisoned? And then when they all died, would you conclude that the chemical being studied has no effect? No, that would very silly. What the Hurtado et al (2015) really needed for the study were pregnant women who eat no fish at all. But that would run into the same ethical problems that prevent toxicologists from conducting experiments with humans. Score this one for Toxicology.
That leaves our nattering nabobs both tied with a record of 1-1-1. Based on their superior alliterative qualities,
the Nutritionists get the nod for the post title.
References
Greger JL (1998). Dietary
Standards for Manganese: Overlap between Nutritional and Toxicological Studies. J. Nutrition 128:368S-371S.
Hurtado JA, Iznaola C, Peña M, Ruíz J, Peña –Quintana L, Kajarabille
N, Rodriguez-Santana Y, Sanjurjo P, Aldámiz-Echevarría L, Ochoa J, and Lara-Villoslada
F (2015). Effects of Maternal Ω-3
Supplementation on Fatty Acids and on Visual and Cognitive Development. J Pediatr Gastroenterol Nutr. 61:472-80
Institute of Medicine (2015). A
Framework for Assessing Effects of the Food System. National Academy Press, Washington, DC.
Official Post Soundtrack
Talking Heads (1977). Don’t Worry About the Government. In: Talking Heads 77, Track 8.
Post Notes
Thesis Post #58. Most related to An Ethical Science and my next post which be about a nutritional dose-response for fish consumption. My last post from Oxford.
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