Compounds of Orientation: acting at very low concentrations

In the beautiful Italian language that I will never master, the letter s sometimes plays the same role that the a does in turning the word symmetric into its antonym. But sometimes it’s a little more subtle. The translation of spaesato  is disoriented. It’s rooted in the word paese, which means village, and with the s added, it literally means “out of one’s village”. When the word was coined in a map-less world, stepping out of one’s paese could very well have led to disorientation.  But what about the etymology of our own word disorient?  Why does “to orient oneself ” contain the word found in Oriental? Orient is derived from a Latin word signifying to rise, as in sunrise, which occurs in the east, where the Orient is located relative to Europe. If one knows the location of the east, it reveals the other cardinal points and helps with direction.

This somehow reminded me of an insect’s orientation plight. Trail pheromones are compounds that are released by some individuals and which then influence other members. Ants rely on them heavily for orientation but not exclusively. They are also known to rely on visual cues to figure out where to go.

Termites are not ants; they’re more related to roaches. Unless the former are winged, they are eyeless, live in the dark and rely heavily on trail pheromones.  termitesNo matter how they nest or look for food, every species releases the compounds from their abdomen’s sternal gland and uses them for orientation.  The quantities involved are minute: 1 nanogram and 0.02 nanograms for example are effective in the  species Constrictotermes cyphergaster.  In six different families of termites and over 60 species, only 8 different trail pheromone compounds have been identified.  These typically are unsaturated alcohols containing 12 carbons, and often the same compounds serve as sex attractants.

But in 2010, when entomologists tested all of these compounds on false termite workers of Glossotermes oculatus, none of them elicited a response. Instead the substance acting as a pheromone was a ketone. Famous ketones of the natural world include vanillin, spearmint, cortisone and the sex hormones progesterone and testosterone.  Again the amount of compound involved was extremely small, the threshold was only 0.01 nanograms per cm of the trail. A gram of the material–the weight of a 5 dollar bill— would be enough to create a trail a million kilometers in length, almost 1.5 round trips to the moon.


(10Z,13Z)-nonadeca-10,13-dien-2-one, a ketone acting as a trail pheromone in Constrictotermes cyphergaster, a species of termites.

What concentration is involved? The average mass of a termite is 2 mg or 2 X 10 -6 kilograms and given that there are a trillion 10 12ng in 1 kg, the threshold concentration of 0.01 ng/(2 X 10 -6  ) kg is equivalent to 5000 parts per trillion or 5 parts per billion. The argument is often made that pollutants at low concentrations are only picked up because of sensitive instrumentation and that we are alarmed without basis. Such a line of reasoning is speculative. Although pheromones are not pollutants, we still have here an example of how sensitive organisms can be to a relatively small number of molecules on a day-to-day basis.


Comedian Rick Mercer Goes to Bat for Science and the Environment

RosettaRosetta landed on comet67p last week, the first time any man-made object landed on cosmic ice. It made me aware that there is a such a thing as a Jupiter family of comets, which were originally from the Kuiper belt. But collisions with other bodies knocked it out of the region. Eventually, Jupiter, that beast of a planet, which does indeed have its own little world around it, captured the comet and set it in a new orbit.


Rosetta’s landing even caught the attention of Canadian Rick Mercer, who made it the topic of his weekly rant. It was comforting to see this comic genius going to bat for science.

It was not the first time he’s acted in that manner. When the Harper government cut funding to the Experimental Lakes Area, he had this to say:

Postscript: In 2017 the Trudeau government created the “Office of the Chief Science Advisor” to offset moves made by the previous government which Mercer criticized.

The Chief Science Advisor’s key functions:

  • “Provide advice on the development and implementation of guidelines to ensure that government science is fully available to the public and that federal scientists are able to speak freely about their work
  • Provide advice on creating and implementing processes to ensure that scientific analyses are considered when the Government makes decisions
  • Assess and recommend ways to improve the existing science advisory function within the federal government
  • Assess and recommend ways for the Government to better support quality scientific research within the federal system”

Compounds like tBHQ in McDonald’s Fries Complicate Life

If one knows nothing about tBHQ, a preservative that prevents oxidation of oils used in processed foods, popcorn and in McDonald’s French fries, a Google search will lead to a variety of information:

(1) Some people who may be raising legitimate concerns about the additive make themselves easy prey for attack by revealing that they are chemically illiterate. They confuse a butyl-derivative with butane, and they are intimidated by the fact that it’s a petroleum byproduct without realizing that a wide array of compounds are petroleum-based, ranging from carcinogenic benzene to aspirin, which is more beneficial than harmful.

(2) McDonald’s own web site does not inspire confidence either. McdonaldsThe full name of tBHQ (tertiary-butylhydroquinone) is incorrectly capitalized and misspelled. But what they say about regulatory approval is indeed accurate: the European Food Safety Authority (EFSA) and the American and Canadian equivalents have given the preservative the thumbs up.

(3) A concentration of 200 mg of tBHQ per kg of fat or oil cannot be exceeded. The limit, reported on the EFSA web site,  is based on dog studies. But due to the small weight of infants, the antioxidant is to be kept out of infant formula. tBHQ does not accumulate in the body; it’s excreted mostly through urine.  After 2 to 4 days of ingesting it, there are no traces of it in the body. The same linked source describes extensive cellular and subchronic studies. Other researchers looked for cancer-causing effects and found none.

(4) But one area had not been investigated—the possibility of allergies.  2014 research published in the Journal of Immunology concluded that:

Overall, these studies suggest that low doses of the food additive, tBHQ, increase IgE (immunoglobin E) response to food allergen and exacerbate clinical signs of immediate hypersensitivity.

potatoesIt’s ironic that our need for the “easy life” , a quick snack or meal on the go creates a need for so much regulation and animal-research that often reveals that additives are not as dangerous but neither as innocuous as they seemed.

Not growing or buying fresh potatoes and peeling and cooking them yourself surely complicates life.