The History of DDT Through an Ellulian Lens

We rarely see the word technique used in the Ellullian sense of the word. Coined by Jacques Ellul in the 1950s when Technological Society was first published, technique refers to an ensemble of methods embedded in every field of human activity. These methods are rationally arrived at and seek efficiency. By such a definition, technique does not only include machines, robots and electronic technology but also economic systems, military and advertising strategies, human resources and management of government departments, corporations and research labs. In technique, spontaneity and tradition are replaced by a complex set of acts with the aim to achieve some kind of quantifiable goal. While technical progress grows irreversibly and exponentially, its far-reaching effects on the human psyche, physiology, culture and environment cannot all be foreseen. It’s through this lens that we’ll examine the history of the pesticide dichlorodiphenyltrichloroethane, abbreviated as DDT.

ddt-spray-beach.jpgIn order to encourage living scientists to continue their excellent work, Nobel Prizes are never awarded posthumously. The problem with that restriction is that a discovery’s full impact on its field and society is usually not immediately apparent. And unfortunately there is no minimum time that has to elapse between publication of the achievement and the granting of the award. One year before the Nobel committee committed its biggest blunder by awarding the 1949 Prize for Medicine for the lobotomy, the 1948 Prize for Medicine was awarded to Paul Müller “for his discovery of the high efficiency of DDT as a contact poison against several arthropods.” DDT had been first synthesized back in 1874 by Zeidler, but Müller found uses for the compound in the 1930s while searching for a contact poison against clothes moths and carpet beetles.  In his acceptance speech, Müller mentioned the heavy World War II outbreak of typhus in Naples in October 1943. Three months later, 1.3 million people were sprayed with DDT over a period of 3 weeks.

body-lice
An Epidemic Typhus species, the type of louse that was killed by DDT.

The poison was not absorbed through human skin but killed body lice which were infected with the cause of typhus fever, Rickettsia prowazekii. The disease, which otherwise would have had about a 40% mortality rate, was brought under control. Hundreds of thousands of lives were saved.

Once technique was involved in war, with its tentacles spread over weaponry, strategy, propaganda and economics, the effects became devastating on an unprecedented scale.  Typhus was more likely to develop in an already poor area impacted by such a war. And often the only way to deal with problems exacerbated by technique is with more technique, which in this case was, again in Müller ‘s words, “an introduction by General Fox of DDT with total exclusion of the old, slow methods of treatment.”

After the war, DDT also became an effective way of fighting malaria by attacking their vector, the Anopheles mosquito. By 1967 endemic malaria was wiped out in Greece, Italy and in many subtropical Asian and Latin American countries. It should be pointed out that draining breeding grounds in those areas also played a key role in eradicating the disease. This wasn’t possible in tropical areas in Africa where, in addition, the necessary infrastructure for a spraying program was often lacking. Consequently only a few African countries participated. A couple of years later, it was learned that some mosquito populations were becoming resistant to DDT.

Insect resistance should not have come as a complete surprise. In accepting his prize almost twenty years earlier, Muller had stated:

Generally speaking the housefly is very susceptible to DDT; unfortunately some fairly resistant species of fly have lately been observed. 

It turns out that within any species being treated with any insecticide, there will always be a few individuals who escape death. These survivors are the ones who continue to reproduce, so they will leave behind more of the genes that made them less vulnerable. (Some recent evidence suggests that only a single gene may be required.) After many generations—and it doesn’t take very long; in a single year mosquitoes can go through 25 to 70 life cycles—a once-rare trait becomes the norm.

ddt
C14H9Cl5 : 1,1′-(2,2,2-trichloroethane-1,1-diyl)bis(4-chlorobenzene) aka dichlorodiphenyltrichloroethane aka DDT

That wasn’t the only issue with DDT.  It’s highly resistant to light and oxygen and to organisms’ mixed-function oxidase
enzymes (MFOs), which normally oxidize and break down fat-soluble toxic substances. Other enzymes can convert DDT to DDE by replacing a chlorine and a hydrogen from the middle of the DDT molecule with a double bond. But DDE is still toxic and is  even more resistant to the action of MFO enzymes. In other words we can consider DDT not to be biodegradable overall. Moreover DDT’s and DDE’s strong tendency to dissolve  in lipids(100 g/L for DDT at room temperature) and not in water (only 2μg/L for DDT) means that fat tissue can act as a sponge: an organism’s intake of DDT will exceed the amount excreted. This mechanism repeatedly increases concentration of the toxin as one organism eats another. The higher the organism is in the food chain, the more DDT it will have in its fat tissue. Populations of high trophic predators such as eagles and falcons were affected when DDT was used heavily as a pesticide. The accumulated poison in their tissue interfered with steroid metabolism. Affected birds became incapable of moving enough calcium into their eggshells.  As the thin shells cracked, their embryos were killed by the entry of bacteria. Along with unrelated pressures that had been placed on the birds, DDT led to their precipitous decline.

Although written in the 1950s Ellul’s Technological Society already mentioned DDT’s unforeseen effects on mammals—there was research revealing DDT’s impact on bones of newborn calves. I couldn’t find any later work that corroborated such a claim, but DDT is eliminated far more slowly in cattle than in humans. Without further input, the half life of DDT in humans is 69 days but 335 days in cattle based on lactation studies in 1965 by RC Laben. More recently (2011), adults with high serum concentrations of organochlorine pesticides such as DDT have been found to have lower vitamin D levels. Although DDT is not a category 1 carcinogen, it is classified as a probable carcinogen based on animal studies. And there are other serious health concerns to be considered. A few years ago, a Lancet review study of the health risks and benefits of DDT stated that indoor application of DDT could be effective in some settings of malaria-infested areas. But they also pointed out that through continuous spraying, mothers could carry a body burden of DDT, which raises the risk of preterm birth and early weaning. Other risks such as neurological effects could also affect mothers and workers receiving and applying the spray, respectively.

Organizations currently dedicated to abating malaria seem to be using a variety of strategies. Non-DDT alternatives have been used in eave tubes, which cause mosquitoes to get fooled into entering the tubes as they follow the CO2 trail coming from human inhabitants inside the homes. Along with better built houses, these have helped control malaria in Tanzania. Elsewhere this approach is being combined with sugar traps and sterilisation of male mosquitoes.

insecticide-ddd-ddt
After the second world war, clothes sprays contained a 5% solution of DDT to kill moths. The same compound was included in moth balls.

What made DDT a serious problem was the scale of its application, a recurring theme when it comes to technique. First used as an insecticide in 1939, it eventually became one of the most ubiquitous pesticides on the planet from 1946 to 1972. It was used on cotton, fruits, potatoes and corn to kill worms, moths, beetles and borers, respectively. Aside from its use against life-threatening diseases such as malaria and typhus, it also served as an agent against far less serious pests such as moths in clothes and insects in museum specimens. With such overzealous applications it’s no surprise that by the mid 1960s human breast milk across the planet suddenly contained twice the maximum levels set by WHO (World Health Organization). These levels were equal to the concentrations needed to cause biochemical changes in rats. Soon after, Sweden issued a two-year moratorium of DDT. The eventual cancellation of DDT’s registration by the USA’s Environmental Protection Agency in 1972 was based on human health concerns, not directly on ecological grounds. From Public Health Reports:

Hayes, a witness for the state, declared DDT safe on the grounds that soldiers sprayed with it in the 1940s and prisoners who swallowed it in studies performed in the 1950s had suffered no adverse effects. Lawyers and witnesses for the petitioners dismantled Hayes’ testimony by focusing on the human health questions left unanswered by such studies: DDT’s long-term toxicity; its effects on the endocrine system and liver; and its effects on newborns, children, and women.

DDT also inspired the synthesis of similar organochlorine pesticides, most of which are fortunately banned today due their toxicity and environmental persistence. The worst of the bunch were the cyclodiene pesticides, which unlike DDT, were absorbed through the skin. Even at low doses these compounds induced convulsions. Meanwhile in a reasonable position, the World Health Organisation supports the ban on DDT in most countries while concluding:

that countries that are relying on DDT for disease vector control may need to continue such use until locally safe, effective, affordable and environmentally sound alternatives are available for a sustainable transition away from DDT.

Needless to say there are many influential people who disagree with Ellul’s analysis of technique. They find the concept too fuzzy and his tone excessively pessimistic. His dismissers include those who believe that DDT should never have been banned anywhere, even if the countries were malaria-free. Oddly some DDT-enthusiasts even villify Rachel Carson, author of Silent Spring, even though, as we mentioned previously, the decision to deregister DDT in the United States was not directly based on environmental concerns. Like Hayes, they are “couched in a political view that remained faithful to a vision of the U.S. as the superpower and global protector it became in the years after WWII.” While not acknowledging the existence of technique’s web, they also feel society does more harm than good by trying to stifle or regulate technology. (Ironically the regulating bureaucracies are part of Ellul-defined technique.) Ellul was not at the opposite end of the spectrum. He was apolitical and certainly never felt that we should get rid of technology; he realised that its abandonment would be suicide for our species. Instead he expressed the need to transcend it. How could that happen? If we remain scientific while letting more than just a trickle of ecological and spiritual sense flow through our beings, we will be on more benign and autonomous tracks.*

*The fact that the word “track” initially came to my mind in the singular, is one of so many reminders of how narrow our points of view can be when contemplating our futures. There was a time, not too long ago, when different civilisations coexisted, unaware of the others’ existence and travelling a variety of paths.

Continue reading “The History of DDT Through an Ellulian Lens”

Queen Bee Chemistry

It is so easy to jump to conclusions when observing and studying honeybees. To the uninitiated, the female workers seem to be the key to the hive. After all, they do so much. They start off early in their lives cleaning the nest. A few days later they are feeding larvae, then secreting wax to build the honeycomb. At about the age of 20 days, they act as guards to the entrance of the nest, and when their glands degenerate, they’re off collecting pollen and nectar for the rest of their lives. After a successful trip, they perform elaborate symbolic dances, revealing both the angular and scalar components of their displacement from flowers to hive. In contrast, the males and the queen bee don’t do any of the above.

But the female workers, as industrious as they may be, do not reproduce and do not exert the strongest influence in the hive. The failure of a single and other type of individual is consistently listed as a cause of honeybee colony mortality.  That individual is the queen bee. She is born in a cell built larger than the others to accommodate her bigger size. But what makes her develop into a queen? After observing that the queen bee larva and adult queen is only fed a so-called royal jelly, a white mixture of protein and sugar secreted from the heads of worker bees, it was long assumed that the mixture held the secret. But a few years ago it was revealed that the key was not necessarily contained in the royal jelly but in what the queen bee was not fed: pollen and nectar. The latter food- source for other larvae contains flavonoids, some of which include inhibitors. Investigators reared larvae in the lab on a royal jelly diet adulterated with para coumaric acid, and by the time they developed into adults, ovary development had been stunted.

queencourt
A queen bee courted by other females. Notice her  larger size and the yellow marker added by a biologist. http://articles.extension.org/pages/73133/honey-bee-queens:-evaluating-the-most-important-colony-member

When not exposed to such gene-silencers, a queen bee will normally emerge from her larval stage five days sooner than other bees. After killing competing virgin queens, she diversifies genetic input by mating with 7 to 17 drones, who die soon afterwards. With the ability to store about seven million sperm, the queen will then be fed and groomed by workers while she lays eggs for the rest of her life. In what surely is a matriarch’s fantasy, the older a queen bee gets, the more prolific she becomes in laying eggs, becoming even more attractive to her servants. But how does this happen?

JBFree_source-Pheromones
The various effects on bee behavior controlled by a complex of a chemical signals from the queen bee. Source: JB Free

It has been known for decades that a pheromone (chemical messenger) is released from the queen bee’s mandibular gland in her lower mouth.  In subsequent experiments, however, the compound that had been identified as E-9-oxodec-2-enoic acid, could not on its own exert any retinue behaviour on worker bees. Retinue behaviour is what’s used to described the way workers groom and feed the queen. It’s only part of the influence that the queen bee’s chemical messengers can have on bee behaviour, as revealed in the adjacent illustration. There are a series of effects with immediate impacts (releaser) and those with long term consequences(primer) on the endocrine and reproductive systems of workers.

beehormones
Three of at least 9 compounds released to make sure the queen bee gets groomed and fed by other females.

Eventually, in the late 1980s Canadian researchers from Simon Fraser University revealed that the original compound was really a mixture of two mirror-image molecules known as enantiomers. They also identified three other compounds from the mandibular gland. When a tube containing the 5-compound mixture was placed in a beehive, the workers left the cells that they were building for new queens and started to press their antennae against the glass while licking the synthetic queen. But the mystery wasn’t entirely solved. As the authors of the same study stated in a review paper 16 years later, the 5-compound mixture is ineffective in some strains of honeybees. The response is influenced by variable genetic factors and by at least 4 other compounds, specifically coniferyl alcohol, another alcohol, methyl oleate and linolenic acid. As the queen ages she releases higher concentrations of the compounds to ensure a positive correlation between the attention she receives and the amount of eggs she lays.

When looking beyond the queen and to the general health of bees, including solitary ones, it was assumed that the concentration of pesticides found in bees was too low to harm them. If inspected individually, each pesticide’s level is indeed below the bee’s threshold. But collectively, along with bee diseases and diminishing flower diversity, pesticides have a detrimental impact on a highly beneficial insect. Whether or not bees produce honey and wax for us, they are the sole and essential pollinators of plants such as squash, zucchini, pumpkins, kiwi, watermelon, cantaloupes and Brazil and macadamian nuts. Besides, their mysteries have justifiably inspired more research than any other insect.

Sources:

  • Honey Bee Queens: Evaluating the Most Important Colony Member
    Bee Health October 07, 2015  Philip A. Moore, Michael E. Wilson, John A. Skinner
    Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville
  •  A dietary phytochemical alters caste-associated gene expression in honey bees. Wenfu Mao, Mary A. Schuler, and May R. Berenbaum. 2015. Science Advances 1(7).

  • Pheromone Communication in the Honeybee (Apis mellifera L.) KEITH N. SLESSOR,1 MARK L. WINSTON,2 and YVES LE CONTE3 Journal of Chemical Ecology, Vol. 31, No. 11, November 2005 (#2005) DOI: 10.1007/s10886-005-7623-9
  • New components of the honey bee (Apis mellifera L.)
    queen retinue pheromone. Christopher I. Keeling*†, Keith N. Slessor*, Heather A. Higo‡, and Mark L. Winston‡ Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4486-91. Epub 2003 Apr 3.

The Science of Canada’s Symbol, the Beaver

2018BIGCOINSUB-7The beaver, Castor canadensis, is an official symbol of Canada, somehow representing our sovereignty. Each time we pick up a 5 cent-coin, the so-called nickel, which except for special collectors’ editions is about 95% steel and only 2% nickel, we see an illustration of a beaver. But how much do we know about the natural history and ecology of our icon?

Like many humans, beavers are monogamous and mate for life. They also impact both the physical landscape and biological diversity in their habitat.  Their exact impact varies from one site to another, depending on the location, relief and habitat type—again parallel to the non-uniform ecological footprint of our societies.

During dry periods, as much as 30% of  water in certain watersheds could be held in beaver ponds. This can decrease erosion when water flow increases to higher levels. If a beaver dam however collapses, the opposite effect can occur. Flooding was  caused by such an occurrence in Alberta the 1990s and in British Columbia in the summer of 2000.

MT386
A beaver chewing on a cottonwood. This will lead eventually to the tree’s production of shoots rich in protective compounds.

The presence of beavers is important for shaping the littoral communities in certain lakes of the Canadian Shield increasing the population of fish, crayfish, diving beetles, large bugs, tadpoles, newts and leeches. This happens not just from the changing water levels but because dams concentrate nutrients.

They are also engaged in a fascinating coevolutionary relationship with the type of trees they use to build dams. Regrowth of cottonwood trees felled by beavers results in the synthesis of much higher levels of phenolic glycosides. These plant compounds then serve as a defence against other mammalian herbivores and beaver themselves, ensuring the long term survival of the cottonwoods. Another beaver-target, the quaking aspen, also uses a chemical defence against beavers. Younger trees, although easier to take down, are avoided by beavers because juvenile suckers contain higher concentrations of salicin, salicortin, tremulacin, and tremuloidin. Juvenile suckers are asexual shoots produced by trees that have been cut down but which still have living roots.

glycosides
Notice that each of the above compounds consists a simple sugar linked to a phenolic compound by replacement of a hydroxyl group in the sugar molecule—hence their name: phenolic glycosides, which protect trees against herbivores. The compounds’  concentrations was measured by HPLC-analysis after methanol extraction. (Structures from chemspider.com)

In the ecological web of mammals, it’s not surprising to see beavers play a more direct role than the consequences of their influence on plant biochemistry.  The world’s second largest rodent is an important food source for wolves and black bears. Abandoned beaver lodges can provide breeding shelters for bobcats and winter shelters for badges and red foxes.

Sources

Ecological impact of beavers Castor fiber and Castor canadensis
and their ability to modify ecosystems Mammal Rev. 2005, Volume 35, No. 3&4, 248–276

Optimal central-place foraging by beavers:
Tree-size selection in relation to defensive chemicals
of quaking aspen https://www.researchgate.net/publication/30848534_Optimal_central-place_foraging_by_beavers_Tree-size_selection_in_relation_to_defensive_chemicals_of_quaking_aspen

Beaver Behaviour and Biology
http://www.beaversolutions.com/beaver-facts-biology-behavior/

Catastrophic Failure of Beaver Dam At Chusnulida
The importance of beaver lodges in structuring
littoral communities in boreal headwater lakes http://www.nrcresearchpress.com/doi/pdf/10.1139/z97-121

Justice Laws Website http://lois-laws.justice.gc.ca/eng/acts/N-17/page-1.html

Enduring the 5-cent coin http://www.mint.ca

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