Persistent Organic Pollutants will remain in the air we breath, the soil we cultivate, the oceans we fish, the landscapes we walk, and frozen polar regions – documenting the diaspora of ‘forever chemicals’ and organic compounds, along with their predicted adverse impacts on future human and ecological health.
ABOUT 'POPs / PBTs'
Something that is presently considered out of sight, does not mean it will always remain out of mind. As once stated by the microbiologist René Dubos; “Men are naturally most impressed by diseases which have obvious manifestations, yet some of their worst enemies creep on them unobtrusively.”
The Normandy landings of Allied troops during the Second World War is often hailed as the largest mobilisation of a seaborne invasion force in world history, but this record frequently eclipses another profound milestone in human developmental history. Up to that particular point in time, the invasion force also served as the largest dynamic experiment for deploying a specific chemical agent to, essentially, deter ‘pest’ insect interactions with humanity. To this end, each of the vulnerable troops within the vast invasion force was armed with an invisible secret weapon; clothing impregnated with a defined ‘wonder chemical’ which intended to provide protection against biting insects, in order to mitigate exposure to the many insect-vector pathogens that were proliferate across Europe during the Second World War. Known commonly as Dichlorodiphenyltrichloroethane – or more simply as DDT – this colourless, tasteless, and almost odourless crystalline substance effectively neutralised the spread of these insect-carried diseases – poisoning swathes of host ‘pest’ species en-masse to cut off paths for pathogen transmission; an ecological warfare agent widely believed to have contributed to the temporary elimination of typhus, amongst other proliferate diseases across the continent.
The compound certainly lived up to its acclaimed ‘wondrous’ reputation. DDT was an easy to produce insecticide, capable of effectively opening up the sodium ion channels in an exposed insect's neurons, causing them to fire spontaneously, to the point where this overstimulation leads to spasms and eventual death of the infected organism. Eliminating the carrier creature of a disease, effectively restricts the transmission vector for that targeted pathogen. DDT was highly effective in this task and could be mass produced in a variety of forms for ease of dispersal, including fine powders, larger granules, aerosols, smoke candles, and charges for vaporizers, as well as lotions, for a diverse range of applicators. There are many entertaining wartime videos or infomercials that demonstrate the lack of technical expertise required to use fumigation equipment. Any operator could douse an entire person in an invisible chemical shield, or provide protection to family homes by simply lighting a DDT candle. Post-war, the commercial success of this compound translated into the growing agricultural sector, enabling crop producers to cultivate increasing yields of produce, raising profits in the process, while also minimising losses to crop-infesting insects as part of quantitative or arithmetical approaches to pest control. This agricultural expansion developed in tandem with the initial applications for this compound as an insecticide to control pathogen vectors – the sole purpose DDT still fulfils today, and to a very limited capacity. Over the period of the 1950–1980’s, on average over 40,000 tonnes of this compound were used annually across the world, with the insecticide being manufactured prodigiously by a dozen companies located in the U.S. One company, Montrose Chemical Corporation of California, was the largest producer on the continent, manufacturing ‘technical-grade’ DDT in bulk from 1947–1982, alongside other chemical compounds.
The culture of DDT use (alongside chlordane, dieldrin, aldrin, endrin, and other similar pesticides that “project a menacing shadow into the future”) experienced an abrupt reckoning in the court of public opinion from 1962 onwards, beginning with the publication of Rachael Carson’s Silent Spring, and reinforced by an increasing number of dissenting scientific voices that simply began to recognise the correlation between indiscriminate spraying campaigns and the mass loss of non-targeted species (birds, animals, and other deemed ‘useful’ insects). One of the inaugural books on environmental science, Carson – a trained marine biologist – documented the profound, adverse environmental impacts already observable from indiscriminate spreading of insecticides, while presenting the case for questioning the chemical industries’ misuse of scientific knowledge to justify the manufacture of synthetic compounds with far-reaching ecological consequences. Paul Hermann Müller – the discoverer of DDT’s insecticidal properties in 1938 – even allegedly highlighted the profound unknowns around how this substance could wholly interact within living biotic cycles. In effect, the unknowns of long-term consequences took centre stage from the known short-termism benefits for DDT use in this discourse. Carson also astutely highlighted the inevitable futility of these ill-conceived spraying campaigns – often leading to side effects like toxin resilience, a stronger resurgence of the ‘pests’ organisms once predators and ecological competitors had been poisoned in the ‘chemical crossfire’, or replacement of a targeted species by another far worse. As the entomologist Alison DeForest Pickett once remarked of chemical control measures; “We move from crisis to crisis, merely trading one problem for another”.
Debates ensued as to whether the wonder chemical could indeed be a toxin to both humans and the environment. Manufacturers mounted, sometimes aggressive, defences and staged several gimmicks to sway public opinion towards the unbridled benefits of DDT. Ecologists assessed the other side of this coin by continuing to evaluate the widespread environmental disruptions emerging from the indiscriminate spreading of the substance, without proper prudence, studies, monitoring, or oversight of their adverse effects on soil, water, wildlife or even human health. Eventually, a culmination of scientific conclusions and public outcry spurred a formal response from the U.S. public health sector, leading to a national pesticide policy that then led to a nationwide ban on DDT for agricultural uses in 1972, in addition to tighter regulation – and adequate testing of other, more toxic compounds – that could also have far reaching effects on environmental conservation. Other nations would soon follow in this phase out of DDT. In 2004, the Stockholm Convention on Persistent Organic Pollutants added DDT to Annex B of its POP listings as one of the inaugural “dirty dozen” entries; restricting the use of this pesticide to limited disease vector controls under the World Health Organisation’s guidelines – principally, as a measure to reduce mosquito swarms to control malaria.
Despite now being strictly controlled, the proliferate use of DDT up to the 1980’s still manifests across a number of durational legacies. The insecticide is highly persistent across a large swathe of environmental conditions; possessing a measured half-life of up to thirty years in soils and, perhaps, even up to 150 years in aquatic environments and deep ocean sediments. The compound can also travel across vast distances via global dissipation patterns, enabling warmer regions of the planet to naturally transport this material to colder regions, eventually leading to higher concentrations in the Polar Regions via ‘grasshopper effects’. POPs have been observed to volatise into the air, and become distributed by precipitation, before making a number of other indiscriminate atmospheric ‘leaps’ across geological territories, until they effectively become trapped by the low polar temperatures. However, today the substances are now being remobilised from these frozen sinks, due to increasing polar temperatures.
The toxicity of this particular substance is also not limited to targeted insect populations, instead causing knock-on biological disruptions to life cycles outside of the intended invertebrate taxa. For example, numerous studies on DDT since 1964 have documented the rising concentrations of this toxin in the tissues of Arctic penguins, in addition to being credited with further reproductive disruptions in afflicted seabird populations that prey on contaminated organisms. This insidious compound tends to bioaccumulate in the fatty tissues of exposed organisms due to its lipophilic properties. DDT is also largely resistant to the processes of metabolism, ensuring that the insecticide bioaccumulates up the food chain to reach higher concentrations in apex birds and mammals, while moderately poisoning each niche along the way. In humans, it is estimated that DDT, and one of its metabolites (DDE), are highly resistant to further metabolism, with a predicted half-life in the body of between six and ten years without further exposure to this substance. Medical studies have yet to conclusively determine whether DDT is indeed a human carcinogenic, though provisional conclusions have regardless classified the material as a ‘probable’ risk factor for several illnesses. Recognising the reality of DDT’s now global distribution, alongside other carelessly spread POPs, and their persistence within, and influences over biological systems, certainly affirms Carson’s ominous sentiment, initially voiced over sixty years ago; “For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death”.
In early April 2021, scientists from Los Angeles, operating on waning rumours, chartered a remotely operated underwater vehicle – an ROV conveniently located in the nearby area for unrelated studies, with a few free hours to spare. Exploring the seabed, shared by fishermen, wildlife, and the nearby urban populations, the ROV uncovered a massive graveyard of over 25,000 barrels, dumped onto the seafloor – the majority of this scattered material being discovered only 12 miles offshore from the city of Los Angeles. Subsequent remote observations and journalist investigations into shipping logs have revealed the bulk of this material to be barrels of acidic sludge, laced with locally manufactured ‘technical-grade’ DDT, and have further attributed this deposition to the Montrose Chemical Corporation, in addition to several other commercial entities who employed ‘deep ocean’ disposal barge companies. According to the math of eco-toxicologist Allan Chartrand (based on shipping logs), Montrose alone contributed about 767 tons of DDT to this vast ocean cemetery between 1947–1961. While samples were obtained from smaller known waste deposits, found during prior excursions in 2011 and 2013, a large portion of this synthetic material has already been dispersed across the aqueous environment – containers of toxic waste apparently sink faster if you intentionally puncture holes in them. The environmental implications for this extensive find are significant. The discovery also interrelate with a nearby Superfund site of Palos Verdes Shelf; an area knowingly contaminated with DDT, along with PCBs, and other improperly disposed toxic effluence, from years of discharging into the Los Angeles sewage system (by Montrose at their Normandie Avenue production plant, alongside other separate facilities). DDT is now very much embedded within the local food chain, impacting the reproduction and lifespans of native fauna and, by extension, the wellbeing of generations of indigenous human populations. But, it will likely continue to produce far-reaching disruptions beyond this ecosystem as it continually travels across regional ocean currents. Prospective cleanup concepts are presently being trialled at the Superfund site but, at present, there is no formal remediation work intended for this extensive graveyard, or financial provisions to even conduct further site surveys.
The concise story of the rise and fall of DDT outlined above, is very much a cautionary tale in the indiscriminate deposition behaviours of an unregulated chemical compound, without adequate monitoring, biological screening, or long-term investigation into counterbalancing the hazards posed to future human or environmental health. In the case of ocean dumping, dilution clearly is not an appropriate solution, as can be seen with the ‘sloppy’ disposal of DDT, alongside other underwater chemical agents, and similar radiological waste operations. The problems just accumulate elsewhere in the biome, across time. ‘Forever chemicals’, and their relatively unavoidable long-lasting legacies, are presently the subject of extensive multidisciplinary research and responsible legislative action by a number of international bodies, most notably the previously mentioned Stockholm Convention on Persistent Organic Pollutants and preceding Aarhus Protocol on Persistent Organic Pollutants. Dozens of candidate substances, and confirmed pollutants that will take generations to degrade, have been identified, with some necessitating strict international regulation or full bans, while others remain in production due to their perceived short-term benefits to various sectors of modern human societies.
The majority of these identified POP substances fall under the traditional ‘-icide’ categories; chemical agents employed to control defined ‘pest’ populations, including insects (insecticide), flora (herbicide), and mycelia (fungicide) amongst other targets, with some recognised substances only serving industrial applications, or remaining as undesirable by-products of various commercial chemical manufacturing processes. Modern examples of the prevailing adverse implications from these emergent contaminants are widely seen today. Most prominently, due to the widespread human health impacts, are the ariel-delivered defoliants (in what could be defined as ‘trauma-POPs’, the warfare ‘rainbow herbicides’ – most prominently the widespread use of Agent Orange – which continues to cause enormous damage and dioxin-related illness), and PFOA-surfaced products (as highlighted by the extended litigation against the company DuPont – a result of Rob Bilott’s renowned investigations on behalf of the Parkersburg community 'downstreamers'), in addition to disturbing revelations of related compounds (PFAS) found across a diverse range of cosmetic products, manufactured by mainstream beauty brands. Our relatively short history of pathologically spraying biocides enables us to retrospectively review the diverse range of environmental impacts arising from their proliferate application; ranging from the immediate traumas wreaked upon wildlife populations, as was the case in the Detroit and Sheldon communities during spraying campaigns in the late 1950s, to the longer-term, unseen implications we are now experiencing today. It is worth highlighting that these ill-advised spraying campaigns did not eradicate the intended target species, but operations eliminate much of their ecological competitors. However, understanding the scope of industrial and accidental POPs, alongside related PBTs, is still a nascent arena of multidisciplinary research. Despite this, the emergent recognition of ‘forever chemicals’ has begun to draw into stark relief the significant responsibility now faced by manufacturers to prove the safety, not just the effectiveness, of their compounds, and the need for long-term monitoring and testing for impacts.
As a part of the foundation’s After the Horizon initiative, we are working with leading industry experts, ethics committees, recognised compliance inspectorates, and chemical-safety technicians, to cultivate a broad catalogue of Persistent Organic Pollutants, and other hazardous long-lived PBT compounds, which have either already been identified as possessing long-term implications for human health and environmental sustainability, or are subject to review and extensive hazardous risk scrutiny under these same POPs and PBTs characteristics. The foundation itself is not involved within establishing the evidentiary studies and risk assessments for hazardous substances. Rather, our focus is to independently consult with these expert parties, and preserve the scientific evidence for prospective detrimental effects of recognised compounds, while effectively archiving this information to ensure that these adverse material legacies cannot be forgotten – for the benefit of those who will almost certainly inherit these far reaching, largely imperceptible hazards, spread across their world. We simply do not wish for these unpalatable toxic legacies to have to be ‘rediscovered’ after decades or centuries of obscurity and silent pollution, as with the emergent case of DDT barrels resurfacing from their shallow cemetery beneath the Pacific waves. Rather, we hope to preserve these records for human posterity and, ideally, establish a semiotic basis for communicating their broad bio-ecological impacts in disrupted communication devices (such as the foundation’s Companion Guide to Earth), as well as through living memory-retention schemes as a collective human document. Posterity should at least know about the persistent chemical legacies they inherit, if they are to readdress or plan around these potential health problems in their lifetimes. In addition and as a secondary goal, this index also aspires to document contemporary remediation efforts, while developing ambitious outreach and engagement platforms to ensure these emergent, ‘forever chemical’ legacies, remain forever known – and understood – in the here and now, for the benefit of informing posterity who cannot ‘have a say’ over our intergenerational pollution issues.
Notes to the catalogue: Given both the longevity and mobility of persistent organic pollutants in the environment, this POPs Index intends to document the identifiable properties, chemical structure, known resistance to ecological degradation, bio-accumulative significance, biological persistence, toxicity, and other POP characteristics for each of the listed substances. In some instances, this information will dovetail with the foundation’s ‘Bio-Chemical Waste’ catalogue; to map known geophysical regions with elevated POP contamination from documented anthropogenic sources. No independent judgements or investigations on defining a permissible or acceptable dosage (through cumulative exposure over time, or otherwise), or similar medical measures for POPs on human community, animal, or environmental health, have been applied to these listed substances. Similarly, the catalogue also doesn’t contribute to seismic signature studies around ‘tentatively identified compounds’ or ‘Ticks’. However, unless a substance is proven to be positively safe through protracted epidemiological studies, precautions and exposure mitigation strategies should always remain in place to avoid exposures to substances that, in large or small amounts, continue to bioaccumulate in an organism's tissues, but references have been made to several scientific studies where possible. Furthermore, direct risks to human health should not be the defining factor to consider, if hazards are evident for non-targeted life caught in the crossfire – feedback vectors which can cause indirect harm. The entire catalogue remains open to peer-review and subsequent updates as, to paraphrase the late Alsatian polymath Albert Schweitzer, ‘man begins to recognise the devils of his own creation’.
Page last updated: 14 Jan 2021