Tag Archives: industry

Aniline Yellow (1861)

yellow powder

Unlike purple and pink pigments, which were rare and expensive enough to be reserved for royalty and high-ranking clergy, yellow pigments were abundant throughout ancient history. Yellow ochre, a powdery mixture of iron oxides, has been used in cave paintings around the world for up to 80,000 years and was still being used by artists in the early nineteenth century. Saffron and turmeric were also used as yellow dyes throughout ancient history. Vincent van Gogh was using mineral yellow pigments such as cadmium yellow and chrome yellow in his mid-nineteenth century paintings. By the mid-nineteenth century, people looking for yellow pigments already had plenty of options. Despite there being no pressure from consumers for a new yellow dye, chemists trying to replicate the fame and fortune that mauveine brought to William Perkin in 1856 were experimenting eagerly in pursuit of that goal.

In 1861, Mêne was reacting aniline with cold nitrous acid to produce a diazonium salt solution. He then added more aniline to the resulting salt solution and shook the flask vigorously and noticed a yellow precipitate formed at the bottom of the flask, which would later become known as ‘aniline yellow’ – the first ‘azo dye’. [1]

The reaction mixture must be kept cool (at around 5 °C) because different temperatures cause different products to form. If the same reactants are mixed warm, then smelly liquid phenol and inert nitrogen gas are formed, both of which are colourless, and neither of which are useful as pigments!

At the time, the ‘aniline yellow’ powder he discovered was considered useless because it didn’t dissolve in water. However, it did dissolve very well in oil. The dye eventually gained some niche uses as a microscopy stain (like fuchsine) but was never utilised by the garment or pigment industry.

After staying relatively unused for over a hundred years, aniline yellow left an unfortunate legacy for itself by becoming the culprit molecule in the Spanish ‘Toxic Oil scandal’ of 1981. A batch of Spanish rapeseed oil had been denatured (deliberately adulterated) with 2% aniline yellow so the company could report it as “machine oil” and take advantage of certain tax breaks. One local refinery obtained the denatured rapeseed oil and attempted to remove the aniline yellow dye so they could sell it on as “pure olive oil” on the market for profit. They sold the oil around much of north-western Spain in unlabelled 5-litre plastic containers.

yellow powder OO PAP map

The first casualty was an eight-year-old boy who died upon arrival at a hospital in Madrid on May 1st, 1981. The rest of his family then presented with an unusual set of symptoms: headache, fever, itchy scalp, lethargy and interstitial lung disease. The hospital diagnosed the family with “atypical pneumonia” and treated them all with antibiotics but they showed little improvement. [2]

Across Spain, 20,000 patients presented with similar symptoms within one month of the incident. Thinking that an unexplained pneumonia outbreak was unfolding, a children’s hospital in Madrid conducted a randomised, double-blind controlled clinical trial on the effectiveness of the antibiotic erythromycin, which is particularly effective on infections of the respiratory system. [3] Unfortunately, they found no difference in recovery or mortality rates between the treated group and the control group and decided to keep looking for potential treatments.

Attempting all avenues, the researchers conducted lifestyle surveys on many patients, which included (among many other things) questions about cooking oil. Sadly, even though the source of the problem was staring them in the face, the results of the oil usage survey questions came back “inconclusive”. [4]

A baby ultimately solved the puzzle. Prognosis for young children was generally worse than for adults after they contracted the strange set of symptoms. Oddly, babies under six months were unaffected even if the entire rest of the family had presented with the pneumonia-like symptoms. Their infants were completely symptom-free. When one baby did get sick, however, this prompted deep and urgent questioning of the parents involved to find out what they did differently from others. One unusual aspect of the baby’s upbringing was that the baby’s grandmother had been ‘supplementing’ baby’s formula powder with cooking oil that was sold in an unlabelled 5-litre plastic container. [5]

Spanish government agencies acted quickly. The Ministry of Health and Consumer Affairs issued a recall of all oil sold in unlabelled plastic bottles within 40 days of the first casualty reporting with symptoms (the 8-year-old boy). Rates of patients presenting with symptoms of Toxic Oil Syndrome, as it would later be called, plummeted after the recall was announced on June 10th, 1981.

OO PAP epidemic graph

The aniline yellow had all been removed. The problem was a side-reaction, completely unknown to the scientists who were purifying the “machine oil”, that formed a new, harmful molecule that was large enough to escape their detection methods.

OO PAP molecule Aniline Yellow plus oil
The culprit: OO PAP molecules

The molecule responsible for Toxic Oil Syndrome is called “OO PAP” in scientific literature. Visual inspection of OO PAP’s structure reveals that it’s quite simply an olive oil triglyceride molecule (triolein) with one of its three fatty acid tails replaced with a large aniline group. [6] When the rapeseed oil was adulterated with 2% aniline yellow to disguise it as “machine oil”, some of the aniline yellow molecules didn’t just blend in with the oil but reacted chemically with it to make OO PAP molecules. ITH, the company who sold the de-adulterated product as “pure olive oil”, was likely unaware of this chemical reaction, and therefore (we assume) also unaware of the poisonous OO PAP that had formed in the oil. While ITH successfully removed the aniline yellow, they failed to remove the OO PAP molecules, which escaped their filtration techniques. [3] Sadly, hundreds of people died and 20,000 more were made ill from OO PAP poisoning, and financial damage was estimated by El País newspaper to be 2 billion pesetas (around 16 million US dollars today). [7] Just like the scandal of the pink fuchsine socks, government and industry were forced to work together to respond quickly to a growing public crisis.

Every chemical – regardless of whether it’s found naturally or created synthetically – has the potential to be beneficial, harmful or harmless depending on the dosage and the way that it’s used. Aniline yellow, like all other chemicals, is incredibly useful when used correctly. It’s a fantastic microscopy stain but totally unsuitable for culinary use.

Today, people use aniline yellow to dye specimens for viewing under a light microscope. Aniline yellow’s dangers are stated clearly on its safety data sheets: handling it today requires training, permits, safety glasses, gloves and a lab coat to avoid all contact with skin and eyes. Now that chemistry has given us a better understanding of the aniline yellow, nobody dare use it to dye foodstuffs. [8]


[1] http://www.chemguide.co.uk/organicprops/aniline/makediazo.html

[2] Paz, Manuel Posada de la. 2001. “Toxic Oil Syndrome: The Perspective after 20 Years.” Epidemiologic Reviews 231-247.

[3] Gelpí, Emilio. 2002. “The Spanish Toxic Oil Syndrome 20 Years after Its Onset: A Multidisciplinary Review of Scientific Knowledge.” Environmental Health Perspectives 457-464.

[4] Flores, Juan Casado. 1982. “Sindrome Toxico en Niños por Consumo de Aceites Vegetales: Modelo Clinico de la Enfermedad, en la Fase Aguda.” Pediatrika 22-26.

[5] Flores, Juan Casado. 1982. “Síndrome toxico por consumo de aceite adulterado. Una encuesta alimentaria esclarecedora.” Pediatrika 17-20.

[6] Paz, Posada de la. 1999. “Epidemiologic evidence for a new class of compounds associated with toxic oil syndrome.” Epidemiology 130-134.

[7] El País. 1981. “2.000 millones de pesetas costará al Insalud la asistencia a los enfermos a causa del aceite.” El País 15.

[8] Southern Biological. 2009. “Material Safety Data Sheet: Fuchsine.” Southern Biological. 08. Accessed 12 19, 2016. http://file.southernbiological.com/Assets/Products/Chemicals/Stains_and_Indicators-Powders/SIP4_6-Basic_Fuchsin/SIP4_6_MSDS_2009_Basic_Fuchsin.pdf.

Combatting Chemophobia With Wine

Ava Winery composes fine vintage wines molecule by molecule in the lab
Ava Winery composes fine vintage wines molecule by molecule in the lab

The wines your great-grandchildren might one day drink on Mars will soon be coming to a bottle near you. Ava Winery is a San Francisco-based startup creating wines molecule by molecule, without the need for grapes or fermentation. With complete control over the chemical profile of the product, Ava’s wines can be created safely, sustainably, and affordably, joining the food technology revolution in creating the foods of the future.

Ava Wines’ business model is somewhat akin to the Star Trek replicator!

For Ava, foods in the future will be scanned and printed as easily as photographs today. These digital recreations will be more than mere projections; they will be true chemical copies of the originals, capturing the same nutritional profiles, flavors, and textures of their “natural” counterparts. Our canvas will be macronutrients like starches and proteins; our pixels will be flavor molecules. Future generations won’t distinguish “natural” from “synthetic” because both will simply be considered food.

Consider ethyl hexanoate, although scary-sounding it is the very chemical that gives pineapples their characteristic smell and also fruity wines a tropical note. From pineapples, or indeed other organisms, ethyl hexanoate can be extracted much more efficiently. By sourcing more efficient producers of each of hundreds of different components, wines can be recreated as their originals.

Future generations won’t distinguish “natural” from “synthetic” because both will simply be considered food.

In fact, by eliminating the variability of natural systems as well as potential environmental contamination, this digitized future of food can increase the safety, consistency, and nutritional profile of foods. Such food products can reduce overall land and resource use and be less susceptible to climate fluctuations. Indeed this future will see significant reductions in the costs of food production as the cost of the raw ingredients shifts to more efficient sources of each molecule.

Processed with VSCO with s3 preset
100 to 300 compounds are responsible for the full flavour of a wine.

So why wine?

We knew there would be a controversial love/hate relationship with our mission to build wine molecule by molecule. To the elite who value the high-end wine experience, our molecularly identical creation of the $10,000+ bottle of 1973 Chateau Montelena will be a mockery; but to the public, the $10,000 turned $20 bottle will be a sensation. To the purists who still believe organic is the only way to eat or drink healthily, our wine will get “some knickers in knots”; but to the nonconformists, our wine will be a contemporary luxury made by contemporary technology.

In short, wine is just the beginning. Soon, Ava hopes to build more food products molecule by molecule further blurring these lines between natural vs. synthetic while simultaneously making luxury items available for all. With our groundwork, the Star Trek future of food might be closer than we thought.

On the Origins of Chemophobia – Part 1

“The Blue Marble” is a famous photograph of the Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft en route to the Moon.

The rise of the environmental movement is most often attributed to the publication of Rachel Carson’s Silent Spring in 1962, which demonised chemicals as it introduced them to the public:

“Chemicals are the sinister and little-recognised partners of radiation entering into living organisms, passing from one to another in a chain of poisoning and death” – Rachel Carson’s Silent Spring, 1962

Later that decade, the Apollo missions and the six moon landings between 1969 and 1972 gave us a new perspective of planet Earth that was so profound that we felt a sudden compulsion to protect its natural beauty. Watch Neil deGrasse Tyson argue this point below.

In 1970, we are still going to the moon, we are still going until 1972, so watch these sequence of events. In 1970, the comprehensive Clean Air Act is passed… Earth Day was birthed in March 1970. The EPA was founded in 1970… Doctors Without Borders was founded in 1971… DDT gets banned in 1972, and we are still going to the moon. We’re still looking back at Earth. The clean water act 1971, 1972 the endangered species act, the catalytic converted gets put in in 1973, and unleaded gas gets introduced in 1973… That is space operating on our culture and you cannot even put a price on that. – Neil deGrasse Tyson in April 2012

Together, Rachel Carson and the Apollo missions made the public in Western countries quickly aware of the Earth and its natural beauty. Humans were portrayed as selfish destructors of a planet that was supposedly most ‘beautiful’ when in its ‘natural’ state. The field of toxicology was spawned in wake of this concern, and had the goal of analysing the toxicity of different chemicals on humans and the environment. As the first edition of Human and Experimental Toxicology stated:

“Politicians cannot be expected to come to rational and acceptable decisions without adequate impartial and objective information, and toxicologists have grave responsibilities to produce such information”. – Human and Experimental Toxicology

While the field of toxicology accumulated a wealth of scientific evidence about ‘chemicals’, this evidence largely hasn’t trickled down to the public and certainly hasn’t allayed their fears. There remains a lingering skepticism about chemicals, especially artificial chemicals, which some people still feel are more harmful than those found in nature.

Take the Think Dirty iOS app, for example, which gives cosmetic ingredients a safety rating out of 9. According to the app’s creators, “Fragrance” gets the worst possible rating (9), while “Natural Fragrance” gets the best rating (1). Black-and-white ‘natural’ vs ‘artificial’ decision-making such as this is completely unfounded and ignores toxicological evidence. This kind of thinking is misleading, has no scientific basis and sometimes causes consumers to make harmful conclusions – no matter how benign their intentions. (More on this in future posts.)

This simplistic thinking is a remnant of the environmental movement back in the 1970s: that ‘selfish’ humans were destroying a ‘pristine’ planet Earth. While the ‘natural/good’ vs ‘artificial/bad’ dichotomy was an effective solution to short-term environmental problems of the time, this black-and-white thinking is actually leading people to make bad decisions today. We can no longer assume that “natural” is always “best”: the issue is actually far more complex than that. Toxicological evidence needs to be made public and easy to digest so that consumers can make more enlightened decisions.

This post is part 1 of a weekly series on Chemophobia. More next week.

Neil deGrasse Tyson – Space as Culture transcript