From mustard gas to Pisa: a short history of environmental mutagenesis

Most fields of science can point to a founding paper. Environmental mutagenesis can point to a founding weapon, one that was tested on fruit flies in a basement in Edinburgh during an air raid blackout, and whose results could not be published for years because the substance itself was classified.

This is a short history of how that started, and of why Pisa, of all places, became one of the field's European centres.

Before the weapon, a word

The word itself predates the chemistry by decades. In 1903 the botanist Hugo de Vries used "mutation" to describe the different forms he kept observing in the evening primrose, Oenothera lamarckiana, mostly as a concept for evolutionary biology rather than anything a person could induce on purpose. It took another twenty-five years for anyone to show that mutations could be deliberately caused rather than simply observed: Hermann Muller did it with X-rays in 1928, and Lewis Stadler and George Sprague showed the same for ultraviolet light in maize in 1936. Both were physical agents. What was still missing, in 1936, was proof that a chemical could do the same thing to a living genome, deliberately and reproducibly.

A weapon, studied twice

Mustard gas was first used as a chemical weapon in 1917, near Ypres in Belgium, which is where the Italian name for it, iprite, comes from. During the First World War it caused roughly 5,000 deaths in Italy's own theatre of the war, and pharmacologists of the period noticed something odd: the burns it produced on skin closely resembled the burns caused by X-rays, which by then were already known to damage cells in ways that could be passed on.

That resemblance sat unexplored for over twenty years. It was picked up again during the Second World War, when Charlotte Auerbach, a German-Jewish geneticist who had fled Nazi Germany for Edinburgh in 1933, was asked by the UK War Office to study the biological effects of mustard gas, working alongside the pharmacologist J. M. Robson. Clear results came almost immediately once testing began in 1941, and by March 1942 the pair could show without doubt that mustard gas caused mutations in fruit flies^cite. The work could not be published until 1946, because mustard gas was a wartime secret, and the confirmation that a chemical agent could directly cause heritable damage only reached the wider scientific world a full five years after it had actually been established.

Auerbach later became the first director of the Medical Research Council's own Unit of Mutagenesis Research, and is still generally credited as the founder of the field. It is a strange origin story for a science: the discovery and its publication were separated by exactly the kind of secrecy the field would spend the following decades trying to work around.

There is a twist to that secrecy worth pausing on. Barred from publishing anything about mustard gas during the war, the first chemical mutagen Auerbach actually got into print, in 1944, was not a weapon at all: allyl isothiocyanate, the pungent compound in mustard oil, found naturally in cabbage, broccoli and other cruciferous vegetables^cite. The substance that opened the field of chemical mutagenesis in the scientific literature was something people had been eating for centuries, long before anyone knew to call it a mutagen at all.

The harbour that would not stay quiet

Italy has its own, largely forgotten, chapter in this story. On 2 December 1943, German aircraft bombed the harbour of Bari, sinking dozens of Allied ships. One of them, the SS John Harvey, was secretly carrying 2,000 mustard gas bombs, and its destruction released liquid and gaseous mustard across the harbour and the city^cite. Hundreds of people, military and civilian, were poisoned; the true cause of their injuries was kept hidden for years, partly for wartime security and partly, by some accounts, on Churchill's own insistence that the deaths be recorded only as burns from enemy action.

The Bari disaster turned out to matter for medicine as much as for military history. A chemical warfare physician investigating the case noted that mustard gas exposure sharply depleted white blood cells, an observation that fed directly into the earliest work on nitrogen mustard as a cancer treatment, the starting point of modern chemotherapy. The same family of compounds that gave the field its founding mutagen also gave medicine one of its first chemotherapeutic agents.

Some of those bombs were never recovered. Loprieno's own account notes that hundreds of tonnes of iprite still sit on the floor of the Adriatic today, in canisters the Allied command had sunk there after the war specifically to keep their wartime use out of public view, and that fragments still occasionally surface in fishermen's nets off the Italian coast.

Building a field out of a secret

Once mustard gas's effects could finally be discussed openly, other chemical mutagens followed quickly: F. Oehlkers's work with plants, M. Vogt's experiments with ethyl urethane, E. Hadorn and H. Niggli's work with phenol, J. A. Rapoport's with formaldehyde, all through the 1940s and 1950s, mostly still on Drosophila. In Italy, the first researcher to take up chemical mutagenesis was Francesco D'Amato, who in 1949 published a study on chromosome aberrations induced in the mitotic cells of Allium, using a technique he had learned during a stay in Sweden.

By the mid-1960s the field had enough of a community to support its own infrastructure. Frits Sobels launched the journal Mutation Research in 1964^cite, with an editorial board that already included four Italians: D'Amato, L. L. Cavalli-Sforza, M. Fraccaro and G. E. Magni. Concern that chemical germ-cell mutagens might be widespread in the environment led an ad hoc committee, meeting in New York in January 1969, to agree on founding a new society^cite. They settled on Environmental Mutagen Society partly because its initials, EMS, already stood for one of the best-known mutagens of the day, ethyl methanesulfonate. Alexander Hollaender became its first president, with Joshua Lederberg, the Nobel laureate, among the other founders; the society formally launched that April in Washington, with around ten European researchers in attendance, and the following July that European contingent, led by Sobels, founded its own sister society in Munich: the European Environmental Mutagen Society, EEMS. It is the same society that, under its current name, the European Environmental Mutagenesis and Genomics Society, is holding its annual meeting in Pisa.

Italy's own institutional base was already forming by then. In 1969, the National Research Council (CNR) established the Laboratorio di Mutagenesi e Differenziamento at the Istituto di Genetica of the University of Pisa, building on D'Amato's earlier work and then led by Nicola Loprieno. Within little more than a decade the lab had become Italy's reference point for the field: a 1981 catalogue from the university's genetics faculty listed 125 Italian papers published in international journals on chemical and environmental mutagenesis. Pisa hosted the EEMS annual meeting itself in 1975, and from 1980 to 1982 Loprieno served as the society's president, a role Angelo Carere, from Italy's national health institute, would later hold again between 2001 and 2003.

From the lab bench to the law

What moved environmental mutagenesis from an academic specialism to something regulators cared about was a run of policy decisions across the 1970s and 1980s, and the young society was not a passive observer of them. EMGS members gave expert testimony at Senator Abraham Ribicoff's 1971 Senate hearing on "Chemicals and the Future of Man", and Hollaender himself was asked to chair a committee evaluating the legislation before it passed^cite; the resulting Toxic Substances Control Act, passed in 1976, became a model other countries would later adapt. A 1975 position paper in Science, written by an EMGS committee, argued that potential mutagens needed to be identified before they reached the environment, not after, and the bacterial test Bruce Ames first described in a 1971 book chapter became one of the standard tools for doing exactly that. The 1969 MRAK report in the United States had already recommended that pesticides be tested for mutagenic potential before approval. In Europe, the sixth amendment to Directive 67/548/EEC, adopted in 1979 and brought into Italian law in 1981, made mutagenicity testing a formal requirement for any new chemical substance placed on the market, typically the Ames test paired with a chromosome aberration assay.

Validating which tests actually predicted real-world risk took most of two decades of international collaboration: a joint US-Japan programme running from 1972 to 1976 found a strong correlation between a chemical's mutagenic activity in vitro and its carcinogenic activity in animals; an international study concluding in 1979 cross-checked 57 independent tests against 52 known chemicals, with Italian laboratories in Pisa and Naples among the participants; a second and third round of validation, coordinated through the World Health Organization's International Programme on Chemical Safety, ran until 1988. By the early 1980s, roughly a hundred mutagenicity tests existed that were fast, cheap and reproducible enough for routine regulatory use, built on exactly the kind of groundwork Auerbach's wartime experiments had started almost forty years earlier.

Italy formalised its own place in this community in October 1991, with the founding of the Società Italiana di Mutagenesi Ambientale, with Loprieno as its first president. The society has been the Italian section of EEMGS since that first day, and later renamed itself SIMAG to put "genomica" alongside "mutagenesi ambientale" in its own name, a small act of definition that most of the field's national societies ended up making for the same reason^cite: the questions genomics and epigenetics could suddenly ask about a mutagen's effects had outgrown what the word "mutagenesi" alone used to cover.

A line that runs through Pisa

None of this was linear or especially fast. It took five years to publish a wartime discovery, another twenty-five for the chemistry of mutagenesis to mature into a recognised discipline, and most of another decade after that for regulators to actually require the tests the field had developed. What is striking, looking back, is how small and international the early community stayed throughout: a handful of labs in Edinburgh, Leiden, Oak Ridge, Munich and Pisa, corresponding, meeting annually, and slowly building the infrastructure that genetic toxicology now takes for granted.

It is the same thread, really, that brings EEMGS back to Pisa.

Sources: this account draws primarily on "Introduzione alla prima edizione", by Nicola Loprieno, in the textbook on environmental mutagenesis written by the Genetics group at the University of Pisa, cross-checked against the University of Edinburgh's biographical archive on Charlotte Auerbach, Wikipedia's entry on the SS John Harvey, the European Environmental Mutagenesis and Genomics Society's own history page, David DeMarini's 2020 history of the EMGS published in Environmental and Molecular Mutagenesis for the society's 50th anniversary, the EMGS's own history page, SIMAG's own website, and a short history of the field written for FISV by Ettore Meccia (SIMAG, Istituto Superiore di Sanità).