The dangers of chemistry

When was the worst era to be a chemist?

Our photographer was recently reading (rereading, in fact) one of his historical photography books, in particular the section recounting the introduction of the daguerreotype.  This was the first really useful method of photography, widely used about 1840-1860.  It involved preparing a very smooth surface of silver, then exposing it to fumes of bromine or iodine or both; placing it in the camera and taking the picture (a matter of minutes, sometimes many of them); and developing it with boiling mercury.

It would be hard to find a routinely-used process combining so many highly toxic chemicals.  Iodine and bromine fumes are poisons, not to be inhaled.  The former was used as an antiseptic because it killed living things, though in a solution rather than as fumes.  Both are related to chlorine, which would also have been useful to sensitize plates, but is a gas at room temperature and thus harder for nineteenth-century workers to handle.  (It was the first poison gas used in warfare, in WWI.)  The very idea of a room full of mercury fumes is enough to turn an OSHA inspector’s hair white.

The daguerreotype process was replaced by the silver halide version, on glass or paper support, and that basic system was the mainstay of photography up until the advent of digital cameras.  The replacement had nothing to do with health risks, but with the ease and convenience of the later system.  A book from 1883 in our possession entitled Photographic Chemistry details a multitude of agents useful in photography as then practiced; many of them are noted as poisons and more are now known to be toxic.

Well, silver halide photography is still practiced.  Indeed, our photographer does it, sometimes working with the chemicals himself.  (They do not include the worst offenders from 1883.)  And artisan-photographers use other, less benign, processes, indeed a few still make daguerreotypes.  But there has been a change in attitude.  The twentieth century saw a great increase in the awareness of chemical hazards.  A 1998 book Historic Photographic Processes has a whole chapter devoted to safety together with warnings interspersed with the recipes.  Now, even standard silver halide materials must by law be disposed of as hazardous waste.

So by the latter half of the last century it was significantly less dangerous to be a photographer or laboratory chemist than it was earlier.  How much earlier?  Well, while mercury was known to the ancients, bromine and iodine were only discovered in the second and third decades of the nineteenth century; the daguerreotype could not have appeared much earlier than it did.  That was indeed a time of almost explosive growth in chemical knowledge.  Many of the chemical hazards that menaced photographers (and contemporary chemists) didn’t exist before then.

So we can, cautiously, place peak poison about the turn of the twentieth century.  By that time a multitude of dangers had been created but there was no general awareness of the extent of the harm they could do.  Eventually ideas of safety caught up, though arguably they still lag behind the inventiveness of research chemists.

That doesn’t mean modern life is safe.  We haven’t even mentioned radioactivity or the inventiveness of biologists.