Pliny the Elder's Contribution to Toxicology & Occupational Health & Safety

Introduction

Pliny the Elder, a Roman naturalist, philosopher, and author, was one of the earliest figures to study the natural world and document his findings. Pliny is known for observing the toxic properties of lead oxide, sulfur dioxide, mercury sulfide, and for describing a rudimentary protective mask. In this article, we will explore Pliny’s observations of these toxic substances and his description of a bladder-mask designed to protect against harmful dusts and metal fumes.

The Toxic Properties of Sulfur Dioxide

In the first century AD, Pliny the Elder documented the properties of various minerals and metals in his seminal work, “Naturalis Historia” (Natural History). Among the substances he studied, Pliny recognized the toxic properties of sulfur dioxide.

Sulfur, a naturally occurring element, was well known for its pungent smell and was commonly used in ancient times for various purposes, including medicine and the production of gunpowder. However, when burned, sulfur produces sulfur dioxide, a toxic gas that can cause respiratory issues and irritation of the eyes, nose, and throat..

Pliny wrote the following about a medicinal substance”plumbum ustum” (burnt lead) that was created by mixing/smelting lead and sulphur:

“In medicine lead is used by itself to remove scars, and leaden plates are applied to the region of the loins and kidneys for their comparative chilly nature to check the attacks of venereal passions, and the libidinous dreams that cause spontaneous emissions to the extent of constituting a kind of disease. It is recorded that the pleader Calvus used these plates to control himself and to preserve his bodily strength for laborious study. Nero, whom heaven was pleased to make emperor, used to have a plate of lead on his chest when singing songs fortissimo, thus showing a method for preserving the voice. For medical purposes lead is melted in earthen vessels, a layer of finely powdered sulphur being put underneath it; on this thin plates are laid and covered with sulphur and stirred up with an iron spit. While it is being melted, the breathing passages should be protected during the operation, otherwise the noxious and deadly vapour of the lead furnace is inhaled: it is hurtful to dogs with special rapidity, but the vapour of all metals is so to flies and gnats, owing to which those annoyances are not found in mines.”

In this passage, Pliny explains the process of mixing and refining lead and sulphur for medical purposes. The passage emphasizes the need to protect the breathing passages during this operation, as the noxious and deadly vapors produced by the lead furnace can be inhaled, causing harm to humans and animals.

Note: the vapor Pliny is describing is a combination of sulfur dioxide and lead oxide, and it is difficult for the author of this article to judge the amounts and proportions involved in this mixture. It appears the vapor is being described as “noxious” so I am assuming there is a fairly significant contribution of sulfur.

Pliny’s Description of a Protective Bladder-Skin Mask and the Toxic Properties of Mercury Sulfide

In “Natural History,” Pliny described a rudimentary mask made from the bladder of an animal, which workers of the era used in the belief that it would provide a barrier against harmful particles and fumes. The mask was designed to cover the nose and mouth, with the animal bladder serving as a filter to trap dust and fumes before they could be inhaled. The bladder skin was used to to filter dust from being inhaled while workers crushed mercury sulfide (HgS, known at the time as cinnabar).

While this early mask may seem primitive by today’s standards, it is likely one of the first written recordings of personal protective equipment (PPE), and Pliny’s description of this mask represents one of the first recorded attempts to protect individuals from occupational hazards.

Pliny’s description of this mask in “Natural History” is as follows:

“Persons polishing cinnabar in workshops tie on their face loose masks of bladder-skin, to prevent their inhaling the dust in breathing, which is very pernicious, and nevertheless to allow them to see over the bladders. Cinnabar is also used in writing books, and it makes a brighter lettering for inscriptions on a wall or on marble even in tombs.”

Note: to further confuse the reader (and myself), the Romans sometimes described both red lead (lead tetroxide) and mercury sulfide as minium. However, we now use the term minium to describe only red lead (lead tetroxide). I noticed several researchers/scholars suggesting that Pliny was suggesting that the workers were trying to protect themselves from red lead, but based on the context of this section of Pliny’s text, I am fairly confident Pliny is referring specifically to mercury sulfide. When Pliny was describing red lead in the preceding lines of this text, he was briefly describing how red lead (lead tetroxide) was an inferior version of minium and how mercury sulfide was sometimes adulterated with red lead (lead tetroxide), but then he sort of abruptly transitions to this discussion about how workers prepared mercury sulfide while wearing bladder-skin masks. That’s my interpretation, anyway.

A Comment about Some Sources Suggesting Pliny “Invented” the Bladder-Skin Mask

There appear to be many reputable and well-known blog articles and textbooks on the topic of Occupational Health and Safety that state that Pliny the Elder “invented” the mask he described in “Natural History.” Still, I have found no evidence of this in any of Pliny’s works that I have examined. I believe this may be nothing more than a common misconception that has simply been repeated without any thought or examination. It also doesn’t make any logical sense that Pliny would have invented this mask because, while Pliny the Elder was a prolific writer, historian, and naturalist, he is not widely known for inventing anything.

A Comment about Some Sources Suggesting Pliny Described Zinc’s Toxic Effects

There is a well-known textbook on the topic of Occupational Safety and Health that suggests Pliny described zinc’s toxic effects. I can find no such reference in Pliny’s work, “Natural History.” Pliny makes frequent reference to cadmea which was the ancient name for calamine or zinc carbonate, and Pliny discusses brass (which is made from copper and zinc), and the ores the Romans worked with would contain some amount of zinc, but I could find no mention of Pliny describing the toxicity of what could now be understood to be zinc.

Legacy of Pliny the Elder

Pliny the Elder’s observations of the toxic properties of sulfur dioxide and mercury sulfide, as well as his description of a protective mask, demonstrate his commitment to understanding the natural world and its impact on human health. His work in these areas can be argued to be an example of very early, tenuous steps in the direction of toxicology, environmental health, and occupational health and safety.

Pliny’s observations influenced our understanding of the dangers associated with exposure to toxic substances, and his description of a protective mask may have been the first recorded instance of personal protective equipment within the context of occupational safety. As we continue to learn more about the hazards of our environment and develop new methods for protecting ourselves from harm, we can look back on the contributions of Pliny the Elder as a testament to the enduring importance of thoughtful study and an inquiring mind.

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