Synthetic pesticides have been a controversial tool in large-scale agriculture. An example of these pesticides is Paris green (copper acetoarsenite or copper arsenite), a sandy, emerald-green chemical compound. It has no odor or taste, but if ingested or inhaled, it releases arsenic, a powerful poison.
The use of Paris green in Puerto Rico and other countries in the first half of the 20th century is a clear example of the tension between pest-free agricultural productivity and the effects of agrochemicals on health and the environment.
Before its toxicity was known, Paris green was used as a pigment in toys, candles, fabrics, book covers, boxes, cards, and wallpaper. Eventually, poisoning cases accelerated, creating a public health problem.
The first commercial advertisements for this compound appeared in August 1919 in the newspaper El Mundo. The pesticide combated mole crickets (Scapteriscus vicinus), beetle larvae, crickets, and other insects affecting sugarcane and tobacco.
Paris green was also aerosolized with special machines to control Anopheles mosquitoes, vectors of the parasite that causes malaria. The pesticide cloud was sprayed into ponds, swamps, and other stagnant bodies of water.
The health effects on farmers didn't take long to appear. Paris green was applied without any special clothing, gloves, or masks, exposing people to skin contact and inhalation. Rain washed the pesticide into streams, rivers, underground aquifers, and other sources of drinking water. The desperation and poverty of those times made Paris green the protagonist of thousands of accidental poisonings and suicides between 1920 and 1950.
The environment was also affected. By eating dead insects, birds were poisoned. Newspaper reports from the time lamented how silent the forests were due to the low abundance of birds like the Grey Kingbird.
Unfortunately, the environmental and health effects of agrochemicals did not end when Paris green fell into disuse. Cases such as those of the insecticides dichlorodiphenyltrichloroethane (DDT) and endosulfan, and the herbicides glyphosate (Roundup) and paraquat dichloride, are a sober reminder of how distant ethical and sustainable agricultural practices for all still appear to be.
The research on the use and abuse of Paris green in sugarcane and tobacco agriculture in Puerto Rico is part of an innovative project that integrates humanities and digital technologies to rescue forgotten or intentionally erased stories to provide the public with an accessible, relevant, and interactive learning experience.
The collection “Caguas: Historia y Cultura” is an audiovisual educational resource that compiles and makes available documents, photos, and maps of Caguas from local and U.S. archives and libraries. This initiative within the digital humanities also explores the founding of the town of Caguas, the enslavement of indigenous people, land appropriation, and the oral histories of the oldest residents of the urban center.
“Caguas: History and Culture” was led by Caguas-born doctors Rosa Elena Carrasquillo, from Holy Cross University in Massachusetts, and José O. Solá, Associate Professor of History, in collaboration with this author. The portal is available at this link.
“This resource brings to light forgotten or erased stories of Caguas activists and radicals, as well as the environmental effects of commercial agriculture. It is an example of interdisciplinary work that presents new answers to historical problems. Our goal is for every student and educator to have free and open access to the study of history,” stated Dr. Carrasquillo.
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The author is a Professor of Physics and Science Education at Morehead State University, Kentucky, and a member of Ciencia Puerto Rico (www.cienciapr.org).