Editor’s Note: This article was originally published on January 11, 2017.
The noxious smell of new coal-tar pavement or sealant being laid on driveways, streets, parking lots, and playgrounds is hard to miss. Have you ever wondered about the toxicity of the shiny black liquid spray but dismissed it as something out of your control? It turns out that these substances contain polycyclic aromatic hydrocarbons (PAHs).
A study conducted by the U.S. Geological Survey (USGS) and Milwaukee Metropolitan Sewerage District revealed that coal-tar sealants are the primary source of PAHs, posing a significant threat to human health and aquatic life in urban and suburban areas. The toxic coal-tar sealants were found to be responsible for up to 94% of the PAHs found in streambed sediment samples collected from creeks and rivers in metropolitan Milwaukee.
The toxins from sealed and blacktopped surfaces, such as PAHs, wash into stormwater storage basins and sewers, eventually contaminating waterways and harming aquatic life. While coal-tar sealants are preferred for aesthetic purposes, they contain up to 1,000 times more PAHs than asphalt emulsions, which are more environmentally friendly.
Regulations banning the sale and use of coal-tar sealants have been implemented in some areas, such as Dane County, Wisconsin. However, the issue extends beyond Milwaukee, with similar problems arising across the U.S. Stormwater runoff contaminated with toxic materials can have devastating effects on aquatic organisms and the environment.
Communities are taking steps to address the issue, with some implementing restrictions or bans on coal-tar products. While the problem of PAH contamination in water is not new, efforts to mitigate its impact are ongoing. The harmful effects of PAHs on aquatic life highlight the urgent need for stricter regulations and environmentally friendly alternatives to coal-tar sealants. Realizing it was no mere coincidence, an investigation was launched.
The culprit behind the strange, nonsensical, and erratic behavior of the men was identified by the chief of the Nervous Department at New York’s College of Physicians and Surgeons as carbon disulfide. This colorless liquid, known to evaporate rapidly at room temperature, had been linked to cases of “acute insanity” in Europe.
Further research revealed that carbon disulfide was used as a solvent in manipulating PAH materials. This substance was initially created to make rubber pliable for tire production through a process called vulcanization. The solvent treated rubber in a cold vulcanization process, offering superior wear properties and countless other applications.
According to reports, carbon disulfide led to a new term, ‘gassed,’ in England, which was defined as ‘the term used in the India rubber business, and it meant dazed.’ The impact of this discovery has been felt by billions of users of rubber products, while a significant number have suffered adverse effects.
Dr. Paul Blanc from the University of California described carbon disulfide as a “very unique toxin” with unpredictable effects on the nervous system, as well as birth defects and menstrual interference. His investigation uncovered references to the toxin dating back to 1849, including warnings to workers regarding its vapors.
Carbon Disulfide — A History of Manufacturing and Testicular Hysteria
Despite early warnings about the dangers of carbon disulfide, the substance continued to cause health issues among workers. Symptoms ranged from weird dreams to memory lapses, premature aging, and loss of sexual desire. Surprisingly, many victims were employed in condom factories.
Reports from the 1880s documented over 60 cases of male “hysterics” in Paris associated with carbon disulfide exposure. One man working in the rubber industry suffered from toxic hysteria after cleaning vulcanization vats containing the substance, experiencing various debilitating symptoms.
Carbon Disulfide and Compromised Federal Standards
Despite the removal of carbon disulfide from tire production, its presence in other industries continues to pose health risks. Workers exposed to the substance at a plastic and rubber manufacturing plant in New York had a significantly higher rate of fatal heart disease compared to others. The toxin is also used in cellophane, rayon, and agricultural applications.
Blanc criticized federal standards for carbon disulfide, labeling them among the least protective globally. Industry lobbyists have vehemently opposed stricter regulations, leaving workers vulnerable to health hazards.
Gas and Wastewater Used to De-Ice Roads
Despite potential dangers, some states still use brine from oil and gas operations to de-ice roads, unaware of its radioactive and toxic components. The wastewater runoff contains harmful substances that can contaminate water supplies and harm aquatic life.
Salt on Roadways Is Toxic to Humans, Animal Life
The excessive use of road salt has detrimental effects on ecosystems, killing insects, amphibians, and plants. Chronic exposure to salt can damage food sources for fish and contaminate drinking water sources.
Solar Panels to Heat Roads — From Concept to Reality
To address road salt issues, innovative solar-powered systems are being developed to clear snow and ice from roads using sustainable energy sources. Un equipo en Worcester Polytechnic está trabajando en la recolección de energía en el pavimento almacenando líquido caliente en tuberías o cámaras aisladas para derretir la nieve y el hielo.
El segundo concepto, de Solar Roadways, tiene un contrato de investigación de $750,000 para trabajar con, otorgado por la Administración Federal de Carreteras, para reemplazar las carreteras tradicionales con paneles solares resistentes que mantendrían las carreteras lo suficientemente calientes para evitar la acumulación de hielo y nieve.
Como sucedió, la primera carretera pavimentada con paneles solares se abrió en el pequeño pueblo de Tourouvre-au-Perche, Francia, con una longitud de poco más de media milla (1 km), recubierta con una película de silicio especial para ayudar a proteger los paneles del exceso de peso de los vehículos.
Fue un proyecto costoso, sin embargo, costando alrededor de $5.2 millones para construir.25 Los paneles solares también cubren ahora 18 millas de carretera en el Centro de Información al Visitante de Georgia en West Point, el primero en los EE. UU., que fue creado para ser un “ecosistema de carretera regenerativa.”26
La esperanza para muchos es que la electricidad generada pueda ayudar a cubrir los costos con el tiempo, pero también que los paneles solares, con diseños que aún se están desarrollando, ayudarán a reducir el uso de sal que en la actualidad se utiliza en 22 millones de millas de carretera, según Seeker.27
Qué Se Puede Hacer y Qué se Está Haciendo
En el noroeste del Pacífico, los científicos tenían un mal presentimiento sobre el potencial de toxinas de escorrentía durante mucho tiempo, pero el estudio de los salmones abrió una puerta que les permitiría no solo estudiar el problema, sino también ayudar a solucionarlo. Según The Seattle Times,28 tienen la intención de utilizar un sistema de filtración simple basado en el suelo.
En 2013, los municipios preocupados por las toxicidades de las carreteras se volvieron creativos para aliviar el problema y encontraron algunas soluciones innovadoras: suero de queso gratis en Wisconsin (ahorrando alrededor de $40,000), melaza de caña de azúcar en Minnesota y jugo de remolacha en Illinois, mezclados con sal para actuar como agentes alternativos de deshielo.
Julann Spromberg, Ph.D., bióloga investigadora de peces para la Administración Nacional Oceánica y Atmosférica (NOAA) y coautora del estudio de los salmones coho, dijo que en muchos casos, todo lo que se puede hacer para muchos de estos problemas es básicamente “dejar que la Tierra haga lo que hace tan bien, lo que ha hecho durante eones: limpiar las cosas”.