Abstract
The Thomas A. Edison National Laboratory in West Orange, NJ was used to research and develop many inventions including experiments with a mercury oxide battery. Historical letter from Ms. Kellogg to Thomas Edison in 1884 reported the outcome of using mercury while conducting research. Preliminary test results showed spread of some contamination to artifact throughout the laboratory but the majority of the mercury was confined to a specific area of the lab. Spillage of elemental mercury in the Small Dry Cell Lab on the third floor of Building 5 leaked through the floor and ceiling on the second floor below. A comprehensive preliminary site risk assessment was conducted to evaluate the location and extent of the mercury contamination. Remediation work was conducted to remove the wood floor and ceiling but the work plan and health and safety plan for the project was inadequate. Workers were exposed to elevated levels of mercury vapor. Changes were made to reduce the risk and occupational exposure. The work was accomplished successfully without mercury poisioning after implementing more elaborate engineering and administrative controls.
Keywords
The machines are now silent, the overhead and task work lights are turned off, and all the workers have left the facility. It is eerily quiet with all of the equipment and machinery shutdown in a place that created so many inventions. Stepping back in history, much of the equipment at the Thomas A. Edison research laboratory in West Orange, NJ was operated with electric motors driving leather belt pulleys while other work tasks were done by hand. Hazardous chemicals were used and stored on wood shelves in the laboratory buildings from 1887 until 1931 (see Figure 1).
Employee entrance to the Thomas A. Edison Laboratory in West Orange, NJ.
During this time, as many as two hundred workers worked in the six building complex. Chemists, technicians, machine operators, and scientific researchers conducted a variety of experiments with cement, alkaline batteries, and rubber substitutes. Most workers labored for ten hours each day for six days a week. There was little time for any rest because Mr. Edison had an ambitious work schedule to patent more inventions. The West Orange, NJ laboratories created nearly 1,093 inventions. In 1955 Thomas Edison gave the laboratory and the Glenmont estate to the U.S. Park Service. Today, the historical site preserves over 400,000 artifacts and five million pages of documents. Visitors can view the history that helped created a better world for everyone.
During the first decade of the twentieth century, Thomas A. Edison spent time developing a storage battery in Building 5 for use in automobiles. Nobody was aware of all of the work done by the employees working for Thomas A. Edison. One area of research was batteries. Edison had a long-standing interest in battery design dating back to his time as a telegraph inventor. For over two hundered years, the development of batteries has been forefront to power electrical devices. In essence, a battery converts chemical energy into electrical energy. Only in the middle of the 1800s did the dynamo and generator become the primary power source during this period of innovation.
On a typical day in 1998, several researchers from Rutgers University scoured over transcripts to find out the remarkable truth to all of the work done. While working on the second floor of Building No. 5, these researchers began to notice something silver dripping for the wood ceiling. When a few drops fell into a coffee cup and floor around the desk, the researchers were alarmed and determined it may be a mercury. The Rutgers University Director of Occupational and Environmental Health and Safety was contacted along with the U.S. Public Health Service for assistance to determine what type of mercury was present (e.g., elemental, alkyl, or organic), the extent of contamination, and the risk of exposure to personnel in the building.
Edison researched nonchargeable batteries made of mercury oxide. A battery should weigh less, be more dependable and more powerful than any other battery on the market. Edison and his staff conducted hundreds of tests on a variety of metals and other chemical substances to find the right combination to make a more effective battery. In 1903, Edison announced that his work was done by developing a potassium hydroxide battery with iron and nickel electrodes. However there were numerous shortcomings. One advantage for mercury battery was the long shelf life (up to ten years) and steady voltage output.
Mercury in Commercial and Industrial Products
Mercury is the Roman name for the Greek god Hermes, the protector of travelers, thieves, and merchants. Mercury is a chemical element on the Periodic chart with the symbol Hg and commonly known as “quicksilver.” It was used in thermometers, barometers, manometers, sphygmomanometers, thermostats, float valves, mercury switches and relays for appliances, fluorescent lamps, and other electronic devices.
Historically, mercury and mercury-containing preparations have been widely used in traditional Chinese medicine and applied in many clinical practices mainly in the form of mercury sulfides. During the second Industrial Revolution, various inventions increased the demand for mercury. While performing routine analysis of human bones collected from an archaeological dig in Portugal, the University of North Carolina—Wilmington biology professor, Dr. Steven Emslie stumbled upon a new discovery—the earliest evidence for mercury poisoning in the history of the human population. Emslie and his team tested bones from 370 individuals excavated from fifty ancient tombs located in twenty-three archaeological sites in Iberia, the southwest peninsula of Europe occupied by Spain and Portugal. Many of the bones were visibly stained red, revealing that cinnabar, a mercury sulfide mineral that is found in volcanic regions, was to blame for the extremely high levels of mercury in the bones. The mercury values in these ancient bones were as high as more than 400 parts per milligram (ppm). For context, the World Health Organization (WHO) recommends that human hair should not contain more than 10 ppm. Values higher than that can lead to neurological disorders, loss of motor skills, harm vital organs, and can be fatal (Emslie 2021). In 1891, Thomas A. Edison’s incandescent lamp contained mercury (compact fluorescent light bulbs had mercury added to them. During WW II, the Ruben-Mallory battery (mercury dry-cell battery) was invented and widely used.
Understanding Mercury Oxide Batteries
Mercury batteries use a chemical reaction either with mercuric oxide (HgO), zinc or manganese dioxide (MnO2) as the cathode in an alkaline electrolyte solution of sodium or potassium hydroxide (Salkind and Ruben 1986). Some mercuric oxide batteries made by manufacturers use cadmium (Cd) (Linden 2002). Mercuric oxide is a non-conductor, so graphite is mixed with it to prevent collection of mercury into large droplets. The voltage was similarly sized to zinc-carbon battery.
The zinc anode was separated from the cathode with a layer of paper or other porous material soaked with electrolyte; this is known as a salt bridge. Small mercury batteries were later developed and widely used in the shape of button cells for electronic watches, hearing aids, cameras, and calculators, and in larger forms for other applications . Samuel Ruben developed a balanced mercury cell which was useful for military applications such as metal detectors, munitions, and walkie-talkies.
Building a mercury oxide battery had advantages and disadvantages. While it had a high energy capacity, it had a long storage life. Mercury-zinc batteries could be stored for up to two years while mercury-cadmium batteries could be stored for ten years without losing a charge. It was highly electrochemically efficient and provided a stable voltage output over the operating period. Mercury oxide batteries were very expensive with limited use. Performance at a low temperature was not good and the toxicity of mercury itself created a problem for both workers and the environment over disposal of the mercury and cadmium.
Today the emphasis is developing secondary batteries that can be recharged and hold the charge for an extended time. Even though the mercury oxide battery never measured up to expectations for the intended purpose, the research process left a path of contamination in the third floor Dry Cell Laboratory in Building No. 5. In 1992, the State of New Jersey prohibits all sales of mercury batteries. In 1996, the United States Congress passed the Mercury-Containing and Rechargeable Battery Management Act that prohibiting sale of mercury batteries unless manufacturers provided a reclamation facility, effectively banning their sale (NEWMOA 2010; Tchobanoglous and Kreith 2002).
Mercuric oxide batteries still are produced for military and medical equipment that need a stable current and long shelf life. Federal law requires manufacturers to have a system for collecting the used batteries and ensuring that the mercury is not released into the environment. Battery users must follow the collection procedures established by the manufacturer along with state and federal requirements (see Figure 4).
Symptoms of Mercury Exposure
Common symptoms of inorganic mercury poisoning include peripheral neuropathy, presenting as paresthesia or itching, burning, pain, or even a sensation that resembles small insects crawling on or under the skin (formication); skin discoloration (pink cheeks, fingertips, and toes); swelling; and desquamation (shedding or peeling of skin). Other notable physiological effects include difficulty breathing, irritability, headache, cough, chest pain, and weight loss (National Institute for Occupational Safety and Health 1973).
Mercury irreversibly inhibits selenium-dependent enzymes, which is necessary for catecholamine catabolism. Due to the body’s inability to degrade catecholamines (e.g., epinephrine), a person suffering from mercury poisoning may experience profuse sweating, tachycardia (persistently faster-than-normal heart beat), increased salivation, and hypertension (high blood pressure).
Affected persons may show red cheeks, nose, and lips, loss of hair, teeth, and nails, transient rashes, muscle weakness, increased sensitivity to light. Other symptoms include kidney dysfunction or neuropsychiatric symptoms: emotional lability, loss of fine motor function, memory impairment, or insomnia. Quicksilver (liquid metallic mercury), colloidal, metallic, or elemental mercury is poorly absorbed by ingestion and skin contact. The vapor is the most hazardous form of exposure. In humans, approximately 80 percent of inhaled mercury vapor is absorbed by the pulmonary system, where it enters the circulatory system and systemically distributed throughout the body.
Letter to Thomas A. Edison
On July 18, 1887, Mr. Edison received a written letter from Mrs. Kellogg. She describes the work being done by her son, Eddie Kellogg who worked in a lab for more than a year. While he suffered several “epileptic” seizures, he continued working. She writes “On the first of March, we became alarmed. . .. He inhaled and absorbed so much mercury and chemicals that his system cannot recover. . ..We found out it (mercury) was in his blood. Now his nerves and muscles are so affected that he cannot control them. His mind is weakened to the like of a boy 6-8 years old. He has a fit nearly every week. . .Eddie told the doctors about quicksilver being poured over him by accident and continued to wear the same work clothes and did not understand the danger.” The original letter is archived at the Thomas Edison historical site in West Orange, NJ. The displayed signs of dementia are a result of severe mercury poisoning such as the case of “Mad Hatters” who were referred to by Lewis Carroll in his book Alice in Wonderland, circa 1865 (see Figure 2).
Copy of the letter was provided by the U.S. National Park Service from Mrs. Kellogg to Thomas A. Edison regarding son’s exposure to elemental mercury.
The following images show the area of concern in Building No. 5. The Small Cell Test Department on the third floor is the area where battery experiments were done using mercury oxide. Spilled mercury trickled down between the wood flooring through the second floor wood ceiling. The images and figures show where the mercury was found inside the room and the work that was done to remediate the interior spaces (see Figures 3 and 4).
Second floor of Building 5—Storage and offices with identified area of concern (not drawn to scale).
Third floor of Building 5—Small Cell Test Department and racks of batteries (not drawn to scale).
Initial Risk Assessment
A Jerome® model 431-X mercury vapor analyzer was used to survey the facility for the presence of mercury. This portable hand-held direct reading instrument scanned all of the building surfaces for Hg vapor in air. The instrument used a stable and reliable gold film technology for workplace health hazard monitoring, spill detection and cleanup analysis. With a significant lower detection level (0.5 µg/m3), it was an excellent instrument of choice to detect low levels of exposure (NYSDOH). The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) and the federal OSHA maximum Permissible Exposure Limits (PELs) occupational exposure limits were used as a reference (American Conference of Governmental Industrial Hygienists [ACGIH] 2022; OSHA 1971). These exposure limits represent the opinion of the scientific community that values at or below these levels does not create an unreasonable risk of illness or disease. Results of the preliminary mercury vapor survey are presented in Table 1.
Investigative Mercury Vapor Survey Measurements in Air—Jerome Analyzer.
Note. These area air samples were not collected in the breathing zone but along museum building surfaces.
Air sample collected in a 30–gallon gray plastic container marked “Hazardous Waste” with old broken mercury tubes.
After collecting hundreds of data points using the Jerome® mercury vapor analyzer, SKC, Inc. passive air samplers were used to evaluate the mercury vapor exposure in air. These devices were placed in locations to corroborate the preliminary findings. This type of air sampling method provided additional evidence of the workplace exposure to occupants working within the interior spaces. Field blank samples were collected to ensure quality assurance of the sample results. All mercury passive samples were collected at a height representative of a person’s breathing zone. Area samples were analyzed by the State of Wisconsin Occupational Health Laboratory (WHOL) in Madison, WI using an in-house method based on the OSHA ID-140 and NIOSH 6009 methods. The limit of detection using the WHOL method is 2.3 µg/badge. The ambient air sample results are presented in Table 2. Other area samples were collected in various other locations within Building 1 to 3 and 5 but some test results were inconclusive either at or below the limit of analytical detection.
Investigative Mercury Vapor Measurements in Air—Passive Sorption Monitors.
Note. Area air samples were collected to evaluate the ambient air exposure inside the museum.
To evaluate surface contamination from handling artifacts, micro vacuum samples were collected for mercury using MSA Escort® air sample pumps, a standard 100 cm2 template, and polyvinyl chloride (PVC) filters in a 37 mm polystyrene cassette. MSA Escort® air sample pumps were pre- and post-calibrated at 3.0 L of air per minute (lpm). Micro vacuum samples of surface dust were collected from interior building surfaces and analyzed by WHOL using the same analytical method described above. The limit of detection (LOD) using micro vacuum sampling technique was 1.1 ng per sample based on a 25 mL dilution. The micro vacuum surface sample results are presented in Table 3.
Investigative Mercury on Building Surfaces—Micro Vacuum Samples.
Note. Samples were collected to evaluate surface contamination from settled dust on the museum artifacts.
Elemental Mercury Contamination
Experimentation in developing a mercury oxide battery resulted in significant mishandling, use and spillage of elemental mercury, which became trapped under the wooden floorboards. Air and surface sample results indicated the mercury spillage was confined to one room on the third floor but surface contamination spread over time to other areas of the facility due to a lack of knowledge of the occupational health hazard during transfer and relocation of the artifacts. The concentration of mercury in the settled dust was low as noted by the surface sampling test results. Personnel were urged to wear disposable gloves whenever handling these stored objects.
An experienced remediation contractor was hired to remove the wood flooring in the Small Cell Test Department on the third floor and the wood ceiling in the Research Office on the second floor below in Building 5 (see Figures 5 and 6). A written workplan and health and safety plan were developed for the work tasks. However, the company had not remediated a building with mercury contamination before. After moving all of the artifacts, tables, and work benches from the room, they began to cut the flooring using a circular saw (see Figures 7 and 8). Ambient mercury levels near the breathing zone quickly exceeded the upper limit of detection (1 mg/m3) using a Jerome® model 431-X mercury vapor analyzer due of the heat of friction using the circular saw. Beads of mercury were clearly visible between and under the flooring between the third floor and ceiling on second floor as shown in Figures 9 and 10. The average of the air monitoring results during initial phase of remediation are presented in Table 4.
Workers vacuuming Hg from 3rd floor beams and ceiling on the 2nd floor in Building 5. Workers wore Level B protection including air supplied respirators and protective clothing and equipment.
Cutting and ripping up the flooring on the third floor in Building 5. Workers used a Sawzall® to cut through the wood flooring to vacuum the beads of mercury within the interstitial space.
Interstitial space between the flooring on the third floor and second floor ceiling in Building 5. Mercury droplets shown inside the red circles.
Area Air Monitoring Results During Museum Remediation Work Activities.
Note. Air monitoring was performed to remove the wood flooring and ceiling to access the interstitial cavity. The exposures exceeded the airborne exposure criteria of the ACGIH and OSHA values.
The work was stopped temporarily to alert the contractor about the elevated levels of mercury vapor in the air. Workers for the U.S. Park Service also were notified of these concerns and the need to change the workplan and upgrade the contractor health and safety plan. After discussing several options, the contractor agreed to change the method to remove the floor using a Sawzall®, which provided less heat from friction to volatize mercury. Beads of mercury between the floor and ceiling were removed with a special High Efficiency Particulate Aerosol (HEPA) vacuum.
Biological mercury samples were collected from members of the contract workforce. These blood levels began to rise from the baseline levels due to the high levels of exposure and the lack of engineering or administrative controls to reduce exposure. Blood collected at the end of the workweek shift rose close to the American Conference of Governmental Industrial Hygienist (ACGIH) Biological Exposure Indices (BEI) for 20 µg of mercury per gram of creatinine, which was close to the level for medical removal (OSHA 1991 (1987)). Employers should not permit any worker to be engaged in work that exposes or likely to expose them to a hazardous chemical based on a medical finding, determination or opinion expressed by an occupational safety and health officer, or medical practitioner that shows that the medical condition places the workers at increased risk of impairment from continued exposure. Beside the airborne exposure, workers failed to properly decontaminate themselves after removing their personal protective clothing and they did not use specialized hand soap needed to remove mercury from their skin. Sample results showed 0.29 to 0.694 mg/m3 of mercury on the workers’ hands after decontamination.
Occupational health training was essential to understand the hazards and controls of the work. In this project, workers received basic OSHA information required to work with hazardous materials but lacked specific training to understand the health hazards associated with mercury. Workers were not informed of the engineering and/or administrative controls reduce the exposure within an acceptable risk. These workers failed to understand the health hazard and risk associated with elevated airborne and skin exposure from the planned work activities and the importance of conducting biological monitoring to evaluate their personal exposure.
Changes were made to the workplan and health and safety plan to reduce the exposures in the work area as well as prevent mercury vapor from escaping from the work area into the nearby support areas on the third and second floors. Some of the recommended changes include:
Change the type of personal protective clothing from Tyvek® to a coated Saranex® suit
Change the type of gloves using an outer (nitrile) and inner cotton glove
Upgrade the level of respiratory protection from Level C (mechanical cartridge respirator) to Level B using supplied air respirators
Design and implement engineering controls using iodine-carbon filtration media to capture the mercury vapor in air that was being liberated within the work area
Implement medical removal protection criteria relative to the ACGIH Biological Exposure Indices
Monitor the decontamination process to prevent cross-contamination
Inform workers of the ambient air and urine test results and medical removal protection
Change Mercon-X™ decontamination solution more often to prevent spread of contamination
Monitor workers hand and shoes after decontamination before entering the support zone
Install separate airlocks to moving equipment and machinery and contaminated lumber
Eliminate all dry sweeping inside the containment area where removal worker was being done
Decontaminate plastic wrap by wiping the surface when removing the wood floor and ceiling from the work area
After these changes were made, both the contract workers and the U.S. Park Service staff felt more comfortable about the work tasks to remove the contaminated wood and ability to protect everyone from exposure to elemental mercury. Blood sample results showed a plateau in the mercury levels so all workers could continue work without medical removal. The level of oversight and project meetings also provided an opportunity for communicating both the level of risk and need to implement tighter controls that otherwise would have not been used on other hazardous waste removal operations.
Mercury decontamination measures used during these types of projects is much different than other types of hazardous materials. Mercury vapor can amalgamate with various materials, which was something that abatement contractors rarely encounter in their line of work. Final clearance test results were acceptable once the contaminated wood and mercury were removed. Table 5 shows the outcome of the project based on the post-remediation clearance sampling test results.
Museum Post Remediation Area Air Monitoring Results.
Note. Area air monitoring was performed inside and outside of the remediated areas of the museum. None of the exposures exceed the airborne exposure criteria of the ACGIH or OSHA exposure values.
Conclusions
This project required a complete risk assessment to determine the source and the extent of the mercury contamination. Resources were allocated to properly measure both the air and surface exposure because of the lack of understanding about the work previously done at the laboratory and movement of artifacts throughout the complex. Once the source of the contamination was determined, a comprehensive action plan was formulated by the remediation contractor. Since only contractor oversight was provided, it became apparent that further assistance was needed by trained occupational health and safety consultants to protect both the contract workforce and other personnel working in the building. Contaminated surfaces on stored artifacts were not considered as part of this remediation project since most artifacts were not routinely handled or used but rather stored. However, the use of gloves was recommended to protect personnel handling these items.
Hazard communication played a special role to inform all stakeholders of the unique hazard and the risk associated with the work and contamination on the artifacts, equipment and machinery, and building surfaces. Workers for the remediation contractor needed to know that peer-reviewed biological monitoring indices and occupational exposure limits for mercury exist to protect workers from excessive exposure to mercury. They also understood how baseline mercury blood or urine levels may be elevated based on dietary needs and work practices. Workers realized that work practices can exceed the level of protection, especially in the case of mercury, when the heat for friction from a circular saw can quickly increase the vapor levels to an unacceptable risk.
Proper mechanical ventilation design and adequate airflow was needed to reduce the ambient exposure and keep the room under negative air pressure. Changing the workplan by using a lower reciprocating tool produced less friction, which was helpful despite the additional time to complete the project. Workers needed to understand that decontamination is more than removing their respirator and personal protective equipment and washing their hands. In this case, poor work practices and habits contributed to cross contamination and skin exposure.
Toxicity of mercury poisoning can occur from vapor in air and a lesser extent by skin contact. Both routes of exposure must be carefully examined to protect the workforce and the public. The effects of uncontrolled mercury exposure can be very severe as noted by the letter to Mr. Edison, circa 1884. Sometimes the exposure may not occur at all depending on various confounding factors such as the form of mercury, frequency and duration of exposure, age and current health status, work practices, selection and use of respirators and personal protective clothing, decontamination methods, medical surveillance and biological monitoring, training and education, and a clear understanding of other confounding factors that influence exposure to the workforce and public.
Footnotes
Declaration of Conflicting Interests
The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author received no financial support for the research, authorship, and/or publication of this article.
