The problem is not with the specific materials, but with the lack of pertinent health data relating to the effects of these materials on potters. The statistics that are available are based on industrial populations of workers whose exposure and duration rates differ significantly from potters working in craft centers, schools and small studios. Large industries such as mining, paper production and metal manufacturing have the incentive (i.e., avoiding litigation) and money to assemble and document health problems associated with their work environment; as a result, numerous records are available in these areas on raw materials and their effects on worker health. These data have been used as the basis for enacting a number of guidelines and regulations relating to the safe handling of raw materials. However, a central question that has not been addressed is whether an accurate extrapolation of industrial statistics can be applied to potters who have much lower exposure and duration rates.
Many negative attitudes can grow in a climate of ignorance and speculation, and ceramic raw material toxicology has become increasingly subject to exploitation and misunderstanding by the uninformed and misguided. Ignorance of ceramic raw materials by the legal profession, exploitation by individuals who make their income from distorting data, and the revenue potential associated with any form of litigation have all led to an increased amount of conjecture and embellished claims regarding the use of raw materials by potters. A steady flow of articles has been published warning of new ceramic "poisons of the month," and the topic of health factors relating to ceramic materials has attracted alarmist "experts" with access to undiscriminating print media.
The potential for litigation has also increased. Not only can an individual potter be sued, but a ceramic supplier can conceivably be named as party to a lawsuit for selling items to the potter that caused the eventual user real or imagined harm. For example, if a potter sells a coffee cup with a glaze containing cobalt carbonate, and the user claims the glaze transferred harmful amounts of cobalt into his body, both the potter who made the pot and the ceramic supplier who sold the cobalt used in the glaze could be named in the lawsuit. Defending against a lawsuit can be an expensive and time-consuming process, and it is typically devastating to the individuals and small businesses in the pottery production field. Few ceramic supply companies or potters would knowingly sell products that could inflict damage or illness on their customers, but good intentions have little to do with the factors driving litigation. Even if negligence cannot be assigned, the time and money required to defend a lawsuit are considerable. In many instances, legal fees are incurred even if the case does not go to court.
A recent court case concerning cobalt carbonate came about by a confluence of events driven by greed, ignorance and an atmosphere of misguided consumer protection. Ignorance of ceramic raw materials by laymen and "experts," along with the legitimate health concerns of a potter, were brought together with lawyers who did not do their homework. Fortunately, the outcome is shedding new light on both the myths and realities regarding cobalt and other ceramic raw materials.
One of the potter's glazes contained 3% cobalt carbonate and was mixed in 30-gallon containers, which were refilled every three years. The glaze was applied by dipping or pouring it on the bisque pottery. The potter glazed six to eight hours per day, five days per week for a five-month period every year. An overglaze wash containing 60% cobalt carbonate was also brushed over some glazes.
The slips, glazes and overglazes were applied to a clay body that was mixed in the studio. All of the pots were fired in a 30-cubic-foot, sprung-arch downdraft kiln to cone 9 (2300ºF.). The potter had smoked a pipe for 33 years, filling his pipe with tobacco approximately 30 times each day. He also consumed approximately four liters of diet soda per day. He ate, drank and smoked in his studio, which he cleaned periodically with a garden hose.
He then went to the Mayo Clinic in Rochester, Minn., and was evaluated by a number of medical specialists, including internists, neurologists, gastroenterologists, rheumatologists, psychiatrists and a physician specializing in occupational medicine. Their findings did not indicate heavy metal poisoning. Significantly, blood and urine tests were negative for heavy metal poisoning, but a test did indicate an abnormally high level of arsenic in his blood. However, one doctor did tell him "symptomatically" his aliments fit cobalt poisoning, but this opinion was unsupported by the medical facts of the case. (The symptoms for cobalt poisoning are characterized by functional effects on the ventricles and enlargement of the heart [cardiomegaly]. There are no demonstrated musculoskeletal or neurologic effects as a result of exposure to cobalt. Gastrointestinal effects primarily from ingestion include nausea, vomiting and diarrhea.1)
The potter alleged he was unable to earn a living and could not work as a result of the ceramic supply company's negligence due to insufficient labeling of their cobalt carbonate product, which also contained manganese and arsenic. He had stopped making pottery because he believed it to be the cause of his health problems. The potter wanted compensation for economic and pecuniary harm, including, but not limited to, past and future medical bills and expenses, and past and future lost wages and income. He further claimed that he had suffered and would continue to suffer pain, emotional and psychological harm and distress, and loss of enjoyment of life. He believed his symptoms were directly related to the cobalt carbonate contained in his slips and glazes. His claim for damages was in excess of $5 million.
Evidence presented by the ceramic supply company's lawyers demonstrated that cobalt, manganese and arsenic poisoning are not found in the general population of potters. Previously, this information had been based on anecdotal reports accumulated over 50 years by individual potters and informal surveys taken at the National Council on Education for the Ceramic Arts (NCECA) annual meetings. A statistically accurate study of potters and their use of raw materials was sponsored at the 2000 NCECA meeting through a Potters Health & Safety Questionnaire that was issued to all participants.2 The questionnaire was also listed on the Internet and was available at ceramic supply companies throughout the U.S. The results of the survey indicated that the four most serious health problems potters encounter in their studios are back pain, carpal tunnel syndrome (repetitive motion), cuts (from glaze shards) and burns (from reaching into hot kilns). While a small percentage of potters reported illnesses attributed to raw materials, a search of the National Library of Medicine data banks and other medical libraries did not reveal any diagnosed cases of potters contracting cobalt, manganese or arsenic poisoning.
The most significant finding, of which potters should take note, occurred at Duke University's Medical Center for Occupational & Environmental Medicine. The potter's actual glaze and slip formulas were tested for respirable and ingestible concentrations of cobalt. The exposure assessment was conducted under controlled conditions duplicating the poor ventilation found in the potter's studio. The exposure to cobalt was tested by a modeling technique in which each activity was carried out identically to the actions of the potter in his studio. The glaze and slip formulas were mixed and applied in the same "spatter" technique used by the potter. Respirable exposure and ingestion levels were calculated for an average adult male based on the mixing operations in the potter's studio.
Test results determined-even allowing for a combination of incidental additive ingestion and inhalation in cleaning, mixing, and glazing activities-that daily absorption of cobalt would be in the range of 170-945 micrograms per day. The levels of cobalt the potter was exposed to in his studio were the same as in the general U.S. population on an average day. This was reflected in the testing of hair, blood and urine-values from which fell within the normal range. A risk assessment for cobalt found no adverse effects in humans at exposures of 3400 micrograms per day.3 The assessment of the potter's studio by Duke University's Medical Center for Occupational & Environmental Medicine is believed to be the first documented case of cobalt material toxicity testing in a private ceramic studio.
Aside from the environment, the general population is exposed to cobalt from many occupational and consumer sources. The most significant source of cobalt is found in food and drinking water. Food ingestion alone can average 5-100 microns per day. Drinking water levels can average from 2 to 107 micrograms per liter per day. Background cobalt air levels can range as high as 0.61 micrograms.4 In addition, cobalt is found in vitamin B12. A typical multivitamin contains 4 micrograms of cobalt in the form of B12.5 Cobalt is a necessary element, with background exposures from vitamin preparations, water and food in the range of 30-37 micrograms per day.
This case represents several related issues concerning the current realities in ceramics. First and foremost are the potter's past and current health, and the debilitating symptoms that he is experiencing. An inaccurate assessment by himself and others has caused a delay in the correct medical treatment of his illness. If nothing else, the medical evidence submitted at trial should eliminate cobalt, manganese or arsenic poisoning as the possible causes for his symptoms. It is hoped that the information presented will direct him to the correct diagnosis and treatment.
The economic impact of the trial on all parties was extensive. Preparation and research for the trial and payment to expert witnesses, in addition to legal and court fees, were substantial. The cost to the ceramic supply company, which is essentially a small business, caused it to revise its selling practices to prevent future litigation. The adjustments will not appreciably increase the safety margins to workers or customers, but will increase the costs to customers. Even though the ceramic supply company defended itself successfully, many companies will eliminate raw materials and services that they feel might cause legal problems. Such preemptive tactics will not serve potters' health interests and will not protect ceramic supply companies from litigation.
The economic balance between safe handling and selling of ceramic materials and reducing legal exposure to lawsuits depends in part on access to expert technical advice, which many ceramic companies cannot afford. Defending against this type of litigation, no matter what the outcome, was a battle that need not have taken place.
A legitimate array of physical symptoms by the potter, which led to a hair sample test for cobalt, caused the potter to seek legal action. When the symptoms did not match cobalt poisoning, manganese and arsenic poisoning were claimed to be the causes of the potter's health issues. While the cobalt carbonate used by the potter did contain 5.6 parts per million of manganese (trace amounts) it did not possess arsenic. Unfortunately, what was most needed at the onset of contemplated legal action was not present-namely, knowledge of ceramic materials and their toxicological effects on potters. Without this understanding, a course of action was taken, giving an economic incentive for the potter and his lawyers to move proceedings along even when the medical facts did not line up with the physical symptoms of the potter. Once the legal mechanism was under way, the costs in time and money for both the defendant and plaintiff started to accrue.
Material safety data sheets (MSDSs) are one good source for this information. MSDSs contain the material's chemical name, chemical family, hazard class, formula, occupational exposure limits, emergency first aid procedures, waste disposal, respiratory protection requirements, and precautions for handling and storage, which can help you establish safety guidelines for raw material handling procedures within your studio. Make sure to request a MSDS for every raw material you purchase, and then review it carefully before using that material. Additionally, look for seminars and courses in material safety at local colleges and craft centers.
You should also take common sense precautions within your studio, such as wearing a National Institute for Occupational Safety & Health (NIOSH)-approved respirator and/or rubber or latex gloves when working with materials that generate dust.
Raw materials, as used by individual and production potters, have a remarkable safety record. There is no room in the ceramic studio for ignorance or misconceptions about the raw materials we come into contact with on a daily basis. When cobalt was placed on trial, it highlighted several areas of concern for pottery suppliers and producers. Ignorance of the toxicological effects of raw materials caused a false diagnosis, which initiated a rush to litigation. The trial caused an economic loss for the potter and the ceramic supply company without an acceptable solution for either party. A lack of knowledge almost perpetuated an incorrect assessment of cobalt carbonate for the pottery community.
Fortunately, with the right information, we can avoid such unnecessary situations from occurring in the future.
1. Hamer, Frank, The Potter's Dictionary of Materials and Techniques, Fourth Ed., A&C Black Publishers Ltd., 1997, pp. 64-65.