Lead Contamination in Contemporary Ceramics Studios: Potential for Community and Worker Exposure Abstract Background

Transcription

1 Lead Contamination in Contemporary Ceramics Studios: Potential for Community and Worker Exposure Courtney V. Stanion, MSEnvE, IHIT Woodhall Stopford, MD, MSPH Abstract The term contemporary ceramics refers to the decoration of pre-fired ceramic forms using leadfree underglazes. Decorated pieces are then covered with an overglaze and fired again. This overglaze, or dipping glaze, may contain a lead silicate frit. When the pieces are dipped in the overglaze, drips can fall to the work or floor, where they can be tracked into the studio. Food and drinks are often available for studio clientele, presenting a potential for ingestion of lead from contaminated hands or serving or eating s. Customers include young children and women of childbearing age, for whom lead exposure can be especially detrimental. Five contemporary ceramics studios were sampled In central North Carolina to determine the potential for lead exposure. After the preliminary survey, safety information concerning controlling lead exposures was made available to each patron. Follow-up sampling was conducted to assess the effect of safety awareness on measured levels. NIOSH Method 9100 (Lead in Surface Wipe Samples) was used for non-porous s, and an EPA vacuum sampling method was used for carpeted areas. A definite pattern of lead contamination was observed, with floor concentrations in the dipping areas ranging from 33 to 793,000 g/ft 2. Floor concentrations in customer areas ranged from 3 to 1650 g/ft 2, with most samples exceeding the HUD recommendation of 100 g/ft 2 for lead dust on the floors of homes. Customer work s and food serving s yielded values ranging from non-detectable to 2295 g/ft 2. The availability of safety information changed work practices. These changes were effective where dipping area floors and work s were sealed but were ineffective where porous s prevented adequate clean up. In order to be able to control leaded glaze contamination, the floor and work s in the dipping area must be sealed. Glaze drips should be cleaned up immediately when they occur. Other measures to prevent lead dust exposures and movement into customer areas include improvements in studio and personal hygiene, use of personal protective equipment by studio employees, prohibition of food in dipping and firing areas, and restriction of customer access to glaze dipping areas. Studios and their personnel should receive periodic lead monitoring tests. If lead contamination of customer areas cannot be controlled, then studios should switch to a leadfree dipping glaze. Background In contemporary ceramics studios, customers decorate pre-fired ceramic forms ( bisque-ware ) with either non-toxic glazes or acrylic paints. Glazes articles are then covered with an overglaze by studio personnel and fired again to vitrify the glazes. This type of studio is fairly new, the

2 first such establishment opened in 1991 in New York City. The Contemporary Ceramics Studio Association was formed in October 1996, and, within a year, had 150 members (Meckelburg, 1997). There were greater than 500 such studios in January 1997, with projections of rapid growth. Contemporary ceramics differs from hobby ceramics in many ways. Traditionally, hobby ceramic glazes are applied to greenware, a term describing clay that has not yet been fired. The decorated greenware has to go through a series of firings before the finished product is achieved. Greenware is particularly fragile, prohibiting shipment and precluding use by inexperienced persons. Therefore, greenware production for use in hobby ceramics studios is usually done on site with only finished pieces (already glazed and fired) being shipped for sale. With the development of glazes that can be painted onto bisqueware, however, the development of a new type of ceramic activity became possible. Bisqueware is hard and reasonably durable, making it much easier to transport and work with than greenware. It can be manufactured in large quantities and shipped around the world. It can be decorated by novices, including children, using non-toxic glazes and acrylic paints. Potentially hazardous operations, dipping and firing, are done by studio personnel. These studios offer an array of ceramic pieces and decorative colors, a pleasant atmosphere and, frequently, snacks and drinks for customers. They are very popular locations for children s birthday parties and other gatherings. There is a particular concern for the potential for lead exposure in these studios for several reasons: shop proprietors are often unaware of hazards, customers are not warned about the presence of lead, and the availability of food presents a potential for ingestion of lead from contaminated hands or s. Additionally, these studios cater to young children, who are especially susceptible to lead poisoning. There is evidence of kidney and central nervous system damage in children at lower blood lead levels than those which produce adverse symptoms in adults (Goldwater, 1985). Many contemporary ceramics studios use lead silicate dipping glazes to finish pieces because of their superior appearance and ease of use (Meckelburg, 1997). Employees handling these glazes are frequently not received training concerning the hazards of lead and appropriate practices to limit exposure and lead dust migration. If the work area is not kept clean, lead dust from dried drips of overglaze can be tracked throughout the studio, creating a potential for customer exposure. Methods In order to determine whether or not use of lead-containing dipping glazes in contemporary ceramics studios presents an unusual potential for lead exposure, we studied five such studios for the extent of contamination with lead-containing dust. Dust sampling of hard s was done using NIOSH Method 9100 (Lead in Surface Wipe Samples, NIOSH, 1994). Because most s were non-porous, this method was modified to use baby wipes in place of filters. Rugs were sampled using an EPA vacuum sampling method for carpeted areas (USEPA, 1995). The vacuum samples were analyzed using NIOSH Method 7082 (Lead by Flame AAS, NIOSH,

3 1994). In each studio, both floors and work s were sampled in the studio and the dipping/kiln areas. Personal air samples were taken in the proprietors breathing zone for two of the studios while they worked in the dipping area. These task-based samples were analyzed using NIOSH Method 7082 (Lead by Flame AAS, NIOSH, 1994). Most of the vacuum samples were straightforward, with one exception. In the carpeted dipping area of Studio C, there was debris on the floor along with a thick layer of overglaze dust. There was over-loading on the filter, requiring the use of a second filter. It is likely that the combined analysis of these two filters underestimates the true contamination level. After presenting the results of the initial sampling runs to each studio, hygiene-related recommendations and information concerning lead dust exposure measures were presented to each studio proprietor. Four of the studios were re-sampled a few months later to judge the effectiveness of this intervention. The characteristics of each of the five surveyed studios can be summarized as follows: Studio Floors in Dipping Floors in customer Type of studio Area area A Rough concrete Concrete Contemporary B Tiled Tile & Carpeted Contemporary C Carpeted Carpeted Contemporary/ Hobby D Rough concrete Concrete Contemporary E Carpeted Concrete Contemporary

4 Results Results for initial and follow-up wipe and vacuum sampling are found in Tables 1 and 2. Studio B had both the least contaminated dipping and studio areas. This was the only studio with a smooth, sealed, nonporous floor in the dipping area. The person who performed the dipping in this studio was fastidious about cleaning up drips of glaze on the floor before they had a chance to dry. The shelves where dipped pieces dried before firing were laid out with paper towels under the drying racks which were discarded and replaced regularly. Other parts of this studio looked quite clean, but the proprietor emphasized that the carpeted portion of the studio was vacuumed no more than once every few weeks and had not been vacuumed in the few days prior to sampling. The remaining studios had either carpeted or rough, porous concrete floors in the dipping room. Dried drips of glaze were encrusted on work s and the rough concrete floor in Studio A dipping room. The floor at Studio D was very similar to that at Studio A. On the first sampling day, the customer area had not been mopped in several days, and there were a few scattered drips of glaze on the floor in the kiln/dipping area. The follow-up sampling at Studio D was performed on a day immediately after the entire studio floor had been mopped. Studios C and E had carpeted dipping areas. Studio E had been open less than two months at the time of initial sampling, while Studio C had been in operation much longer. At Studio C, the proprietor had stopped vacuuming the kiln area because of concern about airborne lead. Instead, a small area rug was laid out in the dipping area over the more permanent carpeting. The proprietor would take this rug outside periodically and shake it out. At the time of sampling, glaze dust, dirt and leaf debris was apparent on the area rug. When sampling was performed again in Studio A, the proprietor had begun cleaning the floor each time he dipped and/or loaded the kiln. However, since the floor was rough, dried glaze was still apparent in recesses in the floor. The variations in lead contamination on work and miscellaneous s can be partially explained by differences in the studios as well. At Studio C, which caters to customers more experienced in ceramics, some lead-containing specialty glazes are used at the customer tables. This may account for the higher results on these tables than others. At Studio A, the refrigerator that was sampled in September had recently been wiped off, but possibly with a contaminated sponge. A few months later, the refrigerator had been moved further from the dipping area, and lead levels were lower. However, a microwave had been placed closer to the dipping area than the refrigerator had originally been. The table in front of the microwave exhibited high levels of lead contamination. At the initial visit to Studio D, the children s coloring table had visible glaze dust on it. The proprietor would stand near this table (at the sink) and smooth down irregularities in the chalky dried glaze. The dust from this smoothing process was then blown off, contaminating the

5 children s area. It was recommended that this be cleaned frequently. Glaze dust was not visible on the table during the follow-up visit and the contamination level was lower. Table 1: Surface Concentrations of Lead Dust in Contemporary Ceramics Studios Type of sampled Customer table Customer floor - hard Customer floor carpeted Dipping area work Dipping area floor hard Dipping area floor carpeted Food serving Studio and Date A-8/97 A-9/97 B-9/97 C-10/97 D-10/97 E-10/ g/ft 2 <5.00 g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft 2 (baby play area) 304 g/ft 2 793,000 g/ft 2 (near dip tank, drying shelf, and kiln) 543 g/ft 2 (glaze drying area) 4310 g/ft 2 (near kiln) 3420 g/ft 2 (near dip tank) 1100 g/ft 2 (top of fridge) Misc g/ft 2 Field blank* (office floor near owners child s toys) 3.19 g/ft g/ft 2 (10/97 - both vacuum) 1030 g/ft 2 (near drying shelf) 245 g/ft 2 (near dip tank) 47.3 g/ft 2 (coffee counter) <5.62 g/ft 2 <5.00 g/ft 2 < 5.00 g/ft 2 (wipe) <2.00 g (vacuum) 472 g/ft 2 (Vacuum) 106 g/ft 2 (Wipe) 3510 g/ft 2 (near back door of studio) 30,224 g/ft 2 (v) 835 g/ft 2 (w) (both near dip tank, drying shelf, kiln) <5.00 g/ft 2 (wipe) 9.93 g/ft 2 (vacuum) 9440 g/ft 2 (top of dip tank) 9570 g/ft 2 (near drying shelf) 7670 g/ft 2 (near dip tank) 738 g/ft 2 (near kiln) 276 g/ft 2 (near dip tank) 292 g/ft 2 (microwave - kiln room) 1590 g/ft 2 57 g/ft 2 (kid s table) (beside sink) 71 g/ft 2 (kid s table) 10.8 g/ft g/ft 2 (wipe) <2.00 g/ft 2 (vacuum)

6 Note: When more than one value is listed for a specific type of in a given establishment, values at the top are furthest away from the dipping tank, and values at the bottom are closest to the dipping tank.

7 Table 2: Follow-up: Surface Concentrations of Lead Dust in Contemporary Ceramics Studios after Safety Recommendations Issued with Original Results Type of sampled Studio and Date A-3/98 B-3/98 D-2/98 E-2/98 Customer table 98 g/ft g/ft g/ft g/ft 2 Customer floor hard 5.3 g/ft g/ft 2 Dipping area work Dipping area floor hard Dipping area floor carpeted Food serving 2495 g/ft g/ft g/ft g/ft 2 (top of dip tank) 9615 g/ft g/ft g/ft 2 (top of refrigerator near front of room) 2295 g/ft 2 (table in front of microwave) misc. ~8600 g/ft 2 (bottom of shoes after 40 minutes in studio) 55.3 g/ft g/ft 2 (floor by kid s table) 6857 g/ft 2 (top of dip tank) 567 g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft g/ft 2 (kid s table) (top of microwave in dipping room) Field blank 5.42 g/ft g/ft g/ft g/ft 2 Note: When more than one value is listed for a specific type of in a given establishment, values at the top are furthest away from the dipping tank, and values at the bottom are closest to the dipping tank. Table 3 shows the personal air sampling results for lead concentration in air. These results give the average air concentration for the periods of time during which the samples were collected. Both were short-term samples (62 and 79 minutes), so do not approximate full shift exposure. Rather, they give an estimate of the average air concentration during the tasks performed while sampling, namely rubbing down imperfections in the dried glaze, blowing off dust created during this process, loading glazed pieces into the kiln, and cleaning the dipping/kiln area. Table 3: Personal Air Sampling Results Studio Task Flow Rate Length of Sample Result A Loading kiln, mopping floor 3 lpm 62 minutes mg/m 3 E Dipping, rubbing down dried 3 lpm 79 minutes mg/m 3 glaze and blowing off leadcontaining dust, loading kiln, vacuuming floor Field Blank <0.002 mg

8 Discussion All sampling results can be compared to the Department of Housing and Urban Development s recommendation of 100 g/ft 2 as the maximum safe lead dust concentration for the floors of homes. This is the only consensus standard available for lead contamination. The HUD level is considered safe for occupants, including toddlers, who spend a large percentage of their time at home. This level would likely protect customers, who might come to the studio for a few hours a month. For work tables (where food may be set down) and food serving s, a lower concentration may be a more appropriate goal. For airborne sampling, exposure limits established by the American Conference of Governmental Industrial Hygienists, the Occupational Safety and Health Administration, and the National Institute of Safety and Health are listed in Table 4. These limits are full shift (eight- or ten-hour) time weighted average (TWA) levels and have been developed to protect the majority of working-age persons. The OSHA standard for lead also includes a housekeeping clause which applies to lead dust accumulation on work s. Table 4: Exposure limits for lead dust in air Organization Exposure Limit ACGIH 0.05 mg/m 3 (8 hour TWA ) OSHA 0.05 mg/m 3 (8 hour TWA) (Action Limit at 0.03 mg/m 3 ) NIOSH mg/m 3 (10 hour TWA) With the exception of Studio B s customer area, all of the floor lead dust concentrations during the first round of sampling exceeded the HUD recommendation of 100 g/ft 2. At the time of follow-up sampling, Studio B had also reduced its dipping area concentrations below this level, but the other studios customer and dipping area floors remained above the HUD recommendation. From these results it is clear that lead dust spreads from the dipping/kiln areas of the studios into customer areas. In only one of the studios (B) were there signs warning employees or customers about the presence of lead. No personal protective equipment was used by any employees at the beginning of this project. After seeing the results and hearing recommendations, however, at least one proprietor has begun wearing gloves and another has a pair of overshoes for dipping and uses a disposable dust mask when loading the kiln. Two of the studios serve coffee and two serve snack foods and cold beverages that are stored in the studios. In all of these establishments, the food and/or drink are located near the backs of the studios, in varying proximity to the kiln room doors. One of the studios that serves only coffee is located next door to a bakery and features special pizza nights, when customers are treated to pizza while they work. One studio has a full-size refrigerator and microwave inside the kiln/dipping room, for use by the proprietors and employees, the s of which were found to

9 be contaminated. Of the food serving s that were sampled, only one (in the generally cleaner Studio B) had a lead concentration below the HUD recommendation for floors. Two studios had children s play areas near the dipping room. At the time of the follow-up studies, one of them (Studio E) removed the children s play area. Studio D had begun cleaning the children s coloring table more frequently, but this still exhibited a concentration of g/ft 2, which is above the HUD level for floors. At the time of the follow-up studies, kiln/dipping rooms were generally cleaner, but only Studio B had brought the level of floor contamination in the dipping area below the HUD standard. Studios A, D, and E had floor s that were not easy to clean and glaze drips or encrusted dust was apparent on these floors. The results for Studio B emphasize that sealed floors and assiduous housekeeping are paramount for preventing the development of lead dust and resultant contamination of customer areas. After safety training, Studio B was most readily able to improve their studio hygiene. The customer areas of this studio, though cleaned no more rigorously than comparable areas of other studios, were less contaminated, even though Studio B had been in operation longer than the other four. At the time of follow-up, Studio E had put down a hard plastic floor cover over the carpet in the dipping area. The authors had also recommended that this area be cleaned before glaze drips could dry. Despite the ease with which this floor could have been cleaned, it was obviously contaminated with dried drips of overglaze. The high level (4048 g/ft 2 ) found on this at follow-up illustrates that the presence of a non-porous floor is not enough to reduce contamination. The non-porous floor must be cleaned rigorously (with a designated cloth or mop) to prevent tracking to other parts of the studio. The air sampling results shown in Table 3 give an idea of the potential levels of airborne lead dust to which employees of contemporary ceramics studios might be exposed while performing work with the dipping glaze. These results are believed to be indicative of typical airborne lead levels during the tasks that were sampled. If employees perform these tasks for only a short period of time each day, these results would indicate a low probability of shift-length timeweighted average exposure limits being exceeded. However, for studios where one employee works with the overglaze for a significant length of time, airborne exposure may pose a more significant risk. Even with low levels of airborne lead, proprietors and employees could still take excessive levels of lead into their bodies through the combination of ingestion and inhalation. Recommendations The following recommendations for reducing lead contamination in contemporary ceramics studios are aimed at reducing customer as well as employee exposure to lead. The kiln/dipping area should have a sealed, hard floor and work s that are easy to clean thoroughly. This should be cleaned after each dipping session and after

10 loading the kiln to prevent tracking of lead dust to other parts of the studio. Porous concrete, carpeting and rugs are not acceptable dipping floor s. Hard floors in customer areas should also be sealed and mopped regularly with a designated mop different from that used in the dipping room. If there are carpets in the studio, they should be cleaned using a HEPA (High Efficiency Particulate Air) vacuum cleaner. Other types of vacuum cleaners will suspend lead dust in the air, creating a potential for airborne exposure. Employees of contemporary ceramic studios where lead-containing glazes are used fall under the Occupational Safety and Health Administration s lead monitoring requirements, which include periodic blood lead testing and blood counts. All persons who regularly use a leadcontaining dipping glaze should have their blood lead levels tested at least annually. Anyone who works with lead-containing dipping glaze should wear, at a minimum, protective gloves and an impermeable apron. Either separate shoes or shoe covers should be used in the dipping/kiln room. Non-disposable gloves and shoe covers should be cleaned or replaced regularly. Protective clothing should be removed before leaving the dipping/kiln area. Pieces that have been dipped should be stored only in the dipping/kiln room until fired. Absolutely no food, drink, or smoking should be allowed or stored in the dipping/kiln room. Persons working in the kiln room should always wash their hands before they leave to prevent spreading contamination to other areas of the studio and to prevent accidental ingestion of lead by putting the hands near the mouth or by handling food. Play areas for young children should either be removed or be placed as far away from the kiln room/dipping area as possible. Customers should not be allowed into the kiln/dipping room. Warning signs about the hazards of lead should be placed in the dipping/kiln room. All customers should be encouraged to wash their hands after each session at the studio. The effectiveness of lead control measures should be periodically monitored. If a studio cannot prevent lead dust from migrating into the customer area, then a lead-free dipping glaze should be used. Summary

11 The results of this preliminary investigation indicate that levels of lead contamination found on s in contemporary ceramics studios can be excessive if appropriate studio design and work practices are not followed. Lead dust from contaminated kiln/dipping areas can migrate into customer areas. All dipping rooms should have a sealed, non-porous floor. Drips should be cleaned up as they occur and work s and floors should be cleaned thoroughly after each dipping session. Additional good housekeeping and personal hygiene practices were shown to effectively decrease levels of lead contamination. If a dipping room contains rugs or porous floors, it is unlikely that good housekeeping measures will be effective at preventing lead dust migration out of the dipping room.

12 References Goldwater, LJ, Wysocki, LM, Volpe, RA, eds. Edited Proceedings: Lead Environmental Health - The Current Issues. May 29-30, 1985, Duke University. Published by Division of Occupational Medicine, Duke University, Durham, North Carolina, USA. Meckelburg, Philip, President of Contemporary Ceramics Studio Association. Telephone Conversation. October 3, NIOSH Manual of Analytical Methods, 4th Edition. United States Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health United States Environmental Protection Agency (USEPA), Residential Sampling for Lead: Protocols for Dust and Soil Sampling, EPA Publication 747-R , March 1995, pp