May 1998 Volume 20 Number 2
May 1998 Volume 20 Number 2
This extract has been prepared to present the information most relevant to the practicing conservator from the Guidelines, which, don't forget, were intended for the building rehabilitation trade and not conservation. We have included here primarily the information on low risk exposures as that is what many of us may experience in our studios. There are many more sections that are relevant, but space did not allow their inclusion. (Tables and Figures cited in the text have not been reprinted here.) A longer edited version of the document will be available on-line (http:palimpsest.stanford.edu/waac/). The bulleted topic headings have been added to make this edited version more compresensible.
Notable sections omitted from this digest are: Chapter 9, pages 12-21, "OSHA Requirements for Residential Lead Hazard Control Work"; Chapter 10, "Hazardous and Nonhazardous Waste; and Chapter 18, "Lead Hazard Control and Historic Preservation."
The complete Guidelines are available on-line at http://www.hud.gov/lea/learules.html. The printed version is available from HUD USER (call (800) 245-2691) for $45.00. The Guidelines are not copyrighted. A representative of HUD USER said no permission was needed to reprint them.
A. Evidence of Lead Poisoning Caused by Renovation (Chapter 4: Lead-Based Paint and Housing Renovation; pp. 3-4)
There is substantial evidence that uncontrolled housing renovation work can cause lead poisoning. One study found that refinishing activity performed in dwellings with lead-based paint was associated with an average 69-percent increase in the blood lead level of the 249 infants living there (Rabinowitz, 1985a). Another study of 370 recently lead-poisoned children found a statistically significant association between household renovation activity and elevated blood lead level (EBL) (p<0.0001) (Shannon, 1992). Other researchers have also reported cases where renovation activity has resulted in EBLs (Fischbein, 1981; Marino, 1990). The Marino case report (named after the physician who treated the family) is summarized here.
Case Report: Renovation and Lead Poisoning.
The Marino case report (Marino, 1990) is an example of how
uncontrolled renovation work can cause lead poisoning in both adults
and children. The dwelling involved was a 2-story, 19th century
Victorian farmhouse with 10 rooms. Most of the wooden floors,
moldings, walls, ceilings, and door frames had been painted with
lead-based paint.
The renovation work included restoration of surfaces by removing the paint down to the bare surface on floors and woodwork and recoating with new varnish. Ceilings were repaired, and wallpaper and paint were removed from a number of walls. Two workers used rotary power sanders, hand sanders, scrapers, torches, heat guns, and chemical paint strippers. The family left the house during most of the renovation work, but returned after it was only partially completed. There was dust throughout the dwelling.
After one of the family's dogs started to have seizures, a veterinarian determined that the dog was lead poisoned. The mother and two children were subsequently tested. The children had blood lead levels of 104 µg/dL and 67 µg/dL, which is 5 to 10 times above the level of concern established by the Centers for Disease Control and Prevention (CDC) (10 µ/dL). The mother had a blood lead level of 56 µg/dL. All three were admitted to a local hospital where they were treated for severe lead poisoning. The mother was 8 weeks pregnant and opted for a therapeutic abortion. A baby-sitter who had two children of her own sometimes cared for all four children in the home. The baby-sitter's two children were also tested and found to have blood lead levels of 80 µg/dL and 68 µg/dL. These two children were also hospitalized and treated for severe lead poisoning.
II. Adult Occupational Exposure to Lead (Chapter 9: Worker Protection pp. 5-6)
Inhalation of dust and fumes, and ingestion resulting from contact with lead-contaminated food, cigarettes, clothing, or other objects, are the major routes of worker exposure to lead. Once absorbed, lead accumulates in the blood, soft tissues, and bones, with the highest accumulation initially in the liver and kidneys (NIOSH, 1992). Lead is stored in the bones for decades, and may cause toxic effects in adults as it is slowly released over time (Silbergeld, 1992). Chronic overexposure to lead results in damage to the kidneys, the gastrointestinal tract, the peripheral and central nervous systems, the reproductive system, and the blood-forming organs. Adverse effects in adults include:
The frequency and severity of symptoms associated with lead exposure increase as blood lead levels increase. The signs and symptoms of chronic lead poisoning are well recognized (Hernberg, 1988; Landrigan, 1985; Proctor, 1988).
Overt symptoms of lead poisoning in adults generally become apparent when blood lead levels are between 60 and 120 micrograms per deciliter (µg/dL) (Figure 9.1). Neurologic, hematologic, and reproductive effects, however, may be detectable at much lower levels. OSHA recommends a blood lead level no greater than 30 µg/dL to prevent reproductive problems, although the medical removal provisions do not take effect until the level reaches 50 µg/dL. In 1990, the U.S. Public Health Service established the national goal of eliminating, by the year 2000, all occupational exposures that result in worker blood lead levels > 25 µg/dL (DHHS, 1990). The mean blood lead level for men in the United States during the period from 1976 to 1980 was 16 µg/dL (Mahaffey, 1982; Annest, 1983). In addition, the American Conference of Governmental Industrial Hygienists (ACGIH) has proposed that worker blood lead levels be controlled to 20 µg/dL (ACGIH, 1993).
Recent studies suggest that adverse health effects can be detected when blood lead levels are below the current OSHA standard for occupational exposure (50 µg/dL). Therefore, the OSHA standard may not sufficiently protect workers' health. OSHA is currently developing a final rule to address this issue (the current rule is an interim final standard).
In males, increased blood lead levels are associated with increased blood pressure, with no apparent blood lead threshold (less than 10 µg/dL). A number of studies have found neurological symptoms in workers with blood lead levels as low as 40 µg/dL. In addition, decreased fertility in men (low sperm count, low sperm motility, and abnormal sperm shape) has been identified at blood lead levels as low as 40 µg/dL.
In women, exposure to lead (as low as 10 to 15 µg/dL) before and during pregnancy is associated with preterm delivery, low birth weight, an increased frequency of miscarriage and still-birth, and problems in early mental development of the fetus (ATSDR, 1990; National Academy of Sciences, 1993).
When a family member is occupationally exposed to lead, leaded dust may be carried home on clothing, on skin and hair, and in vehicles. High blood lead levels in resident children and elevated concentrations of lead in house dust have been found in the homes of workers employed in industries associated with high lead exposure (Grandjean, 1986). Children of workers with lead poisoning or children of any worker exposed to high lead levels should be tested for lead exposure by a qualified health-care provider.
B. Leaded Dust (Chapter 4; p. 4)
It does not take much leaded dust to create a hazard. The use of palm sanders, belt sanders, and sandpaper can increase the amount of hazardous leaded dust by a great deal. Almost any activity that involves disturbing a lead-containing surface will temporarily increase the amount of microscopic leaded dust in the surrounding environment.
To understand how easily leaded dust hazards can be created from jobs disturbing lead-based paint, consider the following example. Suppose renovation work is done on only 1 square foot of painted surface and all the paint inside that square foot is turned into dust by sanding or some other work. If the paint has 1 mg/cm2 of lead in it (the lowest level covered by HUD regulation) and if the dust is spread out over a 100-square-foot area, there will be about 9,300 µg/ft2 of leaded dust present, which is nearly 100 times greater than the allowable level. HUD does not permit more than 100 µg/ft2 of leaded dust to be left on floors following lead hazard control work. In short, dust-generating work performed on even a small area can cause a serious problem if not controlled and cleaned up. Of course working on a small area requires only modest cleaning and control measures, as described in Chapters 8 and 11.
V. Prohibited Activities (Chapter 4; p. 8)
Many traditional methods of preparing a painted surface for repainting, refinishing, or restaining are prohibited if the old paint contains lead, since these methods are known to poison both children and workers. Chapters 11 and 12 discuss safe ways of removing lead-based paint. Prohibited methods of paint removal include:
A. Worksite Preparation Level Selection (Chap. 8: Resident Protection and Worksite Preparation; pp. 6-7)
When planning a lead hazard control job, the worksite preparation levels listed in Tables 8.1, 8.2, and 8.3 should be considered. Since each worksite is unique, it is necessary to pick the level that is the most cost-effective for each specific situation. This judgment should be made by a certified risk assessor, a certified abatement supervisor, or a trained lead-based paint planner/designer. The tables provide guidance on choosing the appropriate preparation level for each job.
The necessary worksite preparation level will depend on:
These Guidelines are performance-oriented and are not specifications. It is possible to select elements from different worksite preparation levels to devise a unique worksite preparation plan for an individual dwelling. Whatever combination of containment measures is selected, the levels of leaded dust outside the containment area must not rise above clearance levels. Containment measures should be designed to prevent the release of leaded dust, which can be spread by workers' shoes or by airborne dust. This flexibility permits owners to select the most cost-effective strategy, while also protecting the public health and the environment.
VII. Negative Pressure Zones (Chap. 8; p. 9)
In asbestos abatement work and lead-based paint removal work on structural steel, it is common to create work sites that are under negative pressure in comparison to the outside of the containment structure. A negative pressure zone is usually created by blowing air out of the work area through a HEPA filter, while air intake is restricted to a lower flow rate than exhaust. This process causes air to leak into the containment area instead of out of the containment area, and reduces dust fall and worker exposure by removing contaminants from the airstream through constant filtration.
Due to the different aerodynamics of leaded dust particles and asbestos fibers, negative pressure zones do not appear to be necessary for most forms of residential lead hazard control work. No effect on airborne lead levels, either inside or outside the containment area, has been associated with the use of an air filtration device commonly known as a "negative air" machine (NIOSH, 1993a). In addition, no effect on cleanup efficiency was noted. Most lead-based paint abatement projects in the public housing program have not found it necessary to use negative air machines. Therefore, the added expense of requiring negative pressure zones for general residential lead-based paint hazard control work does not appear to be justified.
Chapter 17: Routine Building Maintenance and Lead-Based Paint, p 14. Note to Table 17-1 (Chapter 17: Routine Building Maintenance and Lead-Based Paint, p. 6)
High-risk jobs typically disturb > 2 square feet per room. If these jobs disturb < 2 square feet, they can be considered low-risk jobs.
A. Worksite Containment and Occupant Protection (Chap. 17; p. 13) 2. Low-Risk Jobs
For low-risk jobs disturbing a small surface area and not generating much dust, worksite containment consists of a relatively small sheet of plastic (no less than 5 by 5 feet) placed underneath the immediate work area. An exception to this rule is ceiling work where dust contamination is likely to be widespread. For most types of ceiling work, the entire floor and all furnishings should be covered with plastic.
Doors to the work area should be kept closed until cleanup has been completed. The gap at the bottom of the door should be taped shut. Children are not permitted in the work area until the supervisor has visually inspected the cleanup. However, children may be present in adjoining rooms and need not be removed from the entire dwelling (although relocation is preferable). Worksite Preparation Level 1 should be adequate (see Chapter 8).
B. Respirators (Chapter 17; p. 14) 1. Low-Risk Jobs
Respirators are not required unless time-weighted average exposures are greater than 50 µg/m3 as an 8-hour, time-weighted average. Unfortunately, virtually no data exist that characterize maintenance worker exposures. Chapter 9 noted that OSHA requires respirators to be used whenever certain tasks are performed, unless air sampling demonstrates that exposures are low. These tasks include the following:
Respirators must be used in conjunction with a respirator program (29 CFR 1910.134) that requires respirators to be fitted to the individual, cleaned and stored properly, and used within their design limits by individuals medically fit to use them (as determined by a physician), among other requirements.
C. Protective Clothing (Chapter 17; p. 14) 1. Low-Risk Jobs
Protective clothing is not required for low-risk jobs. However, workers must not wear their work clothing home and should ensure that their clothing is laundered separately from their family's clothing.
Protective clothing should be worn if a low-risk job disturbs more than 1 square foot.
Workshoe disposable coverings should be worn to avoid tracking leaded dust throughout the dwelling, unless work will be conducted on ladders. Shoe coverings are not recommended for situations that create a significant risk of workers falling or slipping.
D. Personal Hygiene and Showers (Chap. 17; p. 15) 1. Low-Risk Jobs
Many studies have revealed that poor personal hygiene of workers during lead hazard control jobs can cause lead poisoning. Therefore, thorough washing of the hands and face is required even for low-risk jobs disturbing less than 1 square foot. Eating, smoking, drinking, and applying cosmetics while in the work area should not be permitted. Hand-to-mouth contact should also be minimized. For low-risk jobs, showers are not required.
E. Work Practices (p. 15)
Protective work practices are the same for both low- and high-risk jobs. Surfaces should be wetted when possible to retard the entrainment of leaded dust into the air. A garden sprayer or pump/squeeze bottle can be used for this purpose. Enough water should be used to just coat the surface; use of excessive water can cause runoff and substrate damage. Work should proceed carefully and deliberately to reduce the amount of dust generated.
Wet methods must not be used near electrical circuits due to electrocution hazards.
Children are not permitted in the work area until after completion of all cleanup and final visual inspection.
F. Cleaning (Chapter 17; p. 15) 1. Low-Risk Jobs
A HEPA vacuum is not required for low-risk jobs, since all the leaded dust will be caught by the plastic sheeting. However, limited wet cleaning with trisodium phosphate detergent or other lead-specific cleaners or equivalent should be performed twice on all horizontal surfaces at least 2 linear feet beyond the plastic in all directions. Vertical walls or other building components near the work area should also be cleaned. A mild detergent can be used on those surfaces where the finish is likely to be marred by the use of trisodium phosphate. There should be no visible dust in the cleaned area. Brooms should not be used to clean up dust; only wet methods are recommended.
Appen. 11: One Hour Waiting Period Rationale for Clearance Sampling
This Appendix describes the rationale for why it is necessary to wait no longer than one hour to conduct clearance examinations. Conservative (health protective) assumptions have been made throughout the analysis to ensure that the risk is minimal. The scenario is that no one will enter the room or work area for at least one hour to minimize air turbulence and reentrainment of small particles. The rationale shows why one hour is a safe waiting period and why additional benefits will not be gained by waiting longer.
(Extracted from: "Table 8.1 Interior Worksite Preparation Levels (Not Including Windows") (Chapter 8; pp. 11-12) Level 1
Typical Applications (Hazard Controls): Dust removal and any abatement or interim control method disturbing no more than 2 square feet of painted surface per room.
Containment and Barrier System: Single layer of plastic sheeting on floor extending 5 feet beyond the perimeter of the treated area in all directions. No plastic sheeting on doorways is required, but a low physical barrier (furniture, wood planking) to prevent inadvertent access by resident is recommended. Children should not have access to plastic sheeting (suffocation hazard).
Warning Signs: Required at entry to room but not on building (unless exterior work is also under way).
Ventilation System: Dwelling ventilation system turned off, but vents need not be sealed with plastic if they are more than 5 feet away from the surface being treated. Negative pressure zones (with "negative air" machines) are not required, unless large supplies of fresh air must be admitted into the work area to control exposures to other hazardous substances (for example, solvent vapors).
Cleanup (See Chap. 14 for further discussion of cleanup methods): HEPA vacuum, wet wash, and HEPA vacuum all surfaces and floors extending 5 feet in all directions from the treated surface. For dust removal work alone, a HEPA vacuum and wet wash cycle is adequate (i.e., no second pass with a HEPA vacuum is needed). Also wet wash and HEPA vacuum floor in adjacent area(s) used as pathway to work area. Do not store debris inside dwelling overnight; transfer to a locked secure area at the end of each day. Dust Sampling: Clearance only.
F. Protective Clothing and Equipment (Chapter 9; pp. 21-23)
OSHA requires that employers provide and enforce the use of protective clothing whenever employees are exposed to airborne lead above the PEL (irrespective of respirator use) and as interim protection for employees performing tasks listed in the task-related triggers. Hardhats, goggles, safety shoes, and other personal protective equipment may also be required by other OSHA standards, depending on the type of work performed. These materials must be supplied at no cost to employees.
Leaded dust is not absorbed directly through the skin; however, lead contamination of workers' clothing and person has resulted in lead exposure for workers and their families in the past. The use of protective equipment, in conjunction with good hygiene practices and washing facilities, should prevent contamination of workers' personal clothing and prevent the transfer of lead contamination from the work area to lunch and break areas, personal vehicles, and workers' homes. Workers should be equipped with disposable or reusable coveralls or similar full-body work clothing, gloves, hardhats, safety shoes, disposable shoe covers, chemical-resistant clothing (for skin-contact hazards), safety glasses, face shields, and goggles (in conjunction with portable eyewash equipment).
Since workers may spend most of their time on abatement jobs wearing protective clothing, it should be selected to prevent heat stress. For example, the use of breathable clothing (cotton or paper fabric) is appropriate during most abatement work to reduce the potential for employee heat stress. Shoes or disposable shoe covers should have nonskid soles, particularly for work on plastic-covered surfaces. They should not be used when workers need to climb ladders and scaffolding because they may cause slips and falls; nonskid work boots should be used instead. Work boots or shoes should be removed from the work area only in a sealed plastic bag. Torn shoe coverings also present a serious hazard and should be replaced as often as necessary. Chemical-resistant protective clothing will be necessary for any work involving caustic or solvent-based strippers and other substances that are hazardous upon skin contact. For example, caustic paint strippers require special clothing and gloves (see the Manufacturer's MSDS). Paper suits and shoe covers are not appropriate for chemical processes.
Employers are responsible for cleaning, laundering, and disposing of protective clothing and equipment; repairing or replacing protective clothing and equipment to maintain its effectiveness; ensuring that all protective clothing is removed at the end of a work shift only in designated change areas; ensuring that contaminated clothing is placed in a closed container in the change area to prevent the spread of lead contamination; and notifying in writing anyone who cleans or launders the protective clothing that the clothing is contaminated with lead. Removal of lead from clothing by blowing, shaking, or any other means that disperses lead into the air is prohibited. HEPA vacuuming heavily contaminated protective work clothing as an initial cleaning method is recommended.
I. Medical Surveillance (Chapter 9; pp. 25-26)
Workers must undergo both initial and routine medical surveillance, depending on the level and duration of their airborne exposures to lead. Employers and physicians should consult Appendix C in 29 CFR 1926.62 for detailed guidelines on medical surveillance of lead-exposed workers. All medical examination procedures must be under the supervision of a licensed physician, preferably one who is board-certified in occupational health.
1. Cleaning Hard Surfaces (Chapter 11: Interim Controls; B. Methods of Dust Removal; p. 40)
The standard dust removal procedure for hard surfaces and components (e.g., hardwood floors and window components) is HEPA vacuuming followed by wet cleaning with trisodium phosphate (Milar and Mushak, 1982), or a cleaner designed specifically for lead removal or an equally effective cleaner. One minute per square meter (approximately 10 square feet) did not remove substantially more leaded dust from hard surfaces than faster methods (Ewers, 1993).Therefore, no speed or time restrictions are necessary for hard surfaces (although such restrictions are appropriate for carpeted surfaces, as detailed below).
On hard surfaces HEPA vacuums should be passed over the entire surface with overlapping strokes using normal speed. Trisodium phosphate has been shown to aid in the removal of lead in dust. There is also strong anecdotal evidence that a lead-specific, strippable coating (Grawe, 1993) and a lead-specific detergent (Wilson, 1993) are at least as effective as trisodium phosphate in removing lead. These new products may in fact be more effective than trisodium phosphate, which is now banned in some areas. Any cleaning product may be used, as long as the cleaner's performance is evaluated by determining compliance with clearance criteria and lead-specific cleaning agents.
A. Introduction (Chapter 12: Abatement; Section IV; I. Paint Removal Methods; p. 35)
While paint removal can be performed safely and effectively, it also demands the highest level of control and worker protection for several reasons. Paint removal usually creates the greatest hazard for the worker, either from the hazards associated with the removal process (e.g., heat, chemicals, and sharp tools) or from the lead that becomes airborne or is left as a residue on the surface after removal. Extensive onsite paint removal should usually have an Interior Worksite Preparation Level 4 and an Exterior Worksite Preparation Level 3. Lower levels are possible if the size of the area to be treated is small (see Chapter 8). Because of the lead residues left behind by all paint removal methods, particularly on porous surfaces such as wood or masonry, more extensive cleaning is usually required to meet clearance criteria. Paint removal methods also generate a significant amount of hazardous waste and may be the most costly of all lead abatement methods (HUD, 1991).
A. Performance Standard (Chapter 14: Cleaning; p. 5)
Although the cleaning methods described in this chapter are feasible and have been shown to be effective in meeting clearance standards, other methods may also be used if they are safe and effective. This performance-oriented approach should stimulate innovation, reduce cost and ensure safe conditions for both residents and workers.
C. Difficulties in Cleaning (Chapter 14; p. 5)
While cleaning is an integral and essential component of any lead hazard control activity, it is also the most likely part of the activity to fail. Several common reasons for this failure include low clearance standards, worker inexperience, high dust-producing methods, and deadlines.
1. Low Clearance Standards (Chapter 14; p. 5)
Because very small particles of leaded dust are easily absorbed by the body when ingested or inhaled, a small amount can create a health hazard for young children. Therefore, "clearance standards" are extremely low for acceptable levels of leaded dust particles on surfaces after hazard control activities, and careful cleaning procedures are required. Although it is not possible to remove all leaded dust from a dwelling, it is possible to reduce it to a safe level.
Clearance standards are described more fully in Chapter 15. The permissible amount of leaded dust remaining on each of the following surfaces following lead hazard work is as follows:
These levels are based on wipe sampling. Clearance testing determines whether the premises or area are clean enough to be reoccupied after the completion of a lead paint hazard control project. A cleaned area may not be reoccupied until compliance with clearance standards has been established. To prevent delays, final testing and final cleaning activities should be coordinated.
3. The HEPA/Wet Wash/HEPA Cycle (Chapter 14; pp. 11-13)
Typical Procedures. The usual cleaning cycle that follows lead hazard control activities is called the HEPA vacuum/wet wash/HEPA cycle and is applied to an entire affected area as follows:
The rationale for this three-pass system is as follows:
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