Deadly dust

Construction workers face the greatest health risks from lead exposure. Here’s how to reduce your risk.

With extensive repair-rebuild-replace jobs underway on older buildings throughout the country, it should come as no surprise that many construction workers are exposed to lead, the metal that was a key ingredient in paints, building materials and soldering compounds used for centuries until the 1970s.

To help reduce lead exposure, the Construction Safety Council (CSC) has developed a training module, Lead Safety in Construction, that identifies sources of lead exposure, its dangers and what can be done to minimize exposure.

This article is based on this training module, which is available through the Construction Safety Council’s Web site, www.buildsafe.org.

Lead dangers
Lead has long been blamed for a myriad of maladies. Reports of illnesses due to lead exposure date back to 2000 B.C. While it has damaging health effects, its ability to provide long-lasting protective coatings, its malleability and low melting point have made it a preferred material in a host of construction applications.

The CSC reports that even if lead was totally prohibited from use today, it would still present a hazard to construction workers for the next 25 to 50 years. The CSC estimates that up to 40 percent of the steel structures in the United States have been painted with or contain compounds that contain lead.

The widespread use of lead over thousands of years means that everyone is exposed to trace amounts of lead, regardless of their occupation. However, certain jobs, mostly construction-related, have a potentially high level of lead exposure. OSHA cites the following construction tasks to have a high risk of lead exposure:

Abrasive blasting
Welding, cutting and burning of steel coated with lead-based paint
Lead burning
Hand-scraping or demolition of buildings or surfaces covered with lead-based paint
Manual demolition of building components with lead-based paint
Heat gun removal of lead-based paint
Chipping, sanding or wire-brushing of lead-treated surfaces
Use of lead-containing mortar
Stained glass repair and removal
Industrial vacuuming
Reinsulation with mineral wool

Lead absorption
It’s not completely understood how lead affects the body, but it can cause serious damage. That’s why protection is so important on any job where lead may be disturbed.

The human body absorbs lead through ingestion (eating) or inhalation (breathing). It is readily absorbed into the bloodstream, but is filtered by the kidneys and colon. Chronic exposure will cause it to accumulate in the liver, kidneys, fat and bone.

Scientists believe it takes the body 25 days to filter out half of the lead absorbed into blood; 40 days from other organs and more than 25 years from bone.

Lead exposure can lead to acute (immediate) or chronic (long-term) health effects. Acute effects, caused by inhaling or ingesting excessive amounts of lead, can cause a metallic taste in the mouth, abdominal pain, constipation, arm and leg pain, high blood pressure, reproductive problems and vomiting.

Chronic effects of lead poisoning occur as the metal slowly builds up in the system over years of moderate to low doses of lead exposure. Symptoms of chronic lead poisoning include fatigue, weight loss, insomnia, reduced sex drive and function, blue line on gums, shaky arms, numbness in hands and feet, nervous irritability, fine tremors, dizziness, convulsions, reproductive problems and kidney failure.

For children, the effects of lead are even more damaging. If you have contaminated work clothes, they should not come in contact with children or their clothing and you should follow proper hygiene to reduce or eliminate chances of lead contamination in your home.

There is no clear distinction between safe and unsafe levels of lead exposure. OSHA has established an Action Level (AL) for lead at 30 micrograms per cu. meter of air (calculated as an eight-hour time-weighted average). If lead exposure is suspected, employers must quantify the exposure level and put programs and precautions in place to minimize or eliminate worker exposure.

Employers can measure exposure levels to lead through historical records, x-ray fluorescence, paint chip analysis or through quick-test chemical methods. If tests show levels above the AL, the employer must develop and comply with ways to minimize worker exposure so it does not exceed the personal exposure limit (PEL) of 50 micrograms per cu. meter of air.

If exposure exceeds the AL but is less than the PEL, some actions will be required; if exposure is greater than the PEL, extensive actions must be taken to protect workers.

Employers may be required to track employee or worker health, using lead exposure assessment. Medical tests are used to set a baseline for the worker’s lead exposure and are used to compare lead levels found in future tests. Test results will dictate whether additional safeguards are needed to minimize or eliminate lead exposure. Generally, if a worker has an airborne lead exposure at or above the AL for more than 30 days, the employer must provide a medical surveillance program for the worker.

Managing exposure on the jobsite
When a worker or crew must complete tasks that increase their level of exposure to lead, OSHA requires a written compliance plan, an in-depth document that describes the risk, the tasks associated with the risk and the engineering and administrative controls to be used to minimize the risk. If others work in the area, they must be made aware of the actions needed to reduce their exposure.

Engineering controls modify how work is performed. For example, using a 6' torch instead of a standard torch is an engineering control that increases the distance between the lead source and the worker.

Generally, engineering controls for lead abatement fall into the following categories: substitution, process or equipment modification, isolation or encapsulation.

Substitution uses other materials to remove or replace the lead-based compounds. Use of non-lead based paints or lead-free solder, using shears instead of cutting torches or using chemical strippers instead of abrasion to remove lead-based compounds are good examples.

Process or equipment modification includes using ventilation to pull lead-tainted fumes away from the work area; dust collection equipment on tools; or hydro- or wet-blasting to capture dust.

Isolating the work from others can also help minimize exposure. It may be as simple as erecting signs and barriers or as complex as erecting a negative-pressure enclosure around the work area.

Encapsulation is used to keep the lead-containing material in place. Conventional paints can’t be used as encapsulants. Encapsulation can not be considered lead abatement.

Work practice controls rely on housekeeping, hygiene and established practices for eating and hand washing. Signs and barriers can be used to limit exposure, especially to unauthorized workers.

All work surfaces should be free of lead-laden dust. Vacuuming is effective, but the vacuum system must be equipped with a high-efficiency particulate air (HEPA) filter. Shoveling, dry- or wet-sweeping or brushing can be used but may raise enough dust to create a secondary exposure to airborne lead particles. Do not use compressed air unless it is used with a collection system that captures airborne dust. Workers cleaning up dust should use practices that reduce their exposure and dispose of collected dust properly.

Hygiene important
Hygiene can reduce lead ingestion. Clothing changing areas must be used when lead levels are higher than the PEL and should have separate storage for protective work clothing and street clothing. Showers with cleansing agents and towels should also be provided.

Eating facilities on the jobsite must be protected from airborne lead levels greater than the PEL. Food, beverages, tobacco products and cosmetic items can’t be stored, consumed or used in areas where the lead exposure is greater than 50 micrograms per cu. meter. Employees working in lead abatement areas must change clothes or have surface dust removed from clothing by a HEPA-rated vacuum, downdraft booth or other way that limits dust dispersion. Workers must wash their hands and face before eating, drinking, smoking or applying cosmetics.

Warning signs must be used in areas that exceed the PEL to warn unauthorized people of the danger. They should be placed at entrances and exits to the work area and be far enough away from the hazard to give the worker enough time and distance to avoid the area or take precautions to protect themselves.

Administrative controls rely on managing the work crew to limit or eliminate worker exposure. Job rotations that are thoroughly documented and followed can reduce exposure.

Personal protection equipment (PPE) is considered by OSHA to be a last line of defense against lead exposure. Respirators and other forms of protection must be used when the administrative and engineering controls do not fully eliminate or limit the exposure to below the PEL.

Respirator use
A respirator is required when the PEL can’t be reached with administrative or work practice controls or if a worker requests it. Several respirator styles are available and each have pros and cons with their use and are included in the employer’s written respiratory protection program. It provides a consistent company policy for the respirator selection, training, use, maintenance and program evaluation.

OSHA requires workers be evaluated to assure they can perform tasks while wearing a respirator. OSHA also requires at least annual physicals to ensure workers’ health has not changed. Based on evaluations, the physician can disqualify workers if their health is affected by exposure.

Protective wear
Workers need protective wear if the job takes them into areas with lead levels above the PEL and/or if the employees are exposed to lead compounds that cause skin or eye irritation. Coveralls or other full-body clothing, gloves, hats and shoes or disposable shoe coverlets, face shields, vented goggles and any other needed safety equipment must be used.

Disposal concerns
Lead-contaminated protective clothing must be treated with care. Either dispose of it or clean it. If clothing is transported to another facility for cleaning, clearly mark the containers or bags with: “Caution: Clothing contaminated with lead. Do not remove dust by blowing or shaking. Dispose of lead-contaminated wash water in accordance with applicable local, state and federal regulations.”

Wearing PPE can create heat stress and dehydration, which could lead to heat stroke. Carefully monitor workers for signs of heat stress.

Published in the January/February 2006 issue of Contractor Tools and Supplies magazine.