The federal Occupational Safety and Health Administration (OSHA) inorganic lead standard for general industry has not been updated since its passage in 1978. During the past three decades, extensive research in occupational and non-occupational populations indicates that even low-level lead exposures among adults are associated with adverse health effects and that OSHA’s current permissible exposure limit and medical removal requirements are not sufficiently protective of workers’ health. Current science strongly indicates that workers’ blood lead should not exceed 5 µg/dL over their working lifetime. Occupational lead standards should (1) reduce the concentrations of lead in air that trigger regulatory actions, (2) lower the blood lead level that prompts medical removal from work, (3) enhance medical monitoring for lead-related health problems, and (4) incorporate other improvements related to protective clothing, hygiene practices, training, and education. In addition, the federal government should fully fund the Adult Blood Lead Epidemiology and Surveillance Program and extend it to all 50 states as a means of monitoring the effectiveness of efforts aimed at reducing occupational exposures to lead.
Relationship to Existing APHA Policy Statements
- APHA Policy Statement 9006: Occupational Lead Poisoning
- APHA Policy Statement 8807: Surveillance of Occupational Disease and Injury
- APHA Policy Statement 7418: Surveillance for Occupational Disease
- APHA Policy Statement 20084: Calling for a Global Ban on Lead Use in Residential Indoor and Outdoor Paints, Children’s Products, and All Nonessential Uses in Consumer Products
- APHA Policy Statement20054: Occupational Health and Safety Protections for Immigrant Workers
- APHA Policy Statement 8909: Reducing Health Risks Related to Environmental Lead Exposure
- APHA Policy Statement 7211: Lead in the Environment
In 1978, the Occupational Safety and Health Administration (OSHA) promulgated a general industry lead standard based on the renal, neurological, hematological, and reproductive toxicity of lead among both male and female workers. OSHA established an airborne permissible exposure limit (PEL) of 50 µg/m3 as an 8-hour time-weighted average to prevent the blood lead of most workers from exceeding 40 µg/dL.[2,3] At that time, the background blood lead concentration of adults was considered to be 19 µg/dL. The OSHA PEL was established primarily to prevent signs and symptoms of overt lead poisoning and did not include a margin of safety between the PEL and the level associated with adverse health effects.
During the past three decades, extensive research in occupational and non-occupational populations indicates that low-level lead exposure among adults is associated with adverse health effects and that OSHA’s current PEL and medical removal requirements are not sufficiently protective of workers’ health.[4–10] The background blood lead concentration among adults in the United States is now approximately 1 µg/dL. In the general U.S. population, the increased risk of cardiovascular morbidity and mortality associated with chronic blood lead levels between 10 and 25 µg/dL is well established.[11–13] In addition, there is strong evidence of the adverse cognitive effects on offspring associated with prenatal maternal blood lead levels below 5 µg/dL, with no apparent threshold. Low-level lead exposure during childhood is also associated with cognitive deficits and behavior problems.[15,16]
As a result of ongoing concerns about occupational lead exposures, several years ago the National Institute for Occupational Safety and Health (NIOSH) recommended that the scientific literature on lead be reviewed to clarify low-level health effects. The review was conducted by the National Toxicology Program (NTP), which published its findings in 2012 and concluded that there is “sufficient evidence that blood Pb levels <10 and <5 µg/dL are associated with adverse health effects in children and adults.” Specifically, the NTP found that, among adults, blood lead levels below 10 µg/dL are associated with increases in blood pressure, an elevated risk of hypertension, adverse reproductive system effects, and an increased risk of essential tremor.
In 2013, the U.S. Environmental Protection Agency (EPA) published an integrated science assessment of lead and determined that lead exposure is causally associated with coronary heart disease, hypertension, and hematological, reproductive, and developmental effects; also, the assessment showed that there is a likely causal relationship between lead exposure and cognitive functioning decrements, depression, and anxiety.
There is not an effective national surveillance program for work-related health conditions or diseases, including lead poisoning. Because of data, monitoring, and enforcement gaps, the true extent of elevated blood levels among U.S. workers is unknown. OSHA estimates that more than 1.6 million employees may be exposed to lead at work in both industries in general and the construction industry. In 2013, the industries that accounted for the majority of elevated blood lead among adult workers in the United States were manufacturing, construction, services, and mining.
The best source of population-based data on adult blood lead is the Adult Blood Lead Epidemiology and Surveillance Program (ABLES), a partnership between NIOSH and participating states. At one point, 41 states were participating in ABLES; however, according to the most recent figure, only 30 states are now taking part. The state portion of the program lost federal funding in 2013, but a “reduced level” of funding was restored in 2015.
<>Although the geometric mean blood lead concentration among adults in the United States is approximately 1 µg/dL, elevated blood lead levels persist in a significant number of U.S. adults, mostly due to occupational exposures. For example, between 2002 and 2011, 11,536 U.S. adults were identified as having blood lead levels of at least 40 µg/dL. Among those for whom the source of the exposure was known, 91% of cases were attributable to occupational exposures.
According to ABLES data, 7,529 adults had blood lead levels of at least 25 µg/dL in 2012, and 27,218 had levels of at least 10 µg/dL. Among adults with blood lead of 25 µg/dL or above for whom the source of exposure was known, 93% suffered occupational exposures. In 2013, ABLES identified 20,880 adults with blood lead of 10 µg/dL or above and 5,504 with blood lead of at least 25 µg/dL. Although over-time trends in ABLES data indicate a decrease in the prevalence of blood lead of 10 µg/dL or above among employed adults, the data continue to point to the potential for health effects among thousands of lead-exposed workers.
Although all workers who are exposed to lead are potentially at risk of adverse health effects, there are certain groups who may have greater vulnerability. Pregnant women represent an important population with regard to occupational lead exposure, as both women and their fetuses may be adversely affected. Hypertension in pregnancy is associated with blood lead below 10 µg/dL. Increased risks of spontaneous abortion and preterm birth are associated with blood lead below 10 µg/dL as well, and reduced fetal growth is associated with blood lead below 5 µg/dL.
Hispanic and foreign-born workers may be at increased risk of lead exposure, probably as a result of the industries in which they work. A California Occupational Lead Poisoning Prevention Program report showed that, between 2012 and 2014, 6,051 workers had blood lead levels of at least 5 µg/dL, and 63% to 64% of these individuals had a Hispanic surname. Hispanics make up about 42% of California’s workforce. A study in King County (Seattle), Washington, revealed elevated blood lead levels among workers employed in battery manufacturing, in bridge painting, and at gun ranges, with disproportionately elevated levels among Hispanic battery manufacturing and bridge painting workers and Vietnamese battery manufacturing workers .
Finally, although not an occupational group, the children of workers are an important population to consider when setting occupational exposure limits. According to the Washington State Department of Labor and Industries SHARP (Safety and Health Assessment and Research for Prevention) program, approximately 3% of children with blood lead levels of 10 μg/dL or greater are exposed to lead brought home from the workplace. Studies have documented that parental lead exposure is associated with elevated blood lead in children due to lead dust being carried home on clothing and shoes and that eliminating lead pathways from the workplace to the home is critical in protecting children’s health. A case report published in 2015 highlighted this problem. An electronic scrap recycling worker’s two children had blood lead levels of 18 and 14 μg/dL, attributable to take-home exposures.Children exposed to lead are at risk of IQ decrements, behavioral problems, decreased academic performance, delayed puberty, and reduced postnatal growth. As a result of multiple risk factors and environmental injustice, non-Hispanic Black children have higher blood lead levels than non-Hispanic White children, and limited information is available on the extent to which paraoccupational lead exposures contribute to this problem.
For decades, researchers have recommended an update to OSHA’s occupational lead standard to be more protective of workers and to reflect current scientific understandings of health risks from lead.[9,27–29] In addition, the Association of Occupational and Environmental Clinics has concluded that “the evidence for adverse effects [of lead] at levels of exposure far below those currently permitted by OSHA speaks forcefully for an immediate reduction in permissible exposure levels in the workplace.” In 2015, NIOSH “designated 5 µg/dL…of whole blood, in a venous blood sample, as the reference blood lead level for adults.” Therefore, blood lead levels of 5 µg/dL or below are considered elevated. In summary, current science strongly indicates that blood lead levels among workers should not exceed 5 µg/dL over a working lifetime. Notably, this does not account for a margin of safety.
Ethical issues: Since lead is one of the most extensively studied occupational exposures and the evidence linking low-level lead exposures to adverse health effects is strong, it is unethical to continue to expose workers and their families to a known hazard. In addition, OSHA has adopted stringent and feasible standards to protect workers from other toxic metals, including chromium, cadmium, and beryllium, but has not yet acted on inorganic lead.
Evidence-Based Strategies to Address the Problem
In general, workplace exposure standards are designed to maintain worker exposures well below levels known to cause serious adverse health effects. To date, no threshold for adverse health effects has been identified for lead. The current OSHA lead standards are based on outdated toxicity information that did not include consideration of the major cardiovascular and reproductive risks now known to exist at low blood lead concentrations. Currently, OSHA requires that workers be medically removed from lead exposure if they have one blood lead measurement of 60 µg/dL or higher or three measurements averaging 50 µg/dL or higher.
In the absence of updated federal policies on occupational lead, the California Occupational Lead Poisoning Prevention Program is advocating for revised state standards with the goal of maintaining long-term blood lead concentrations among all workers at less than 5 to 10 µg/dL. In the case of women who are pregnant or who are planning to become pregnant, a blood lead concentration below 5 µg/dL is advised. Recent physiologically based pharmacokinetic modeling conducted by the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment indicated that, to ensure blood lead below 10 µg/dL in 95% of workers over a working lifetime, permissible exposure levels for lead in workplace air should not exceed an 8-hour time-weighted average of 2.1 µg/m3. Washington State’s OSHA program is also in the process of updating its occupational lead standard.
Implementation of work practice controls (wet cleaning methods, local exhaust ventilation on power tools, isolation of work areas from non-work areas) minimizes the potential for lead exposure, and such controls are currently in use as a result of the requirements of the EPA Renovation Repair and Painting Rule. Studies have documented that improved hygiene practices in the case of both employees and the work environment lead to decreasing blood lead levels.[33–36] In July 2017, Washington State released a proposed occupational lead regulation that incorporates the current science and technology available for exposure monitoring, task-based assessments, engineering controls, medical surveillance, work practices, use of personal protective equipment, and hygiene practices to reduce workplace lead exposures.
The proposed law directs employers to evaluate employee exposures to lead, establish exposure control plans using “task-based assessments,” and provide protection to employees for each task. A rigorous housekeeping program is also proposed to reduce airborne lead dust levels in workplaces and to minimize the risk of lead ingestion from lead dust accumulating on surfaces. Cleaning practices include using appropriate wet cleaning methods or vacuums that minimize the spread of lead into the air and sampling to ensure that lead on surfaces with which employees have contact is within acceptable levels. In addition, items contaminated with lead should be properly disposed of, and lead-containing materials should be kept in tightly covered containers to minimize spills. Facilities for hand washing must be provided near lead exposure areas. Employees should also be provided with break, lunch, and changing rooms that are free of lead contamination. Employees should be prohibited from eating, drinking, smoking, chewing gum, or applying cosmetics in lead exposure control areas.
When possible, lead should be phased out of industrial processes and consumer products and replaced with materials of lower toxicity. The production of lead-acid batteries accounts for more than 85% of all lead consumed in the United States. New electrolyte chemistries and technologies are being explored and applied in industries in an attempt to transition to safer lead-acid battery alternatives (e.g., vanadium); however, at present there is no drop-in replacement for lead use in batteries.
There are many safer alternatives for other uses of lead. The Massachusetts Toxics Use Reduction Institute prepared an alternative assessment methodology to evaluate the technical, economic, and environmental and occupational health feasibility of alternatives for lead in electronics, sheet lead, wheel weights, fishing sinkers, pigments, and shooting ranges. In addition, according to a recent report, the arms industries in North America and Europe have developed nontoxic bullets (e.g., steel, bismuth, copper, tungsten) that are as effective as their lead counterparts and comparably priced. The U.S. Department of Defense has converted to lead-free reserve cartridges, and many law enforcement and military training centers are making the same transition. Lead-free alloys are used by the military and promoted by the Electronics Manufacturers Association to replace lead-based solders. The painting industry has substituted lead in paint with titanium-oxide and other chemicals. Resources exist to provide information on safer substitutions and processes through industry organizations (e.g., BizNGO), and European databases such as the Substitution Support Portal help businesses with other specific applications.[43,44]
Several industries, such as the electronics industry, have successfully transitioned to safer compounds or production methods.[40,45,46]
A few educational programs have also been found to be effective in reducing lead exposures among workers and their families.[47–49]
There is broad scientific consensus on the health effects of low-level lead exposure. Objections to updating the occupational health standard are likely to be made on the basis of costs and burdens on employers; however, there are no recent studies in the published literature that quantify the costs to lead-using industries in the United States of a more health-protective federal occupational lead standard. With respect to costs to workers and the health care system, a recent study conducted by Levin estimated $141 million in annual “direct medical costs” of occupational lead exposures in the United States. When direct and indirect costs are considered together, they are in excess of $392 million. It should be noted that these cost estimates probably understate actual costs, in that Levin’s study considered only the impact of blood lead concentrations in excess of 30 µg/dL, did not incorporate the costs of cardiovascular mortality, and relied on limited estimates of the extent of occupational lead exposures.
- The OSHA action level and permissible exposure level for lead and medical removal requirements should be based on up-to-date peer-reviewed science, which supports a standard to maintain all workers’ blood lead levels at less than 5 µg/dL.
- OSHA should revise the medical surveillance requirement, including blood lead testing, so that all employees with potential lead exposures are covered. Improved work practices, engineering controls, and blood lead biomonitoring should not be triggered by personal airborne lead level measurements alone, but also by the potential hazard involved in altering or disturbing lead-containing materials.
- OSHA should revise clothing and hygiene requirements for lead workers on the basis of up-to-date peer-reviewed science to reduce lead exposures, minimize lead dust in and around workplaces, and prevent paraoccupational exposures among children and other household members.
- States should set their own standards independent of OSHA, as Washington and California are now in the process of doing. State standards must be at least as stringent as OSHA’s standard.
- OSHA and state occupational health agencies should increase enforcement to ensure that all employers comply with regulations regarding provision of blood lead testing to lead-exposed workers.
- State or local public health departments or state labor programs should provide free blood lead testing to workers whose employers fail to provide it, who fear participating in testing offered by their employer, or who lack insurance coverage for testing.
- State or local public health departments should also make free blood lead testing available to children and other family members of lead-exposed workers. This should include pregnant women and other adults in the household.
- The federal government should fully fund the Adult Blood Lead Epidemiology and Surveillance Program and extend it to all 50 states as a means of evaluating the effectiveness of occupational health and safety efforts aimed at reducing blood lead levels among workers.
- Congress should increase funding of educational programs for health care practitioners to facilitate recognition of lead-related illnesses.
- State and local health departments and state labor programs should work with occupational medicine and nursing associations to encourage training of health practitioners in taking occupational/environmental histories and determining baseline blood lead levels among patients who are exposed to lead.
- When possible, employers should eliminate the use of lead in workplaces. Safer alternatives to the use of lead in commercial and consumer products should be developed and promoted.
- State and local governments should develop educational and training programs for employers with technical expertise to assist in the transition to safer alternatives. The European Union has formulated products without lead, and U.S. manufacturing companies need assistance and incentives to adopt safer substitutes for lead. Currently, OSHA education centers offer a course titled “Transitioning to Safer Chemicals” to assist and provide employers with hands-on experience with processes, key methods, tools, databases, and resources to promote adequate substitutions. More programs are needed.
- State and local governments, OSHA training education centers, and others should work with community-based organizations to develop effective educational resources that provide information to underserved workers and their families about the hazards of lead and steps they can take to protect their health.
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