Lead poisoning is not just a childhood hazard. Even tiny amounts of the toxic metal can cause high blood pressure and heart disease in adults, according to a new analysis released by the U.S. Environmental Protection Agency this past June. Yet the federal Occupational Safety and Health Administration (OSHA) has not updated its general workplace standards for lead exposure since establishing them 35 years ago. As a consequence, thousands of Americans working in industries such as lead-battery manufacturing, renovation and automobile repair inhale or ingest lead dust at levels that public health experts now consider unsafe.

California is not waiting for the federal government to make a move; its Division of Occupational Safety and Health (Cal/OSHA) is already working toward tightening up its similarly outdated regulations on lead exposure. If California succeeds and demonstrates that its lead-related businesses can survive tougher regulations, it could set an influential precedent. Given the state’s substantial industrial base and status as the world’s ninth-largest economy, “it would be a model for the rest of the country that revisions are feasible,” says Michael Kosnett, a member of a Cal/OSHA public advisory committee on lead standards and an occupational medicine physician at the University of Colorado School of Medicine in Denver.

Originally mandated in 1978 to protect against classic lead poisoning—which can cause anemia, nerve and kidney damage, and in severe cases, convulsions and death—current workplace regulations generally prohibit exposures that result in employees accumulating more than 40 micrograms of lead in every deciliter of blood (mcg/dl). If levels exceed 50 or 60 mcg/dl, the rules require “medical removal”: temporarily pulling a worker from job duties, with full pay and benefits, until levels recede.

But as detailed in the Science of Health column in Scientific American’s September 2013 issue, numerous studies in the last 20 years have linked concentrations of lead in the blood below 40 mcg/dl to subtle, long-term health issues, including damage to the heart, brain and kidneys. The new EPA analysis, which assessed the best available data on the metal’s impacts on the ecosystem and human health, further bolsters that new scientific consensus. The body of evidence is “just getting stronger,” says EPA health scientist Mary Ross, based at the National Center for Environmental Assessment. The research indicates, for example, that by modestly raising blood pressure, lead can push a lot of people at risk of cardiovascular trouble into the dangerous territory of hypertension and heart disease—and raise their likelihood of dying from heart attacks or strokes. Other studies associate small amounts of lead with cognitive decline in older adults. The element builds up in the skeleton, but can leak back into the blood as bones thin with senescence.

Given the mounting evidence, occupational health researchers have criticized federal OSHA’s regulations for failing to adequately safeguard workers against cumulative exposures to lead and have called for the agency to update its standards, to no avail. Despite the lack of regulatory action on the matter, many lead-related companies have taken the initiative to adopt better engineering controls—such as proper ventilation equipment to reduce levels of lead dust in the air—and hygiene protocols to decrease employee exposures to the metal, says Perry Gottesfeld, director of the nonprofit Occupational Knowledge International in San Francisco, and a member of the Cal/OSHA advisory panel.

But voluntary efforts do not go far enough, Gottesfeld and others say. Whereas data from the National Institute for Occupational Safety and Health indicate that the proportion of U.S. workers with blood levels of lead above 40 mcg/dl has gradually declined over the decades, at least tens of thousands of workers still have blood lead levels of 10 mcg/dl or higher—exposures that could still be harmful. And some firms still fail to comply even with the existing standards, Gottesfeld notes: Last year, federal OSHA fined automotive battery manufacturing behemoth Johnson Controls for serious, willful and repeated violations (pdf) that exposed workers at an Ohio plant to hazardous amounts of lead.

In 2009 the California Department of Public Health’s Occupational Health Branch (OHB) adopted more protective medical guidelines that advised physicians to generally keep workers’ lead levels below 10 mcg/dl (and below five mcg/dl in pregnant women) as well as initiate medical removal at 20 or 30 mcg/dl, depending on circumstances, until levels recede below 15 mcg/dl. California based the guidelines on recommendations published two years earlier by a group of experts, including Kosnett in Colorado and OHB’s Barbara Materna and Karen Hipkins.

The guidelines, however, are neither mandatory nor legally binding. So in 2010 Materna and Hipkins’s branch petitioned Cal/OSHA to update its regulatory standards. The Western Occupational and Environmental Medical Association, representing health care providers in California and four other states, had submitted a similar petition. In response Cal/OSHA convened a public advisory committee that has met twice, in 2011 and 2012, to consider the idea. Besides lowering the medical-removal threshold, the proposed revisions would mandate more extensive blood testing to monitor employees’ lead exposures as well as cut down on lead in the air in workplaces. Whereas the EPA in 2008 slashed its national air quality limits for the element to 0.15 microgram per cubic meter of air to protect public health, the federal and California OSHAs both permit up to 50 mcg per cubic meter.

Among businesses that work with lead, the proposed regulation changes have stirred up resistance from some firms, but have drawn support from others. Battery Council International, representing lead-based manufacturing, supply, recycling and distribution companies in North America, is strongly opposed. The trade association, which says that the average blood lead level of lead-battery workers is already less than 20 mcg/dl, testified in January 2012 that it preferred a medical-removal threshold of 40 mcg/dl. (This past June, however, it announced a new voluntary program to reduce employee blood concentrations by 2017 to below 30 mcg/dl, and to remove workers if they exceed that level.)

More generally, Battery Council International argues against applying public health department recommendations to the occupational health world, which operates under different principles. Under federal and state law, workplace safety and health regulations must identify and protect against “material impairments” of health or functioning, says David Weinberg, the organization’s legal counsel. Although many epidemiology studies have reported increased risks of subtle health problems across an entire population due to small amounts of lead, the organization questions whether such statistical projections would legally qualify as evidence of material impairment in individual workers, Weinberg says.

The law also requires that occupational regulations are economically and technically feasible. But the burden of meeting more stringent lead standards—such as the expenses of added engineering controls, of increased blood testing for lead in workers and of losing employees to medical removal while still paying their salary and benefits—might drive some companies to move out of the U.S., the battery association says. Even if they currently have good controls on lead exposure, Weinberg notes, some businesses may have to remove or dismiss older supervisors who accumulated higher amounts of lead in their bodies over many years, some of it from everyday, nonoccupational exposures in past decades when lead dust from the use of leaded gasoline and paint pervaded the air, soil and homes.

Yet other businesses support the proposed new lead standards as prudent and reasonable, including the Association of Environmental Contractors (which removes old leaded-paint contamination) and, surprisingly, one battery industry maverick, the RSR Corp. RSR owns three lead battery recycling plants located in California, Indiana and New York State. The company has put a lot of energy and capital investment into lowering workers’ lead exposures because “it’s the right thing to do,” says Scott Bevans, manager of RSR’s Quemetco lead smelting plant near Los Angeles. For instance, the plant added exhaust ventilation hoods above identified sources of lead dust and employees receive training on good work practices and hygiene routines, such as properly using “clean” versus “dirty” locker rooms to keep their street clothes separate from lead-tainted work uniforms and protective equipment. As a result of such measures, the average blood lead level in Quemetco workers last December was 9.2 mcg/dl, down from 13.1 mcg/dl in December 2002, Bevans says.

The plant crew typically undergoes quarterly blood tests for lead, and anybody exceeding 15 mcg/dl gets monthly monitoring and receives counseling to identify exposure sources and mitigate them. For instance, after Gregory Barlow, a supervisor in the “battery wrecker” department, tested at 22 mcg/dl two years ago, he gradually reduced his blood lead level to around 14 to 16 mcg/dl by switching to a different type of respirator mask and making sure to always wash his hands before eating lunch. Although some firms may say that it is not feasible to meet the tougher proposed standards, “clearly it is feasible because RSR can do it,” Kosnett says.

For now, the effort to revamp the lead regulations has been stalled as Cal/OSHA waits for a complicated technical analysis—delayed more than two years—that will help determine the limits on airborne lead that would be necessary to keep blood lead concentrations sufficiently low. The report, which the California health department commissioned from the state’s Office of Environmental Health Hazard Assessment, is expected this fall, according to a spokesperson.