When I first started as a lead rubber bearing (LRB) supplier 12 years ago, I’ll admit I was focused almost entirely on what these devices do for structures—how they absorb seismic energy during earthquakes, keep buildings and bridges standing when the ground shakes violently. It wasn’t until a client in Portland, Oregon, asked me about the materials inside our bearings, specifically the lead core, that I started digging into the human health impacts. That question turned out to be one of the most important conversations I’ve ever had in this industry, because it made me realize that while LRBs are critical for public safety during natural disasters, their components require responsible handling throughout their entire lifecycle. Today, I want to share what I’ve learned about lead’s effects on human health, how we as suppliers address those risks, and why transparency around material choices matters more than ever.
First, let’s ground this in what a lead rubber bearing actually is, for anyone who might not work in seismic engineering. An LRB is a type of elastomeric isolator—high-damping devices placed between a structure’s foundation and its superstructure. They’re made of alternating layers of natural or synthetic rubber and steel plates, with a solid lead core running through the center. When an earthquake hits, the rubber flexes and the lead core deforms, dissipating energy so the structure doesn’t move as much as it would without isolation. This technology has saved countless lives and reduced billions in property damage over the past 50 years, and it’s part of a larger family of seismic solutions that includes products like the high damping isolation rubber bearing (HDRb) for buildings and high bridges, linear natural rubber seismic isolation bearing (LNR), rubber bearings for space frame applications, and friction pendulum systems—all designed to protect communities from seismic events.
But the lead core, while essential to the bearing’s performance, is a heavy metal with well-documented toxic properties. That’s the part that raised red flags for my client, and for many others as we’ve grown. Let’s break down how lead from LRBs could potentially come into contact with humans, and what that exposure means for health.
Lead is a neurotoxin, and there’s no safe level of exposure for humans—especially children and pregnant people. That’s the key takeaway from decades of research from organizations like the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and the Environmental Protection Agency (EPA). Unlike many other materials, lead accumulates in the body over time; it doesn’t get flushed out easily. The most common routes of exposure from LRBs are threefold: during manufacturing, during installation, and at the end of the bearing’s life.
Starting with manufacturing. When we produce LRBs, we heat lead to melt it, then pour it into molds inside the rubber layers. This process creates lead dust and fumes, which are invisible and can be inhaled by workers if proper safety protocols aren’t in place. Even short-term exposure to high levels of lead fumes can cause headaches, dizziness, and nausea, but the bigger risk is long-term, repeated exposure. For factory workers, chronic inhalation of lead dust can lead to elevated blood lead levels (BLLs), which over time can damage the nervous system, kidneys, and reproductive organs. I’ve visited manufacturing facilities around the world, and I’ve seen firsthand that suppliers who cut corners on ventilation, personal protective equipment (PPE), and worker training put their employees at serious risk. That’s why at my company, we invest in state-of-the-art fume extraction systems, provide free BLL testing for all factory staff, and require full respirator gear and protective clothing during lead core installation. We also work only with suppliers who meet strict OSHA (Occupational Safety and Health Administration) standards for lead exposure limits.
Next, exposure during installation. When LRBs are placed at a construction site, workers have to handle the bearings, cut any excess rubber or steel, and sometimes drill holes to secure them. If the lead core is damaged during installation, small lead particles can break off and contaminate the site. Construction sites are busy places—workers might eat lunch on site without washing their hands, or track lead dust back to their homes, exposing their families. I remember a project in Seattle a few years ago where a contractor didn’t properly contain lead dust during LRB installation, and the site had to be shut down for two days while hazardous material teams cleaned the area. That delay cost the contractor tens of thousands of dollars, but more importantly, it raised concerns about worker safety. To prevent this, we provide our installation partners with detailed training on lead handling, including how to use vacuum systems to capture dust, wet cutting techniques to reduce particle spread, and proper decontamination procedures for tools and workers. We also require on-site lead monitoring during installation to catch any issues before they become hazards.
The third, and often overlooked, area is end-of-life management. LRBs have a lifespan of 50 to 75 years, depending on the environment they’re in. After that, they need to be removed and disposed of, or recycled. If a bearing isn’t properly disassembled, the lead core can leach into soil or groundwater over time, especially if the bearing is exposed to moisture or extreme temperatures. Lead in soil and groundwater can then make its way into the food chain—for example, if a community gardens on contaminated soil, or drinks water from a well that’s been polluted. The CDC estimates that even low levels of lead in drinking water can cause developmental delays in children, lower IQ, and behavioral problems. As a supplier, we take responsibility for the entire lifecycle of our LRBs. We’ve partnered with a specialized recycling company that can safely remove the lead core, melt it down, and reuse it in new products—no waste goes to landfills, and there’s no chance of lead leaching into the environment. For projects nearing the end of a bearing’s life, we provide guidance on proper removal and recycling to property owners, because we believe our commitment to safety doesn’t end when the product is installed.
Now, it’s important to put this in context: the health risks from lead in LRBs are far lower than the risks of not using seismic isolation at all. A 2019 study by the Pacific Earthquake Engineering Research Center found that unreinforced buildings in a major earthquake could have fatality rates as high as 30%, while buildings with LRBs have fatality rates of less than 1%. That’s a trade-off that has to be carefully considered. But that doesn’t mean we can ignore the lead’s risks—our job as suppliers is to minimize those risks as much as possible, while still providing a product that saves lives during earthquakes.
I also want to address a common question I get: are there alternatives to lead core bearings? The answer is yes, though they come with their own trade-offs. HDRbs, for example, use rubber with special additives to provide damping, so they don’t need a lead core. They’re popular for smaller projects or when lead restrictions are in place. LNR bearings use natural rubber with low damping, so they rely on other components to control movement. Rubber bearings for space frame applications often use composite materials instead of lead. The friction pendulum system uses a steel and sliding surface design, with no lead at all. But these alternatives aren’t perfect. HDRbs generally have shorter lifespans than LRBs, and they’re more sensitive to extreme temperatures. LNRs require additional devices to handle seismic energy, which adds complexity and cost. Friction pendulum systems are ideal for large bridges but might be overkill for a small school building. For most medium to large-scale projects, LRBs are still the most effective and cost-efficient solution, which means addressing their lead-related risks is critical.
Over the years, we’ve worked with independent third-party laboratories to test our LRBs for lead leaching, both during manufacturing and in simulated end-of-life conditions. The results show that when our products are installed and disposed of properly, lead exposure is minimal—far below EPA limits for public safety. But we don’t stop at testing. We’ve implemented a traceability system that lets us track every lead core in every bearing we produce, from the raw material to the finished product, so we can account for every pound of lead and ensure it’s handled responsibly throughout its lifecycle.
We also invest in community outreach, especially for projects in areas where lead contamination is already a concern. For example, a school district in Denver was worried about installing LRBs because of local soil lead levels from old paint. We worked with them to develop a plan that included testing the site before installation, using sealed barriers to prevent any lead dust from mixing with existing soil during installation, and post-installation monitoring to confirm no lead was released. The school district ended up approving the project, and the new building is now one of the safest in the district during an earthquake. That’s the balance we strive for: protecting people from earthquakes without putting them at risk from lead.
I want to be clear that no supplier is perfect. There are still companies in the industry that cut corners on safety to save money—using low-quality lead, skipping worker training, or disposing of bearings in regular landfills. Those practices put entire communities at risk, and they’re why transparency is so important. At our company, we publish all our test results, safety protocols, and lifecycle management plans on our website, because we believe customers have a right to know exactly what they’re buying.
As someone who’s been in this industry for more than a decade, I’ve seen the difference that seismic isolation can make. I’ve walked through a building in Taiwan that survived a 7.2 magnitude earthquake with almost no damage, because it was fitted with LRBs. I’ve met parents in California who sleep better at night knowing their kids’ school is protected. But I’ve also met factory workers who’ve had to deal with the health consequences of lead exposure, and that’s what keeps me up at night. The two goals—protecting people from earthquakes and protecting them from lead—don’t have to be opposing. They can go hand in hand, if suppliers prioritize safety at every step.
If you’re a structural engineer, architect, property owner, or contractor looking for seismic isolation solutions that balance performance with human health safety, we’re here to help. Whether you need an LRB for a high-rise, an HDRb for a bridge, a rubber bearing for a space frame, an LNR for a residential building, or a friction pendulum system for a large infrastructure project, we can provide products that meet the strictest safety standards, with full transparency around material handling and lifecycle management. Contact our team today to discuss your project, and let’s work together to build structures that protect communities from both earthquakes and the risks of harmful materials.
References:
World Health Organization. (2023). Lead Poisoning and Health. Geneva: WHO Press.
Centers for Disease Control and Prevention. (2022). Fourth National Report on Human Exposure to Environmental Chemicals. Atlanta: CDC.
Pacific Earthquake Engineering Research Center. (2019). Seismic Isolation Performance: 20 Years of Field Observations. Berkeley: UC Berkeley.
U.S. Environmental Protection Agency. (2021). Occupational Lead Exposure Standards. Washington, DC: EPA Office of Enforcement and Compliance Assurance.
International Association of Seismic Isolation. (2020). Lifecycle Management of Seismic Isolation Bearings. Ottawa: IASI Press.