Internal corporate records reveal that the plastics and chemical industry has known for more than 50 years that ingested plastic particles can migrate across the gut and lodge within vital human organs, according to an investigation by the Los Angeles Times.
The documents, uncovered during legal battles and archived at the University of California, San Francisco and Columbia University, trace the industry’s awareness back to a 1974 scientific conference in New York. While mainstream toxicologists were focused on occupational chemical hazards at the time, corporate scientists took close note of research showing that tiny particles of polyvinyl chloride, or PVC, could quickly enter the bloodstream and spread through the body.
A 1974 presentation warned of organ infiltration
The groundbreaking research was presented in May 1974 by Gerhard Volkheimer, a German gastroenterologist from Berlin’s Charité hospital. Volkheimer documented a physiological mechanism known as persorption, demonstrating that solid particles could pass through the intestinal wall. In experiments across several animal species, including dogs and pigs, ingested microscopic PVC particles crossed into the lymphatic system and blood, appearing in the liver, lungs, kidneys and brain within two hours.
Volkheimer also confirmed that the synthetic particles crossed the placenta and could be detected in breast milk and cerebrospinal fluid. Using potato starch as a human proxy due to its similar behavior, he observed comparable absorption into human blood and milk. Decades before the term “microplastics” was coined in 2004, his presentation warned that ingested synthetic materials do not simply pass through the digestive system unabsorbed.
Corporate memos reveal internal debate
Company memos show that executives at major manufacturers moved quickly to evaluate the findings. Howard Kusnetz, manager of industrial hygiene for Shell Oil Co., sent a summary detailing Volkheimer’s discovery to the company’s medical director, noting how rapidly the particles entered the bloodstream, the Los Angeles Times reported.
In a 1975 memo, an assistant safety director at petrochemical maker Union Carbide noted that the Volkheimer study had “been cited often as a ‘horror story’ on ingesting PVC resin.” To defend against regulatory pressure on plastic food containers, the executive suggested highlighting a 1947 industry-funded study that found animals fed a similar polymer did not show illness.
Industry groups continued tracking Volkheimer’s work through the 1990s. Tracey Woodruff, a professor of epidemiology and population health at Stanford University, told the Los Angeles Times that the documents show chemical leaders chose to keep quiet about microplastic contamination while the materials saturated consumer markets, drawing parallels to the corporate strategies once used by the tobacco and asbestos industries.
The American Chemistry Council strongly contested that view. “Scientific debate over what the evidence shows is not silence. It is how sound science and effective policy advance,” Craig Davis, senior director of plastics chemistry at the trade group, told the Los Angeles Times. Davis stated that animal experiments do not prove real-world human harm and noted that the sector continues to fund independent research initiatives.
Mounting health evidence
The revelations arrive as modern environmental scientists locate microplastics in nearly every part of the human anatomy, including blood, arterial plaque, lung tissue and placentas. Exposure has been associated in recent health studies with elevated rates of cardiovascular disease, reproductive disorders and cellular inflammation.
Earlier this month, a study published in the journal Nature challenged the historic assumption that plastic remains chemically inert inside living tissue. Researchers led by Columbia University found that microscopic plastic fragments trigger reactive oxygen species when exposed to water, unleashing unstable molecules capable of rupturing red blood cells and damaging biological tissues.
Federal lawmakers are currently weighing measures such as the proposed Microplastics Safety Act to expand public health research into synthetic particles, while international bodies continue to debate enforceable restrictions on plastic manufacturing and packaging.
