Recently CNN News on-line reported the following:
Tiny shards of plastic are increasingly infiltrating our
brains, study says (1/2)
By Sandee LaMotte, CNN
Updated 2:50 PM EDT, Fri August 23, 2024
Human brain samples collected at autopsy in early 2024
contained more tiny shards of plastic than samples collected eight years prior,
according to a preprint posted online in May. A preprint is a study which has
not yet been peer-reviewed and published in a journal.
“The concentrations we saw in the brain tissue of normal individuals, who had an average age of around 45 or 50 years old, were 4,800 micrograms per gram, or 0.5% by weight,” said lead study author Matthew Campen, a regents’ professor of pharmaceutical sciences at the University of New Mexico in Albuquerque.
“Compared to autopsy brain samples from 2016, that’s about 50% higher,” Campen said. “That would mean that our brains today are 99.5% brain and the rest is plastic.”
That increase, however, only shows exposure and does not provide information about brain damage, said Phoebe Stapleton, an associate professor of pharmacology and toxicology at Rutgers University in Piscataway, New Jersey, who was not involved in the preprint.
“It is unclear if, in life, these particles are fluid, entering and leaving the brain, or if they collect in neurological tissues and promote disease,” she said in an email. “Further research is needed to understand how the particles may be interacting with the cells and if this has a toxicological consequence.”
The brain samples contained 7% to 30% more tiny shards of plastic than samples from the cadavers’ kidneys and liver, according to the preprint.
“Studies have found these plastics in the human heart, the great blood vessels, the lungs, the liver, the testes, the gastrointestinal tract and the placenta,” said pediatrician and biology professor Dr. Philip Landrigan, director of the Program for Global Public Health and the Common Good and the Global Observatory on Planetary Health at Boston College.
“It’s important not to scare the hell out of people, because the science in this space is still evolving, and nobody in the year 2024 is going to live without plastic,” said Landrigan, who was not involved with the preprint.
“I say to people, ‘Listen, there are some plastics that you can’t escape. You’re not going to get a cell phone or a computer that doesn’t contain plastic.’ But do try to minimize your exposure to the plastic that you can avoid, such as plastic bags and bottles.”
CNN reached out to the American Chemistry Council, an industry association, but did not hear back before publication.
Nanoplastics ‘hijack’ their way into the brain
For the study, researchers examined brain, kidney and liver
tissues from 92 people who underwent a forensic autopsy to verify cause of
death in both 2016 and 2024. Brain tissue samples were gathered from the
frontal cortex, the area of the brain associated with thinking and reasoning,
and which is most affected by frontotemporal dementia (FTD) and later stages of
Alzheimer’s disease.
“Based on our observations, we think the brain is pulling in the very smallest nanostructures, like 100 to 200 nanometers in length, whereas some of the larger particles that are a micrometer to five micrometers go into the liver and kidneys,” Campen said.
Microplastics are fragments that can range from less than 0.2 inch (5 millimeters) or about the size of a pencil eraser, to 1 nanometer. A strand of human hair is about 80,000 nanometers wide, according to the US Environmental Protection Agency. Anything smaller is a nanoplastic that must be measured in billionths of a meter.
Nanoplastics are the most worrisome plastics for human health, experts say, because the minuscule pieces can take up residence inside individual cells.
“Somehow these nanoplastics hijack their way through the body and get to the brain, crossing the blood-brain barrier,” Campen said. “Plastics love fats, or lipids, so one theory is that plastics are hijacking their way with the fats we eat which are then delivered to the organs that really like lipids — the brain is top among those.”
The human brain is about 60% fat by weight, far more than any other organ. Essential fatty acids, such as omega 3s, are key to the strength and performance of the brain’s cells. Since the human body can’t produce essential fatty acids on its own, they must come from food or supplements.
Diet is the main route of exposure for micro- and nanoplastics, said Landrigan, who is the lead author of a March 2023 report from the Minderoo – Monaco Commission on Plastics and Human Health, a global consortium of scientists, health-care workers and policy analysts charged with following plastics from creation to final product.
Translation
根據 5 月發佈在網路上的預印本，2024 年初在檢屍時收集的人類大腦樣本中含有的微小塑膠碎片比八年前收集的樣本更多。預印本是尚未經過同行評審並在期刊上發表的研究。
該研究的主要作者、Albuquerque的新墨西哥大學的製藥科學攝政教授Matthew Campen 說:「我們在平均年齡約為45 歲或50 歲的正常人的腦組織中看到的濃度為每克4,800 微克，即重量的0.5%」。
Campen 說：「與 2016 年屍檢大腦樣本相比，這個數字高出約 50%」; 「這意味著我們今天的大腦 99.5% 是腦，其餘的是塑膠」。
然而，沒有參與預印本的新澤西州皮斯卡塔韋Rutgers大學的藥理學和毒理學副教授Phoebe Stapleton表示，這種增加僅顯示了暴露程度，並沒有提供有關腦損傷的資訊.
她在一封電子郵件中說：“目前尚不清楚，在生活中，這些顆粒是否液體，可以進出大腦，或者它們是否聚集在神經組織中並助長疾病” ;“需要進一步的研究來了解這些顆粒如何與細胞互動，以及這是否會產生毒理後果。”
根據預印本，大腦樣本中的微小塑膠碎片比屍體腎臟和肝臟樣本中的塑膠碎片多 7% 至 30%。
兒科醫生、生物學教授、波士頓學院全球公共衛生和共同利益計劃以及全球行星健康觀測站主任Philip Landrigan博士說:「研究發現，這些塑膠存在於人類心臟、大血管、肺、肝臟、睪丸、胃腸道和胎盤中」。
沒有參與預印本的Landrigan說:「重要的是不要把人們嚇壞了，因為這個領域的科學仍在不斷發展，到 2024 年，沒有人會在沒有塑膠的情況下生活」。
「我對人們說:『聽著，有些塑膠是你無法逃脫的。你不會得到不含塑料的手機或電腦』。但請盡量減少接觸可以避免的塑料，例如膠袋和膠瓶」。
CNN聯繫了這行業的協會, 即美國化學理事會，但在發表這之前沒有收到回應。
奈米塑膠「劫持」進入大腦
在這項研究中，研究人員檢查了92
名在2016 年和2024 年接受法醫屍檢的人的腎臟和肝臟組織，以核實死因。腦組織樣本是從額葉皮質採集的，額葉皮質是大腦中與思考和推理相關的區域，也是受額顳葉失智症
(FTD) 和晚期阿茲海默症影響最嚴重的區域。
Campen 說： “根據我們的觀察，我們認為大腦正在吸入最小的奈米結構，例如長度為 100 到 200 奈米，而一些較大的顆粒（1 微米到 5 微米）會進入肝臟和腎臟。”
微塑膠的尺寸是從小於 0.2 英吋（5 毫米）或大約鉛筆橡皮擦大小到 1 奈米的碎片。根據美國環保署的數據，一根人類頭髮的寬度約為 80,000 奈米。任何更小的東西就是奈米塑膠，必須以十億分之一米為單位進行測量。
專家表示，奈米塑膠是對人類健康最令人擔憂的塑料，因為這些微小的碎片可以駐留在單一細胞內。
Campen說： 「這些奈米塑料以某種劫持方式穿過血腦屏障到達大腦」; 「塑膠喜歡脂肪或脂質，因此一種理論認為，塑膠正在劫持着我們所吃進的脂肪，然後將它輸送到真正喜歡脂質的器官 - 大腦是其中最主要的器官」。
以重量計算，人腦的脂肪含量約為 60%，遠多於任何其他器官。 必需脂肪酸，例如歐米伽 3，是大腦細胞力量和能力的關鍵。由於人體無法自行產生必需脂肪酸，因此必須從食物或補充劑中取得。
Landrigan說，飲食是接觸微塑膠和奈米塑膠的主要途徑。他是摩納哥明德魯塑膠與人類健康委員會 (Minderoo – Monaco Commission on Plastics and Human Health) 2023
年 3 月報告的主要作者, 這是一個由科學家、衛生保健工作者和政策分析師組成的全球聯盟，負責追蹤塑膠從生產到最終產品的整個過程。
（待續）
Note:
1. Essential
fatty acids, or
EFAs, (必需脂肪酸) are fatty
acids that are required by humans and other animals for normal physiological
function that cannot be synthesized in the body. As they are not synthesized in
the body, the essential fatty acids must be obtained from food or from a
dietary supplement. Essential fatty acids are needed for various cellular
metabolic processes and for the maintenance and function of tissues and organs.
(Wikipedia)
2. The goals
of the Minderoo-Monaco Commission on Plastics and Human Health are to
comprehensively examine plastics’ impacts across their life cycle on: (1) human
health and well-being; (2) the global environment, especially the ocean; (3)
the economy; and (4) vulnerable populations—the poor, minorities, and the
world’s children. On the basis of this examination, the Commission offers
science-based recommendations designed to support development of a Global
Plastics Treaty, protect human health, and save lives. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10038118/)
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