原田英語の時事英語ジュニア｜英語ニュース ワークシート（高校生レベル）
Class ____ No. ____ Name ____________________
人の脳にマイクロプラスチック？8年で約1.5倍に増えていたという研究
Brains Hold More Plastic Than Livers, Study Finds
1Scientists in the United States have found that human brain tissue may contain more tiny plastic particles than the liver or kidneys. The study was led by toxicologist Matthew Campen of the University of New Mexico. It was published in the journal Nature Medicine in February 2025. The team examined tissue collected during autopsies.
2Brain samples held seven to 30 times more plastic than liver and kidney samples. In people without brain disease, plastic made up roughly 0.5 percent of the brain tissue by weight. Campen said that amount is roughly equal to one standard plastic spoon. Much of it was nanoplastics, shards so small that they may be able to pass through the barrier that normally protects the brain.
3Samples from 2024 contained about 50 percent more plastic than samples from 2016. The researchers linked this rise to the growing amount of plastic waste in the world. Polyethylene, which is widely used in packaging and containers, was the most common type. The team suspects that much of this plastic reaches people through food.
4Brains from people who had dementia contained even more plastic. However, the scientists stressed that this does not prove plastic caused the disease, since the illness itself might allow particles to build up. Phoebe Stapleton, a Rutgers University scientist who was not involved, said it is still unclear whether the particles stay in the brain and cause disease. Campen also said that current methods could overestimate or underestimate the real amounts.
5The team is now working on more precise measurements. Because plastic takes decades to break down, the researchers expect plastic levels in the environment to keep rising for years.
Words 単語
| tissueB1 | 名 | （体の）組織the material that a part of the body is made of |
| particlesB2 | 名 | 粒子、ごく小さなつぶvery, very small bits of something |
| autopsies外 | 名 | 解剖（autopsy の複数形）checks of a dead body to learn why the person died |
| standardB1 | 形 | 標準の、ふつうのnormal, of the usual kind |
| barrierB2 | 名 | 障壁、さえぎるものa wall or thing that stops something from passing |
| suspectsB1 | 動 | （～ではないかと）思う、疑うthinks something is probably true |
| stressedB1 | 動 | 強調した（stress の過去形）said strongly so people would notice |
| overestimateB2 | 動 | 多めに見積もる、過大評価するto guess that an amount is bigger than it is |
| preciseA2 | 形 | 正確な、精密なexact and correct in every small detail |
| decadesB2 | 名 | 数十年（decade の複数形）periods of ten years |
単語のレベル：CEFR-J（『CEFR-J Wordlist Version 1.6』 東京外国語大学投野由紀夫研究室. （URL: https://www.cefr-j.org/download.html より 2026年8月ダウンロード））
1. Reading Quiz 本文の内容に合うものを選ぼう
Where was the study published?
A. In a school newspaperB. In the journal Nature MedicineC. On a social media siteD. In a cooking magazine
How did the brain samples compare with liver and kidney samples?
A. They had less plastic.B. They had no plastic at all.C. They had the same amount of plastic.D. They had seven to 30 times more plastic.
What did the researchers link the 50 percent rise to?
A. The growing amount of plastic wasteB. Better microscopesC. Changes in the weatherD. People eating less food
What did the scientists say about dementia?
A. Plastic is proven to cause it.B. Plastic cures it.C. The study does not prove plastic caused it.D. People with dementia had no plastic.
Why do the researchers expect plastic levels to keep rising?
A. Plastic disappears in a few days.B. Plastic takes decades to break down.C. Plastic turns into water.D. Plastic is no longer made.
2. True or False 正しければ T、違っていれば F
( ) The researchers examined tissue collected during autopsies.
( ) Most of the plastic in the brain was polystyrene.
( ) An outside scientist said the study proves plastic harms the brain.
( ) The measuring methods may not give exact amounts.
3. Fill in the Blanks 下の語から選んで空らんをうめよう（形を変えずに）
tissuebarrierautopsiesparticlessuspectsstandard
The team _____ that much of this plastic reaches people through food.
Campen said that amount is roughly equal to one _____ plastic spoon.
The team examined tissue collected during _____.
Scientists in the United States have found that human brain _____ may contain more tiny plastic particles than the liver or kidneys.
However, the scientists stressed that this does not prove plastic caused the disease, since the illness itself might allow _____ to build up.
Much of it was nanoplastics, shards so small that they may be able to pass through the _____ that normally protects the brain.
4. Word Order 語を並べかえて正しい文にしよう
( collected / during / examined / tissue / The / autopsies / team ) .
( plastic / more / contained / dementia / Brains / people / had / who / from / even ) .
( now / more / The / measurements / on / is / team / working / precise ) .
5. Think and Write 英語で答えてみよう
Do you think governments and companies should do more to cut plastic waste? Why?（政府や企業はプラスチックごみを減らすためにもっと行動すべきだと思いますか？その理由は？）
Why is it important for scientists to say what they do not know yet?（科学者が「まだわかっていないこと」をはっきり言うのは、なぜ大切なのでしょうか？）
Answers 解答
1. (1) B (2) D (3) A (4) C (5) B
2. (1) T (2) F (3) F (4) T
3. (1) suspects (2) standard (3) autopsies (4) tissue (5) particles (6) barrier
4.
- The team examined tissue collected during autopsies.
- Brains from people who had dementia contained even more plastic.
- The team is now working on more precise measurements.
全文訳
1アメリカの科学者たちが、人の脳の組織には肝臓や腎臓よりも多くの小さなプラスチック粒子がふくまれているかもしれないことを明らかにしました。この研究を率いたのは、ニューメキシコ大学の毒性学者マシュー・キャンペン氏です。研究は2025年2月、学術誌「ネイチャー・メディシン」に発表されました。チームは、解剖のときに採取された組織を調べました。
2脳の試料には、肝臓や腎臓の試料の7〜30倍のプラスチックがふくまれていました。脳の病気がなかった人では、プラスチックが脳の組織の重さの約0.5%をしめていました。キャンペン氏は、その量はふつうのプラスチックのスプーン1本分ほどにあたると話しました。その多くはナノプラスチックで、ふだん脳を守っている「関門」を通りぬけられるかもしれないほど小さなかけらでした。
32024年の試料には、2016年の試料より約50%多くのプラスチックがふくまれていました。研究者たちは、この増加を世界で増え続けるプラスチックごみと結びつけています。包装や容器に広く使われるポリエチレンが、いちばん多い種類でした。チームは、このプラスチックの多くが食べ物を通して人の体に入っているのではないかと考えています。
4認知症だった人の脳には、さらに多くのプラスチックがありました。ただし科学者たちは、病気そのものが粒子をたまりやすくしている可能性もあり、プラスチックが病気の原因だと証明されたわけではないと強調しました。研究に加わっていないラトガース大学の科学者フィービー・ステイプルトン氏は、粒子が脳にたまって病気を引き起こすのかどうかは、まだはっきりしないと話しました。キャンペン氏も、今の測定方法では実際の量を多めにも少なめにも見積もってしまう可能性があると述べました。
5チームはいま、より正確な測定に取り組んでいます。プラスチックは分解されるまでに何十年もかかるため、研究者たちは環境中のプラスチックがこの先何年も増え続けると見ています。
文法ポイント：so ～ that ...（とても～なので…）
程度と結果を表す。本文の shards so small that they may be able to pass through the barrier は「とても小さいので関門を通りぬけられるかもしれないかけら」という意味。
出典：UNM Health Sciences、CNN (WRAL) ほか（記事は原田英語の時事英語ジュニアのオリジナル）｜https://www.haradaeigo.com/jijieigo-junior/news/2025-02-03-microplastics-in-human-brains/