TED日本語 - スティーブン・パランビ: 水銀の足跡を追って

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TED日本語 - スティーブン・パランビ: 水銀の足跡を追って

TED Talks

水銀の足跡を追って
Following the mercury trail
スティーブン・パランビ
Stephen Palumbi

内容

海の健康と私達自身の健康には、強固で驚くべき繋がりがある、と海洋生物学者スティーブン・パランビは言います。海の食物連鎖の底辺に溜まる毒が、どのように人間の体へと入っていくのか。彼は、日本の魚市場で発見された衝撃的な汚染の実例と共に説明します。彼の研究は、海と、そして人類を健康に導く道を指し示します。

Script

It can be a very complicated thing, the ocean. And it can be a very complicated thing, what human health is. And bringing those two together might seem a very daunting task, but what I'm going to try to say is that even in that complexity, there's some simple themes that I think, if we understand, we can really move forward. And those simple themes aren't really themes about the complex science of what's going on, but things that we all pretty well know. And I'm going to start with this one: If momma ain't happy, ain't nobody happy. We know that, right? We've experienced that. And if we just take that and we build from there, then we can go to the next step, which is that if the ocean ain't happy, ain't nobody happy. That's the theme of my talk. And we're making the ocean pretty unhappy in a lot of different ways.

This is a shot of Cannery Row in 1932. Cannery Row, at the time, had the biggest industrial canning operation on the west coast. We piled enormous amounts of pollution into the air and into the water. Rolf Bolin, who was a professor at the Hopkin's Marine Station where I work, wrote in the 1940s that "The fumes from the scum floating on the inlets of the bay were so bad they turned lead-based paints black." People working in these canneries could barely stay there all day because of the smell, but you know what they came out saying? They say, "You know what you smell? You smell money." That pollution was money to that community, and those people dealt with the pollution and absorbed it into their skin and into their bodies because they needed the money. We made the ocean unhappy; we made people very unhappy, and we made them unhealthy.

The connection between ocean health and human health is actually based upon another couple simple adages, and I want to call that "pinch a minnow, hurt a whale." The pyramid of ocean life ... Now, when an ecologist looks at the ocean -- I have to tell you -- we look at the ocean in a very different way, and we see different things than when a regular person looks at the ocean because when an ecologist looks at the ocean, we see all those interconnections. We see the base of the food chain, the plankton, the small things, and we see how those animals are food to animals in the middle of the pyramid, and on so up this diagram. And that flow, that flow of life, from the very base up to the very top, is the flow that ecologists see. And that's what we're trying to preserve when we say, "Save the ocean. Heal the ocean." It's that pyramid.

Now why does that matter for human health? Because when we jam things in the bottom of that pyramid that shouldn't be there, some very frightening things happen. Pollutants, some pollutants have been created by us: molecules like PCBs that can't be broken down by our bodies. And they go in the base of that pyramid, and they drift up; they're passed up that way, on to predators and on to the top predators, and in so doing, they accumulate.

Now, to bring that home, I thought I'd invent a little game. We don't really have to play it; we can just think about it here. It's the Styrofoam and chocolate game. Imagine that when we got on this boat, we were all given two Styrofoam peanuts. Can't do much with them: Put them in your pocket. Suppose the rules are: every time you offer somebody a drink, you give them the drink, and you give them your Styrofoam peanuts too. What'll happen is that the Styrofoam peanuts will start moving through our society here, and they will accumulate in the drunkest, stingiest people. (Laughter) There's no mechanism in this game for them to go anywhere but into a bigger and bigger pile of indigestible Styrofoam peanuts. And that's exactly what happens with PDBs in this food pyramid: They accumulate into the top of it.

Now suppose, instead of Styrofoam peanuts, we take these lovely little chocolates that we get and we had those instead. Well, some of us would be eating those chocolates instead of passing them around, and instead of accumulating, they will just pass into our group here and not accumulate in any one group because they're absorbed by us. And that's the difference between a PCB and, say, something natural like an omega-3, something we want out of the marine food chain.

PCBs accumulate. We have great examples of that, unfortunately. PCBs accumulate in dolphins in Sarasota Bay, in Texas, in North Carolina. They get into the food chain. The dolphins eat the fish that have PCBs from the plankton, and those PCBs, being fat-soluble, accumulate in these dolphins. Now, a dolphin, mother dolphin, any dolphin -- there's only one way that a PCB can get out of a dolphin. And what's that? In mother's milk. Here's a diagram of the PCB load of dolphins in Sarasota Bay. Adult males: a huge load. Juveniles: a huge load. Females after their first calf is already weaned: a lower load. Those females, they're not trying to. Those females are passing the PCBs in the fat of their own mother's milk into their offspring, and their offspring don't survive. The death rate in these dolphins, for the first calf born of every female dolphin, is 60 to 80 percent. These mothers pump their first offspring full of this pollutant, and most of them die. Now, the mother then can go and reproduce, but what a terrible price to pay for the accumulation of this pollutant in these animals -- the death of the first-born calf.

There's another top predator in the ocean, it turns out. That top predator, of course, is us. And we also are eating meat that comes from some of these same places. This is whale meat that I photographed in a grocery store in Tokyo -- or is it? In fact, what we did a few years ago was learn how to smuggle a molecular biology lab into Tokyo and use it to genetically test the DNA out of whale meat samples and identify what they really were. And some of those whale meat samples were whale meat. Some of them were illegal whale meat, by the way. That's another story. But some of them were not whale meat at all. Even though they were labeled whale meat, they were dolphin meat. Some of them were dolphin liver. Some of them were dolphin blubber. And those dolphin parts had a huge load of PCBs, dioxins and heavy metals. And that huge load was passing into the people that ate this meat. It turns out that a lot of dolphins are being sold as meat in the whale meat market around the world. That's a tragedy for those populations, but it's also a tragedy for the people eating them because they don't know that that's toxic meat.

We had these data a few years ago. I remember sitting at my desk being about the only person in the world who knew that whale meat being sold in these markets was really dolphin meat, and it was toxic. It had two-to-three-to-400 times the toxic loads ever allowed by the EPA. And I remember there sitting at my desk thinking, "Well, I know this. This is a great scientific discovery," but it was so awful. And for the very first time in my scientific career, I broke scientific protocol, which is that you take the data and publish them in scientific journals and then begin to talk about them. We sent a very polite letter to the Minister of Health in Japan and simply pointed out that this is an intolerable situation, not for us, but for the people of Japan because mothers who may be breastfeeding, who may have young children, would be buying something that they thought was healthy, but it was really toxic. That led to a whole series of other campaigns in Japan, and I'm really proud to say that at this point, it's very difficult to buy anything in Japan that's labeled incorrectly, even though they're still selling whale meat, which I believe they shouldn't. But at least it's labeled correctly, and you're no longer going to be buying toxic dolphin meat instead.

It isn't just there that this happens, but in a natural diet of some communities in the Canadian arctic and in the United States and in the European arctic, a natural diet of seals and whales leads to an accumulation of PCBs that have gathered up from all parts of the world and ended up in these women. These women have toxic breast milk. They can not feed their offspring, their children, their breast milk because of the accumulation of these toxins in their food chain, in their part of the world's ocean pyramid. That means their immune systems are compromised. It means that their children's development can be compromised. And the world's attention on this over the last decade has reduced the problem for these women, not by changing the pyramid, but by changing what they particularly eat out of it. We've taken them out of their natural pyramid in order to solve this problem. That's a good thing for this particular acute problem, but it does nothing to solve the pyramid problem.

There's other ways of breaking the pyramid. The pyramid, if we jam things in the bottom, can get backed up like a sewer line that's clogged. And if we jam nutrients, sewage, fertilizer in the base of that food pyramid, it can back up all through it. We end up with things we've heard about before: red tides, for example, which are blooms of toxic algae floating through the oceans causing neurological damage. We can also see blooms of bacteria, blooms of viruses in the ocean. These are two shots of a red tide coming on shore here and a bacteria in the genus vibrio, which includes the genus that has cholera in it. How many people have seen a "beach closed" sign? Why does that happen? It happens because we have jammed so much into the base of the natural ocean pyramid that these bacteria clog it up and overfill onto our beaches. Often what jams us up is sewage.

Now how many of you have ever gone to a state park or a national park where you had a big sign at the front saying, "Closed because human sewage is so far over this park that you can't use it"? Not very often. We wouldn't tolerate that. We wouldn't tolerate our parks being swamped by human sewage, but beaches are closed a lot in our country. They're closed more and more and more all around the world for the same reason, and I believe we shouldn't tolerate that either. It's not just a question of cleanliness; it's also a question of how those organisms then turn into human disease. These vibrios, these bacteria, can actually infect people. They can go into your skin and create skin infections.

This is a graph from NOAA's ocean and human health initiative, showing the rise of the infections by vibrio in people over the last few years. Surfers, for example, know this incredibly. And if you can see on some surfing sites, in fact, not only do you see what the waves are like or what the weather's like, but on some surf rider sites, you see a little flashing poo alert. That means that the beach might have great waves, but it's a dangerous place for surfers to be because they can carry with them, even after a great day of surfing, this legacy of an infection that might take a very long time to solve. Some of these infections are actually carrying antibiotic resistance genes now, and that makes them even more difficult.

These same infections create harmful algal blooms. Those blooms are generating other kinds of chemicals. This is just a simple list of some of the types of poisons that come out of these harmful algal blooms: shellfish poisoning, fish ciguatera, diarrheic shellfish poisoning -- you don't want to know about that -- neurotoxic shellfish poisoning, paralytic shellfish poisoning. These are things that are getting into our food chain because of these blooms. Rita Calwell very famously traced a very interesting story of cholera into human communities, brought there, not by a normal human vector, but by a marine vector, this copepod. Copepods are small crustaceans. They're a tiny fraction of an inch long, and they can carry on their little legs some of the cholera bacteria that then leads to human disease. That has sparked cholera epidemics in ports along the world and has led to increased concentration on trying to make sure shipping doesn't move these vectors of cholera around the world.

So what do you do? We have major problems in disrupted ecosystem flow that the pyramid may not be working so well, that the flow from the base up into it is being blocked and clogged. What do you do when you have this sort of disrupted flow? Well, there's a bunch of things you could do. You could call Joe the Plumber, for example. And he could come in and fix the flow. But in fact, if you look around the world, not only are there hope spots for where we may be able to fix problems, there have been places where problems have been fixed, where people have come to grips with these issues and begun to turn them around. Monterey is one of those.

I started out showing how much we had distressed the Monterey Bay ecosystem with pollution and the canning industry and all of the attendant problems. In 1932, that's the picture. In 2009, the picture is dramatically different. The canneries are gone. The pollution has abated. But there's a greater sense here that what the individual communities need is working ecosystems. They need a functioning pyramid from the base all the way to the top. And that pyramid in Monterey, right now, because of the efforts of a lot of different people, is functioning better than it's ever functioned for the last 150 years.

It didn't happen accidentally. It happened because many people put their time and effort and their pioneering spirit into this. On the left there, Julia Platt, the mayor of my little hometown in Pacific Grove. At 74 years old, became mayor because something had to be done to protect the ocean. In 1931, she produced California's first community-based marine protected area, right next to the biggest polluting cannery, because Julia knew that when the canneries eventually were gone, the ocean needed a place to grow from, that the ocean needed a place to spark a seed, and she wanted to provide that seed.

Other people, like David Packard and Julie Packard, who were instrumental in producing the Monterey Bay aquarium to lock into people's notion that the ocean and the health of the ocean ecosystem were just as important to the economy of this area as eating the ecosystem would be. That change in thinking has led to a dramatic shift, not only in the fortunes of Monterey Bay, but other places around the world.

Well, I want to leave you with the thought that what we're really trying to do here is protect this ocean pyramid, and that ocean pyramid connects to our own pyramid of life. It's an ocean planet, and we think of ourselves as a terrestrial species, but the pyramid of life in the ocean and our own lives on land are intricately connected. And it's only through having the ocean being healthy that we can remain healthy ourselves.

Thank you very much.

(Applause)

海はとても複雑です 健康とは何かという問いもまた複雑です 同時に考えるなんて 目を背けたくなる しかし 私がこれから伝える事は 複雑に絡み合った中にも 理解すれば 私達を前進させる 単純な事柄がある ということです それらの単純な事柄とは 複雑な科学などではなく 馴染みのある事柄です まずはこんな言葉から ママが不幸だとみんなが不幸 経験から知っていると思います これを理解して まずはここから始めれば 次のステップに進めるはず 海が不幸なら 誰も幸せになれない このスピーチのテーマです 色々な方法で私達は海を不幸にしています

これは1932年の「缶詰横丁」 当時「缶詰横丁」には 西海岸で最大の 缶詰製造産業がありました そして 膨大な汚染物質を 大気と海に蓄積しました 私の職場 ホプキン海洋研究所 その教授 ロルフ・ボリンが 40年代 こう書いています 入り江に浮かぶカスから立ち上るガスは とても醜悪で 鉛を含んだペンキを黒くしてしまいました 缶詰工場の従業員達は 悪臭の中 一日を過ごすのがやっとでした しかし彼らはこう言いました 「何の匂いか分かるかい?」 「お金だよ」 そこでは汚染はお金を意味し 人々は耐え忍びました 皮ふや体に汚染を吸い込みながら お金の為に 私達は海を そして人々を不幸にし 彼らの健康を奪いました

海と人間の健康との繋がりは また別の格言に基づいています その格言とは 「小魚をつねれば鯨が泣く」 海洋生物のピラミッド 生態学者が海を考える時 非常に異なる観点から 一般の人とは違う物事を見ます なぜなら 生態学者は 物事の相互関係を見るからです 食物連鎖の底辺 小さなプランクトンが どの様にして 中層に位置する生物の餌になるのか 図の頂点に至るまで考えます そして その命の流れ 底辺から頂点までの流れこそ 生態学者の見る流れなのです 「海を救おう 海の健康を取り戻そう」と訴える時 私達が守ろうとしている物 それがピラミッドなのです

さて なぜ人間の健康と関わってくるのか? なぜなら ピラミッドの底に 在るべきでない物を押し込むと とても怖い事が起こるからです 私達が作り出した汚染物 例えばPCBなどは 体内で分解できません それらはピラミッドの底へ入り 次々と捕食動物の間を漂い上がり 頂点まで辿り着きます そうする間に 蓄積されていくのです

理解する為にゲームをひとつ 想像するだけで大丈夫です 発泡スチロールとチョコのゲーム ボートに乗っているとします 発泡スチロールのピーナッツを 1人2粒渡されます なにもできないのでとりあえずはポケットに ルールは 毎回お酒を勧める度に お酒と一緒に ピーナッツも渡します すると ピーナッツは 廻りめぐって 一番ケチで飲兵衛な人の元に 集まっていきます (笑) 消化できないピーナッツが 一ヶ所に集まり どんどん積み上がる 何のからくりもありません これこそまさに PCBに起こる事なのです ピラミッドの頂点へ蓄積するのです

さて ピーナッツの代わりに この美味しそうなチョコを 持っているとしましょう 何人かは 渡す代わりに 食べてしまう 蓄積する代わりに 私達の間をめぐり 消費されていくので 一ヶ所には溜まりません この違いこそ オメガ3の様な 体に良い天然物と PCBとの違いです

PCBは蓄積されます 残念な事に 実例があります サラソタ湾やテキサス州やノースキャロライナ州の イルカにPCBは蓄積します 食物連鎖のなかで プランクトンから魚へ 魚からイルカへ 脂溶性のPCBは イルカに蓄積されます さて そのイルカ達 全てのイルカにとって PCBを体外に出す方法は たった1つ それは何か? 母乳です これはサラソタ湾のイルカの PCB含有量を示す図です オス:大量 子供:大量 授乳を終えたメス: 少量 意思とは関係なく メス達は自分の子に 授乳によって PCBを渡しているのです その子供達は長生き出来ません 初産による子供の 死亡率は 60~80%です 母親達は 子供に 大量の汚染物質を流し込み 多くを殺してしまいます 母親は次の子を産めますが この汚染物質の蓄積に 払う代償は あまりに大き過ぎます 第一子の死

海の食物連鎖におけるもう1つの頂点 それはもちろん 人間です 私達は同じ場所からくる 肉を食べています 東京のスーパーで売られている 鯨の肉 それとも 本当は? 数年前 私たちは 分子生物学研究室を こっそり東京に作り そこで鯨肉サンプルの DNAテストを行い 正体を突き止めました いくつかは実際に鯨肉でしたが 「違法な鯨肉」ですが それはまた 別の話です いくつかは 全くの偽者でした ラベルは偽りで 実際はイルカの肉 イルカの肝臓や脂肪だったのです そしてそれらの各部位には 大量のPCBや ダイオキシンや重金属が含まれていました それら大量の汚染物は 人間の体に流れ込みます 事実 大量のイルカが 世界の鯨市場で 食肉として販売されています イルカだけでなく 汚染されているとは知らずに それを食べる人々にとっても この事実は悲劇なのです

このデータを発見したのは数年前 鯨肉として売られている肉が 実際は汚染されたイルカである 私は その事実を知る おそらくただ一人の人間でした EPA基準の200~400倍もの量が 含有されていたのです こう思ったのを 覚えています 「これは偉大な科学的発見だ」 しかし 恐ろしい発見でした 科学雑誌でデータを公表してから それについて演説をするという 通常の手順を 科学者人生で初めて 破りました とても丁寧な手紙を 日本の厚生労働大臣宛てに送り 私達ではなく 日本の人々にとって 許されざる状況なのだと 指摘しました 授乳中の母親が 幼い子を持つ母親達が 汚染された肉を 体に良いと信じ 買っているかも知れないのだと これが日本で 様々な運動の引き金となりました 誇りを持って言えますが 今日本に 偽装表示の商品は ほとんどありません これが良いこととは思いませんが 日本で鯨肉の売買は続いています けれども少なくとも表示に偽りはなく 汚染されたイルカの肉を 買ってしまう心配はありません

日本だけではありません カナダ北極圏やアメリカ そして欧州北極圏 それら地域の食生活と アシカやクジラの食生活が 世界のあらゆる場所から PCBを集積させ 彼女達のもとへと運びます この女性達の母乳は有毒です 彼女達は 子供を母乳で育てることが 出来ません 食物連鎖と 彼女達が一部を担う 海のピラミッドが集めた 毒のせいで 彼女達の免疫システムは損なわれ さらに 子供達の発達も 危険にさらされます ここ十年 世界はこの問題に注目し この女性達の為に 問題を軽減してきました ピラミッドではなく 食生活を変えることで 問題を解決する為に 彼女らをピラミッドから外しました しかしこの策は 根本的解決にはなりません

ピラミッドを壊す方法は 他にもあります 底に物を詰め込めば 詰った下水道の様に 逆流します 養分や汚水 化学肥料を ピラミッドの底に詰め込むと 頂点まで逆流します 何が起るかはご存知の通り 例えば 赤潮 毒性の藻類の異常発生 海を漂い 神経性の被害を与えます バクテリアやウィルスの 異常発生も起り得ます この海岸では2度赤潮が起り コレラ菌を含む ビブリオ属の バクテリアを含んでいます 「海岸閉鎖」のサインを見たことある人? どうして起るのか? ピラミッドの底に 沢山詰め込みすぎて 詰ったバクテリアが 海辺まで溢れ出てくるのです 大抵は汚水が原因です

国立公園や州立公園の入り口で こんな看板を 見たことがありますか? 「生活排水が 公園中に溢れているため 立ち入り禁止」 滅多にありませんよね? 公園だと 耐えられないのに 海岸は頻繁に閉鎖されます 同じ事が世界中で起っている これは容認すべきではありません 問題は清潔さだけでなく それらの生物がどのように 病気の原因になるのか それも問題です それらは実際人に影響を及ぼします 皮ふに入り込み 感染症を引き起こします

NOAAによるグラフです 過去2年間における ビブリオ菌による人への感染 その増加を示しています サーファーはこれを熟知しています サーフサイトで見れるのは 実際のところ 天気や波の状況だけでなく いくつかの海岸では 糞尿警報を見ることができます 最高の波が来ていたとしても 危険だということです サーフィンを楽しんだ後 直すのが難しい病原菌を 持ち帰るかも知れないからです そのうち幾つかが持つ 抗生物質抵抗性遺伝子が 事態を悪化させます

それと同じ病原体が 有害な藻類を発生させます それがまた別の化学物質を生み出します 藻類異常発生から派生した毒物の 簡単なリストです 貝中毒 シガテラ毒魚 下痢性貝毒…これは知らぬが仏 神経性貝毒 麻痺性貝毒 全て食物連鎖の一部です 藻類異常発生が原因で リタ・コーウェルが 興味深い話を追っています 人間ではなく 媒介生物コペポーダによって 人間社会に持ち込まれる コレラについて コペポーダは甲殻類です 数分の1センチの大きさで 病気の原因となる コレラ菌を 足に抱えて運びます それは世界中の港で コレラの蔓延に火をつけ 人々は貨物船が それらの媒介生物を 運んでしまわないよう 注意する様になりました

では どうするのか? 問題は混乱した生態系の流れです ピラミッドはうまく作動せず 底からの流れは 塞がれ詰まっている こんな時どう対処するか? できる事はいくつかあります 配管工のジョーを呼ぶとか 彼がやってきて 直してくれるかもしれない しかし実際 見回してみれば 解決の希望を持てる 場所だけでなく 既に問題を解決した所 把握し改善に向かう 場所もあります モントレーはその1つです

初めに示したとおり 私達はモントレー湾の生態系を 汚染や缶詰産業などによって 苦しめました この写真が1932年 2009年 劇的に変化しています 缶詰工場はなくなり 汚染は減少しています しかし 重要なのは 個々の社会が必要なのは 正常な生態系だという事です 正常に機能するピラミッドが必要です モントレーの ピラミッドは今 人々の努力によって 過去150年で 最もよくに機能しています

偶然起ったのではありません 多くの人々の時間と労力そして 開拓者精神の賜物です 左の写真 ジュリア・プラット 私の出身地パシフィック・グローブの市長 海を守る為には 何かをしなければと 74才で市長となりました 1931年 カリフォルニア初の 地域密着型の海洋保護地域を 汚染源缶詰工場のすぐ横に設定しました 彼女は知っていたのです いつか缶詰工場がなくなった時 海は育つ場所を 芽を出す場所を必要とする事を その種を用意したかったのです

デビットとジュリー・パッカードは モントレー水族館を作るのに貢献し 人々に 海と海洋生態系の健康は その生態系を食する事と同じくらい 地域経済にとっても重要なのだと 認識させました その認識の転換は モントレー湾の富にだけでなく世界中に 劇的な変化をもたらしました

最後に 私達の真の目的は 海のピラミッドの保護です 海と私達のピラミッドは つながっています ここは海の惑星です 私達は陸上動物ですが 海のピラミッドと 私達の陸上での生活は 複雑につながっています 海を健康に保つ事でのみ 私達は健康でいられます

ありがとう

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