swimming with whale sharks is a thrill for tourists in t the philipippines. but it's's not so good the big water? could that be possible? dawe meet bavarians now fearing for ththeir long-term health. but we start in el salvador, where gang violence has left many men behind bars yearning for a second chance at life. curbing immigration into the u.s. -- that's one of president

trump's key concerns. and he seeks support by describing potential horror scenarios. pres. trump: this vicious gang has transformed once peaceful, beautiful communities into blood-stained killing fields. host: he's referring to ms-13, a gang founded in los angeles by latin american immigrants 30 years ago. the u.s. government had members deported back to their countries of origin, like el salvador. there, the gangs cornered the markets on drug dealing, prostitution, and racketeering, and donald trump fears that criminals like these could easily enter the u.s. illegally. in its struggle to get a handle on the situation, el salvador's government has had thousands of gang members jailed.

he's been behind bars for 10 years now after being jailed for murder. chalatenango jail was built to house 300 inmates. it's currently home to 1720 members of the ms-13 gang. murderers, rapists, extortionists, all cooped up together. tattooed on their fafaces, the nameme of their gang. el trucha: ms-13 is my family. it offers me protection and respect. some people look at us as if we were from outer space. but in my eyes we're quite normal. we are like brothers who help each other out. reporter: many of these men will never r see the outside world again. they live in their own world with its own rules. why are you here? alexander: murder, like everyone else here. it's normal. reporter: not for me. alexander: in el salvador it is. it's a tradition here.

reporter: el salvador is one of the world's most dangegerous countries. 70,000 gang members terrorize this tiny central american nation. there are 10 murders each day. the state fights fire with fire. it's 4:30 a.m. in the capital, san salvador. the crack police unit, the jaguars, are out on the streets. the e situation in the capitals akin to a war zone. walter: you cover us up front. and he'll protect us from behind. reporter: just a day earlier, two of their colleagues were killed by gang m members. walter: we're going to locations where police have come under fire in previous deployments. that's why we have to be prepared for anything. reporter: the squad heads to the district of san jacinto, which is controlled by the barrio 18 revolutionaries gang. the police's mission this morning is to track down gang members. walter ln and his s team

frequently have to enter enemy territory. the state has lost its authority in all too many places. die. reporter: and today, again, the police meet with a wall of silence. people here claim to know nothing ababout gang activitiesn the district. the police need the locals' help, but the e fear of revenges great. and there's nowhere to hide. pedro: we live in fear. as soon as you leave the neighborhood, another gang has you in its sights. reporterer: the police is ofon accused of brutality, too. anyone with a tattoo, often a sign of gang membership, is treated as a suspect. in the struggle for control,

both sides play hardball. these sneakers hanging on telephone lines demarcate a gang's territory. the city is crisscrossed with borders, many invisible. if you don't respect them, you could pay a very high price. bus drivers s live especially dangerously. their routes cross various gang territories, making them open to extortion. each gang wants its share. alfredo: we drive through all the zones. anything can happen to you on the street. there is a lot of crime. reporter: the bodyguard serving catalino miranda follows him everywhere. the country's biggest bus operator refuses to follow the gangs' rules. he doesn't pay any protection money. that makes him a target. he has already survived four attempted hits while on his company's premises. catalino: we have surveillance

reporter: he spends 25,000 euros caa month on security. there are security cameras on his buses, too. each journey is monitored closely.y. condititionsike this a are bad r business. miranda believes t that el salvador must rid itself of its gangs if it is to have a future. catalino: you need to have courage to take on the gangs. in el salvador we say ththat there's a lot of talk, but few people have the backbone to really stand up to it all. before you set up a business here, you have to coconsider te possibility of various things. kidnapping, harassment, extortion. reporter: el salvador's gang problem has its roots in the united states. in the 1980's, salvadorian immigrants set up criminal operations in los angeles. the u.s. deported the newly-formed gangs back to el salvador.

the government's only answer to the problem is putting gang members behind bars, isolating them from the outside world. the inmates aren't allowed visitors. despite the tough conditions inside, we don't witness any agagession here in c chalatenan. the prisoners sit totogeer quietly. it's obvious that el trucha is the one giving the orders here. like a proud prison governor, he shows us prison activities. bible studies, handicrafts, and painting courses, with motifs depicting the stuff of dreams. el trucha: some of us have discovered talents we didn't know we had. some guy might suddenly realize that he can paint. reporter: el trucha wants to see his family again, which is why he wants to demonstrate that criminals and murderers can reform. he has a message for el salvador's leaders.

el trucha: we have changed. please recognize that. we need reintegration programs and work. we shouldn't b be treated as f we're scum forever. we're human beings too. reporter: it sounds like a chance for dialogue. but both sides are unwilling to make concessions. somehow, gangs and government must come up with answers if they are to stop the spiral of violence. host: and now to europe, where drinking water is of the very highest quality. at least that's what we're told. european environmental authorities have conducted widespread testing. and 98.5% of all samples met e.u. standards. sounds good. but that doesn't mean it's uncontaminated. as a result of excessive fertilizing, nitrate has seeped into the groundwater. in germany, 28% of measuring

stations report elevated levels of nitrate. sewage from the chemical industry contains a whole series of toxic substances. including pfoa, a chemical that makes clothing waterproof, but may be linked to cancer in humans. repoporter: on thehe surfac, altötting is the essssence of bavaria. idyllic, conservative, and squeaky clean. but if y y look clososer, the regionon is tainted d by sometg you can'n't see, smellll, or g. ededmundichlereras lived here s whole fe. he ner thoug twiwicebout drinkingatater fm the tap. it w d dubbethe pupure in thee region. . buthat cononviction s shattered d when he had d his d tested amimid a widening p pfoa scandal in t the district t of altötting.

edmund: mymy blood has over r3 miogograms of pfoaoa per liti. my w wife has the same. and not a daday goes by whwhee don't talk about pfoa. it's depreining. tens of thousands of people here in theltöttindistrict a affefected. rereporter: for thpast three years, concernedititizens ve been mting o oa regular basisto y everytng on thtable. they fl distri adnistrato have do too ttle, antoo lateo ininfo the puic on pf levels the water. fofor frank brememauer, it waa shock to find out he was contaminated. frank: my plasma was refused when i tried to donate to a blbld bank. we fmed this group because w were not informed about the pfoa contamination here in the district. only after pututting pressure n the authorities have we achiev a rtaiain degree of

transparency. reporter: : but just how dangers is pfoa for humans? irina zastenskaya is technical officer for r chemical safafett ththe who's euroropean centerr envivironment and health. irina: pa a is a psiststent d bibio-accumulatiting substanceh popotentially haharmful effectr human health it's c classified the ininternational l agency for research o on cancer as s possy carcininogenic for h human hea. andespspite much morore studis are neededed to confirirm the hh efcts,s, now we have evincnce thatat high concenentration ofa in humuman blood relelates o disorders,s, thyroid gland function disisorders, andd productiveve health disorders. rereporter: evenen though manyny citizensns knew nothing about , pfoa has been in altöining for. district adminisators satheynyny dn't warn citins soonerg about ,

because the concentration was always under the guideline value. district environmental protection head robert müller says therere was, and is, , no e for alarmismsm. robert: ever since the authorities wewere made awararf pfoa in the late 1990's,hehe distct a admintratioion ovided extetensive informrmation ad regular upupdates to thehe cits of altötting. in the meantime, carbon filtraration systemsms have bn installed d so that the e ente populationon has access s to pf-f-free drinkiking water. reporter: pfoa was produced and used at altötting's gendorf chemical complex for over four decades until 2008. pfoa was ithe air and the plant's wastewatater, which is channeled into the river alz. the chemical ultimately seeped into the region's soil and groundwater. the u.s. company responsible, 3m, has agreed to pay for actitivated carbon filtration systems s to purify the e dring

water supppply for the n next0 yeyears. but thihis don't fifie cocontamination n of the soild grououndwater. we asked 3m to comment. >> 3m commissioned a detailed soil investigation. it concluded that the most significant intake of pfoa for people in the altötting district is through consumption of drinking water. the state office for health and food safety was unable to detect any relevant pfoa concentrations from the food chain. industry and authorities are currently discussing how best to manage the soil within the district. reporter: according to that 2018 study, over 192 square kilometers around the chemical park are contaminated. however, it has concluded that the levels represented no endangerment. orgagac farmer andreas bernhofer and d his wife have e four yog children. they all havave at least t ten s too much pfoa in their blood.. even hisis animals havave tesd positive for the chemical.

andreas: my family and i moved here eightht years ago.. at that point we h had no pfoan r r blood. nonow we're heheavily continat. i am shocked b by just how fat ouour levels got so high.. it can't't be just frorom the w. 's frorom our animimals and de food w we grow here.e. reporter: of all the contaminated areas in the region, the levels in the öttinger forest are mosost seve. ededmund pichlerer loves ths fore.. bunow he c't even llect mushrooms here eit been coaminatedy pfoa,art both for uand for gerations toto com bunow he c't even llect it will probably takcenturie before is gogone

e animals are coaminated yoouheimat h b been dlyooms. f damad. reporter: ednd p picer hasasl. he hes he wot lose h heal to it. pfoaill be oicially nnedhasasl. roughouthe e.u. of july 20. but thfull sca of theproblr decades to come. host: : we meet enagagers from around the wld and ask what's imrtant t them. >> i am a global teen. host: today, our global teen comes from colombia.

juan: my name is juan carlos contreras nobles and i am 16. i live in sempegua in the department of cesar in colombia. i have four siblings. two sisters and two brothers. one of the boys is my twin. the girls are four and 11 years old. and the boys, my twin brother is 16, like me, and my big brother is 18. my father works in construction and he also fishes here in the ciénaga de zapatosa. my mother is a housewife and she also earns money by cooking for other people.

yes, i'm fascinated by t the lessons, because i want to learn so that i can get ahead. in my free time i like to do homework or read up on things we don't learn about in school. i like go swimming at the beach with m my friends. and i also like to play football or other traditional games here in the village. i like vallenato. we live in a vallenato region. it's music that gives people a way to express their feelings, their dreams, and desires. ♪

i also like it because it's music that me and my brother can play together. i can write a song and then sing it right away at school or for our family. when we talk about the environment, i think the biggest problem is deforestation. humans created a crisis and hahe completely overrun nature. it makes me happy to live in a simple, peaceful village that's filled with wonderful, good-hearted people. host: the world is a wonondros plplace, both onon land and ine sea, a and humans arare ngry fr knowleledge of both.h.

so what's the world's biggests plpfish? whale sharks.d and ine these gentle giants can weigh up to 12 tons and the largest ever measured was 14 meters long. and while they are free to swim the seven seas, a coastal town in the philippines has discovered a way to get them to stick around. reporterer: just before e 5:0n the morning,g, josé, a a fishen deep, waiting for him liard the. toto mysterishadowgiants of thte he knows they'll be there. they come every day, as they've been doing f for the past t six yearars, when thisis story be. josé: we lk k aftethe whwhal sharks and me sure ty get fo.

wewe depd on thehale sharks for our livi.. reporter: the whale shks havav changed everhingng ioslob, josé's le e and the liveveof all the other villers. but it'she creates themlves thahave expienced the re change. usuall e known fi traravethe oceans in ararch okrill.l. t the pt, the fishermenappens e view the w wle sharks s fofor. rivavals that deplpleted their already slslim catch. whale sharks were also hunte for stomomers chinana. rjojé: they were only intnteres. already slslim catch. they said d they could s sell k fins at a a high price.. but we don't do that. it'sororbidden we earn a loof m mon thanks to our nene, th..ree them. urists come to s thehe srks. and we le e off at.

reporter: for the whale ararks, it m must em likike feast. 100 kikilos of krillll a day, e if necesessary. some eventually moveve on, but there are alalways one or r two cruising abobout, sucking g upt the fiermemen to in ththei direrectn, from dawn to onon. josé: in the past we were to thate weweren'allowewed feed don't t coain anything tox..thm b we'd d ve given them poon,,? reporter: and thenen the hordesf tourists w wouldn't have come, eithther. huntnted elsewhere, in osl,, these huge fish have found vovoted fa. course, there are certain ruleles, such as a f four-meter safefety zone. t peopop often g far tooclost. perhapbecaususe r too many pele now come to s them.

the number of vitotors h inineased six-fold sce 2 201 turning oslolob into one o ofe bibiggest urisist atactionons e philippines. the fascinatioexexerted thehese gentle giants is simply too rorong to sistst. > its big mouth, and its si. >> it's keke a b -- dinn. >> yeses, it's amazizing. it's o once in a lififetime. 's a good thing for tourism ththe ea, as well, you knonow at i meme? so, i don't thinink it's a bad thing. >'m not surure if they're hu, bubut i dot ththink at thehey shouldld be fed. reporter: whwhy do you thihinky shshld not be fed? >> so they can roam around and . reporter: every day in oslob,s this r relationship p betweenn and beasast really a h healthyd

sustainable one? we notice injuries, fresh wounds on a whale shark's fin. what might have caused that? we shohow the imes to marine bibiogist rafael manrie.e. 's beeeeresearchining ale shrafael: that has to be a enspropeller.rval. especially, look at how clean thcut is.. shth's not frorom somethingg gnawing g on it or anynything e that. thatat's a very shsharp, direct. reporter: is he able t to survi? rafael: he might be able to survive.e. luckily,y, he stilhahas a biof the top of the tail fiththere. but t he'sefinititelgoing to have to wawaste a lot momore ey when it cocomes to gettiting f. reporter: for the whale arark pert, , it's clear thahat theres a connnnection betweween the feg of thehese huge fishsh and thr ininjuries.

rafaelif a a wle shark is aiained at a b bt means food, thth it is not completyy reasonab to thinththat ty coulsesee anher r bo which i not e of theegular fdingng bos and d after it, resulng an injury. repoporter: in oslslob, everye says thahat they want t to prot e whale sharks. but at thendnd of thday,y, big siness takes precedence overrye ththe welfe ofof theig fisish.ot the fishing g village is n now but burstiting at the seseams. the boat tririps alone bririnn araround four mimillion euros sa year. fidel: if theyeyon't feed these whale sharks, they'll go awayy agagain. thenen everything g will go bao how itit used to be. reporter: no o wanantshat. papaicularly not josé, who's no the oud d owneof a k karke machine.e. he's also bubuilt a house.e.

he's grarateful to the w whale shararks, and for r every day t they c come. josesé: i earn m much more thi did d fore. back then i earned eig euros a weweek. nowawadays i can e earn up to . and wewe only work u until no. wewe finish at 1:00 p.m. reporter: a a lot of thingngs e imimproved in ososlob. t there's no happy ending fort. rultitimately, theyey are the s who wiwill pay the p price fore ose encounter with humankind. hostand here'shat's cookinghe s who wiwifor xt week. price fore the dedemand for chicken is growing in g ghana, so it't's g imported from europe and the u.s. consumumers want lotots of it,d as cheapap as possible, , a ce

this time. don't forget to write us, glglobal3000@d@dw.com. and check out our new facebook page, dw women. ♪ [captioning performed by the national captioning institute,

>> today on "earth focus"... coal ash. it's a toxic waste being dumped across the ununited states. . some people living c e to these dumps have unique health proroblems. is coal ash o blame? we look for answers, coming up, on "earth focus." in pennsylvania, 3 adjoining countnties are e the hot spot oa rare cancer. in juliette, georgia, radioactive water flows from the tap. these problems may seem unrelated, but with a closer look, these two communities share a common denominator--coal ash, and lots of it.