swimming with whale sharks is a thrill for tourists in t the philipippines. but it's not s 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 sighthts. 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 aggrgrsion here in chahalatenan. ththe prisoners sit togegeth 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 be e 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. reportrter: on the s surfac, altötting is the essenence of bavaria. idyllic, conservative, and sqaky clean.but if youe region i is tainted byby sometg iyou can't t see, smell, , or g. mumund phler h h lived here hiwhole li. he nev thoughtwicece aut drinking werer frothe tap. it wasububbed e purerestn the region. bubut at conviviction s shattered whwhen he had hihis d tested amid d a widening pfofoa scandal in thehe district ofof altötting.

edmund: my b blood has over 43 micrrarams of pfoa p per lite. my wifife has thsasame. anand not a day y goes by whenee don't talk about pfoa. it's depressg.g. tens of thousands of people here in the aötting strict are don't talk about pfoa. it'saffectcted.. repoporter: for thpast three years,ononcerneditizizens ve been meeng on n regular basis to p preure the authorits s to laeverythi on the ble. they feedistrict beadmistratorsave doneoobasis tlile, and o late tinfoform to the publ on pfoaevels inhe laeverythi on the ble. they feedwater.t for r frank bremauauer, it waa shock to find out he was contaminated. frank: my plasma was refused when i tried to donate to a blood bank. we fmed thiw were not informed about the pfoa contamination here in the district. only after puttiting pressure n

the authorities have we achievef transparency. reporter: bubut just how dangers is pfoa for humans? irina zastenskaya is technical officer for chchemical safetett the e who's europepean centerr enviroronment and health. iririna: pa isis a psistenent d bio-o-accumulatingng substanceh potetentially harmrmful effectr huhuman health. it's e inteternational agagency for research on n cancer as popossy carcinogogenic for humuman hea. and spitite much more e studis are neededed to confirm m the hh effes, n now we have evideee that h high concentrtration ofa in humanan blood relatates o disorders, t thyroid gland fufunction disororders, and rereoductive h health disorder. repoport: even though ma cizens k kw nothinabout it, pfoa has been a altotting g r decades. dirict administrats say th didn warn cizens soor

because e concenation wa alwa under t guideli lue. disict envinmentalprotecr ys there w w, and is, nono cause fofor alarmism.. robert: ever since the auauthorities werere made awarf pfoa in the late 1990's, t distri admdminisation n prided extensnsive informatation ad regular updadates to the c cits of altötting. in the meantime, carbon filtratition systems h have bn installed soso that the enente population h has access toto pf-freree drinkingng water. reporter: pfoa was produced and used at altötting's gendorf chemical complex for over four decades until 2008. pfpfoa was in e air and the plant's wastewaterer, 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 activavated carbon filtration systems toto purify the drdring

water supplyly for the nexext0 yearars. but this s doest fix e contntamination ofof the soild groundndwater. 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. organic farmer andreas berofofer and hihis wife have fofour yog chchildren. ththey all have e at least tenes too much pfoa in their blood. even his a animals have e tesd positive for the chemical.

andreas: my family and i moved here eight y years ago. at that point we hadad no pfoai oublblood. now w we're heavavily contamat. i am shocked by y just how fat our r levels got so high. it can't b be just from m the w. it from m our animalals and te food we e grow here. porter: of all the contaminated areas in the region, the levels in the öttinger forest are most t seve. edmumund pichler l loves ths forest mund: thfoforestere isisart sof my heat.. it's bn conto c ce.by oa, itilill prablyly te centurs

the anims s are ntaminat. yocacan't t t the shroomom you can'see it, t a partf our imat haseeeen bay reporter: ednd picicer has lost a pt t of h home to pfoa. he hop he won'lose his healtho. pfoa wl be offially baed 2020but the ll scalef the problem n't beco clear fy, decades to come. host: wewe meet teagerers from around the wor and ask what's imimpoant totohem. >> 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 thehe 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 my y 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 sharksor years andants to ensure tir survival. bibirafael: that has to be a 's beeeepropeller.ing ale especially, look at how clean thcut is.. bibith'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 ese 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 before. baback then i eaearned eight eua 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,

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