>> are you a photographer? my interest is deeply historical and academic though i am sure that there will be a day in the not too distant future i will try my hand at something though i am particularly fond of the early technologies my children have a greater command of the newer technology than i do and they've had a long fascination thinking historically and theoretically about photography and perhaps there will be a early on. >> which photograph is in your

office or at home. >> it is a photograph of a young man which was shared with me by a collector in maryland who has an enormous collection of early photographs and there was something about his command in the camera. there's a certain strength and while we know the list he is also something clearly of presence and that in particular is important. hispanic early photography and

the making of african-american identity. this is booktv at duke university. >> james talks about the history of drinking water and the safety and scarcity. the professor says unsafe drinking water is the single largest killer in the world. this was conducted at the end. it's part of the booktv college series. >> now we have the professor at duke. in this book you write unsafe drinking water is the largest killer in the world. >> i was surprised to find that. the statistics are somewhat

rough but over half of the population is estimated will suffer from a lot of disease. >> why do we not have clean drinking water parks is it hard? >> the challenges that we are facing with drinking water are different than dc. it's been a challenge for every society throughout history and for each society whether it was egypt or rome or durham north carolina everyone thinks their water is safe enough because that is their background. but we probably couldn't be paid to drink some of the water

>> in the u.s. we have safe tap water? >> we don't spend the money it takes and in some respects it changes a bit. if you set risk-free i would have said no we don't and what i mean by that is what i said a minute ago that we accept the trade-off and it was quite remarkable i could go anywhere in the u.s. right now whether it is bangalore or tallahassee or santa barbara and i don't give a second thought to the drinking water which is at a point historically a short period of time because for most of history it hasn't been safe from our perspective. >> but like you said you can go anywhere in the u.s..

>> in the rich countries there are some that have their own sort of particular but there are other parts where you want to avoid the drinking water if you can and the reason for that is twofold and part of it is water provision and sanitation. they were the first great society to provide safe drinking water is where the two aspects. many countries don't have the infrastructure so they get contaminated. one of the statistics is that a

year or two ago for the first time in history since they came down they lived in urban settlements. we have now become an urban species and in the case for drinking water it's huge because providing safe drinking water is much more difficult than in the more dispersed populations. >> is bottled water safer than tap water cracks >> guest: >> there is no reason to think so. one of the reasons is convenience. if you go to a grocery store or gas station and you don't want something sugary you drink for the bottled water.

if i had gone to a gas station in the 70s they would have pointed me to the hose by the radiator so first is convenience and the second is fashion. the students i teach now have a see-through container in their desk but it's this notion of safety and the reason why it is unlikely that it's safer than tap water is for some strange reasons bottled water is regulated by the food and drug administration and tap water is much more rigorous there are more tests that are done every day. moreover if bottled water doesn't cross the state line effectively the federal government isn't going to be

involved. they had an ad campaign that compared the tap water into turned out about about roughly a third of the bottled water contaminants just because it comes in a bottle doesn't mean it's cleaner. in the developing companies it is safer but that is a different situation. >> what is the importance of fluoride are >> it's important to strengthen the in enamel. the peer reviewed literature says the biggest concern is that

it can lead to brittle bones were discoloration of teeth. i haven't come across any science that talks about links to autism or disorders and my own views the big concern about fluoride fall into the same concern which is the notion of liberty and autonomy the government is doing something to your body that you have no control. it's linked with vaccines and mental health programs. it's one of those issues people feel very deeply but it's not a cause for concern.

>> what do you do at duke university? >> i chair at the school of law and environment. i teach the international environmental law natural resources, administrative, i sweep the halls sometimes when they need someone extra. >> you teach contracts and environmental law? when it comes to the standards where does the u.s. rank? >> historically we've been not only a leader that he play in their we've really developed the first generation of standards across the country that were forcible and give citizens the right which was innovative and aggressive. since then some things have

moved forward into some haven't and unfortunately in my view it's become a partisan issue and it's been cut off and the partisanship so for instance you look at the climate change there is a lot going on at the state level and federal level but if you compare that it's hard to say that they are a leader in that regard. >> how important was the safe water act? it was important because it provided the uniform standards in the country. thof the more important was actually 1914 when the commerce commission required the common carriers had to use chlorinated water.

adding clothing to the water was the single most important public health option in the history. it was commonplace in the u.s. and europe. one of the wright brothers died into these were waterborne diseases. with the addition of corina turns out the passage was very sensitive to chlorine so the government wasn't willing to politically dictate to the states and governments you must chlorinated overview of water so they said look we can't regulate the common carriers and so if you have a train or bus passing through and you're going to provide them water it better be chlorinated.

>> pooh discovered chlorine in water? >> it happened probably in scotland they were the first place to chlorinated water. in fact it's a very interesting lawsuit. the contract with jersey city basically said they would provide fewer and hold some water and so what they had been doing up to that it was basically through attrition you pass the water through these barriers that stand and they were sued by the city because they didn't trust them into the judge basically said i know

you're not used to this but i've been persuaded that it will provide wholesome water as well. >> what about converting seawater to regular water. is that technology second-generation or third-generation? >> it's quite developed and there are different variants. where you find it basically is along the coast. australia is getting into it, and a lot of people said that is the answer to water scarcity and it can be part of the answer. there are three big challenges. first is that water is heavy and it doesn't move uphill. unless you are on the coast it can be expensive so one of the shocking statistics, the state of california roughly 20% of electricity consumed the state

of california for water. the 20%. and so it isn't going to be the solution for the inlay and communities. the second problem is that it's expensive. essentially there are two types. one is where you keep the water and the second is reverse osmosis you force it to filter out the salt and the third problem is environmental