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Science communication is important in today's technologically advanced society. A good part of the adult community is not science saavy and lacks the background to make sense of rapidly changing technology. My blog attempts to help by publishing articles of general interest in an easy to read and understand format without using mathematics. I also give free lectures in community events - you can arrange these by writing to me.

Saturday, 31 October 2015

Lead (Part 1): Clair Patterson - Determining an Age of the Earth and his Crusade to Remove Lead in the Environment

Claire Cameron Patterson (1922-1995) was an American geo-chemist who, in 1953 worked out that the Earth is 4.55 billion years (Ba) old, give and take 60 or 70 million years.  This was a remarkable achievement in an environment of ever-changing estimates of the Earth's age ranging from 100 million years to 3.5 billion years.  Patterson's value of 4.55 Ba has stuck and even after 60 years, the age of the earth, in round numbers is still quoted as 4.5 Ba.  Patterson was a pioneer of radiometric geo-chronology; the science that uses radioactive isotopes and their decay products which are present in a rock, to evaluate the date when the rock was formed.  

Arthur Holmes, called the father of modern geochronology, started dating rocks in 1910 using uranium-lead dating methods and perfected many of the procedures in the following 40 years. Holmes is recognized for his perseverance against the well-entrenched feeling of geologists regarding the age of rocks, especially of a much younger Earth. 
In fact, there was really no method available for determining an absolute geological timescale and everybody worked with relative ages of different types of rocks based on fossil records - a highly unsatisfactory situation. One could say that it was Holmes' mission and ambition to find an absolute geological time scale and do away with the uncertainties in interpreting data relating to the age of rocks, sediments, fossils - in effect set out a time scale against which dynamics of our planet's evolution could be understood.
It might be fair to say that by measuring absolute ages, Arthur Holmes's work elevated geology to a 'Science' capable of making quantitative analysis  and predictions that could be empirically confirmed.  His work also provided a time scale for life sciences against which Darwin's evolution could be understood.

During WWII, Patterson worked on the Manhattan Project and was based in Oak Ridge.  The work in Oak Ridge concerned with the enrichment of uranium-235 for the atomic bomb and the experience with mass spectrometers was invaluable for Patterson to develop the radioisotope dating methods.  Lead (Pb) is the stable end product in the decay of uranium (U).  Uranium is radioactive and the two relevant isotopes of U have masses 238 and 235 decaying with half-lives (time for half of a sample of the radioactive isotope to decay) of 4.48 and 0.7 Ba respectively, resulting in end products of Pb isotopes of masses 206 and 207.  Essentially, for determining the age of a rock or a meteorite, one is required to measure minute quantities, of the order of pico-grams (a billionth of a milligram) of U and nano-grams (a millionth of a milligram) of Pb isotopes.  Patterson developed methods to measure such minute quantity of lead present in his samples. 

 In addition to the ages of Earth, Moon, and meteorites,
radiometric dating has been used to determine ages of fossils, timing of glaciations, ages of mineral deposits, recurrence rates of earthquakes and volcanic eruptions, the history of reversals of Earth's magnetic field, and the age and duration of a wide variety of other geological events and processes.

George Tilton in the biographical account describes Patterson's next big project to measure the isotopes of lead in ocean sediments with a view to obtain information about the ages and compositions of the landmasses draining into the oceans.  In 1962, Patterson showed that the ocean surface water contained up to 10 times more lead than deep ocean water. Other metals like barium did not show this trend.  
He showed further that blood lead levels in Americans was over 100 times the prehistoric levels and attributed this to the vast quantities of lead entering the environment from sources like paint, petrol, solder and water pipes.  It seemed that the population en mass was being poisoned by the prevailing industrial activity.

The lead contamination problem was so pervasive that even the blanks, used as standards, were contaminated with lead and the measured lead levels were grossly under-estimated.  

The response from big business was as expected. They did everything in their powers to discredit and isolate Patterson.  Patterson's results were called 'rabble rousing'. Even the regulatory bodies did not believe what Patterson was trying to tell them which in his view required immediate action.  It took Patterson almost two decades to have his views totally accepted by the Environmental Protection Agencies with a significant improvement in the health of the people throughout the world.

In Part II, I shall look at lead as an environmental poison and its effects on the human body.  In Part III, I shall discuss the inadequacy of our regulatory systems and put the lead poisoning episode in relation to many other failings in the way our system works.
http://www.bbc.co.uk/news/business-40593353  History of Lead Poisoning and links to previous BBC reports on Lead Poisoning

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Tuesday, 20 October 2015

Hidden Dangers in the New Technologies...???

It is never easy to be anything but positive about the onward march of technological developments happening all around us.  After all, over the past 200 years or so science and technology (ST) has vastly improved our lot - both materially and intellectually. It is all too easy to forget that the benefits of ST have not always come without hiccups - some recent examples come to mind as nuclear proliferation, thalidomide children, DDT, plastic pollution and of course the burning of fossil fuels. The problems can arise unexpectedly without warning - not that we should not have anticipated most of these but problems come because our civilization/system is not set up to properly analyse and act on potential threats.  Even when threats are identified, our response is half-hearted and generally inadequate.  We live in a divided world.

The new technologies include the digital- including artificial intelligence (DT), bio- & genetics (BTG)  and nano- (NT).  Working together, they promise to solve all problems facing mankind - that is what they say.
We already see the wonders of digital - its impact on our daily lives has been swift and massive.  Communications, WWW, Sensors, Smart Meters are a few of the areas impacted by DT - the expected arrival of the Internet of Things (IoT) will transform the way we manage our lives. Threats to our privacy and to our institutions with unique legal and social systems, etc are very real.  Advances in AI might make robots more intelligent than humans in our lifetime.  The emergence of Super Intelligence is considered by many as given - the only question seems to be when?  How this will affect our position in the Universe is the subject of some serious debate with many scholars warning about the possibility of the extinction of humans.
Carbon life making way to the silicon life!!

Our understanding of the molecular basis of life sciences has resulted in an explosion of advances in bio-technology and genetics.  We hear about conquering diseases, personalized medicine, 3-D printing of organs without the dangers of rejection etc.  In parallel, we also learn about creating new forms of life - genetic engineering will give us modified and also new plant species, new microbes.  How these will interact with existing life forms?, will some of these be toxic? are questions we have no way to answer.  Will some nefarious element release a highly contagious synthetic virus virulent to humans and how will we cope?

Ability to manipulate objects at nano scale has given us unimaginable array of new material objects - we are now able to move atoms and molecules individually and arrange them the way we desire. Nature could do it but we have begun to improve nature's nano-technology.  Artificial photosynthesis promises to harness more of the Sun's energy for generation of food and everything else. Nano sized robots (nanobots) will self assemble and bottom-up manufacturing will result in zero waste and much increased efficiency.  Nanobots will clean up our polluted planet, reverse climate change by removing carbon di-oxide from the atmosphere and the oceans - the list of benefits is endless.  You identify a problem and NT will design a system to tidy things up!  But what if nanobots get out of control and continue to replicate without stopping - will the whole world turn into an assembly of nanobots? - Drexler, the father of nanotechnology, was very worried - he called this scenario the grey goo!

The above scenarios could completely destroy the world and the human race, but I do not think that things will go that way - at least not in the short term.  Super Intelligence threat is very real and could materialize in due course. But what I am sure is that we humans do not anticipate dangers well. We have survived by patching things up - most of the time not very well. New technologies will generate their own unique hazards - some of them might affect the whole globe very quickly, some might only be detected after it is too late and some of them might have no ready remedy.

I give here just one example to highlight the issues.  Carbon Nano-Tubes (CNT) are wonder materials and have found many applications.  One even talks about building a space-elevator with CNTs to launch payloads to build future space colonies!  CNTs are tiny - a few nanometer (nm) or so in diameter and typically a few micro-meters in length.  They are not unlike asbestos fibres which have caused serious illness in people who were unfortunate to inhale them.  CNTs are no different and can easily find their way into the human and animal systems -are not dealt properly by the immune system and it seems that they also affect the hosts in a manner that is unpleasant and can be dangerous.  There are many studies about the deleterious effects of  CNTs on mice and humans.
CNTs are widely used in industry and the current production of CNTs is more than 10000 tonnes per year and increasing rapidly.  The problem is that CNTs are also produced by catalytic converters in automobiles, burning of coal in houses in countries like India.  They seem to be produced far too easily and unexpectedly in many systems.  Because of their chemistry, CNTs can attach pollutant molecules and efficiently deliver them to humans. With increasing industrial production of CNTs with additional inventories coming from other human activities, it is only a matter of time when illnesses like asthma will be common.  How will be deal with such a threat is not clear.
Below I have listed some useful references about toxicity of CNTs...

Anthropogenic Carbon Nanotubes Found in the Airways of Parisian Children

Study says Carbon Nanotubes as Dangerous as Asbestos
 By Larry Greenemeier | May 20, 2008

A Review of Carbon Nanotube Toxicity and Assessment of Potential Occupational and Environmental Health Risks
Chiu-wing Lam  et al. 2006
Researcher warns of health risks with carbon nanotubes
  Date:  January 19, 2011

As a parting thought, if human health is indeed affected by nano-material ingestion then the new generations will be less able to cope with stresses of life - stresses will also increase as rapid changes in technologies will create situations that human societies will find difficult to adjust.  What will Super-Intelligence think of us then? - worth preserving or could do without!

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