Environmental and Public Health Issues-Contd 2


ok so lets get started from where we left
in the previous video if you remember we were trying to talk about different ways of doing
that those response those calculations that we were trying to do so if you remember in
terms of the calculation that we were looking at ah just to recap very quickly we were looking
at the potential in factory for carcinogen chronic daily intakes so all these you see
all these formulas all these values that will come for that we need to find out the concentration
so we need to know the concentration data then only you can use those formulas isnt
it you need to know what is there in that environmental sample and in terms of things
coming from the what solid phase to liquid phase we need to know the concentration which
is present so in this particular lecture we will try to talk about how we get those concentration
if some of you have if if you have taken either of my previous nptel courses there also we
have talked about that so it could be a reputation but again this is relevant for this course
so we will talk about in terms of when how we get this environmental concentration and
how we use the data so lets start with this and then between depending
on the time we can get to some other topic within this particular video so in terms of
in terms of the determination of concentration usually for if its an air sample what we will
do we will we will do a air sampling using a air sample or we can find out how much is
there you always hear about particulate matter two point five pm ten or sox or dogs how those
data comes so you always always try to try to understand that first of all why we need
that data and i think we have explained that good enough then how the data is collected
that is very important to know because if there is a something wrong with the data say
tomorrow you become a in charge of a city where you are looking at the pollution for
per one particular city or for a state or even from a country or global whatever if
you dont understand the data collection properly and then you cannot really pinpoint what could
be the potential error in the data because if you have the bad data you all those calculations
that we did in the previous video will have the bad numbers
so to have a proper data collection is always needed so lets look at how they are done so
in terms of the air pollution we generally determine using some sort of air samplers
so we will have the air sampler at the site and the air sampler will get those air will
pass through that and there is a mechanism will not worry too much about what mechanism
is there thats the analytical chemistry people who will worry about that but there is a mechanism
through which with that said the data is extracted so when the say this is one sensor i am trying
to pass air through that or if you if i pass through a air like lets keep it like this
so i am passing an air from here and it will come out from this side
so while the air is passing through this particular many times we call them a column or some sort
of filter and then i can separate those contaminant then i can have i may have a detector that
when you i separate the contaminant it may react with the media present here the with
the reaction of the media is a sense take response will be generated and i can measure
that response and looking at the intensity of the response i can correlate that response
with the concentration of that particular contaminant just to explain you in a simple
way its a there are a lot of of course theres a lot of other things that goes in there and
these things with this you have your computer you have your software so you can control
many of things that is happening over you can even have the frequency of collection
you can set it up to a data logger where data can be directly transmitted to that particular
data logger from data logger you can use it you can even download it on your smartphone
using an app so a lot of things is possible and those things
are being done in different places depending on how much money you want to spend and how
much what is the severity of the situation so concentration of pollutant we have to these
are the ways like for the air pollution for the water what we are usually worried about
is if things are in one of the one of the things that we worry about things coming to
the water phase if they if there is a contaminant in the solid phase if there is a contaminant
which is present in the solid phase whether it will come to the water in terms of the
hazardous waste per scenario we try to determine using what is known as a tclp test
so tclp test is essentially is trying to find out if a hazardous waste when its put in a
landfill like municipal solid waste landfill condition whether it will create ah with what
what does the amount of lead concentration which will come from the solid phase to the
liquid phase and when it comes to the liquid phase in the event that there is a breakage
in the liner that leach it will percolate through the ground and can potentially contaminate
the groundwater so thats thats in thats the scenario of tclp
but tclp is we use tclp protocol was developed earlier we do lot of other leaching tests
today tclp is just simulating what will happen in a landfill it does not simulate what will
happen in a say outside it landfill environment when the rainwater is the its the water which
is in contact with this with the solid waste so in that scenario we do other testing but
more or less nowadays for most of the batch testing procedure most not all we use that
the the basic concept we use the same the leaching fluids keeps on changing so lets
look at how this tclp is done and then i will try to explain how the other tests differ
from here and when we use what kind of tests to find out the concentration especially in
the water phase when we are worried about things moving from electronic waste as a solid
when it goes to the liquid phase so this is one example example procedure in
terms of how waste is like the leaching is done so you have a solid waste in the our
case this will be electronic waste so here do you have a solid waste so this will be
in our case it will be electronic waste now we have to size reduced to less than one centimeter
now to reduce this is whats the protocol requires you have to reduce the size to less than one
centimeter but think about electronic waste you have a cpu cpu has the steel cpu has plastics
cpu has a lot of wires cpu has printed wire board motherboard ram all those different
things are there now how will your size reduce it to less than
one centimeter its its very very tedious job and if you reduce it to less than one centimeter
there is always a argument that why why we need to reduce it to length this and because
thats will never happen in the environment so why this less than reduce reduction less
than one centimeters is still there in any of these regulatory this is a regulatory test
this is a test which is required as per regulation so why it is there the reason it is there
enough of course when it was made a waste was not there in the picture a waste is a
recent phenomena this things was developed the tclp test was developed in like early
eighties late seventies early eighties so at that time e waste was not there so they
were not looking at e waste in terms of making this test but since this is the regulatory
test used for other waste it is also used for electronic waste the stuff there is a
challenges here challenge in terms of how to get the representative sample so as i said
you have metals you have plastic you have casing you have pipes i am sorry you have
like a wires and then different types of wires you have a motherboard your other component
so when you have this whole thing together first of all how to take this hundred gram
what is the basis of taking this hundred gram like whether if i take all this metals i dont
include any of those circuit board will it it will not be a representative sample if
i take those entire circuit board that also is not a representative sample
so we have to decide how to take a representative sample one approach for that is to do is take
the weighted average so you what you do you take your cpu break it apart and then you
weigh the different components and in the same proportion you take the waste to make
a total waste of hundred grams so that is one way to do it now but again as the regulation
requires you to less than one centimeter so you have to do it actually otherwise its not
a true tclp but then there are alternatives which we will talk about that you will see
that we can go for even we dont have we can go for tests with which we essentially will
be similar to tclp test and maybe more realistic but may not be but doesnt have to be do the
size reduction but thats always a challenge but why we do the size reduction of less than
one centimeter the reason for that is to increase the surface area
so as you can see theres a smaller smaller pieces these are smaller pieces has a bit
more if you add up all the surface area here that is actually greater than the surface
area of this particular total hundred grams over there so why surface area is important
again more the surface area more the reaction better the reaction that means more leaching
will takes place more contaminant can go from the solid phase to liquid phase remember these
are the regulatory tests so regulatory test means you have to be you try to predict the
worst case scenario you are always trying to find out in the worst case scenario what
can potentially happen so you are trying to be as conservative as possible in terms of
predicting the potential environmental pollution coming from the disposal of this electronic
waste or any waste for that matter so once you have the size reduction of less
than one centimeter you leach it for hundred grams i dont at eighteen or eighteen hours
or thirty rpm now again why this leaching again we try what we are trying to do is we
are in the in terms of as i said thirty rpm thirty revolutions per minute so you are letting
it tumble you are letting it tumble for thirty in a in a its a its a basically its a rotator
so it keeps on rotating at thirty rpm and so why would do that to increase again the
contact we want maximum reaction to take place we want whatever the things in the solid phase
whatever could possibly come to the liquid phase we want them to come to the liquid phase
so that we can have a more conservative estimate of potential environmental pollution
so once you have that then you filter ah filtering is done filtering where we are filtering solid
with the leachate what we are interested in this part because this is even if it is there
why if we are interested in the liquid phase the water concentration what we are interested
in what is whatever is present in this part and then we analyze the leachate and get the
concern using some instruments and that a get a concentration of save certain milligrams
per liter now this concentration is important in terms of looking at what is the potential
risk what is the potential risk of having this electronic waste in a scenario where
do we have this x milligram per liter of say lead because lead is the one of the most common
contaminant that we always encounter in terms of electronic waste
so we are always worried about like what is this lead concentration which will come out
in the liquid phase and then it can contaminate the surface water or potentially groundwater
and all that so this is how a typical leaching test is done now for the tclp test for the
tclp test what we do tclp again what what what is the tclp test it is caught toxicity
characteristic leaching procedure when we do it where we do it to find out whether a
solid waste is a hazardous waste or not there is a hazardous waste especially for a for
the toxicity characteristic there are other characteristics out there that that tclp is
not the only test for hazardous waste determination there are a lot of other things that goes
there in hazardous waste determination but for the toxicity characteristic especially
from the hobby metal and organics too but most for my electronic waste point of view
its mostly the heavy metals that we are worried about and most number one is lead that we
are worried about of course we have cadmium arsenic and other things are also there but
in terms of the lead leachability in the tclp test what we are trying to predict is if we
take this electronic waste and put it in a msw landfill which was the municipal solid
waste landfill whether the lead concentration or the contaminant concentration other contaminants
as well whether those contaminant concentration that will come to the leachate is is its a
high enough so in case there is a breakage in the liner
whether that will go and contaminate the groundwater so thats the whole rationale behind tclp test
which was explained in great detail in the solid waste class that we offered on nptel
last semester so those videos are also available on public domain and on youtube so in case
of this so once we have this concentration we can predict whether its its it potentially
harmful or not so so one thing i havent explained to you yet if you go back and look at this
particular is like a schematic one thing which i havent explained into is in terms of here
i said leach hundred grams for eighteen hours at thirty rpm
now when we say leach if you remember if you see the picture here we have a liquid now
what is that liquid is it just a normal water or what kind of what kind of liquid we will
use to simulate different conditions tclp test since it is to simulate the worst case
scenario in a msw landfill we are looking at an msw landfill municipal solid waste landfill
there we try to the liquid that we have here is essentially so like acetic acid so from
this side lets see lets clean it up a little bit so we will have so the liquid that is
what we are using it over here is acetic acid ch three coh plus sodium hydroxide and its
a buffered solution with a ph of five point nine three plus minus point zero five because
it cannot have a exact ph so this is the ph value
so ph is around five point nine three plus minus point zero five and it is a mixture
of csco three plus sodium hydroxide now again why acetic acid why acetic acid because municipal
solid waste landfill what we have municipal solid waste landfill mostly organic matter
organic matter which would be non organic is not really creating much difficulty there
it is the organic matter so organic matter once it degrades will produce some acid and
ultimate acid that is produced is the acetic acid so if you remember from any wastewater
class that you have taken hydrolysis acidogenesis acetogenesis and then you have the methanogenesis
so acetogenesis produces you the acetic acid now the acetic acid is there in the municipal
solid waste landfill thats what we are using acetic acid over here so just to simulate
that condition then why sodium hydroxide sodium hydroxide is added just to make it a buffered
solution now what is a buffered solution buffered solution that means is you have in buffered
solution you are trying to have buffered means resistance to ph change so we want a ph of
five point nine three oh sorry thats four point nine three sorry that is not five point
nine three its a four point nine three its four point nine three plus minus point zero
five sorry for that so so its four point nine three see anybody can make mistake so so dont
feel bad if you make a mistake i always learn from mistakes
so its four point nine three plus minus zero five thats the ph that we use so we what we
are trying to do is sodium hydroxide is added to make it a buffered solution as you know
so acidic acid is a weak acid it doesnt have much buffering capacity so thats why we add
sodium hydroxide to have a buffered as its a buffered solution at four point nine three
ph you so thats the liquid that is used in here now if we want to use the same lets clean
it up so that so if you want to use similar procedures in some other tests if you want
to use what will happen outside the landfill what then this liquid has to change because
acetic acid sodium hydroxide was for municipal solid waste landfill condition
now if i am interested in to see what will happen with a natural rainfall now natural
rainfall what is there if you think about natural rainfall just just before we talked
about the air pollution there i mentioned as well one of the things that we worried
about from the natural rainfall is which can potentially come down with the rainfall is
sox and nox now sox and nox means what sulfuric acid nitric acid and they simulate acid rain
condition that the acid rain condition if you want to simulate thats what you have
so in terms of acid rain condition what here the liquid that we will use to simulate those
kind of is a diluted solution of sodium hydroxide h two so four and hno three so everything
is there there is a logic for everything again i keep on telling in my classes online offline
all the time dont try to memorize try to understand memorization we will forget the day your exam
is over or what that but if you try to understand it will be with you for a longer period of
time and even if you forget something you can all once you come back and revisit it
is quick to recovery collect but memorization stuff doesnt is not really quick to recollect
so always try to understand the concept so thats more important so i think thats then
we can have for other type of leaching so leaching conditions we can have other liquids
being used will not worry about that for right now will as we if needed we will talk about
that later in your when you try to understand something else you will see that too so difficult
we are performing a tclp is collecting a representative sample and size reduction as i said less than
once intimate its very difficult to do that so how what we do typically one option we
try to do is we cut it by hand option one is you try to cut everything by hand ah its
so you have your cpu you disassemble and you have different components in here and so disassemble
different components and then you try to size reduce my hand up sorry just a minute
so you have you are trying to size reduce using different types of like a precise reduce
by hand which is not an ideal scenario but you may have to do that use these tools to
get that and here is your sieve if to make sure the size is less than one centimeter
so its so actually one one dimension has to be less than one centimeter so that it can
pass that sieve so thats not all the dimension has to be there so it basically you can make
a long long strips of width is less than one centimeter but thinking about that you may
think that thats are you going crazy will this really happen in a natural scenario we
say if i put this e waste in the municipal solid waste landfill whether it will really
break it down to less than one centimeter thats typically will not happen then the question
is why you are even making me do that so that they are trying to make you do that
the regulation is trying to make it do that as i was trying to explain earlier as well
to make it a worst case scenario so that we this is them this is the worst thing that
can potentially happen nineteen nine point nine percent time probably it will not happen
so then the discussion also comes at something which will not happen you know pretty much
that it will not going to happen while you are because you are increasing the cost so
why you are even doing this so but since the regulation as i said when the tclp tests were
designed the us was not in picture this kind of waste is used for this kind of test is
used for several industrial wastes like ash contaminated soil and they already have a
low particle sizes but since now this is e waste and other stuff we may have to design
a newer test but until we have those tests we work with what is the existing test so
it does act as a screening tool but it may not give you in a very good true picture which
you will see as well that many times it doesnt do that which we will talk about as we make
progress so so thats one way of doing it and now that
what is the other way of doing it you can grind it so you can put it in a grinder like
this so you take your e waste and take it to a grinder and then you grind it in here
and so grinder will give you some some some size reduction then you do the further size
reduce by hand as we did in the previous slide and then you get here sample and you work
with that sample in terms of the different leaching test so thats another option for
us to try so and what else we can do another option is we can drive we can lets bleach
the whole thing because think about if when the electronic waste get disposed especially
in a landfill setting what will happen you have you have broken down the e waste it one
compactor passes on top of that it may cross it a little bit but other than this you dont
expect things to break down like metals plastics they will just stay there over time there
will be some wear and tear but you dont get less than less than one centimeter
so in that case one option is lets take lets just disassemble so you take the electronic
waste and then just disassemble them you disassemble them up sorry you disassemble them and then
you try to find out that concentration you try to try to get the concentration in here
in terms of lube after you pass it through but that in that case you need a much bigger
vessel you need a much bigger vessel than what is typically used for the tclp test or
these leaching test so with that in mind that kind of gives you some idea of how the different
types of leaching could potentially be done and why we are again why we are doing this
leaching stuff to get the data we have to collect the data to and that data will be
useful in doing those cancer risk non cancer risk and all those calculations
so what i did is i just give you a very quick overview of how the data is collected and
then lets let us try to look at once you have the data how will you try to make use of that
so we have to look at what are the whether that contaminant is a carcinogen or non carcinogen
if its a non carcinogenic calculation is slightly different way if its a carcinogen the calculation
is done in a safe different way the carcinogen will have to be more careful so for the non
carcinogen effect we assume that there is the exposure of threshold so and what is an
exposure threshold it is the amount it is the concentration above which you will is
you start seeing adverse effect below which you dont see that so thats your assume that
known carcinogen there is an as exposure threshold any toes less than threshold would not increase
that adverse effect so lowest dose is which is known as the lowest
observed adverse effect level or we call it loael the highest dose that does not create
a response is called no observed adverse effect which is called in noael and then we can calculate
reference dose called by acceptable daily intake we can find out that indicates a level
of human exposure which is likely to be without acceptable risk and you can you can take their
noble values which is a no observed adverse effect level and then there is a all typos
here actually this should be noeal this needs to noael which is no observed adverse effect
levels so this is what needs to come here so ena got switched so so for the non carcinogen
we take that noble value and then we have we used lot of uncertainty factor
now why we use this uncertainty factor what is the what why we have to use this uncertainty
factor the reason we have to use this uncertainty factor is since this data is always generated
using mais guinea pigs and the doses species and we are talking about humans so when you
have these mice and guinea pigs that is being used as the species to get these numbers get
these numbers we not not in this one the other like no loael and noael and other values so
we have to try to take that mice and rabbit data and extrapolate it to what could potentially
be the human data and thats your in that case you apply certain uncertainty factor because
you are moving from one species to another species so thats why you need to go those
exercise ok so once you have that how we do that once
you have the data what we do with that we we plot this with what is known as the dose
response curve now dose response curve is your you have a as you increase them so at
a certain from here you are increasing of sorry just a minute so from here as you increasing
the dose for one particular contaminant up to certain level there is no effect because
up to certain level say most of this contaminant whether you talk about chromium or arsenic
or other stuff we do use them a little bit we do use them in terms of a dietary supplement
and all that when they go at a higher concentration then only it becomes a problem so how does
the smaller concentration you dont see any effect at from here you start seeing some
impact showing up and then you start looking at increase in the number so what you do is
you will take the no observed of adverse effect level and this loael is actually she needs
to move to this side so that should be on this side so thats your
this is no up no effect here we start seeing effect so that needs to come just before this
arrow thats where this loael needs to come and then when it goes above that you start
seeing increase in in the response and then ultimately what happens it kind of flats out
so it starts so if you keep you can start from it will you start from where i can s
and then this is the on top like an s and the bottom s and the trace basically something
like you have undo we i dont need to redraw that because its right here so you have these
then you start seeing the effect and then after a certain concentration things get starts
flattening out so thats a call a typical s curve thats the s curve for that dose response
we call it a dose response curve so that dose milligram per kilogram and the
response could be the way we have measuring it so its again just a quick what are the
other things here so loael will be here so after loael you start seeing an increase in
effect and then things get splat two out and we calculate this reference dose which is
actually much less than these values that we get so we are adding some uncertainty and
then we are also adding some factor of safety there to get those rfd values so that probably
explains that stuff and then we also talked about hazard index and hazard quotient so
maybe we will start lets see yeah probably yet lets do this slide here and then we will
close so that next we can talk about different concept
so in terms of the hazardous index and a hazardous quotient its a its its a terminology essentially
its used to in the hazard quotient is used to compare the actual exposure of with the
r rfd to see whether the actual dose is safe or not so we will collect the data as i was
trying to make i mentioned in the previous particular video will collect their data will
calculate the average daily dose will get the average daily dose during the exposure
period we can get this data up from our collection and then we divided by r fd r fd has been
generated the over several years of research so these rfd values now available for most
of the common pertinent so if average daily dose divided by rfd if
that number is known as their hq which is the hazard quotient so hq is less than one
that means rfd is actually more daily dose is less so there is no significant risk of
systemic toxicity but if h q is greater than one there are chances of potential risk so
if in that case is a chance of potential risk so when exposure involves more than one chemical
the sum of the individual hazard question is used to measure the potential toxicity
which is known as the hazardous index so we if he is more than one chemical is there we
can put things together and then we can find out what its a measure that ordinary potential
toxicity which is also known as the hazard index
so hi is actually some of the hazard quotient so hazardous index is solve the hazard quotient
and thats how we get these numbers so this is the important concept in terms of the hazard
index and hazard quotient so with that lets stop in this particular video so this is the
fourth video of the second week and then we have will have the last video coming up for
this particular week and so this is again if you in this particular video what we try
to learn we try to learn first of all in terms of the data data quality why the data is important
how it is going to how we are going to collect it different environmental sampling for that
and then you look at the procedure in little bit in detail of how we do it for the liquid
to sample the concentration coming to the liquid phase from the solid phase different
scenarios how to get a representative sample and then we talked about this hazard index
and hazard quotient so with that lets stop now and in the next
video we will continue this discussion but with slightly different angle so a different
angle in terms of the bio concentration biomagnification and all that so again thank you very much
do take the quiz and i may i would encourage you to take the exam its up to you of course
its up to you you have to register for the exam the information probably you before given
to you or maybe already been provided so enjoy the course any question send us an feedback
send us an email i am sorry send us a question on the discussion forum and we will respond
to you again thank you

Leave a Reply

Your email address will not be published. Required fields are marked *