[Music] you [Music] okay so let's get started with the third module of the second week so in this week if you remember the first two modules two module the first two videos we try to look at different contaminants where they are used in electronics why they are used in electronics what are the health impact environmental impact then we also looked at some of the case studies one from China and then I so do you the case will make a very quickly you be sure that we China one we went into detail in terms of the data and then we looked at quickly some of them from a photographic tool you can you may want to call it in terms of the impact in Cana as well as in Nigeria so which was your Legos so just to put things in perspective then now what we will start talking about more in say we looked at these these are bad we what we are calling her these are bad these are harmful but how we calculate that how we calculate that at what concentration they are really bad so that is called a concept of health risk assessment we talked about the exposure scenario as well in the previous one of the previous video in this week so in terms of exposure scenario and the concentration level how we do this risk assessment calculation so how that math is done will try to try to answer it over here so we'll go over some of the basics of the methodology and then we'll try to have some examples so in terms of the risk assessment what is we basically is trying to get generate data so that we can relate response to those as a dose response curve which you may have seen it it is very similar to even if when you take the medicine isn't it you take a certain dose and based on that dose there is a response the body gets the response the body gives in terms of something getting better and if you don't get better response what doctor will do he will change the medicine and give you some other medicine so any dose you give there is a response so that's so based on that similarly for the contaminants too for the toxicants as well that if there is a certain dose of course the body will have sort response so the risk management or the risk assessment and the risk management in the process of the decision-making so we have to say everything has a risk while crossing a road has a risk as well while driving from point A to point B has a risk even swimming in a swimming pool is arrest going to the beach has a risk so everything has certain amount of risk what we need to do is to manage that risk we have to we have to make the decision in a certain way so that we can allocate our natural resources and locate the natural resource so that we can minimize this risk some of some material may have based on their toxicity level other stuff has higher risk versus the other so we can so risk management or first for the once the risk assessment is done then the risk has to be managed where we have the property make certain decision to how to allocate naso resource to protect the public health and the environment associated with that so it says it's a four-step process it's let me try to move this on that side yeah so we can see it's a risk assessment is a four-step process the first thing is we need to find out the hazard identification so as you can see the top tip top box over there that's the hazard identification now what does that mean we have already done that so from the last few videos that what we have been trying to do we have been trying to identify that different chemicals which are present in the electronic waste stream so those are the hazard and I'm talking now I'm kind of discussing it just from the fair from a waste perspective there are that hazard identification in a transportation sector will be defined in a slightly different way but for the electronic waste those contaminants those elements that we already talked about in the last couple of videos those are our hazard then we have to we and then we need to know their concentration so that's the identification of the hazard so that part we kind of already looked at now the next step will be like at what level it is becoming becoming available to the public or what level we are getting exposed to that you saw in that if you remember from the China case study which we talked about the different levels of presence in ppm two point five different element so those are we had a base when a other city which was very far from the US processing facility and then we have a small we had tools to sample said one was near the US processing fellows facility one was away from us processing facility and we compared the numbers so that's and the exposure we already talked about inhalation dermal and injection so that's your exposure that's how it will get exposed then we need to do that those response assessment how that particular dose is what kind of effect we get for that we do is he fifty lc50 I see fifty those kind of calculation and based on hazard then exposure as well as the dose based on these three aspect we do risk characterization we try to identify what is a real risk yes the risk is there something may be very toxic but if it is not we are not exposed to it say if you have a cyanide in a small bottle kept somewhere in a lab in a corner I'm not going to touch that so I'm not going to expose to it so unless unless I get exposed then only there is a risk if I'm not exposed to it there is no risk that that's the hazardous material that's the hazardous chemical just sitting there but I'm not I'm not touching it I'm dead serious for some it's not getting into my body either through my nose or through my food or through my skin so if it's not it's there is our risk is not there so that's what we need to look at the exposure assessment and then exposure based on the exposure what is the dose response and and then based on that we can characterize what is the risk and once we know the risk we have to manage that risk even when you talked about those of you who have Britisher that all of you must have taken a watercourse so when we talk about this water quality standard when you have 10 microgram per liter of arsenic as a drinking water standard that also has a one in a one-in-a-million cancer risk so out of a million people we are taking there okay out of a million people let's take that one person will it still have cancer at the level of ten micrograms per liter ideally we should try to bring it as close to zero as possible but as you go to closer to zero you need more advanced technologies more that means more cost so at some point of time you need to manage the risk because you may have to see how to better use your resources the economic resources that the country has so it's a four step process again risk assessment hazard identification exposure scenario dose response risk characterization and finally we have to manage that risk so that's so that's the risk management part so in terms of look at some of this basic definition hazard identification is where you have the process of determining whether or not a particular chemical is so you are looking at whether or not a particular chemical is casually linked to particular health effects we already talked about that those responses you try to characterize the relationship between those of an agent and recei the incidence of adverse health effect that you do mostly in the lab setting in the lab setting you feed these the chemicals to guinea pig mice and other species and you start seeing that impact and that's how you get those data and in terms of the dose response curves so that is done for that aspect then you do the exposure assessment which involves reminding the size and nature of population which is exposed you look at the size of the population you look at the nature of the population and then you try to find out as well as the length of time and the toxic and consideration so that's basically what kind of exposure they are getting and based on these integration of F of three steps we try to find out what is the actual risk what is the risk and then we try to characterize that risk from there so so hazard identification is the first step whether the exposure of a particular chemical likely to have an adverse effect or not and toxicant will primarily enter the body in three different pathway inhalation ingestion and dermal contact then you did generate the information through testing on microorganisms animals by acute or chronic carcinogenic a chronic bio asses so that's what you try to find out there hazard then acute toxicity chronic toxicity you can go for ld50 acute toxicity is a short period chronic is a long period so that's the photochemical so a long term exposure ld50s which kills 50% of the population so is that those at which kill 50 percent of the population so we need all those we we have to do all those kind of calculation based on the data that we collect using those toxicity testing on different animals different species so for short term carcinogens Asha is we try to look at this specific procedures specific organ so mice or rats are subjected to non mutagens to find out whether the tumor will develop chronic is mostly costly complex long lasting test involves hundreds and thousands of animals over a long period of time so both things are looked at minimum test requirement they say say even when you do these kind of testing when you try to come up with these doors response you have to do is testicle e relevant datasets so there is a national toxicology program in the u.

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they have stablish the following minimum requirement for a acceptable chronic bioassay so you need to test at least two species of rodents at least 50 ml and fifty female species has to be tested at least two doses might be administered with no dose control so that's you have these are the bare minimum that you need to do then on human studies data obtained from animal studies or method is difficult to interpret for humans so some substance may cost can costumer to rat but may not cost occur to human so what by attempting to find correlation between disease rate environmental factors a quantitative relationship between exposure and risk can be developed so we try to do some like a model some extrapolation a statistical model to come up with that so in terms of if you look at the parameter for determining exposure and disease if you have exposed you had exposed and not exposed with disease and without disease so exposed and with diseases a with without diseases B and that not exposed C and D so the attributable risk is the difference between the odds of having disease with the exposure and odds of having disease without exposure so it is exposed and having the disease as a not exposed but it still have the disease of B so that if you look at relative risk so relative risk becomes what a divided by a plus B is what with disease you are exposed so that's your whether you are supposed to get it so it that's the attributable difference and then C is when that C numbers were not exposed but it still got the disease so it's a C divided by C plus D so that's the fraction kind of gives you the value where you can get the disease even without being exposed to that so so we look at that's a relative risk we define that as a relative risk then odds ratio is where you have a times D divided by B times C where you have there with disease you have exposed with disease not exposed without disease so that's kind of that's the that that's that's what you expect isn't it you are exposed it should get the disease not exposed should not get the disease so that's again it's similar to relative risk so number one if it's number is above one it will suggest that there is a relationship between exposure and risk and B and C not exposed and getting the disease exposed not getting exposed but doesn't get disease so that's the B and C so that's a be a multiplied by D divided by B multiplied by C so that gives us the odds ratio and if it's greater than one it gives some indication that yes exposure and risk is related attributable risk is where you have a divided by a plus B where you get the disease because again a with exposure and minus C divided by C plus D because you are getting their disease even without being exposed so that's so that's your attributable risk attributable risk is the difference between the odds of having the disease with the exposure and odds of having disease without exposure so these are the different terminology used in terms of the risk assessment when we are trying to pair appointed exposure and disease different parameters that we use and then there is a PD AMA logical data analysis epidemiology chuckle data is when you have a population which got exposed to certain contaminants and then got sick so the data collected from them it's not the rat and mice data it's just it's the data on the humans so epidemiology is a huge area there are if there are certain departments of Epidemiology as a part of College of Public Health so you there's a huge area of research and teaching and all that and what we don't see that much popular in Indian context in fact the whole public health education unfortunately after our independence this public health became part of they went to like to the doctors and it's not really a doctor it's kind of between the doctors and the engineers so that's a environmental engineer and the medical doctors something in between will be the public health professional environmental health professional and its environmental health is one aspect of public health public health is a huge program and it's it needs to be developed it's actually it's a good bridging point between engineers and medical medicine field where we start looking at the interaction because ultimately what's the goal goal is to better human our humans should be more productive there should be less less sickness people should be we should we need to be proactive in terms of the preventing the health because that's a proactiveness of health prevention is what is public health but unfortunately a clip our health sector is becoming reactive rather than proactive and that proactive comes in the public health aspect so let's look at the CPD homological data study so in evaluation of this personal records of an employees of a plant it the plant is manufacturing vinyl chloride 200 workers 50 double of cancer so and liver cancer I'm sorry there are is missing here a control group consisting of individual with a smoking history similar to the exposed workers and who are unlikely to go in the in-content vinyl chloride had 24 with live cancer and 450 who did not develop liver cancer so find out the relative rates attributable risk and odd ratio for those data so again what we the previous slide we can set up the table here as well so let's look at the 2×2 matrix so we have with disease without disease so some people got exposed to vinyl chloride and we had 15 people which you got liver cancer and then other we had 24 people which were here we had not never encountered a vinyl chloride but had 24 with the liver cancer and 450 who did not develop liver cancer so we had 450 who were not exposed in develop liver cancer here they are exposed but 15 people got liver cancer and 185 did not get liver cancer so again remembering the previous slide the two slides before relative risk we can divide this is now a yeah what we have a B C and D so we had what a divided by so this Plus this so that's the relative risk in terms of exposed and disease divided by not exposed to getting disease so it's more than one odds ratio is 1 point 5 2 which is 15 times 450 this times this attributable risk is 15 times 200 if minus 24 so you get point 0 to 4 so that's the risk in terms of where if you are exposed you will get more chances of getting it so that's a multiplied by 2 point 4 percent or something like that so so that's kind of how we do some of these data analysis in terms of what whether the risk is there or risk is not there so the so this this kind of calculations are useful in terms of finding out like a human health risk assessment part of that then in terms of the carcinogens when we look at there are equity evidence from clinical study pitama logical evidence there are different groups Group a group B C and D and E is a human carcinogen B 1 and B 2 probable human carcinogen C is possible human carcinogen based on it's probably don't know for sure bees is sure shot that it is a human carcinogen there has been enough data to prove that B lab data is kind of shows that yes it could be human carcinogen but we are and there are some anecdotal evidence from epidemiological data as well but we are not really hundred percent sure as as such possible human carcinogen is based on the rat and my study we see that yes there are some indication that yes it could be human carcinogen but we haven't reached the surety stage yet we need we don't have a PD more logical and other data to support that Group D is not classified group is evidence of non carcinogenic T so it's not that we don't it's not carcinogen so these are the classification that you see and weight or evidence categories for human carcinogen intuitive so we look at human evidence if you have sufficient this a limited evidence is there inadequate so sufficient of course limited evidence inadequate evidence no data or no evidence so based on that as you can see so animal evidence and human evidence so in if it's this soars like a a with where you have human evidence as well as the animal evidence this is limited so if it's limited it's not sufficient it's kind of inadequate no data or no evidence so based on weight of evidence category for human carcinogen ability based on the lab data we can try to look at the human evidence and try to correlate which one kind of works out where so based on all these data we try to generate this dose response curve the desert response curve is you do a certain exposure and for exposure you look at what is the corresponding impact so for substance that induces a carcinogen response it assume that exposure of any kind will create some likelihood of expert cancer for non carcinogen we assume that there is some threshold dose below which there will be no response to major dose proposed like human hit model and multistage model so one hit model is the relationship between the doors and the lifetime risk probability we can put it in this kind of equation where you're like it those and that and the lifetime probability of cancer which is PD can be expressed as 1 minus e to the power of minus Q 0 plus Q 1 times T now what is this Q 0 Q 0 and Q and the parameters pick to fit the data and so when D is equal to 0 result will be expressed as the background rate of cancer so there's no DOS so there's no DOS so this is the data that we'll get that's the background that's a background data so now as you increase D values as the dose goes up you will see the your probability also will keep on changing so ad is no risk of cancer ever background which is a D is P D minus p 0 P D is the this value at a date but for any particular just to explain that just to get you very clear P D is with this is the dose q1 and q2 are the parameters factory pick to fit the data so they are basically constant so now as you increase the D value you will see that changes in the probability now a D is equal to 0 that means no additional dose that's the background probability for having that particular cancer now as we increase the D the numbers will change so to find out that it's no risk of the cancer above the background background was when p 0 and DZ was d is equal to 0 so that's the that's we are calling it p 0 now when d has a certain value we are calling it P D so P D minus p 0 is giving us what is the additional risk so value of AD is approximately equal to Q and D for small doses at a small doses this is actually equal to probably to a closer to Q and times D so that's just so that's that's the one hit model now the multistage model is where you take the dose and the lifetime risk probability of cancer P DS divided by 1 e to the power of minus Q 0 Q 1 times DQ and times d square and and then the list goes on so this is the EPA choices multistage model they go for this multistage model in terms of within the probability it is a linear at low doses if you have a low dose it is linear with constant of proportionality picked in a way that the probability of overestimating the risk is 95% so you try to always try to over estimate rather than under estimate so here you can again D is equal to zero will give you background and then when as the D changes you will have that PD giving you the what is the probability of that cancer so that's this is called multistage model now we can calculate the potential factor for carcinogen so resulting those response curve as the incremental risk of cancer above the background data on the y-axis and the life time can serve toxicant along the x-axis at low doses that dose response curve is assumed to be linear but the slope of the DOE response curve is called the potential factor or the slope factor that's some people call it a slow factor some people call potenti factor so that's the slope of slope so this is potency factor is the incremental lifetime cancer risk divided by chronic daily Intek so that's how we define potential factor whatever is the life time cancer is divided by the daily intact which is a milligram per kilogram per day and again so that's the denominator is the door's averaged over the entire lifetime it has units of average milligram of toxicant absorbed per kilogram of body weight per day so that's the denominator and so that's how we calculate potency factor or the slope factor now since risk has no unit the units of potency factor as milligram per kilogram day as a inverse of that now that we can rearrange that equation and then we can find out the incremental lifetime cancer risk so if you put that incremental if you from the previous one if you go back to the previous slide you can see potentially factor is incremental lifetime cancer risk divided by the chrony deli in Dec so this way we can call it CDI this is a potential factor so if you want to find out this value over here if you want to if you are interested in this thing over here just a minute let me grab that so if you are interested in incremental lifetime cancer risk which is being tried to do in the next slide and let's get rid of that over here so in terms of incremental lifetime cancer rates which you see over here so that's what it's CDI which was a crony delay in tech times the potential factor so we just rearrange that equation now potentially factor is there potentially factor of the slow factor is available in the integrated risk is a risk information system so IRAs database the EPA database has that potential factor so we can get the data from there so now incremental lifetime cancer risk is CDI which is a chrony delay in Dec intake so we can find this particular value once we know the potential factor so we can calculate what is the incremental lifetime cancer risk and as a set potential factor all the SLO factor as we want to call it is available in the EPA database IRAs database for most of the most of the contaminants most of their chemicals okay so being said that if we can calculate generally CDI can be found out by the equation given below we can calculate the CDI which is the what we call was that chronic daily intake and what that would be you can take the average daily dose so average daily dose how much milligram per day and then the body weight so that's kind of gives you milligram per kilogram per day so that's CDI values now if the contaminant is in drinking water then CDI can be expressed like a concentration in milligrams per liter times integrate how much liters per day so if you say so you have a certain contaminant X milligram per liter typically people consume two liters of water per day so intake rate is around two liters per day exposure is how much days per life then you divided it by body weight in kg average body weight 70 years say the typical life 365 days per year so that if the exposure route that can be written up for the injection route for the injection rod this is how the equations can be written up if it's an inhalation route again you have milligram per cubic meter and how much cubic meter of air we take per day in our body exposure days per life body weight years of life how many days per year so express both ingestion as well as the inhalation Draft so just to give you some examples there will be some math problem associated with that in your exam as well so make sure that you understand this concept you know if you watch the video again and again if you need to but make sure you understand it if you don't have if you don't understand let us know we'll be happy to answer questions for you but do let us if you are if you need help feel free to send us in cushion on the discussion forum we'll be more than happy so and then so now we need to know the concentration isn't it it says that what is the concentration in there so we – we need to know the concentration values so how we can how we get the concentration values there are different ways of determining generally determined through air sampling using air sampler for the air for the water we can do direct observation we can measurement of pollutants for how much potentially it may leach out there are different t leaching test can be done t CLP is one test which is done which those of you have taken solid waste class before we have talked about there in t CLP a few have taken solid waste class from anywhere you may have talked about t CLP as well so it's one of the it's basically to find out how much contaminant will leach in a MSW landfill scenario so let's on that part but if you are in the body we also have we can use the test of simulating gastric acid of the body so our gastric acid of the body could be simulated in today we can try to find out different things gets ingested into the body however how much it will be absorbed so there are different ways of doing that we'll talk about its I think we can talk about this at EC LP in in the next class because it's a little bit longer in the next video it's a little bit of longer discussion on that so what we have done in this particular video again as in the issue area I am trying to say that what we are going to learn and then towards the end I'm trying to summarize what we have learnt so that you can relate to it and you should that's how what was the learning objective and what was actually what what we achieved so in this particular video the thing was we were more concerned looking at the risk assessment and risk management so we I tried to give you some example first of all we looked at into what are the different components of risk assessment hazard identification those response exposure scenario risk characterization and then the risk management now in terms of the risk we also looked at different candidates carcinogen non carcinogen how we calculate these hazard so like a slow factor or potentially factor in chronic daily intake rate how those numbers are God so we kind of talked about that and as part of the process of those calculation now we are at this stage where we need to know the concentration of these chemicals getting say in this case getting from electronic waste into the soil or into the water so how we do that calculation we'll continue that in the next video so again look at the videos look at the reading material any question put it on the discussion board we'll be more than happy to answer and if but I hope that you keep enjoying this course we are this is we have finished now the third video of the second week and that the four will again I will see you in the next video thank you.