Hello.
Welcome to this module on risk assessment and lifecycle analysis as part of the ecology
and environment course.
My name is Ravi Krishna from the chemical engineering department at IIT Madras.
In the next few lectures we will be discussing aspects about health risk assessment and several
factors that cause health risk and we will also discuss why - how we can manage this
kind of health risk.
So as the slide shows a general overview of what we will be addressing in this particular
module.
Public health concerns about health effects due to environmental factors.
We k now that we see newspaper, news, in the media, public media and also we see it around
us sometimes there are a lot of concerns about public health.
The earliest big large-scale incident about public health was the London smog somewhere
in the early in the mid 20th century where there was a lot of smoke in London and people
did not know where it was coming from.
It's around about the 1940s or 50s and in the 50s around World War II that time and
people did not know where it was coming from and it caused a major outcry and a public
health problem.
That was one of the first instances of that.
The other instance is smog in Los Angeles and more recently dust in New Delhi.
So these are all issues that the public faces when we are looking at a certain issue in
the public domain and people are worried about it and then we seek answers.
The questions that are raised as as these kind of health effects are where these health
effects observed earlier.
The first question people ask us is something that is new and it was not seen earlier.
And the next question obviously is what is causing these health effects.
So there's something some factor that is responsible for these health effects.
And in the case of London smog and the Los Angeles smog and dust in Delhi it is visible.
So the the physical manifestation in the cities whether preceded the health effects and people
obviously were afraid that something will happen to the health.
But oftentimes you don't see that.
You don't see a physical manifestation.
You irst see the health effect and then one tries to investigate what is the cause of
this kind of problems.
For example, you might have a health effect that is arising from drinking water from a
particular well but you might not even see what is causing it and so therefore investigation
of those kind of effects becomes much more difficult, but it all comes under the same
scope in that there are health effects and then we would like to know what is causing
them and is it because of pollution.
Sometimes people assume that pollution is a cause of it and the reason we do that whenever
we have health effects there are multiple reasons why one can have health effects.
One can be - one can have a genetic predisposition to that or a particular which is nothing related
to an environmental factor.
So these kind of reasons also exists for health effects.
So we would like to isolate if it is an environmental reason that is causing this problem.
So and if it is established that it is because of pollution into the environment, the next
question one would like to ask is who is causing it, who is responsible and this comes the
question of liability.
The liability is a very important aspect.
We will discuss this briefly in one of the modules later.
So who is responsible because as we talked about there are different cases in our society
where one particular section of the society is responsible for environmental pollution
and the rest of the society has to bear the consequences which is health risk or any other
form of risk, then there is a responsibility of the person who is polluting to take care
of it, to pay for it, and the scope of that is what is classified as liability.
And then the next question people ask is okay it's done, the damage is done or it is being
done so we know who is responsible.
So is it possible to control or remedy the ill effects of pollution?
This comes under the purview of what we call as environmental management and the next question
when you do all this and there is a cost involved in this and that is who will pay for it.
This comes under liability and also compensation.
So there are health effects which means there is going to be expenses, medical expenses
and there are some compensation is given either to a society at large or to the government
or some such entity which is determined after an investigation, and the last question that
one would like to ask is is it possible to predict this health risk, and what we mean
by predicting is health risk is there are different classes by which - different types
of events by which this kind of health risk can arise.
One is due to normal operation; business as usual.
People are doing something some activity and as a result of that we would like to know
if a health can be predicted based on that activity.
The second aspect is if there is a sudden accident that kind of thing would it be possible
for us to predict and emergency response or prepare ourselves for an emergency response.
The idea of health risk assessment or risk assessment in general.
Risk assessment is the term used very widely.
It's used for economic risk, risk for environmental health, risk use for financial risk, risk
for other things also social risk assessment.
So in the entire purview of risk assessment health this is very important because it pertains
to human beings and therefore we are asking all these questions.
And finally we would like to ask is there an organized methodology.
It seems like it should not be a knee-jerk reaction where something happens or a reactive
process where something happens and then we group around and try to evolve a solution
but is there an organized methodology where right from the beginning we incorporate the
principles of the risk assessment and reduce.
When we do risk assessment it implies that we are - we have a goal for reducing the risk
and therefore can we implement these principles right at the stage of the design and this
is where this lifecycle analysis or LCA and the associated tools that we use will it comes
into play.
Along with this there is also organizations which are regulatory bodies and international
body agencies which also have guidelines.
One of those is is the ISO guidelines.
The ISO number for environmental assessment.
They have a -- they keep revising their guidelines and in order to help people to plan this process
of risk assessment in a more organized manner.
So with this introduction we will go ahead in this module in this particular lecture
and talk about environmental health risk and the definition of that.
So we address the following questions; what is environmental health risk in this particular
lecture and then how does it happen, and how do we characterize it in a sense how do we
quantify it because we need solutions.
We need also to quantify risk because there may be several risks and we would like to
know which one is the more severe one so we can address that first because our resources
are limited.
And there are different types of health risk and how can technology help in this and this
lecture and the following lectures.
There are a few lectures that we will cover this question in.
One of the things that has come out of in the discussions also in the other modules
when we talk about ecology and environment, we also talk about economics as a consequence
or as a very important factor in it which determines how effectively we do some of these
things.
For example, in the previously we said we have there is liability, there is compensation
and all that and the reason why people are focused on this is all of this cost money.
Doing environmental health risk assessment and preventing it and managing it costs money.
And in general people see environmental management as an overhead.
What we mean by overhead is it is not essential to the economic activity of a particular process.
It is seen as an externality.
It's seen as something it is as a nuisance in some sectors.
So the goal in the current scenario in the way the governance is going is that we would
like to incorporate environmental management into the basic design of a particular process
whoever the process may belong to it, may be an industry.
It maybe a government.
It maybe any other agency that is trying to do something including remediation work.
So what are we really worried about?
We are worried about health effects.
Health effects such as respiratory ailments.
It includes shortness of breath, allergy, something some problem with the stomach, the
gastric ailments or a long-term illnesses such as cancer or effect to other critical
organs and a lot more.
So when see - we look in newspapers we are always concerned that we have an ailment we
would like to see there is an external factor involved in it and this external factors usually
is an environmental factor.
For example how do we get these health effects.
This one possibility as I mentioned earlier is predisposition of the body to react to
certain things but sometimes it's also inherent.
There may be a deficiency that may be happening, but there are environmental factors that may
be responsible for this.
The most commonly seen environmental effect is allergy; nasal allergies.
When we go out in the road many people suffer from nasal allergies.
We have runny nose.
We are sneezing and that kind of thing.
And so we know we can relate that we have a respiratory ailment.
So it must be something that we breathe, something in the air that we breathe.
Air is clean.
We usually don't expect this kind of behavior but if there is something harm in the air
we breath we may have a respiratory ailment.
Similarly if something is there in the food or the water we drink we get - we may get
elements to the digestive system or other internal organs and we also can have ailments
to the skin or eyes when we have direct contact with these harmful substances.
In the environmental jargon the method by which a chemical can get into the body or
a person can get exposed to a particular harmful substance is called as an exposure to that
particular material and there are different pathways.
As we have discussed here already if you breathe it is called as an inhalation pathway.
And if we eat it's called as an ingestion pathway.
And if you come in contact with it for eyes and the skin it's called as a dermal pathway.
So these pathways are related to media in the environment.
So we have in the environment we have air, we have soil and we have water.
The three are the major compartments in the environment.
We also have sediment.
Sediment is something is the mud that is present under water in lakes, rivers or ocean floor.
We also have animals and plants that live in these medias which survive in this media
and which rely on this environmental media.
Together we call this as environment.
So when we are talking about environmental pathways we are talking in relation to human
beings.
Humans are taking material from the components of the environment.
So we eat, we breathe the air.
We drink the water.
We also rely on the animals and plants for our food and so if there is a harmful substance
and so the human beings here I call as a receptors.
A receptor is a general term that is used in environmental - in the convention of environmental
sciences is anything or anybody who receives a particular substance.
So this can be anything.
A receptor need not be a human being.
It can be a plant.
It can be animal.
It can be air, water, soil or a building.
So in the context, overall context of this we don't definite differentiate between the
class of receptors; anything can be receptor.
A sensor can be a receptor.
So it's a general term but in the context in our context we are worried about human
health risk assessment.
So our receptor here in most of the cases is a human being and let's say there's a substance
A that does not belong to the environment.
So it's a natural environment it's not there.
So it's a substance that is introduced.
So in the context of things when we are talking about health risk assessment we have a health
effect and we want to know what is the cause of this.
We are saying pollution a cause of this and the reason we ask is there are some natural
causes also which can cause some of this ailment.
For example pollen is released by trees, by flowers in a particular season and we all
know that during a particular season people are very susceptible to nasal allergies.
They say it's the season and lot of pollen is in the air and therefore certain cities
have a lot of pollen and therefore somebody is susceptible to this kind of this thing.
And that's the reason I classify this as a substance not belonging to the environment
which is the signature of pollution.
Somebody is doing something which does not belong in nature and therefore if it is released
in the environment so what happens?
So if a substance that doesn't belong in environment comes through and it goes into every part
of the environment and if it enters every face of the environment then it can enter
the human beings and when it enters human beings and over a period of time a constant
exposure of this particular environmental phase to human beings this thing grows, it
accumulates in the human being and at a certain point when it accumulates a human receptor
can fall sick.
So this in general is the exposure pathway and then it will manifest health effect.
So toxicology is a term that is used in order to formalize this health effect.
So the health effect is an effect.
Toxicology is the reason why one may have a health effect.
So when we talk about health effect there are two kinds of health effects.
One is called as an acute health effect which is where the effects are seen immediately
in a very short time scales for example this time scales are the seconds, minutes and hours.
So for example, if you go into a room where there is a harmful chemical immediately your
eyes are irritated or you have sneezing.
It's a quick effects.
It's acute but it's is quick, fast and if some of these acute effects can also lead
to fatalities in certain cases where extremely poisonous substances are there and it can
lead to fatalities.
On the other hand we have something called as chronic effects where the effects are not
observed immediately and physiological effects are seen after prolonged exposure and are
manifested.
What we mean by manifested is symptoms start showing up very late and sometimes it can
be months, years or even decades before it shows up and for the same reason why it has
to show up for it to show up it needs to accumulate in the body to some certain extent and several
categories of chronic effects we have gradual internal organ damage.
Then we have teratogenicity which is birth defects.
Mutagenicity which is transmitted by genes to the next generations and then we have carcinogenicity
which is cancer-causing.
So there are different chemicals that are known or suspected to cause cancer or suspected
to cause some of these things and we will see what we mean by suspected reasons.
The chronic effects are instance more dangerous because we don't see the effect immediately.
Somebody is exposed to something for a short period of time they say it's everything is
fine they go on with their business and they keep doing it for 10 years without realizing
that there's been a slow exposure over a period of time and therefore they may be exposed
to something that may cause a long-term ailment.
So it's called as a chronic and a lot of things that we see in the environment in terms of
pollution and contamination and the health effects come under this category because the
concentrations of some of these chemicals are very small but due to accumulation over
a long period of time, it can cause an effect.
So we need an index of toxicity or toxic.
What we mean by index is the following.
So there are two different substances A and B have different toxicity, say Mercury and
common salt.
Obviously one milligram of mercury if you ingest one milligram of mercury and one milligram
of salt the effect is not the same.
From one milligram of Mercury which is likely to be more hazardous than more dangerous more
toxic to a human being than one milligram of salt.
So in order to characterize the toxicology we use what is called as a dose response curve.
The dose response curve is a relationship of the response of a receptor such as a human
being to the amount of substance that is ingested by the receptor.
So in this the dose response can be a straight line like this which says that for every nonzero
amount of material that is ingested there is a positive response, there is a certain
response.
We just call it as a no threshold response.
There are also responses which is called a threshold where below a certain dose nothing
happens.
There is no response at all and there are also things like non linear responses here.
So one of the things that one has to keep in mind is dose response, the response is
only limited by the way in which we can measure the response.
So as we have gone ahead in technology in medical diagnostics technologies this response
our sensitivity of the responses which means the capacity the capability of our for us
to detect a response has also increased and therefore we are now able to see a lot more
response of health effects symptoms that earlier we were unable to see until it reaches a certain
point.
This directly relates to technological advances in diagnostics and in the ability for us to
measure certain components in the system.
So this dose response relationship curves will change over a period of time as and when
we have new information available.
So this is not set in stone and this is liable to change as - so you keep hearing news reports
that some substance which 20 was considered to be safe is now considered unsafe.
That's because we know more about the response because we we are able to measure responses
more accurately now than 20 years ago.
So a response is a measurable effect in health and so but then we are worried about human
health and how do we measure human health.
So if we take ten people in a classroom sitting and I am working on a blackboard with a chalk
piece and two of them start sneezing when I work with a blackboard when I erase the
dust on the blackboard.
So the problem is there is a lot of all the receptors and we know that from practical
experience that in a given population of receptors all of them do not behave in the same way
for a particular stimulus.
If you have a pollutant that is in this room that is present in the air at a certain concentration
all of us are not going to be experiencing the same level of response and therefore that
provides a challenge and it forces us to use statistics as a tool for determining quantitative
markers for these kind of things.
So when we are dealing with large populations we are dealing with society at large, so if
you are dealing with the population in India which is close to a billion we need to make
decisions, policy decisions based on these kinds of responses and therefore that becomes
a problem and you have to use statistics as a tool that will help us make decisions.
We are not going to talk about statistics in this course but it is important to keep
in mind that a dose response curve is only as good as its statistical validity and that
one has to keep that in mind but we cannot measure health effects directly in human beings.
There are ways to do it in what is called as epidemiology.
It is also a statistical tool say we have 100 students in the class 20 of them fall
sick whenever I open a blackboard I start writing on blackboard which means that there
is some relationship between me writing on the blackboard and their health effect.
So that is said an indirect statistical relationship.
It does not have direct proof.
You can only have direct proof if you have physiological evidence and sometimes it is
not easy to get live physiological evidence.
Now it's becoming even easier to do it but in general it is not easy because it requires
the consent of the human being and therefore it's not easy.
So we're also talking about toxicology which means that we would like to know what is the
toxicity of a particular chemical and I am going to produce now.
If I'm going to manufacture something which has properties, useful properties for other
things that we do and this is the crux of this module in that we are trying to make
some process some material that has usefulness in some other aspect of our society, but then
we would like to know what is the impact of this.
So in other words risk assessment is also known as impact assessment or environmental
impact assessment or health impact assessment.
So we can't use it on human beings.
We can't take a new chemical and those human beings we didn't say what happens to them.
That defeats the entire purpose of it.
So people have used surrogates such as animals in order to test it and you see this very
often.
We see that this product, certain products are you will see labels saying that certain
products have been tested on animals and it has shown especially mammals because that
is similar to the system that human beings have and it is shown that the response is
similar to that of human beings and there has been a lot of controversy about this and
some people don't like doing this and many corporations have moved away from this kind
of systems and we see a whole societal response to this kind of things.
So as a population also we are divided in this kind of responses but something to keep
in mind.
More recently we have biological methods and biochemical methods that we don't have to
do this anymore.
We can directly take a particular tissue and then see the response of a particular chemical
on that and we chock the entire biochemical response of the system in a human body where
it goes and all that.
So in the system where we use animals some examples of the toxicity indices that represent
the dose response curve or example such as the LD50 which is lethal dose 50 which indicates
that there's a mass that will kill 50% of the population.
This is a mass of a chemical or a dosage of a chemical that will kill 50% of a population.
This 50% is important because again we talk about susceptibility of different components
of a population, different individuals in a population to a particular dose.
So we need some kind of limits, more than 50% which means it is acceptable which is
a significant amount of risk is not acceptable.
It's a significant amount of risk that is posed to the population and therefore it may
be taken seriously.
This is of course controversial because in a population of whatever be the population
always the difficult question to answer is what is acceptable risk.
So in this case it says that at this dose of chemicals 50% of the population may suffer
a fatality.
So is it okay if one in a million suffers the fatality and is that acceptable health
risk and this is a very difficult question to answer from a societal point of view and
as we do several things in our society.
Sometimes these kind of questions are linked to economics.
So if we say that having an automobile running cars on the road has a risk of one in a million.
So one in a million person can have a serious health effect because of vehicles on the road.
So if we are very strict about it we say we should ban all vehicles.
We should ban all combustion devices in our society and our society will collapse.
So here is where I think the concept of sustainability comes into play and it is not an easy question
to answer as you would have already realize from the material presented in other modules
about sustainability that it is not an easy question to answer.
So it's a question that requires the participation of society at large even to determine what
is an acceptable health risk and this is something for all of you to ponder about when you look
at some of the data and the statistics about these kind of things.
So as I had mentioned earlier we focus our discussion on human beings as primary receptors
but we also extend it to other components in my mind we should and because they are
all related to us in some way or the other.
So this is the argument that is placed by most people who say that if you have to protect
our environment for the future generation.
So and environment must be given a chance to regenerate itself so that it is.
So as a result of this toxicology discussion it's now is mandatory that every material
that is produced must be tested for toxicology.
So whenever you have a material that is produced by a company they have something called as
a material and safety data sheet which contains all this information.
It must contain toxicology information and exposure information which means if I'm exposed
to it by inhalation or by drinking or by skin contact what will happen and these numbers
must be presented and they must be tested and validated by a government regulatory agency
before it can get into the environment.
So and so based on our toxicology effects we can infer that toxicity is likely to be
higher for higher mass of ingestion.
A general rule that we have is that the mass, the dose that we ingest is equal to concentration
multiplied by the volume.
For example if you drink four liters of water every day and ingestion of a chemical A in
one day through the water, if there is a chemical A in the water that you find how much of A
in the water is acceptable.
So if the concentration or that is the mass of A per liter of water multiplied by four
liters of water will give you the amount that you are ingesting every day and this therefore
dependent on the concentration and the time of exposure.
So over a period of time you are going to be accumulating a certain amount.
The same calculation can be done for air we breathe.
If there is a chemical in there we are breathing about at a rate of two to eight liters per
minute and you can calculate how much of air.
All this assumes that this chemical is accumulating in the body and not metabolizing because the
body also has the capacity to react to transform this chemical into something more benign or
something more dangerous; both of these things can happen in the body.
The body also has the capacity to filter it out.
So nothing may happen.
It may just come out but we don't know.
What we in this context we take an approach that is called as a conservative approach
we say we call it as a worst-case scenario.
In the worst case what will happen.
So if you take a worst-case scenario one of the advantages, one of the utilities of this
equation that I presented here is that you can determine what is this concentration that
is acceptable in water if you drink, if you are alive for say 80 years or 80 years you
drink four liters of water a day how much of concentration of A is acceptable in there.
So this is a basis for determining standards for water quality and air quality.
So you can see that it's a big long equation a sequence of things that need to happen in
order to determine the standards and the standards also imply that how much of money should I
spend in treating the air and water and how should I manage it.
So we have seen that this is there where does this A come from.
The next question we ask is -- so there is A in the environment we are exposed to it
so we are falling sick.
So where does it come from?
That's the next question and it comes from somewhere.
It comes from a source something is responsible for it and it is releasing it at some rate
and it's getting into the environment.
Different types of sources can be based on processes for example we have combustion,
construction technology this is a very limited set of process.
Everything that we do for our daily lives is a process.
So me writing on the blackboard is a process that is itself it is.
It may not be very significant.
It maybe applicable only to a small group of population but this classification is done
based on the activity or based on the product.
So you have erosion, manufacturing, a waste disposal.
On the basis of a product we have consumer goods.
We have energy production.
So there's power plant or nuclear power plant or anything like that and we have specialty
chemicals, medicines we have technological appliances such as cellphones and we have
vehicles and when we have sources pollutants coming out of sources we have the chemicals
of concern or pollutants of concern that can come here, can get into air, water.
They can also be presented - be presented as suspended solids in water.
They can be present as particulate matter suspended in air.
They can be organic or inorganic.
These are all classifications that people can come up with and sometimes there are specific
chemicals that come out only from a particular kind of industry and it is easy for us to
check and based on this toxicological index and the exposure.
So chemicals are ranked.
There are lakhs of chemicals that we manufacture.
If you open any catalog of a chemical company and so how do we rank them.
We can't.
We have to rank them because some of these chemicals are used in such small quantities
they may never get into the environment and even if they do they are in such small quantities.
So the ranking is done based on the amount that gets into environment and also the exposure
that we are likely to have and so a combination of this will give you a toxicity index that
these chemicals have to be ranked in this particular manner.
So it's not sufficient that a process uses a hazardous material.
We have seen that exposure is important and how that the chemical from a particular source
goes to the environment and then goes to receptor which we call as in the second line which
says how does material it travels from a source of environment and to a receptor?
How long does it take and can we intervene?
So this is the next set of questions that we logically will ask and this will be answered
in our next lecture.