Environmental Toxicology

Environmental Toxicology
Unit-VII

Syllabus
• Environmental risk assessment solid and
hazardous waste management rules,
hazardous waste control and remediation,
evaluation of toxicity, toxic materials : their
physiological and metabolic effects

• Environmental Toxicology, is a multi-
disciplinary field of science concerned with the
study of the harmful effects of various chemical,
biological and physical agents on living
organisms.

• Rachel Carson is considered the mother of
environmental toxicology, as she made it a distinct
field within toxicology in 1962 with the publication of
her book Silent Spring, which covered the effects of
uncontrolled pesticide use.
• Rachel Louise Carson (May 27, 1907 – April 14,
1964) was an American marine biologist and
conservationist whose book Silent Spring and other
writings are credited with advancing the global
environmental movement.

“Silent Spring”
• Late in the 1950s, Carson turned her attention to
conservation, especially environmental problems that
she believed were caused by synthetic pesticides. The
result was Silent Spring (1962), which brought
environmental concerns to an unprecedented share of
the American people. Although Silent Spring was met
with fierce opposition by chemical companies, it spurred
a reversal in national pesticide policy, which led to a
nationwide ban on DDT and other pesticides, and it
inspired a grassroots environmental movement that led
to the creation of the U.S. Environmental Protection
Agency. Carson was posthumously awarded the
Presidential Medal of Freedom by Jimmy Carter.

Agent Orange Vietnam War
• During the Vietnam War, between 1962 and 1971,
the United States military sprayed nearly
20,000,000 U.S. gallons (75,700,000 l) of chemical
herbicides and defoliants in Vietnam, the goal was
to defoliate rural/forested land, depriving guerrillas
of food and cover and clearing sensitive areas such
as around base perimeters. The program was also
a part of a general policy of forced draft
urbanization, which aimed to destroy the ability of
peasants to support themselves in the countryside,
forcing them to flee to the U.S. dominated cities,
depriving the guerrillas of their rural support base.

Effects on the Vietnamese People
Health Effects
• The Vietnam Red Cross reported as many as 3
million Vietnamese people have been affected by
Agent Orange, including at least 150,000 children
born with birth defects. According to Vietnamese
Ministry of Foreign Affairs, 4.8 million Vietnamese
people were exposed to Agent Orange, resulting in
4,00,000 people being killed or maimed, and
5,00,000 children born with birth defects.

Effects on the Vietnamese People

• Environmental Toxicology, is a multi-disciplinary field of
science concerned with the study of the harmful effects of
various chemical, biological and physical agents on living
organisms.

• Harmful effects of chemical and biological
agents can include toxins from pollutants,
insecticides, pesticides, and fertilizers all of
which can impact an organism and its
community through shifts in species diversity
and abundance.
• Resulting changes in population dynamics
impact the ecosystem by altering its productivity
and stability.

• There are many sources of environmental
toxicity that can lead to the presence of toxins
in our food, water and air.
• These sources include organic and inorganic
pollutants, pesticides and biological agents, all
of which can have harmful effects on living
organisms.

• Pollutants Polychlorinated Biphenyls (PCBs) are
organic pollutants that are still present in our
environment today despite being banned in many
countries such as the United States and Canada. Due
to the persistent nature of PCBs in aquatic ecosystems,
many aquatic species contain high levels of this
chemical.
• For example, fish farmed salmon have been shown to
have significantly higher PCB levels.

Pollutants Polychlorinated Biphenyls
(PCBs)

Heavy Metals
• Heavy metals found in food sources, such as
fish can also have harmful effects. These metals
can include mercury, lead, aluminum and
cadmium. It has been shown that fish are
exposed to higher cadmium levels and grow at a
slower rate than fish exposed to lower levels or
none.

Pesticides
• Pesticides are a major source of environmental toxicity.
These chemically synthesized agents have been known
to persist in the environment long after their
administration. The poor bio-degradability of pesticides
can result in bio-accumulation of chemicals in various
organisms along with bio-magnification within a food
web. Pesticides can be categorized according to the pests
they target. Insecticides are used to eliminate agricultural
pests that attack various fruits and crops.
• Herbicides target herbal pests such as weeds and other
unwanted plants that reduce crop production.

Insecticides
• Dichlorodiphenyltrichloroethane (DDT) is an
organochlorine insecticide that has been banned due to
its adverse effects on both humans and wildlife. DDT
was widely used by farmers in order to kill agricultural
pests. In 1962, the harmful effects of the widespread and
uncontrolled use of DDT were detailed by Rachel
Carson in her book The Silent Spring. Such large
quantities of DDT and its metabolite
Dichlorodiphenyldichloroethylene (DDE) that were
released into the environment were toxic to both animals
and humans

Dichlorodiphenyltrichloroethane
(DDT)

• DDT is not easily biodegradable and thus the chemical
accumulates in soil and sediment runoff. Water systems
become polluted and marine life such as fish and
shellfish accumulate DDT in their tissues. Furthermore,
this effect is amplified when animals who consume the
fish also consume the chemical, demonstrating bio-
magnification within the food web.
• The process of bio-magnification has detrimental effects
on various bird species. Rapid declines in bird
populations have been seen various parts of the world.

Environmental Risk Assessment Solid and
Hazardous Waste Management Rules
• Hazardous wastes are considered highly toxic and
therefore disposal of such wastes needs proper attention
so as to reduce possible environmental hazards.
• Industrial growth has resulted in generation of huge
volume of hazardous wastes in the country. In addition
to this, hazardous wastes sometimes get imported mainly
from the western countries for re-processing or recycling.
• Inventorisation of hazardous wastes generating units in
the country is not yet Completed. Scientific disposal of
hazardous wastes has become a major environmental
issue in India.

• Hazardous Wastes (Management and
Handling) Rules, 1989 have been framed by the
Central Government and amended in 2000 and
2003 to deal with the hazardous wastes related
environmental problems that may arise in the
near future

• Environmental management of hazardous wastes has become a
major concern in India as haphazard dumping of hazardous
wastes results in severe environmental impairment.
• The adverse effects of hazardous wastes as well as the significant
potential risks posed by them to the life and its supporting
systems are increasingly recognized Rapid growth of industries
in India has resulted in generation of increasing volume of
hazardous wastes. Both indigenously generated and imported
from other countries for recycling or reprocessing need
scientific treatment and disposal. However, only a few secured
landfill sites are available in the country for disposal of
hazardous wastes in an environmentally sound manner.

• An illegal dumping of hazardous wastes by the industries may
cause severe environmental pollution. The Ministry of
Environment and Forests (MoEF) has promulgated Hazardous
Wastes (Management & Handling) Rules, 1989 and amended
the same in 2000 and 2003 for proper management and
handling of hazardous wastes in the country. These rules also
deal with the ban for importing a few categories of hazardous
wastes. India has also ratified the Basel Convention on trans-
boundary movement of hazardous wastes in 1992, which is a
significant tool for controlling and monitoring of import and
export of hazardous wastes and its proper management.

Illegal Dumping of Hazardous Wastes

Characteristics of Hazardous Wastes
• Hazardous wastes, which may be in solid, liquid or
gaseous form, may cause danger to health or
environment, either alone or when in contact with
other wastes . Hazardous wastes can be identified by
the characteristics that they exhibit viz, ignitability,
corrosivity, reactivity, or toxicity.

Process Wastes
• Hazardous wastes in India can be categorized
broadly
• into two categories, viz,
• i) hazardous wastes generated in India from
various industries, and
• ii) hazardous wastes imported into or exported
to India. Hazardous wastes are being generated
in the country by various industries.

• Inventorisation of hazardous wastes generating
units and quantification of wastes generated in
India are being done by the respective States.
Pollution Control Boards (SPCBs) or Pollution
Control Committees (PCCs). Depending on the
physical and chemical characteristics of
hazardous wastes, these may be categorized into
three categories, viz. , recyclable, incinerable
and landfill.

• The hazardous wastes may be categorized as
recyclable when resource recovery is possible
by reprocessing the waste, as incinerable when
it is possible to incinerate the wastes for
destruction and energy recovery, and as landfill
waste when this is not suitable either for
resource or energy recovery, but suitable for
dumping with or without any treatment.

• Management and disposal The major issues of concern
for hazardous wastes in India
• Industrial incinerators in use are generally not efficient
and are merely a combustion chamber and source of
emission of dioxins and furans. Environmentally sound
management of hazardous Wastes would require
Common Hazardous Waste Management Facility
(CHWMF) for industrial clusters spread all over the
country, as it is not possible to have hazardous waste
management facility for each unit, particularly in the case
of small and medium scale units

Common Hazardous Waste
Management Facility (CHWMF)

Health effects of Hazardous Wastes
Health effects of hazardous wastes / substances
• Hazardous wastes are considered very harmful to man
and environment. These wastes pose a severe
environmental hazard to the human health and to
various components of environment, viz. soil, air or
water Health impacts of hazardous pollutants have been
studied in great detail by many organizations and
individuals including the Government Organizations in
India and other countries. In addition to research on
health impacts, there are impact-related guidelines
advocating for a full-fledged Health Impact Assessment
(HIA) developed by several organizations

Health effects of Hazardous Wastes

Hazardous Wastes
(Management and Handling) Rules, 1989
Hazardous Wastes (Management and Handling)
Rules, 1989
• As amended to date, were notified in the country
under the provisions of the Environment
(Protection) Act, 1986, for management and
handling, and import of hazardous wastes into the
country. These rules were amended in 2000 and
2003, to bring the Rules in line with the
requirements of the Basel Convention and also to
improve the applicability and implementation
aspects with regard to imports of hazardous waste.

Hazardous Wastes

Hazardous Wastes (Management and
Handling) Rules, 1989

Hazardous Wastes
• Apart from Ministry of Environment and
Forests (MoEF), Central Pollution Control
Board (CPCB), State Pollution Control Boards
(SPCBs) / Pollution Control Committees
(PCCs) have been delegated certain powers for
control and regulation of hazardous wastes

Recycling of Hazardous Wastes
• Hazardous wastes having the resource values
are recycled or reprocessed for value
recovery. Used oil, battery wastes and other
non ferrous wastes like zinc, lead are
commonly recycled in India.
• Used oil contains high levels of various heavy
metals like lead, cadmium, arsenic and
chromium etc. It also contains contaminants
such as chlorinated solvents, polychlorinated
bi-phenyls and other carcinogens.

Recycling of Hazardous Wastes
• It is estimated that one gallon of used oil is
sufficient to contaminate one million gallons
of ground water. Import of used oil/waste oil
is banned in India due to its potential
pollution hazard. However used oil is a
precious and non-renewable resource and
can be recycled back to pure lube oil again
and again.

Electronic Wastes
• Over the years, our dependence on the
electronic products has grown manifold, both
for domestic and for office uses, and this has
resulted in generation of electronic wastes (E-
waste) all over the world.
• E-wastes are a fast growing waste stream. On
an average, E-waste makes up approximately
1 percent of municipal solid waste (MSW)
stream as per the study report of EPA.

Electronic Wastes
• These E-wastes contain hazardous substances,
such as lead, mercury, chromium, etc. A
television and CRT monitor contains about
four pounds of lead on an average. E-waste
may contribute high level of Hg
Contamination in Municipal solid waste.

Recycling of E-waste
• Re-cycling of E-waste is a need of the day to
reduce/ avoid pollution, and to extract
valuable and limited resources. Recycling
reduces the energy used in new product.
Manufacturing. In developed countries,
municipalities, public and private
organizations accept used / waste computers
and other electronics for recycling.

Recycling of E-waste
• Now electronics manufacturers like Dell and
HP are offering recycling services in some
countries.

Legislations and Regulations for
Hazardous Wastes
• There are 36 types of industrial processes
listed in Schedule-I of Hazardous Wastes
(Management & Handling) Amendments Rule,
2003.
• As per Rule 11 of the Hazardous Wastes
Rules, 1989, import of hazardous wastes
from any country to India shall not be
permitted for dumping. Import of hazardous
wastes

Hazardous Wastes
• Import of hazardous wastes may be allowed for
processing or re-use as raw material, after
examining each case on merit by the Ministry of
Environment & Forests.
• In Schedule 8 of Hazardous Wastes Amendment
Rules, 2003, 29 categories of hazardous wastes,
prohibited for import and export. Wastes
containing Hg, As, Waste Asbestos (Dust or
Fibres), waste oil etc., are in the list of banned
wastes for import and export.

Hazardous Wastes

Hazardous Wastes
• Any person importing hazardous wastes shall
maintain the records of the hazardous wastes
imported as specified in Form 6A, and the
records so maintained shall be open for
inspection by the MoEF / CPCB / SPCB / PCC,
or an officer designated by these regulatory
bodies.

Hazardous Wastes
• The Ministry of Environment and Forests (MoEF)
is the nodal agency for environmental matters in
India. It exercises control over imports of
hazardous wastes under the Hazardous Wastes
Rules.
• Hazardous Substances Management Division
(HSMD) of the MoEF deals with the
management of hazardous wastes (both
indigenous and imported), hazardous chemicals
and major chemical accidents.

Basel Convention
• Basel Convention deals with the trans-boundary
movement and disposal of hazardous wastes as
well as other chemical wastes by regulating and
controlling the movement of scheduled
hazardous wastes from OECD countries
(Organisation for Economic Co-operation and
Development) to non OECD countries. India
ratified the convention in 1992 showing India's
commitment to solve the problem of trans-
boundary movement and disposal (or dumping)
of hazardous wastes through international
cooperation.

Hazardous Wastes
• It is difficult to develop alternative technology for total
elimination of hazardous wastes generation. In
developing countries, the thrust on economic
development is often given priority to production costs
than the best available technology and this results in
more wastes generation.
• The MoEF has elaborately identified various treatment
and disposal options of different hazardous waste
streams that include physical / chemical treatment,
landfill, biological treatment, incineration, recycle and
recovery and solidification etc. As on today, the most
often used option for disposal of wastes is secured
landfill.

Hazardous Wastes
• The other options should be given also equal
weightage to reuse and recycle of such wastes
for resource recovery before deciding for a
landfill.
• Environmental Impact Assessment (EIA) is
being practiced all over the world to decide a
site of secured landfill to ensure less negative
impact of such facility on human and
ecological systems.

Toxicology
• Toxicology can be deﬁned as that branch of
science that deals with “the detection,
occurrence, properties, effects, and regulation
of toxic substances,”

Routes of Exposure
• There are four routes by which a substance can
enter the body: inhalation, skin (or eye) absorption,
ingestion, and injection.
• Inhalation: For most chemicals in the form of
vapours, gases, mists, or particulates, inhalation is
the major route of entry. Once inhaled, chemicals
are either exhaled or deposited in the respiratory
tract. If deposited, damage can occur through direct
contact with tissue or the chemical may diffuse into
the blood through the lung-blood interface.

Routes of Exposure
• Upon contact with tissue in the upper
respiratory tract or lungs, chemicals may
cause health effects ranging from simple
irritation to severe tissue destruction.
Substances absorbed into the blood are
circulated and distributed to organs that have
an affinity for that particular chemical. Health
effects can then occur in the organs, which
are sensitive to the toxicant

Routes of Exposure
• Skin (or eye) absorption: Skin (dermal) contact can
cause effects that are relatively innocuous such as
redness or mild dermatitis; more severe effects include
destruction of skin tissue or other debilitating
conditions. Many chemicals can also cross the skin
barrier and be absorbed into the blood system. Once
absorbed, they may produce systemic damage to
internal organs. The eyes are particularly sensitive to
chemicals. Even a short exposure can cause severe
effects to the eyes or the substance can be absorbed
through the eyes and be transported to other parts of
the body causing harmful effects.

Routes of Exposure
• Ingestion: Chemicals that inadvertently get into the mouth
and are swallowed do not generally harm the
gastrointestinal tract itself unless they are irritating or
corrosive. Chemicals that are insoluble in the fluids of the
gastrointestinal tract (stomach, small, and large intestines)
are generally excreted. Others that are soluble are
absorbed through the lining of the gastrointestinal tract.
They are then transported by the blood to internal organs
where they can cause damage.
• Injection: Substances may enter the body if the skin is
penetrated or punctured by contaminated objects. Effects
can then occur as the substance is circulated in the blood
and deposited in the target organs.

Routes of Exposure
• Once the chemical is absorbed into the body, three
other processes are possible: metabolism, storage, and
excretion. Many chemicals are metabolized or
transformed via chemical reactions in the body. In
some cases, chemicals are distributed and stored in
specific organs.
• various excretory mechanisms (exhaled breath,
perspiration, urine, faeces, or detoxification) rid the
body, over a period of time, of the chemical. For some
chemicals elimination may be a matter of days or
months; for others, the elimination rate is so low that
they may persist in the body for a lifetime and cause
deleterious effects.

Health Effects
• Human health effects caused by exposure to
toxic substances fall into two categories:
short-term and long-term effects. Short-term
effects (or acute effects) have a relatively
quick onset (usually minutes to days) after
brief exposures to relatively high
concentrations of material (acute exposures).
The effect may be local or systemic.

Health Effects
• Long-term effects (or chronic effects) are those with
a long period of time (years) between exposure and
injury. These effects may occur after apparent
recovery from acute exposure or as a result of
repeated exposures to low concentrations of
materials over a period of years (chronic exposure).
• Usually the major effects of a chemical will be
expressed in one or two organs. These organs are
known as target organs which are more sensitive to
that particular chemical than other organs.

Respiratory Tract
• Many chemicals used or produced in industry
can produce acute or chronic diseases of the
respiratory tract when they are inhaled .The
toxicants can be classified according to how
they affect the respiratory tract.

Respiratory Tract
• Asphyxiants: gases that deprive the body tissues
of oxygen
• Simple asphyxiants are physiologically inert
gases that at high concentrations displace
• air leading to suffocation. Examples: nitrogen,
helium, methane, neon, argon.
• Chemical asphyxiants are gases that prevent the
tissues from getting enough oxygen.
• Examples: carbon monoxide and cyanide.

Respiratory Tract
• Irritants: chemicals that irritate the air passages.
Examples: hydrogen fluoride, chlorine, hydrogen
chloride, and ammonia.
• Necrosis producers: Chemicals that result in cell
death and edema. Examples: ozone and nitrogen
dioxide.
• Fibrosis producers: Chemicals that produce fibrotic
tissue which, if massive, blocks airways and
decreases lung capacity. Examples: silicates, asbestos,
and beryllium.

Respiratory Tract
• Allergens: Chemicals that induce an allergic
response. Examples: isocyanates and sulfur
dioxide.
• Carcinogens: Chemicals that are associated
with lung cancer. Examples: cigarette smoke,
coke oven emissions, asbestos, and arsenic.

Skin
• Skin. The skin is, in terms of weight, the largest single
organ of the body. It provides a barrier between the
environment and other organs (except the lungs and
eyes) and is a defense against many chemicals.
• The skin consists of the epidermis (outer layer) and the
dermis (inner layer). In the dermis are sweat glands
and ducts, sebaceous glands, connective tissue, fat,
hair follicles, and blood vessels.
• Hair follicles and sweat glands penetrate both the
epidermis and dermis. Chemicals can penetrate
through the sweat glands, sebaceous glands, or hair
follicles.

Skin
• The ability of skin to absorb foreign substances
depends on the properties and health of the skin
and the chemical properties of the substances.
• Absorption of a toxic chemical through the skin
can lead to local effects through direct contact,
such as irritation and necrosis, and systemic
effects.
• Many chemicals can cause a reaction with the
skin resulting in inflammation called dermatitis.

Skin
These chemicals are divided into three categories:
Primary irritants: Act directly on normal skin at the
site of contact (if chemical is in sufficient quantity
for a sufficient length of time).
Skin irritants include: acetone, benzyl chloride,
carbon disulfide, chloroform, chromic acid and
other soluble chromium compounds, ethylene
oxide, hydrogen chloride, iodine, methyl ethyl
ketone, mercury, phenol, phosgene, styrene, sulfur
dioxide, picric acid, toluene, xylene.

Skin
• Photosensitizers: Increase in sensitivity to light,
which results in irritation and redness.
Photosensitizers include: tetracyclines, creosote,
pyridine, furfural, and naphtha
• Allergic sensitizers: May produce allergic-type
reaction after repeated exposures. They include:
formaldehyde, phthalic anhydride, ammonia,
mercury, nitrobenzene, toluene diisocyanate,
chromic acid and chromates, cobalt, and benzoyl
peroxide.

Eyes
• The eyes are affected by the same chemicals that affect
skin, but the eyes are much more sensitive.
• Acids: Damage to the eye by acids depends on pH and the
protein-combining capacity of the acid.
• Alkalies: Damage that appears mild initially but can later
lead to ulceration, perforation, and clouding of the cornea
or lens.
• Organic solvents: Organic solvents (for example, ethanol,
toluene, and acetone) dissolve fats, cause pain, and dull the
cornea. Damage is usually slight unless the solvent is hot.
• In addition, some compounds act on eye tissue to form
cataracts, damage the optic nerve, or damage the retina.

Central Nervous System.
• Neurons (nerve cells) have a high metabolic
rate but little capacity for anaerobic
metabolism. Subsequently, inadequate oxygen
flow (anoxia) to the brain kills cells within
minutes. Some may die before oxygen or
glucose transport stops completely.

Central Nervous System
• Because of their need for oxygen, nerve cells are
readily affected by both simple asphyxiants and
chemical asphyxiants. Also, their ability to
receive adequate oxygen is affected by
compounds that reduce respiration and thus
reduce oxygen content of the blood. Other
examples are compounds such as arsine, nickel,
ethylene chlorohydrins, tetraethyl lead, aniline,
and benzene that reduce blood pressure or flow
due to cardiac arrest, extreme hypotension,
hemorrhaging.

Liver
• Liver injury induced by chemicals has been
known as a toxicological problem for
hundreds of years. It was recognized early
that liver injury is not a simple entity, but that
the type of lesion depends on the chemical
and duration of exposure.

Kidneys
• A number of materials are toxic to the kidneys:
• Heavy metals, may denature proteins as well as
produce cell toxicity. Heavy metals (including
mercury, arsenic, gold, cadmium, lead, and silver) are
readily concentrated in the kidneys, making this organ
particularly sensitive.
• Halogenated organic compounds, which contain
chlorine, fluorine, bromine, or iodine.
• Metabolism of these compounds, like that occurring in
the liver, generates toxic metabolites. Among
compounds toxic to the kidneys are carbon
tetrachloride, chloroform, 2,4,5-T (a herbicide), and
ethylene dibromide (a fumigant).

Guidlines
• Several reference sources are available that
contain information about toxicological
properties and safe exposure limits for many
different materials.
• However, because most of the data is for
animal exposures, there may be problems in
trying to use the data for human exposure
guidelines.

Guidlines
• Other sources give some general guides on
chemical exposure. They may say that the
chemical is an irritant or corrosive, or they may
give a warning like "AVOID CONTACT" or
"AVOID BREATHING VAPORS." This gives the
user information about the possible route of
exposure and effects of the exposure. However,
this does not give a safe exposure limit. One may
question whether the warning means to "AVOID
ANY POSSIBLE CONTACT" or whether there is a
certain amount that a person can contact safely
for a certain length of time.

References
Environmental Management
Bala Krishnamoorthy- PHI publication
Wikipedia- The online free Encyclopedia
http://www.nioh.org/

“If we have no peace, it is because we have forgotten
that we belong to each other.”
― Mother Teresa

Environmental Toxicology

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