Transcript Calorie math Food guide pyramid

Lab No 2
Physical factors in the environment,
their influence on human health,
practical uses, advantages,
and disadvantages
Radiation
Radiation is energy in
motion
Ionizing radiation
 is radiation composed of particles that individually carry
enough energy to liberate an electron from an atom or
molecule without raising the bulk material to ionization
temperature. Ionizing radiation is generated through nuclear
reactions, either artificial or natural, by very high temperature,
or via production of high energy particles in particle
accelerators.
 When ionising radiation is emitted by or absorbed by an atom,
it can liberate a particle (usually an electron, but sometimes an
entire nucleus) from the atom. Such an event can alter chemical
bonds and produce ions, usually in ion-pairs, that are
especially chemically reactive. This greatly magnifies the
chemical and biological damage per unit energy of radiation.
Ionizing radiation
 Particle radiation: alpha particles, beta
particles, electrons, neutrons, atomic ions or
photons.
 Electromagnetic radiation: X-rays, and
gamma rays,far ultraviolet, near ultraviolet
and visible light, infrared radiation.
Non-ionizing radiation
 Radiowaves,
 microwaves,
Radioactive materials usually release:
 Alpha particles which are the nuclei of helium,
 Beta particles, which are quickly moving
electrons or positrons,
 Gamma rays (electromagnetic radiation).
 Alpha rays can often be
shielded by a piece of
paper
 and beta rays by a sheet of
aluminium.
 Gamma rays are less
ionizing than either alpha or
beta rays, but protection
against them requires
thicker shielding. They
produce burns, and cancer
through mutations.
Acute radiation syndrome
 (radiation poisoning, radiation sickness or radiation
toxicity), is a constellation of health effects which present
within 24 hours of exposure to high amounts of ionizing
radiation. They may last for several months.The terms refer
to acute medical problems rather than ones that develop
after a prolonged period.
 The onset and type of symptoms depends on the radiation
exposure. Relatively smaller doses result in gastrointestinal
effects such as nausea and vomiting and symptoms related
to falling blood counts such as infection and bleeding.
Relatively larger doses can result in neurological effects and
rapid death. Treatment of acute radiation syndrome is
generally supportive with blood transfusions and antibiotics.
Chronic radiation syndrome
 Similar symptoms may appear months to
years after exposure as chronic radiation
syndrome when the dose rate is too low to
cause the acute form.[6] Radiation exposure
can also increase the probability of
developing some other diseases, mainly
different types of cancers.
Ionizing radiation→mucosa, bone marrow
↓
Bleeding, infection
↓
ARS, chronic radiation syndrome or death
Hiroshima
 It is best known as the first city in history to
be destroyed by a nuclear weapon when the
United States Army Air Forces (USAAF)
dropped an atomic bomb on it at 8:15 A.M.
on August 6, 1945, near the end of World
War II.
 It directly killed an estimated 80,000
people. By the end of the year, injury and
radiation brought total casualties to 90,000–
140,000.[17]
Nagasaki
 During World War II,
the atomic bombings
of Hiroshima and
Nagasaki made
Nagasaki the second
and, to date, last city
in the world to
experience a nuclear
attack.
 The mushroom cloud
over Nagasaki→
The Chernobyl disaster
 was a catastrophic nuclear accident that
occurred on 26 April 1986 at the Chernobyl
Nuclear Power Plant in Ukraine. An
explosion and fire released large quantities
of radioactive contamination into the
atmosphere, which spread over much of
Western USSR and Europe.
 28 ASR fatalities
 206 ASR survivors
The Fukushima Daiichi nuclear
disaster
 was a series of equipment failures, nuclear
meltdowns, and releases of radioactive
materials at the Fukushima Nuclear Power
Plant, following the Tōhoku earthquake and
tsunami on 11 March 2011. It is the largest
nuclear disaster since the Chernobyl disaster
of 1986.
Uses of ionizing radiation
 X-ray can be used in medicine for
diagnostic procedures and to kill cancerous
cells.
 radiation sterilizes
Natural background radiation
 cosmic radiation (comes from outside of our
solar system),
 solar radiation (most of solar radiation is
electromagnetic radiation, the sun also produces
particle radiation, the solar particles are mostly
protons),
 external terrestrial sources (potassium, uranium
and thorium),
 radon (radon-222 is produced by the decay of
radium-226 which is present wherever uranium is.
Since Radon is a gas, it seeps out of uraniumcontaining soils found across most of the world
and may concentrate in well-sealed homes).
Human-made radiation sources
The most significant source of human-made
radiation exposure to the general public is
from medical procedures, such as
diagnostic X-rays, nuclear medicine and
radiation therpy. Some of the major
radionuclides used are I-131,Tc-99,Co-60,
Ir-192, Cs-137. These are rarely released
into the environment.
In addition, members of the public are exposed to
radiation from consumer products, such as tobacco
(polonium-210), building materials, fuels (gas,
coal), ophthalmic glass, televisions, luminous
watches and dials (tritium), airport X-ray systems,
smoke detectors (americium), road construction
materials, electron tubes, fluorescent lamp starters,
lantern mantles (thorium), nuclear power plants,
etc.
 radiation enhances mutations
Biological effects of radiation on
living cells may result in a
variety of outcomes, including:
1. Cells experience DNA damage and are able to
detect and repair the damage.
2. Cells experience DNA damage and are unable to
repair the damage. These cells may go through
the process of programmed cell death, or
apoptosis, thus eliminating the potential genetic
damage from the larger tissue.
3.Cells experience a nonlethal DNA mutation
that is passed on to subsequent cell
divisions. This mutation may contribute to
the formation of a cancer.
There are four ways in which we
can protect ourselves from
irradiation:




time
distance
shielding
containment.
Time
 For people who are exposed to radiation in
addition to natural background radiation,
limiting or minimizing the exposure time
will reduce the dose from the radiation
source.
Distance
 In the same way that the heat from a fire is
less intense the further away you are, so the
intensity of the radiation decreases the
further you are form the source of the
radiation. The dose decreases dramatically
as you increase your distance from the
source.
Shielding
 Barriers of lead, concrete, or water give
good protection from penetrating radiation
such as gamma rays and neutrons.
Containment
 Radioactive materials are confined in the
smallest possible space and kept out of the
environment. For medical use, for example,
are dispensed in closed handling facilities,
while operate within closed systems with
multiple barriers which keep the radioactive
materials contained.
X-rays
 (or Röntgen rays) are a form of
electromagnetic
radiation
with
a
wavelength in the range of 10 to 0.01 nm,
corresponding to frequencies in the range
30 to 30 000 PHz (1015 hertz). X-rays are
primarily used for diagnostic radiography
and cristalloghraphy. X-rays are a form of
ionizing radiation.
Wilhelm Conrad Röntgen
 was a German physicist,
who, on 8 November 1895,
produced and detected
electromagnetic radiation in
a wavelength range today
known as X-ras or Röntgen
rays, an achievement that
earned him the first Nobel
Prize in Physics in 1901.
Marie Skłodowska-Curie
 was a French-Polish physicist and
chemist, famous for her pioneering
research on radioactivity.
 Her achievements included a
theory of radioactivity, techniques
for isolating radioactive isotopes,
and the discovery of two elements,
polonium and radium. Under her
direction, the world's first studies
were conducted into the treatment
of neoplasms, using radioactive
isotopes.
X-rays
 Since 2005, X-rays are listed as a
carcinogen by the U.S. government.
Radiotherapy,
a
curative
medical
intervention, now used almost exclusively
for cancer, employs higher energies of
radiation.
Terahertz radiation
 Tarahertz radiation are electromagnetic
waves in the region between 300 gigahertz
and 3 terahertz corresponding to the
wavelength of < 1mm and 100 micrometers.
It is a non-ionizing radiation. It can be used
for security screening to uncover concealed
weapons on a person, remotely.
Microwaves
 Are electromagnetic waves
with
wavelengths longer than those of terahertz
(THz) wavelengths, but relatively short for
radio waves. Microwaves have wavelengths
approximately in the range of 30 cm
(frequency = 1 GHz) to 1 mm (300 GHz).
 They are commonly used for heating in
microwave ovens
Radio waves
 It is the portion of electromagnetic spectrum in
which electromagnetic waves can be generated
by alternating current fed to an antenna
 Radio waves are used for radio and television
broadcasting, communication with marines and
with aircrafts, navigation, magnetic resonance,
mobile phones, radars, etc.
Visible light
 It is the portion of the electromagnetic
spectrum that is visible to the human eye. A
typical human eye will respond to
wavelengths from 400 to 700 nm, although
a typical eye has its maximum at 555nm,
in the green region of the optical spectrum.
Approximate boundaries for the
spectral colours:
violet
380-450nm
blue
450-495nm
green
495-570nm
yellow
570-590nm
orange
590-620nm
red
620-750nm
Infrared radiation
 It is an electromagnetic radiation of a
wavelength longer then that of visible
light but shorter than that of radio waves. It
has a number of technological uses
including target acquisition and tracking by
the military, remote temperature sensing,
thermography,
short-ranged
wireless
communication, spectroscopy and weather
forecasting,
night
vision,
infrared
photography.
Ultraviolet
 Ultraviolet light is an electromagnetic radiation
with a wavelength shorter than that of visible
light but longer than X-rays.
 UV induces vitamin D production in the skin.
(Vitamin D deficiency causes rickets). UV is used
in treatment of psoriasis and vitiligo. UV is
used for sterilization (as it kills viruses and
bacteria) and for fire detection.
Harmful effects of UV
 UVA (wavelength between 315 and 400nm)
contributes to the ageing of skin (wrinkles),
DNA
mutations,
oxydative
stress,
melanoma development.
 UVB (280-315nm) causes most sunburns.
majority of sunscreens protect against UVB
only. It causes eye damage (‘welder’s eye’,
cataract,
pterygium and
pinguecula
formation).
 UVC (100-280nm) causes skin cancer.
Uses od UV
 UV A and B are used in treatment of
psoriasis and vitiligo
 Exposure to UV B produces vitamin D in
the skin
 UV C is used to sterilize
Sound
 Sound is a disturbance of mechanical
energy that propagates through matter as a
wave. Sound is characterized by the
properties of sound waves, which are
frequency, wavelength, period, amplitude
and velocity or speed. Humans perceive
sound by the sense of hearing. Humans can
hear sounds with frequencies between 20
Hz and 20kHz.
 Human ear is most sensitive to
frequencies around 1000-3,500Hz.
 Sound above the hearing range is known
as ultrasound.
 Sound below the hearing range is
infrasound.
Age-related hearing loss
 With age humans progressively lose the
ability to hear higher frequencies.
Job-related hearing loss
 Prolonged exposure to a sound pressure
level exceeding 85dB can permanently
damage the ear, resulting in tinnitus and
hearing impairment (job-related hearing
loss, loss of sensitivity to all sound
frequencies).
Sound pressure level
 where p is the sound pressure and p0 is a
reference sound pressure. (When using
sound pressure levels, it may be important
to quote the reference sound pressure used.)
 a unit of sond pressure level is a Bell [B]
(it is an objective scale)
 a unit of perceived loudness for pure tone
is phon. The phon scale is a subjective one.
Noise
 A noise is an unwanted sound.
 Health effects of noise are: hearing loss, tinnitus,
hypertension, vasoconstriction, cardiovascular
diseases, stress, headache, fatigue, stomach ulcers,
headrush, low-birth-weight in babies, birth defects
(harelip, cleft palate, etc.), sleep disturbances,
increase in aggressive behaviour.
Environmental noise regulations
 A maximum outdoor level of 60 to 65dB.
 Occupational
safety
organisations
recommend that the maximum expopsure to
noise is 40 hours per week at 85 to 90dB.
Ultrasound
 It is a sound with the frequency greater than
the upper limit of human hearing,
approximately 20,000hertz.
Medical sonography
(ultrasonography)
 It is a useful ultrasoundbased diagnostic medical
imaging technique used to
visualize
muscles,
tendons, many internal
organs (the heart), their
size, structure and any
pathological lesions.
 Ultrasonography is also
used to visualize fetus
during
prenatal
care.
Ultrasonography
is
regarded as safe test.
Other uses of ultrasounds
 Cleaning teeth
 Extracorporeal shock wave lithotripsy uses
a powerful focused ultrasound source to
break up kidney stones
 Cataract treatment
 Liposuction
Infrasound
 It is a sound with a frequency too low to be
detected by the human ear.
 Used for earthquake detection.
 Used for tornados detection.
 Effect in humans:anxiety, sorrow, nervous
feelings.
Vibration
 Vibration is a mechanical motion, which can be
periodic, aperiodic or a mixture of the two.
 Vibration is a physical occupational hazard at
workplace and can cause hand-arm vibration
syndrome (HAVS-usually associated with use of
vibrating tools), whole body vibration syndrome
(WBVS-in truck drivers for instance) and
vibration white finger (it is the vascular
component of HAVS, white colour is secondary to
Raynaud’s disease, other symptoms include
tingling, pain, numbness).