Lab No 2Physical 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 radiationParticle 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

HiroshimaIt 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 fatalities206 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 radiationcosmic 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 uranium-containing 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:

timedistanceshieldingcontainment.

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 UVUVA (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 ultrasound-based 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 teethExtracorporeal shock wave lithotripsy uses

a powerful focused ultrasound source to break up kidney stones

Cataract treatmentLiposuction

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).