• 1895 - Wilhem Conrad Roentgen discovered X-rays and in 1901 he received the first Nobel Prize for physics.

• 1903 - Marie Curie and Pierre Curie, along with Henri Becquerel were awarded the Nobel Prize in physics for their contributions to understanding radioactivity, including the properties of uranium.

• 1942 - Enrico Fermi and others started the first sustained nuclear chain reaction in a laboratory beneath the University of Chicago football stadium.

• 1945 – Nuclear bombs dropped on Japan.

Historical Awareness

Case Study - Sunburn

Solar radiation wavelength Visible light – 400 to 760 nmUltraviolet radiation (UV) - >400 nm (sunburn)Infrared radiation - <760 nm (heat)

UV radiationStimulates melanin (dark pigment) that absorbs

UV protecting cellsHealth Effects

2 to 3 million non-malignant skin cancers130,000 malignant melanomas Sunburn – acute cell injury causing inflammatory

response (erythema)Accelerates aging process

Radium Girls

"Not to worry," their bosses told them. "If you swallow any radium, it'll make your cheeks rosy.“

The women at Radium Dial sometimes painted their teeth and faces and then turned off the lights for a laugh.

From: 'Radium Girls' By Martha Irvine, Associated Press, Buffalo News, 1998

Case Study - Radium

1898 – Discovered by Marie Curie

1900-1930 – Radium Therapy - used to treat arthritis, stomach ailments and cancer

Accepted by American Medical Association

WWI – Use of radium on watch dials

1920s – U.S. Radium corporation employed young women to paint watch dials

Late 1920s – Radium girls sue, win and

receive compensation

Opium War of 1839-42Great Britain has a monopoly on the sale of opium which it forces on China. Eventually getting control of Hong Kong.

Consider our societies current “wars on drugs”.

Historical Events

Life & Radiation

• All life is dependent on small doses of electromagnetic radiation.

• For example, photosynthesis and vision use the suns radiation.

Radiation

NonionizingUltraviolet, visible, infrared, microwaves, radio & TV, power transmission

IonizingRadiation capable for producing ions when interacting with matter – x-rays, alpha, beta, gamma, cosmic rays

Electromagnetic Spectrum

10-14 10-12 10-10 10-8 10-6 10-4 10-2 1 102 104 106 108

Wavelength in Meters

1010 108 106 104 102 1 10-2 10-4 10-6 10-8 10-10 10-12 10-14

Broadcast

Short waveTV

FM

RadarInfrared

Near Far

Visible

UltravioletX Rays

Gamma Rays

Cosmic Rays Power Transmission

Ionizing Radiation Nonionizing Radiation

Energy - Electron VoltsHigh Low

Nonionizing Radiation

Sources• Ultraviolet light• Visible light• Infrared radiation• Microwaves• Radio & TV• Power transmission

Nonionizing Examples

• Ultraviolet – Black light – induce fluorescence in some materials

• Vision – very small portion that animals use to process visual information

• Heat – infrared – a little beyond the red spectrum

• Radio waves – beyond infrared• Micro waves• Electrical power transmission – 60

cycles per second with a wave length of 1 to 2 million meters.

Ultraviolet - Sources

• Sun light• Most harmful UV is absorbed by the

atmosphere – depends on altitude• Fluorescent lamps• Electric arc welding

Can damage the eye (cornea)• Germicidal lamps• Eye damage from sun light• Skin cancer

Ultraviolet - Effects

• High ultraviolet – kills bacterial and other infectious agents

• High dose causes - sun burn – increased risk of skin cancer

• Pigmentation that results in suntan • Suntan lotions contain chemicals that

absorb UV radiation• Reaction in the skin to produce Vitamin D

that prevents rickets• Strongly absorbed by air – thus the danger

of hole in the atmosphere

Visible Energy

• Energy between 400 and 750 nm• High energy – bright light produces of

number of adaptive responses• Standards are set for the intensity of

light in the work place (measured in candles or lumens)

Infrared Radiation

• Energy between 750 nm to 0.3 cm• The energy of heat – Heat is the transfer

of energy• Can damage – cornea, iris, retina and

lens of the eye (glass workers – “glass blower’s cataract”)

Microwaves & Radio Waves

• Energy between 0.1 cm to 1 kilometer• Varity of industrial and home uses for

heating and information transfer (radio, TV, mobile phones)

• Produced by molecular vibration in solid bodies or crystals

• Health effects – heating, cataracts• Long-term effects being studied

Electrical Power

• Standard in homes and businesses• Highest level of exposure from electric-

power generation and distribution system (high voltage power lines)

• Medical system – Magnetic imaging• Acute health effects – shock• Long-term health effects appear to be

few but may some data do suggest adverse effects

Ionizing Radiation

Ionization Defined

Radiation capable for producing ions when interacting with matter – in other words enough energy to remove an electron from an atom.

Sources – x-rays, radioactive material produce alpha, beta, and gamma radiation, cosmic rays from the sun and space.

Ionizing Radiation

Paper Wood ConcreteAlpha

Beta

Gamma

Energy

Low

Medium

High

Radioactive Material

• Either natural or created in nuclear reactor or accelerator

• Radioactive material is unstable and emits energy in order to return to a more stable state (particles or gamma-rays)

• Half-life – time for radioactive material to decay by one-half

Alpha Particles

• Two neutrons and two protons Big particle

• Charge of +2• Emitted from nucleus of radioactive atoms• Transfer energy in very short distances (10

cm in air) because its big• Shielded by paper or layer of skin• Primary hazard from internal exposure ingestion

• Alpha emitters can accumulate in tissue (bone, kidney, liver, lung, spleen) causing local damage

Beta Particles

• Small electrically charged particles similar to electrons

• Charge of -1• Ejected from nuclei of radioactive atoms• Emitted with various kinetic energies• Shielded by wood, body penetration 0.2

to 1.3 cm depending on energy• Can cause skin burns or be an internal

hazard of ingested

Gamma-rays

• Electromagnetic photons or radiation (identical to x-rays except for source)

• Emitted from nucleus of radioactive atoms – spontaneous emission

• Emitted with kinetic energy related to radioactive source

• Highly penetrating – extensive shielding required

• Serious external radiation hazard

Gamma-raysGamma can be a problem in nuclear wars,and in using gamma for treatment. In hospitals you need very thick walls in gamma-rooms to stop them from penetrating to outsideShield is usually made from LeadThere is a massive wall in tel aviv, in case of a nuclear war, everyone will go inside the walls, completely isolated from outside.

There can be a psychological problem because of having so many people in such a small area for very long.

X-rays• Overlap with gamma-rays• Electromagnetic photons or radiation • Produced from orbiting electrons or free

electrons – usually machine produced outside nucleus

• Produced when electrons strike a target material inside x-ray tube

• Emitted with various energies & wavelengths• Highly penetrating – extensive shielding

required (usually lead, stronger than concrete, so u need a less thick wall)

• External radiation hazard• Discovered in 1895 by Roentgen

X-rays• Soft x-ray:• When a patient takes an X-ray, some particles

will reflect from the patient, those reflected radiations have low energy, but they’re still a little harmful, so theses soft X-rays (reflected) can be a hazard to other people around the patient (doctors and nurses)

• Sometimes with an old/very young patient, a person will help the patient to position himself correctly for the X-ray, this person is in danger of soft X-rays, even if they stay away from the primary radiation

Ionizing Radiation Health Effects

We evolved with a certain level of naturally occurring ionizing radiation from cosmic radiation, radioactive materials in the earth.

We have mechanisms to repair damage. Sometimes the damage may skip the repair mechanism, so you have a mutation

Radiation Units

Older units:

Curie (Ci): was used to measure activity of a source, to know if a source is more active than others

It is the number of disintegrated atoms per unit time

It does not measure health effects

Radiation UnitsOlder units:

Roentgen:

Measures ionization power.

when a radioactive material hits a medium, changing it to the ionized form, then measure how many ions are produced

Joul/KG

Doesn’t show health effects.

Radiation UnitsOlder units:

Rad: (Radiation absorbed dose)

When a radiation hits a body/tissue, it’ll give it energy, how much of radiation energy is absorbed into the medium is rad.

Still, not health effects

Radiation UnitsOlder units:

REM: Radiation equivalent man (wiki says its Roentgen equivilent man)

Measures the amount of damage that occurred in a tissue after it absorbs energy

Radiation UnitsOlder units:

There’s a relationship between rad and rem, they decided that X-ray should be standard, which means for X-ray radiation, REM = rad

Means that REM is amount of damage that occurred in a tissue that absorbed one rad of X-ray

Radiation UnitsOlder units:

Every radiation has a Coefficient, called quality factor.

Quality Factor X rad = REM

Example:

If beta was given with the same energy as an X-ray, it will deal more damage than the X-ray. Alpha even more damage. (10 times more Damage; quality factor = 10)

Radiation UnitsOlder units:

So to know REM from rad, you need to know the type of radiation and the quality factor of that radiation.

New Radiation Units

Exposure – X (joul/kg)

(Related to energy)

Absorbed Dose – Gray (Gy) (amount of energy absorbed) instead of

rad

Equivalent Dose – Sievert (Sv) (makes different sources of radiation

equivalent) instead of REM

Standards

Occupational Exposure Guidelines

100 mSv over 5 years (average 20 mSv/year) with a maximum of 50 mSv in any one year

General public – back ground about 3 mSv/year – Guideline 1 mSv/year

If someone’s exposed to radiation above the standard exposure, they get a break to reduce the exposure

Standards

Notice how occupational is 20, general public is 3.

Remember, workers are 20~60 years old, with usually a better health than the general public.

The general public contains elderly, young children, sick people ..etc so their exposure has to be lower

That is why occupational health is different from public health

Dose Response Tissue

Examples of tissue Sensitivity

Very HighHighest mitotic activity

White blood cells (bone marrow)Intestinal epitheliumReproductive cells

High Optic lens epitheliumEsophageal epitheliumMucous membranes

Medium Brain – Glial cellsLung, kidney, liver, thyroid, pancreatic epithelium

Lowlowest mitotic activity

Mature red blood cellsMuscle cellsMature bone and cartilage

Dose Response Issues

Dose(Sv)

Effects / organ Time to death

Death(%)

1-2 Bone marrow Months 0-10

2-10 Bone marrow Weeks 0-90

10-15 Diarrhea, fever

2 weeks

90-100

>50 Neurological 1- 4 hrs 100

Dose Response IssuesNotice how its 100% death if it involves the brain. Anywhere else, there’s a possibility that they survive if they’re provided excellent support. Which is expensive

once an accident inside a hospital in france resulted in a few workers getting a rapid very high exposure of radiation, in the hospital, they isolated them completely.

They had to give them huge amounts of blood, up to 500 units of blood. That is unaffordable.

Dose Response IssuesThe first 14 days are the most crucial ones, if you survive for the first 14 days there’s a good chance you’ll recover completely..

The doctor read the 2 tables in slides 37, 38, focusing on neurological effects.

The closer you are to the radiation source, the more your dose will be. Meaning those closest so the source of radiation are in the most danger.

• Rate of decay of radioisotope• How long it takes to lose half their

strength

• Can range from very short to billions of years

• Carbon – 5730 years, which makes it valuable for dating (fossils)

Half-life

TimeReduce the spent near the source of radiation.

DistanceIncrease the distance from the source of radiation.

Its actually distance squared, so if you move away 2 meters, you’ll get ¼ of the radiation.

ShieldingPlace shielding material between you and the source of

radiation.

Remember if there’s a nuclear war, its not just about the initial effect, the after-effect is also important, and just as dangerous.

Remember that Bone morrow radiation exposure causes weak immunity

Reducing Exposure

• Occupational exposure guidlines are 100 mSv in 5 years (average, 20 mSv per year) with a limit of 50 mSv in any single year.

• General public the standard is 1 mSv per year. (Natural background radiation is approximately 3 mSv/year.)

Recommended exposure limits are set by the US National Council on Radiation Protection (NCRP) and world wide by International Council on Radiation Protection (ICRP).

Regulatory Status