Radiation and it's effects

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RADIATION & IT’S EFFECTS – A few pointers:

RADIATION & IT’S EFFECTS – A few pointers By : Dr. Sam A. Thamby Faculty of Pharmacy AIMST University ( Malaysia )


Ionizing Radiations Ionization : when an electron is removed from a neutral atom and a pair of ions are produced (negatively charged electron and positively charged atom). Ionization of the atoms in the human body causes harmful biological effects . The ions are highly reactive ; damage critical cell structures , including proteins and DNA ; Knowledge about the nature and the probabilities of adverse health effects of ionizing radiations is based on…. Animal studies ; Occupational health studies (miners-radon-high incidences of lung cancer); Studying patients exposed to radiation for medical treatments ; Observing the effects of human exposures at high doses (survivors of the Chernobyl disaster, bombings in Hiroshima and Nagasaki);

Ionizing radiations (contd’.):

Ionizing radiations (contd’.) 2 types of ionizing radiations’ effects: Threshold effects : Non-stochastic (or deterministic) effects ; Dose-effect relationship (directly proportional); E.g., Ingestion of toxic substances; Non-stochastic effects have a definitive relationship b/n exposure and the effect ( proportional; has a threshold dose below which these effects do not occur) Non-threshold effects : Stochastic effects (random probability of occurrence, can’t be predicted accurately); ‘All-or-none’ outcome ; E.g., Following exposure to high levels of radiation, a person may have a high risk of developing cancer; the intensity of the cancer won’t necessarily be severe ; E.g., Cancers, genetic defects;

Ionizing radiations (contd’.):

Ionizing radiations (contd’.) Human beings are exposed to ionizing radiations mainly from… Natural sources (cosmic radiations); Indoor exposure (from building materials); Radon exposure ; Medical treatments (cancer therapy, X-rays); Consumer goods (smoke detectors, light switches, illuminating watches and clocks); ( < 0.5% ) When exposed to high doses of radiations, the common effects are… Skin burns ; Bone marrow damage ; Sterility ; Acute radiation sickness ; Death


Non-ionizing radiations All forms of non-ionizing radiations are part of the EM spectrum . EM radiation is a form of energy that consists of an electric and a magnetic component . These waves travel at the speed of light (approx. 3 x 10 8 m/sec in vacuum); Includes UV radiations from the sun , which can cause… Eye cataracts leading to blindness (partial or total); Skin cancer ; Immune system damage ; In recent years, there is an increase in the hazards due to the depletion of the stratospheric ozone layer .

Non-ionizing radiations (contd’.):

Non-ionizing radiations (contd’.) Electro Magnetic Fields (EMFs) : Type of non-ionizing radiations which everyone is exposed to ; These radiations develop around electric power lines , electric machinery , home radio transmitters , portable telephones . Usually, the doses are too low to cause any adverse effects ; However, certain suspected adverse health impacts (like cancer) due to EMFs have been reported but, not suitably validated . High-intensity light is also a type of radiation that can cause blindness (e.g., looking straight at the sun for a long time); UV radiation exposure leads to…. skin cancer ; people with light skin are at higher risk. eye cataracts (direct exposure of the lens to UV radiation); immune system ‘changes’ , leading to potential infectious diseases;

Non-ionizing radiations (contd’.):

Non-ionizing radiations (contd’.) Visible radiations : Type of non-ionizing radiations; not as powerful as UV radiations ; Mainly causes damage to the eye after overexposure ; Laser : delivers much larger energy directly to the eye than normal light; can even burn the skin ; * LASER stands for Light Amplification by Stimulated Emission of Radiation.

Contaminant sources and effect continuum:

Contaminant sources and effect continuum


Human Exposure Assessment Human exposure : Refers to the absorption into , and action on the human body as a result of coming into contact with radioactive / physical / chemical / biological agent(s) ; The units of exposure to a chemical are usually mg/ml/hour . Total exposure analyses ‘all exposures’ to the ‘contaminant’ (routes of exposure). Internal dose : Amount of the contaminant absorbed in body tissues upon inhalation , ingestion or absorption (topical). Biologically effective dose : Amount of the absorbed or deposited ‘contaminant ’ that contribute to the dose at the target site where the adverse event occurs ; As the dose is difficult to measure, the parameter usually considered is ‘ Exposure ’. Estimates of the dose can be made based on the exposure and animal testing .



Human exposure assessment (contd’.):

Human exposure assessment (contd’.) Exposure assessment includes evaluating the total exposure (from all possible sources). Analysis of exposure includes direct and indirect monitoring methods . Personal monitoring under ‘Direct methods’ refers to ‘personal environmental monitoring’ (immediate environment of the person). Environmental monitoring under ‘Indirect methods’ refers to ‘environmental area monitoring’(larger area). Environmental monitoring measures concentrations of the contaminants to which the individuals may be exposed. Biological monitoring measures the dose , ‘ body burden ’ at the time of exposure.

Human exposure assessment (contd’.):

Human exposure assessment (contd’.) Personal exposure monitoring For air contaminants : personal air-monitoring devices, samplers; For waterborne contaminants : sampling from the water source; For skin exposure : by patches attached on the skin, which are later removed and analyzed; Effectiveness of latex gloves (to protect the skin) is established by wearing cotton gloves beneath the latex gloves. The cotton gloves are then later analyzed for contaminants. The results indicate … whether and to what extent contaminants penetrate the latex gloves; how frequently latex gloves should be changed to prevent exposure;



For Your Information…:

For Your Information…


Alpha radiations : Alpha particle is a heavy particle (usually ‘He’ nucleus); Has a charge of +2; Gives up energy in short distance (mostly through ionization); Does not have high penetrating power ; Is easily shielded against when the source is external to the human body (cannot penetrate the skin surface); If particles emitting alpha radiation are inhaled or ingested, they can ionize atoms in living cells, causing significant damage . Beta radiations : Due to emission of electrons from the nucleus; Better penetrating power , are smaller and lighter than ‘ α ’ particles ; Has lower ionization rate than ‘ α ’ particles; Are hazardous if inhaled or ingested ; Usually shielded against by using plastic and light metals ;


Gamma radiations : A form of EM energy emitted from the nucleus , along with beta radiations; Has higher energy , frequency ; can penetrate easily ; but has lower rate of ionization ; Both internal and external sources are hazardous ; Neutron radiations : Free neutrons can be a form of radiation when released from the atomic nucleus; Can induce significant cell damage by ionization ; Neutron activation : when neutrons pass through a material, they get absorbed by the nuclei of the material, causing the material to become radioactive, unstable and then, decay.

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