Long and Short term effects Flashcards
1
Q
What are Early Effects of radiation?
A
Biological effects of radiation that occur relatively soon after receiving high doses of ionizing radiation
2
Q
Where does evidence of early effects of radiation come from?
A
Studies on laboratory animal and data observed from irradiated human populations
3
Q
What kind of imaging are early effects not common in?
A
Diagnostic imaging (except high dose fluoroscopic procedures)
4
Q
What type of radiation produces early effects?
A
Substantial doses of ionizing radiation
5
Q
What are somatic effects?
A
Biological damage sustained by living organism as a consequence of exposure to ionizing radiation
6
Q
What are genetic effects?
A
Effects upon future generations because of irradiation of germ cells in previous generations
7
Q
What are somatic effects dependent on?
A
Length of time from the moment of irradiation to the first appearance of symptoms
8
Q
How are somatic effects demonstrated?
A
As early somatic effects or late somatic effects
9
Q
What do early tissue reactions depend on?
A
The duration of time after exposure to ionizing radiation
10
Q
As radiation dose increases what effect does it have on the severity of early tissue reactions?
A
The severity of these effects increase
11
Q
What is a threshold as it pertains to early tissue reactions?
A
A point at which the reactions appear and below they are absent
12
Q
What does the amount of biologic damage depend on?
A
The actual absorbed dose of ionizing radiation
13
Q
When do early tissue reactions appear?
A
Within minutes, hours, days or weeks of the time of irradiation
14
Q
What are some types of high-dose early tissue reactions?
A
Nausea, erythema, blood disorders, fever, fatigue, epilation, intestinal disorders, dry and moist desquamation, depressed sperm count in males, temporary or permanent sterility and injury to the CNS
15
Q
What dose of radiation results in many of the high-dose effects?
A
6 Gyt
16
Q
What is Acute Radiation Syndrome?
A
Radiation sickness that occurs in humans after whole-body receives large doses of ionizing radiation in a short period of time and is demonstrated by a collection of symptoms
17
Q
Where is data obtained from to study the effects of ARS?
A
- atomic bomb survivors
- Marshall islanders who were subjected to fallout
- Nuclear radiation accident victims
18
Q
What are the three separate dose-related symptoms associated with ARS?
A
- Hematopoietic syndrome
- Gastrointestinal syndrome
- Cerebrovascular syndrome
19
Q
What radiation doses produce Hematopoietic syndrom?
A
From 1-10 Gyt
20
Q
What radiation doses produce gastrointestinal syndrome?
A
Appear at a threshold dose of 6Gyt and peak at 10 Gyt
21
Q
What radiation dose produces cerebrovascular syndrome?
A
Results from doses of 50 Gyt or more
22
Q
What are the 4 stages of ARS?
A
- Prodromal stage
- Latent period
- Manifest illness
- Recovery or death
23
Q
What is the prodromal stage of ARS?
A
Initial stage of symptoms appearing at 1 Gyt dose
24
Q
What symptoms appear as part of the prodromal stage?
A
Nausea, vomiting, diarrhea, fatigue and leukopenia
25
When does the prodromal stage appear?
Within hours and may last up to 3 days after exposure
26
What is the latent period of ARS?
The second stage where the patient is apparently well and appear to be recovered
27
When does the latent stage appear in ARS?
Around a week after exposure
28
How long does the latent period last?
From a few hours (with highest doses) to weeks for the lowest doses
29
What is the manifest illness stage of ARS?
When the 3 manifest illness stages appear, each based on dose of radiation received (Hematologic, Gastrointestinal or Cerebrovascular)
30
What is the hematopoietic system?
Manufactures the corpuscular elements of the blood and is the most radiosensitive vital organ system in humans
31
In what dose range is Hematopoietic syndrome not lethal?
When doses of 1-2 Gyt are received
32
What is the main feature of hematopoietic syndrome?
Destruction of the bone marrow, which results in a depression of all blood cell counts
33
What are the symptoms of hematopoietic syndrome?
Nausea, vomiting, diarrhea, decrease in number of red blood cells, white blood cells and platelets, hemorrhage and infection
34
When may death occur in Hematopoietic syndrome?
6-8 weeks following exposure over 2 Gyt
35
When is hematopoietic syndrome considered to be more severe?
At the high end of dose ranges up to 10 Gyt
36
When can patients who survive hematopoietic syndrome expect to make a full recovery?
In around 6 months, but they will be at an increased risk of long term effects in life
37
What are the different measurement ranges Gastrointestinal Syndrome occurs in?
6-10 Gyt, or 1000-5000 rad
38
What is the survival rate of Gastrointestinal syndrome?
0% its always lethal
39
What is the lethal aspect of gastrointestinal syndrome?
Damage to the stem cells of the intestinal epithelium that result in severe vomiting and diarrhea, accompanied by intestinal bleeding
40
What is the impact of stem cell death in gastrointestinal syndrome?
When the stem cells die, the existing ones are no longer able to produce new cells and the lining wears away
41
What are the other symptoms of Gastrointestinal syndrome?
Severe nausea, vomiting, diarrhea, fever, fatigue, loss of appetite, lethargy, anemia, leukopenia, hemorrhage, infection, electrolyte imbalance and emaciation
42
When does death occur in gastrointestinal syndrome?
Within 3-10 days after the appearance of major symptoms
43
What is the most severe manifest illness of ARS?
Cerebrovascular syndrome
44
What are the different measurement ranges Cerebrovascular Syndrome occurs in?
Above 50 Gyt or 5000 rad
45
What is the main feature of cerebrovascular syndrome?
Destruction of cells in the brain and spinal cord
46
What are the main symptoms of Cerebrovascular syndrome?
All the same symptoms as hematopoietic and gastrointestinal plus excessive nervousness, confusion, lack of coordination, loss of vision, burning sensation of the skin, loss of consciousness, disorientation, shock, periods of agitation, alternating with stupor, loss of equilibrium, meningitis, prostration, respiratory distress, vasculitis and coma
47
When does death occur in cerebrovascular syndrome?
Within hours to 3 days after radiation exposure
48
How was ARS caused by the Chernobyl accident?
During the explosion at the side, contaminants were ejected upward into the atmosphere 3 miles high
49
Of the 444 people working at the plant what were the immediate impacts?
2 people died instantly and 29 died within 3 months of exposure
50
What were used to identify the casualties of the Chernobyl exposure?
Biological symptoms that matched those of the 3 manifest illnesses
51
What did survivors of the atomic bomb in Japan demonstrate in terms of radiation sickness?
Late tissue reactions and stochastic effects (leukemia)
52
What did the atomic bomb and Chernobyl cause the medical community to recognize?
The need for a thorough understanding of ARS and subsequent support to persons affected
53
What is Lethal Dose 50/30?
Signifies the whole body dose of radiation that can be lethal to 50% of the exposed population within 30 days
54
What is the LD 50/30 dose for adult humans?
3-4 Gyt without medical support
55
What threshold model does LD 50/30 follow?
A threshold non-linear model, where responses won't show until over 1 Gyt and lethality begins between 3-4 Gyt for 50% and full lethality peaks at 6 Gyt
56
What are the three other measures of lethality?
LD 10/30, LD 50/60 and LD 100/60
57
Which of the three additional measures of lethality are more accurate for humans?
LD 50/60
58
What part of cells enable them to possibly repair and recover when they're exposed to sublethal doses of radiation?
Repair mechanisms
59
What do the repair cells do to help recovery?
The surviving cells begin to repopulate, which permits the organ to regain some or most of its functional ability
60
What determines the organs potential for recovery?
Overall health of the irradiated person and the amount of functional damage sustained
61
Which cells have a better prospect of recovery when exposed to sublethal doses of radiation?
Oxygenated cells vs hypoxic cells
62
Why do oxygenated cells have a higher prospect for recovery?
Because they are nutrient rich
63
What effect does repeated radiation injuries produce?
A cumulative effect
64
What percent of radiation-induced damage is irreparable?
0.1
65
What percent of radiation-induced damage is repairable?
90% over time
66
What are the impacts to local tissue as a result of high radiation doses?
Significant cell death which leads to atrophy of organs and tissues
67
What is the consequence of organs and tissues sustaining radiation damage?
They may lose their ability to function or recover
68
What type of recovery can occur in organs and tissues?
Partial or complete, depending on type of cells and dose received
69
If organs or tissues fail to recover what happens?
Necrosis or death of the biologic structure
70
What do organ and tissue response to radiation exposure depend on?
- Radiosensitivity
- Reproductive characteristics
- growth rate
71
What are the tissues that suffer immediate consequences of irradiation?
- skin
- Reproductive organs
- Bone marrow
72
What are the 3 layers of the skin?
- Epidermis (outer layer)
- Dermis (middle layer)
- Hypodermis (subcutaneous layer)
73
What are the accessory structures of the skin?
Hair, sensory receptors, sebaceous glands and sweat glands
74
What are the effects of ionizing radiation on the skin?
- Radiodermatitis
- Desquamation
- Epilation
- Erythema
75
What is radiodermatitis?
Significant reddening of the skin
76
Why is the skin relatively radiosensitive?
Because it is constantly regenerating
77
What is Desquamation?
Shedding of the outer layer of skin (peeling then flaking)
78
What is epilation?
Hair loss that can be temporary or permanent based on dose received
79
What disease was treated by radiation that produced epilation?
Ringworm
80
Which radiation procedures cause significant skin damage?
Orthovoltage radiation therapy and interventional procedures using high-level fluoroscopy
81
What are the effects of radiation on male reproductive systems?
Gonadal doses can depress male sperm populations or cause genetic mutations in future generations
82
What are the effects of radiation on female reproductive systems?
Gonadal dose may delay or suppress menstruation
83
What dose level can depress male sperm populations and delay menstruation?
Doses as low as .1 Gyt
84
Why do testes and ovaries respond differently to irradiation?
Because of the method in which the cells are produced and progress to maturity
85
What are the stages of sperm development?
Spermatogonia > Spermatocyte > Spermatid > Sperm
86
What are the stages of egg development?
Primordial follicle > Mature follicle > Corpus Luteum > Ovum
87
What are the gonadal stem cells of females?
Oogonia
88
What do Oogonia develop into?
Oocytes during late fetal life
89
What stage of gonadal development are most susceptible to radiation in females?
Oocytes in the mature follicle
90
What does irradiation of ovaries cause?
- atrophy
- Delayed menstruation
- Sterility
- Genetic mutations
91
What dose results in delayed or suppressed menstruation?
100 mGy (10 rad)
92
What dose produces temporary sterility in females?
2 Gyt (200 rad)
93
What dose produces permanent infertility in females?
5 Gyt (500 rad)
94
What dose produces genetic mutations in females?
250-500 mGy (35-50 rad)
95
What are the stem cells of the testes?
Spermatogonia
96
What are the most sensitive stage of sperm development in males?
Spermatogonia
97
What are the 4 possible effects of irradiation on testes?
- atrophy
- Reduction in sperm count
- Sterility
- Genetic mutations
98
What dose produces reduction in sperm count?
100 mGy (10 rad)
99
What dose produces temporary sterility in males?
2 Gyt (200 rad)
100
What dose produces permanent sterility in males
5 Gyt (500 rad)
101
What dose produce genetic mutations in males?
100 mGy (10 rad)
102
What was a former source of monitoring image personnel for radiation damage?
Hematologic depression
103
What were the only means of monitoring radiation workers in the 1920/30s?
Periodic blood counts
104
What dose of ionizing radiation produces a measurable amount of hematologic depression?
.25 Gyt whole body dose
105
What does the hematopoietic system consist of?
Bone marrow, circulating blood and lymphoid organs
106
What do cells of the hematopoietic system develop from?
A single precursor cell called the pluripotential stem cell
107
Of the 3 parts of the hematopoietic system which one is the most susceptible to irradiation?
Bone marrow
108
Why is the bone marrow the most susceptible?
Its the site of most blood cell manufacturing and damage to the marrow can cause a decrease in all types of these cells
109
Which blood cell type is the most sensitive to radiation?
Lymphocytes
110
Why are the lymphocytes the most sensitive?
They have a short life span (few hours) and are slow to recover
111
How do granulocytes respond to radiation?
With an initial rise in numbers followed by a sharp decrease
112
How do platelets respond to radiation?
They are relatively resistent
113
Which blood cell type is the most resistent?
Red blood cells (erythrocytes) since the live about 120 days
114
What is cytogenetics?
The study of cell genetics with emphasis on cell chromosomes
115
How is a cytogenetic analysis of chromosomes conducted?
Through the use of a chromosome map called a karyotype
116
What does a karyotype consist of?
A photograph or photomicrograph
117
How is a karyotype contructed?
Individual chromosomes are cut out and paired with sister chromosomes
118
How are chromosome pairs aligned in a karyotype?
By size from largest to smallest
119
At what stage of cell division can chromosomal damage by radiation be evaluated?
Metaphase
120
What two forms of chromosomal damage observed in metaphase?
Chromosomal aberrations and chromatid aberrations
121
What threshold model does damage to chromosomes follow?
A non-threshold model
122
What are late effects?
Consequences of radiation exposure that appear months or years after the exposure.
123
What are the two types of late tissue effects?
Stochastic or Tissue reactions
124
What are Stochastic effects also known as?
Probabilistic effects
125
What are stochastic effects?
Mutational or randomly occurring biologic changes that occur months or years after high level and possibly low level of radiation exposure
126
What are examples of Stochastic effects?
Cancer and genetic effects
127
What is the relationship between stochastic effects and disease incidence?
Directly proportional - disease incidence increases proportionally with dose
128
What is relationship between severity of disease and dose?
They're independent of each other - severity is not dose dependent
129
What is the threshold of Effects?
No threshold
130
What are examples of late biologic damage?
- Cataracts (late tissue reaction)
- leukemia (stochastic)
- Genetic mutations (stochastic)
131
What is epidemiology?
A science that deals with the incidence, distribution and control of disease in a population
132
What do epidemiological studies consist of?
Observations and statistical analysis of data, such as the incidence of disease within groups of people
133
What studies are included in epidemiologic studies?
The risk of radiation- induced cancer
134
What are the incident rates at which irradiation related malignancies occur determined by?
Comparing the natural incidence of cancer occurring in a human population with the incidence of cancer occurring in an irradiated population
135
What are determined from the epidemiologic studies?
Risk factors for the general human population
136
What is the significance of epidemiologic studies to radiobiologists?
They use the information from the studies to formulate dose-response estimates to predict the risk of cancer in human populations
137
What is another term for Carcinogenesis?
Tumorigenesis
138
What is carcinogenesis?
The formation of cancer
139
What is the most significant late stochastic effect?
Cancer
140
What is the occurrence of cancer and the threshold?
Random occurrence that does not have a threshold
141
Is the severity of cancer dose related?
No
142
How is a radiation dose-response relationship demonstrated?
Graphically through a curve
143
What does a radiation dose-response graph map?
The observed effects of radiation exposure in relation to the dose of radiation received
144
What is represented on the horizontal axis of the graph?
Dose received
145
What is represented by the vertical axis of the graph?
Biological effects observed
146
What is a general rule of the DR relationship?
As radiation dose escalated so do most effects
147
What are the DR relationship graphs used for?
To predict the risk of occurrence of malignancies in human populations that have been exposed to low levels of ionizing radiation
148
How are the observed effects of radiation demonstrated?
By the incidence of a disease or the severity of an effect
149
What are the two types of DR curves?
Linear and non-linear
150
What are the two types of threshold records in a DR curve?
Threshold or non-threshold
151
What is a Sigmoid DR curve?
An S shaped curve (non-linear)
152
What are Sigmoid curves generally used for?
In radiation therapy to demonstrate high-dose cellular response
153
What is a threshold?
A point at which a response or reaction to an increasing stimulation first occurs
154
How does threshold apply to radiation?
It means that below a certain radiation level or dose, no biological effects are observed
155
When would biological effects begin with a threshold relationship?
Only when the threshold or dose level is reached
156
What is non-threshold as it pertains to radiation?
Indicates that the radiation absorbed dose of any magnitude has the capability of producing biological effects
157
For the linear non-threshold curve, what is the relationship between dose and biological effects?
Directly proportional, the severity of biological effects increase directly with the magnitude of absorbed dose
158
What is a general rule of nonthreshold doses?
That no radiation dose can be considered absolutely safe
159
What is BEIR?
Committee on the Biological Effects of Ionizing Radiation
160
What did the BEIR committee concluded in 1980?
That most stochastic and hereditary effects at low dose levels from low-LET radiation, follow a linear-quadratic non-threshold dose response curve
161
What did BEIR do in 1990?
Revised risk estimates to conclude that the risk of radiation exposure was about 3-4 times greater than previously projected
162
What type of DR curve does the BEIR committee recommend for most types of cancer?
Linear non-threshold curve
163
What does the LNT curve imply?
That the biological response to ionizing radiation is directly proportional to the dose received
164
What must radiographers never fail to employ with diagnostic imaging?
Aggressive radiation safety measures since it follows an LNT curve and all radiation exposure levels possess the potential to cause biological damage
165
What does the BEIR committee believe the LQNT model is more accurate to reflect?
The stochastic and genetic effects at low-dose levels from low-LET radiation
166
What effects are presumed to follow the LQNT curve?
Leukemia, breast cancer and heritable damage
167
What acute reactions to radiation exposure are demonstrated through a linear threshold dose-response curve?
Skin erythema and hematological depressions
168
Why are Sigmoid curves best used for radiation therapy?
They demonstrate high-dose cellular responses to radiation absorbed within specific locations, such as skin, lens of the eye and blood cells
169
What does the curve indicate for different effects?
Different effects require different minimal doses
170
What happens at the tail of the sigmoid curve?
Indicates that limited recovery occurs at lower doses
171
For the highest radiation doses what happens to the curve?
The curve gradually levels off and then veers downward because the specimen or tissue dies before observable effects appear
172
What does continued use of the linear dose-response model have the potential to do?
Exaggerate the seriousness of radiation effects at lower dose levels from low-LET radiation
173
What id the linear dose response model accurate in representing?
The effects of high-LET radiation at higher doses
174
What approach have regulatory agencies adopted when assessing risk?
Use a conservative approach that may overestimate risk but will not underestimate it
175
What are somatic effects?
When living organisms that have been exposed to radiation sustain biological damage
176
What are the two classifications of somatic effects?
Stochastic and tissue reactions
177
What are is a general rule of stochastic effects?
The probability that the effect happens depends on the dose received, but the severity of the effect is not based on dose
178
What is an example of stochastic effect?
Occurrence of cancer
179
What is a general rule for tissue reactions?
Both the probability and the severity of the effect depend upon dose
180
What is an example of tissue reactions?
Cataracts
181
What are the full list of Late Tissue reactions?
- Cataract formation
- Fibrosis
- Organ atrophy
- loss of parenchyma cells
- Reduced fertility
- Sterility
182
What are Teratogenic effects?
Effects of radiation on the embryo-fetus in utero that depend on the fetal stage of development and radiation dose received
183
What are types of Teratogenic effects?
- Embryonic, fetal or neonatal death
- Congenital malformations
- Decreased Birth weight
- Disturbances in growth/development
- Increased stillbirths
- Infant mortality
- Childhood malignancy
- Childhood mortality
184
What are the two types of stochastic effects?
Cancer and Genetic effects
185
What are late somatic effects?
Consequences of radiation exposure that appear months or years after exposure
186
What do late somatic effects result from?
- previous whole or partial body acute exposure
- previous high radiation doses
- long term low level doses sustained over several years
187
Why are risk estimates for humans contracting cancer from low level radiation controversial?
There is no conclusive proof that low level IR exposure below 0.1 Gy cause any significant increase in risk of cancer
188
What are the 3 categories of adverse health consequences that the medical community believes require studies on at low-level?
- Cancer induction
- damage to the unborn from irradiation in utero
- Genetic effects
189
What does cells that survive initial irradiation possess?
They retain a “memory†of the event which are responsible for producing late effects
190
In theory, what cells or organs could produce stochastic effects?
Damage to one or a few cells can produce stochastic effects
191
What is the relationship between tissues reactions and late onset?
Typically tissue reactions do not usually demonstrate a late onset
192
What are the 3 major types of late effects?
- carcinogenesis
- cataractogenesis
- embryologist effects
193
Which type of radiation dose can risk be measure for in human populations?
High doses of
194
Why are low dose risk non directly measurable?
The risk is overshadowed by other causes of cancers in humans or the risk could be 0
195
How are risk estimates for cancer determined for low-doses?
High dose data is extrapolated, where risk has been directly observed, and just applied to low-doses
196
What are terms are risk models usually given in?
Absolute risk or Relative risk
197
What do both risk models predict?
The number of excess cancers, or cancers that would not have occurred in the population in question without the exposure to ionizing radiation
198
What does the absolute risk model forecast?
Forecasts that a specific number of malignancies will occur as a result of exposure
199
What does the relative risk model forecast?
That the number of excess cancers will increase as the natural incidence of cancer increases with the advancing age of the population
200
What have epidemiological studies for determining risk of cancer for diagnostic radiology?
That the benefit to that patient of the information gained from imaging greatly exceeds the minimal theoretical risk
201
What type of effect does 1989 BEIR V report the LQNT model be used for?
Leukemia
202
What model does BEIR Committee recommend Linear model be used for?
All other cancers
203
How does the linear model apply to the occurrence of cancer from high and low doses?
Accurately assesses the risk for high dose information but exaggerates risk for low doses
204
How does the linear quadratic model apply to the occurrence of cancer from high and low doses?
The model satisfactorily assesses risk from high doses but underestimates the risk for low doses
205
What has been used to prove ionizing radiation induces cancer?
Lab experiments with animals and statistical studies of human populations
206
How long can it take for cancer to appear in humans?
May take 5 or more years
207
How does the physical appearance of cancer from ionizing radiation compare to cancer from different agents?
They don’t appear different at all
208
What human evidence exists for radiation carcinogenesis?
1. Radium watch dial painters from the 1920s
2. Uranium miners from 1950s
3. Early medical radiation workers
4. Atomic bomb survivors
5. Patients with benign postpartum mastitis who were given radiation therapy
6. Evacuees from Chernobyl
209
How has the incidence of leukemia changed over the years?
It has slowly declined since the late 1940s
210
How has the incidence of other radiation-induced malignancies changed over the years? The
They have continued to escalate since the 1950s
211
What types of cancers has there been an increase in since the 50s?
Solid tumors such as thyroid, breast and bone cancer
212
In general what is the rate of natural incidence of breast cancer in Japanese women?
Much lower than incidence in women from the US or Canada
213
What have studies of Japanese atomic bomb survivors proven in regards to breast cancer?
That ionizing radiation can induce breast cancer and incidence of breast cancer in these women has risen with radiation dose
214
What is the relative risk for breast cancer for female atomic bomb survivors?
Ranges form 4:1 up to 10:1
215
What have studies from Japan identified regarding ionizing radiation as a cancer causing agent?
That high doses of IR cause cancer, but radiation isn’t a highly effective cancer causing agent
216
What was revealed in follow-up studies of bomb survivors from 1950-1987?
An excess of only 250 cancer deaths were attributed to radiation exposure, meaning that of 300 survivors only 1 died due to malignancies attribute to radiation exposure
217
What have more recent studies of the atomic bomb attacks revealed?
That more gamma radiation exposure and less neutron exposure caused radiation damage
218
What is the percent breakdown of neutron vs gamma radiation from the atomic bomb?
10% neutron and 90% gamma radiation
219
What radioactive material was spread as a result of the Chernobyl disaster?
Iodine-131 was spread and concentrates in the thyroid of those exposed
220
What is the most pronounced health effect of Chernoybl?
Thyroid cancer
221
What was administered to children in Poland and other countries to prevent thyroid cancer?
Potassium iodide
222
What is nonspecific lifespan shortening?
The reduction of lifespans as the result of ionizing radiation exposure
223
What effect does a single dose of 2 Gyt have on the eyes?
Induces the formation to cataracts
224
What is the result of cataractogenesis?
partial or complete loss of vision
225
What type of radiation is effective in producing cataracts?
Highly ionizing neutron radiation
226
What type of DR curve do radiation induced cataracts follow?
Threshold non-linear dose response relationship
227
What are the 3 stages of gestation?
- Pre-implantation (0-9 days after conception)
- Organogenesis (10 days post conception - 12 weeks)
- Fetal stage (12 weeks to term)
228
What does the period of gestation dictate when it pertains to exposure?
It dictates the effects of ionizing radiation
229
What trimester is the most radiocensitive?
1st trimester because its when the embryo begins to divide
230
At which stage of gestation is the embryo most susceptible to congenital abnormalities?
The organogenesis stage
231
What happens to a embryo in the first two weeks of fertilization?
If the embryo is irradiated its certain death
232
What happens to embryo sensitivity as the pregnancy progresses?
It decreases as gestation progress
233
What were the embryonic effects from Chernobyl?
No apparent abnormalities were seen in babies born immediately after the explosion, but in the 5 years after higher effects were reported
234
What are genetic effects?
Biological effects of ionizing radiation on future generations
235
What are types of irradiation mutation?
- radiation-induced damage to the DNA molecule in the sperm or ova of an adult
- may Manifest as various diseases or malformations
- may be transmitted to successive generations
236
What are spontaneous mutations?
Modifications of genetic material that occur naturally and without cause
237
What are examples of spontaneous mutations?
Hemophilia, Huntington's disease, sickle cell anemia, cystic fibrosis and hydrocephalus
238
What are mutant genes incapable of?
Governing cells chemical reactions or controlling amino acid sequence
239
What is doubling dose?
The radiation dose that causes the # of mutations occurring in a given generation to increase to 2X their original occurance
240
What is the radiation double dose equivalent for humans?
1.56 Sv
