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Occupational MedicineProf. Francesco S. Violante
Noise, Ionizing and Non-ionizing Radiations,
Sound = a series of pressure variances (oscillations) propagating through an elastic medium (a solid, a liquid or a gas) and perceived by the human ear as sound sensation
Noise = an undesired and annoying sound that, due to its physical characteristics, is potentially able to cause a temporary or permanent physical or psychic damage to the human organism (Giaccai, 1995 mod.)
Noise
Λ = Wavelength: horizontal distance between two subsequent crests or troughs
A = Amplitude of the wave: maximum wave range
T = Period: time required for one oscillation
Physical Characteristics
Frequency = Number of oscillations per second. It is measured in Hz (the human ear can detect frequencies between 16 and 16000 HZ)
Acoustic intensity = sound energy radiated by the source (acoustic power, W) per unit area perpendicular to the direction of propagation (W/m2)
Timbre = refers to sound quality and is determined by the wave shape
Physical Characteristics
Noise intensity is usually measured in Decibels (dB). The Decibel is the logarithm of the ratio between a reference sound intensity and the intensity which is being measured
minimum pressure variance value
detectable by the human ear for a pure tone of 1000 HZ
Range: from 0 dB, which corresponds to the hearing threshold level, to 120 dB, which corresponds to the pain threshold level
Unit of measurement
Sound is transmitted through air (external ear middle ear) and bone conduction (middle ear inner ear)
The auditory apparatus (inner ear, organ of Corti) transforms sound (mechanical energy carried by sound waves) into action potentials that reach the cortical acoustic areas through the acoustic nerve, determining the sound sensation
Perception
External ear: gathers sound waves and transmits them to the middle ear
Middle ear: transmits and amplifies the sound energy from the eardrum to the oval window through the ossicular chain and the contraction of the stapedius and tensor tympani muscles
Inner ear: transduction of mechanical energy (acoustic waves) into an electric signal (action potentials of the acoustic nerve)
Perception
Anatomy of the Ear
Organ of Corti
The discrimination of sound frequency takes place at the level of the organ of Corti thanks to a tonotopic localization of receptors (high frequencies near the staples, low frequencies at the cochlea)
The discrimination of sound intensity depends on the number of impulses reaching the cortex
Perception
Sounds with intensity levels >70-75 dB induce a reflex contraction of the stapedius and tensor tympani muscles, which attenuates by 20 dB the acoustic energy reaching the inner ear (low-pitched tones)
This mechanism is not effective in case of:chronic exposures (due to adaptation and muscular fatigue)Impulsive noises (reaching the inner ear
before the reflex occurrs)
Perception
Clock ticking 20 dB
Whispering 30 dB
Conversation 60-70 dB
Motor vehicles on a highway 100 dB
Rock concert, circular saw 110 dB
Taking off airplane 120 dB
Intensity of noise: examples
Industrial sectors with noise rates frequently ≥ 85 dBA:
Engineering sector Building sector Wood sector Textile sector Paper mills Food industry
Occupational Exposure
Distribution of 9.368.000 Production Workers who had Noise Exposure Levels of 80 dB or greater (USA)
Percentage trend of noise-induced hypoacusias and deafness with respect to the total number of occupational diseases (diseases “tabled” in D.P.R 336; year of manifestation: 1985-1999)
Source: INAIL data processed by ISPESL
0
10
20
30
40
50
60
70
80
90
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
INDUSTRIA Lavorazioni agricole a carattere industrialeChimica CostruzioniElettricità Legno e AffiniMetallurgia MinerariaTessile e Abbigliamento TrasportiVarie
Percentage trend of hearing loss cases compensated by INAIL, by occupation (“tabled” occupational diseases only)
Source: INAIL
0 5 10 15 20 25 30 35 40 45 50
Meccanico
Muratore
Falegname
Operatore
Carpentiere (e aiuto)
Saldatore
Montatore
Tessitore
Fabbro ferraio
Minatore
Altre occupazioni
TOTALE(85-99)
1995-1999
1990-1994
1985-1989
Prevalence of Hearing Loss > 45 Dbhl for the General Population in Great Britain (Davis, 1988)
Percentage trend of hearing loss cases compensated by INAIL, by age (”tabled” occupational diseases only)
0 5 10 15 20 25 30
Fino a 14
15 - 19
20 - 24
25 - 29
30 - 34
35 - 39
40 - 44
45 - 49
50 - 54
55 - 59
60 - 64
65 ed oltre
1995-1999
1990-1994
1985-1989
Source: INAIL
Auditory effects
Temporary Threshold Shift (TTS) Hypoacusia due to chronic acoustic trauma Hypoacusia due to acute acoustic trauma
(injury)
Extraauditory effects
Noise effects
Auditory effects Temporary Threshold Shift (TTS) =
elevation of the auditory threshold as compared to rest
TTS2 or physiological auditory fatigue is measured 2 minutes after the end of exposure
and has a duration of 16 hours
TTS16 or pathologic auditory fatigue is masured 2 minutes after end of exposure and has
a duration of more than 16 hours
Physiological auditory fatigue (TTS2)
It varies among subjects but remains constant in the same subject
It increases proportionally with sound pressure, for stimuli over 70 dB
It begins with stimulating frequency and then extends to other frequencies according to increase in intensity
Recovery is proportional to the logarithm of time (most of the recovery takes place within the first hours)
It does not usually exceed 30 dB
Auditory effects
Hypoacusia due to chronic acoustic trauma
If noise exposure persists (daily occupational exposure≥ 85 dBA or attention value) the temporary damage to auditory cells (TTS) progressively tends to become permanent
Permanent Threshold Shift (PTS) orhypoacusia due to chronic acoustic trauma or noise-induced hypoacusia
Auditory effects
Example of audiometric tracing of noise-induced hypoacusia
The damage affects the organ of Corti (external ciliated cells)
It is a bilateral neurosensorial (or perceptive) hypoacusia, almost always symmetrical, progressively irreversible and evolutive, as a result of persistent exposure to noise
It mainly concerns high frequencies ranging from 3000 to 6000 Hz with an initial peak at 4000 Hz
Auditory effects
Onset is progressive (and nearly always insidious), and develops in four phases:
p Initial phase: at the end of the work-shift, the worker complains of tinnitus (buzzing, ringing) ,“full ear” feeling, headache, giddiness, daze, asthenia, etc.
p Audiometric phase: symptomatology is absent (a slight intermittent tinnitus at most) and the damage is revealed only by an audiometric test (deficit at 4000 Hz)
Hypoacusia due to chronic acoustic trauma
p Onset phase: appearance of auditory deficits (hypoacusia) for high-pitched tones (4000 and 6000 Hz), combined with difficulty conversating, especially in noisy environments, and need to turn up the volume of radio or TV
p Illness phase: appearance of auditory deficits (hypoacusia) for speech frequencies (500 and 2000 Hz), which can affect social life; permanent and/or nocturnal tinnitus (with insomnia) and appearance of the “recruitment” phenomenon (distorted and annoying perception of noises of relatively high intensity) are also possible
Hypoacusia due to chronic acoustic trauma
Diagnosis
Pathological and working anamnesis Risk assessment for exposure to noise Tonal audiometry (with determination of air and
bone conduction) performed in silent cabin in conditions of acoustic rest, preceded by otoscopic examination
Vocal audiometry Tympanometry and reflectometry Evoked auditory potentials
Hypoacusia due to chronic acoustic trauma
Synergic effects with noise
Vibrations
High temperatures
Organic solvents (derived from benzene)
Carbon sulphide
Carbon Oxide
Cyanides Methylmercury
Pesticides
Hypoacusia due to chronic acoustic trauma
Epidemiological studies
Risk factors associated with hearing loss: - Old age - Previous ear surgery - Decline of cognitive function - Diabetes mellitus - Hypercholesterolemia - Use of analgesics - Smoking
(E. Toppilla et al., Individual Risk Factors in the Development of Noise-Induced HearingLoss. Noise Health. 2000; 2(8): 59-70)
They seem to be attributable to the connections between the acoustic pathways and CNS areas different from the auditory cortex
E.g. the reticular zone, which is connected via descending pathways to the mechanisms that control voluntary motility, spinal reflexes, with the hypothalamus (and the neurovegetative system)
Extra-auditory effects
They seem to be attributable to the connections between acoustic pathways and CNS areas, different from the auditory cortex, related to the neurovegetative system
Sleep disorders Reduced attention and concentration Anxiety and irritation Reduction in working efficiency Increase in cardiac frequency and arterial pressure Increase in gastric secretion
Extraauditory effects
Ionizing and Non-ionizing Radiations
Ionizing RadiationsIonizing radiations are electromagnetic
particles and waves whose energy is sufficient to directly or indirectly ionize the atoms they pass through, so as to modify matter properties
It is believed that any exposure to ionizing radiations provokes “biological effects”, which are generally harmful; type, appearance and severity of such effects can differ widely
Electromagnetic Radiations
X raysGamma rays
Corpuscular Radiations
Alpha particleBeta particleNeutronsNrotons
Ionizing Radiations
Alpha rays Particles carrying a double positive charge,
composed of two helium nuclei (2 neutrons and 2 protons)
Source: radioactive atomic nuclei with a high atomic number
Penetrating power: extremely weak, skin basal layer (100-fold weaker than beta rays) Radius in tissues: few µ
Ionizing power: very high (1000-fold higher than that of beta particles)
Dangerousness: dangerous only if emitted inside the human body
Ionizing Radiations
Beta rays Particles made of electrons (beta-) and positrons
(beta+) emitted by a decaying nucleus. Some high-speed beta particles interact with matter, emitting x rays (natural x rays)
Source: radioactive atomic nuclei, accelerators Penetrating Power: weak, 1 cm below skin
surface (100-fold stronger than alpha rays, but 100-fold weaker than gamma rays) Radius in tissues:: few mm
Ionizing Radiations
Ionizing power: minimal Dangerousness: always harmful with internal
sources; harmful for structures at less than 1 cm from the skin
Ionizing Radiations
Neutrons The neutron is, together with the proton, one of
the two components of atomic nuclei; neutrons have no electric charge and lose energy through interaction with the atomic nuclei of the materials they pass through
Source: nuclear reactors and accelerators, nuclear explosions
Dangerousness: high. The source is always external and emissions cease only when the source is switched off
Ionizing Radiations
Gamma rays Source: radioactive atomic nuclei, nuclear
explosions Penetrating power: strong (100-fold stronger
than that of beta rays). A few centimeters of lead reduce the intensity of these rays by a factor of 2
Ionizing power: they produce secondary electrons that ionize air
Dangerousness: always dangerous, even when emitted by external sources
Ionizing Radiations
X rays Electromagnetic radiations similar to gamma
rays, but with a lower frequency Source: artificial production (x-rays tube),
collision between electrons and matter Penetrating power: high Ionizing power: high Dangerousness: high, but lower than that of
gamma rays
Ionizing Radiations
Ionizing Radiations
Natural backgroundRadioactivity is a natural phenomenon, we
are constantly exposed to natural radiationsExternal sources cosmic radiations, radioactive substances contained in the
soil and in building materials
Internal sources radioactive substances which are inhaled or ingested and
the radioactive constituents of our body, especially potassium 40
Ionizing Radiations
Absorbed dose (D) Indicates the quantity of energy imparted by
radiation and absorbed by tissues and results from the interaction of radiation with matter
D = dE / dm = ratio of energy imparted to a given volume to the mass contained in that volume; the higher the absorbed dose, the more severe the effect of a radiation
The unit of measurement (SI) is the Gray (Gy)
Ionizing Radiations
In order to compare the effects of different types of IR, a numeric coefficient or QF is used (it depends on the LET# and is linearly proportional to the RBE* of each type of IR)
# number of ionizations produced per unit path length in the biological medium
* ratio of the dose of a “standard” radiation (produced by a 250-kv x-ray source), expressed as D250, to the dose of the analysed radiation (Dr) that is necessary to obtain the same biological effect (= D250/Dr)
Ionizing Radiations
Dose equivalent (H) The product of absorbed dose in tissue (D) and the
quality factor (QF) is defined as dose equivalent (H=QFD).
The unit of measurement (SI) is the Sievert (Sv)
Since the QF for x and rays is 1, Sv and Gy for x and rays are equivalent
We often refer to dose or absorbed dose equivalent per unit time, that is intensity or absorbed dose rate (Gy· s-1), or dose equivalent rate (Sv· s-1)
Ionizing Radiations
BIOLOGICAL EFFECTS OF IONIZING RADIATIONSIONIZING LIVINGRADIATIONS MATTER
ELEMENTARY PHYSICAL PHENOMENA
IONIZATIONS
FREE RADICALS
DIRECT AND INDIRECT ACTIONS
BIOLOGICAL EFFECTS
It is believed that, to inactivate cells, IR damage some essential macromolecules (biological target) as DNA, proteins, sugars and complex lipids
The effect of IR on the biological target can occur either by direct or indirect action
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS
> ionizing ability> damage
Direct action Target molecules are directly damaged by rupture
of molecular links The target is a structure, which is:
Sensitive to IREssential in the biological system
Direct actionCellular macromolecules get damaged by free
radicals, resulting from water radiolysis
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS
Ionizing radiations damages
DETERMINISTIC DAMAGES: Somatic effects: appearing in the
irradiated individual
STOCHASTIC DAMAGES: Somatic effects Genetic effects: occurring in the offspring
of the irradiated individual
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS
This damage is exclusively somatic There is a threshold level The severity of damage depends on the dose The latent period is usually short (late onset in
some cases) Dose-effect relationship is represented by a
sigmoid curve Damage can be:● direct (early):mainly affecting parenchymal cells● indirect (late): affecting vascular and connective
tissue structure● generalized● localized
DETERMINISTIC DAMAGE (graded or non-stochastic damage)
Dose-effect relationship
DETERMINISTIC DAMAGE (graded or non-stochastic damage)
Law of Bergonié and Tribondeau
Cells sensitivity to IR radiation is:directly proportional to their mitotic
activityinversely proportional to their degree of
differentiationOn the basis of this principle, a tissue
radiosensitivity scale can be defined
DETERMINISTIC DAMAGE (graded or non-stochastic damage)
Tissue Relative Radiosensitivity
Linfatic tissue, hemopoietic marrow, germinal epithelium of the skin and of the small intestine
Very High
Skin, other epithelial tissues (cornea, crystalline lens, mucosa of the digestive tract) High
Growing bone and cartilage Moderate
Salivary glands' epithelium and liver epithelium; renal and pulmonary epithelium
Medium
Muscle, nervous tissue (CNS and peripheral tissue), mature bone and cartilage Low
GENERALIZED DETERMINISTIC DAMAGE
Whole-Body Radiation SyndromeAcute radiation to the whole body or to a
large portion of the body (global radiation) gives rise to the so-called
Acute Radiation Syndrome: It is characterized by three worsening
clinical stages (hematologic, gastrointestinal and neurologic stage) developing according to their respective dose thresholds
Radiation disease (prodromic phase)Dose = 1-2,5 Gy
Severity of radiation is inversely proportional to the latency of symptoms
nausea, vomiting, diarrhea, anorexia, headache, dizziness, asthenia, olfactory and taste anomalies, cardiac arrhythmias, hypotension, irritability, insomnia
GENERALIZED DETERMINISTIC DAMAGE
Hematologic Syndrome
Dose = 2.5 – 4.5 Gy
It results from the damage affecting the staminal compartment of hematic cells
Early fall of lymphocytes and granulocytes (24 – 48 ore), followed by a latency period of two weeks, associated with relative well-being
Late fall of erythrocytes and platelets
GENERALIZED DETERMINISTIC DAMAGE
Trend of blood cells as a function of time, following whole-body radiation at moderate dose rate (< 10 Gy)
60
20
5 10 15 20 25
100
Days after radiation
Cell %.
vs controls
Lymphocytes
Granulocytes
Platelets
Erythrocytes
GENERALIZED DETERMINISTIC DAMAGE
Hematologic Sindrome
Fever associated with shivering, asthenia, malaise, headache, hair loss
Appearance of petechias, gum hemorrhages, worsening anemia, marked asthenia and disphnea, infections
Death by cardiovascular collapse
GENERALIZED DETERMINISTIC DAMAGE
Gastroenteric Syndrome
Dose = 5 - 20 GyIt results from the damage affecting the intestinal mucosa, due to failed maturation of stem cells Early appearance of nausea and vomiting, with significant worsening after 3-5 days from radiation Violent diarrhea with watery and bloody stools Electrolytic imbalance with malnutrition Septicaemia Death within 1 or 2 weeks in conditions of hyperpyrexia, septic status, dehydration
GENERALIZED DETERMINISTIC DAMAGE
Neurologic SyndromeDose = 10 - 50 Gy
It results from the increase in permeability of encephalic vessels
cerebral oedema, endocranic hypertension with nervous tissue damage (always lethal).
sudden onset and fast development rapid exitus due to marked prostration, apathy,
drowsiness, coma with or without convulsions
GENERALIZED DETERMINISTIC DAMAGE
THE LITVINENKO CASE
Polonium is a rare radioactive metalloid found in uranium minerals
Polonium-210: isotope of polonium, alpha-emitter with a half-life of 138,39 days (1 milligram of this metalloid emits as many alpha particles as 5 grams of radium)
THE LITVINENKO CASE
Polonium is a toxic element, it is highly radiactive and dangerous to manipulate
It emits alpha particles, which travel only a few centimetres in the air and can be easily shielded, although in case of penetration into the organism (by inhalation or ingestion), they have a high ionizing power and can cause damage to the tissues
THE LITVINENKO CASE
The symptomatology of polonium poisoning presents with the usual symptomatology of whole-body radiation: From vomiting, nausea and diarrhea (all the more violent, the higher the radiation) to bone marrow destruction and the consequent increase in infections and hematic losses
In order for damages to be detectable, the absorbed dose has to be about 1 Sv (a thoracic radiography is about 20 millionths of an SV and the natural radiation background is about 2 thousandths of an SV per year)
THE LITVINENKO CASE
THE LITVINENKO CASE
It is not clear how much polonium was used to kill the former spy
The duration of his agony, about 3 weeks, gives us some clues …
Subjects exposed to less than 5 Sv live longer than 3 weeks and can even survive
The former secret agent is likely to have received a dose comprised between 5 and 15 Sv
THE LITVINENKO CASE
i.e. the same quantity of radiations absorbed by those who were about 800 m from the Hiroshima explosion
If ingested, this radiation dose would correspond to a ten-millionth of a gram of Polonium
Estimates on the lethal dose vary widely
THE LITVINENKO CASE
DETERMINISTIC LOCALIZED DAMAGESkin In the past, it was used as a “biological
dosimeter”.Doses ≥ 2 Gy in single fraction initially provoke
erythema (following dilation of skin capillaries) lasting 48-72 hours; at a late stage, dermic and hypodermic lesions (secondary lesions to the microcircle) appear, associated with fibrosis and possible thrombosis and formation of microvascular telangiectases.
In more severe cases, chronic radiodermitis may develop (sclerosis and ulcer).
Male GonadsGerminal cells are more radiosensitive than
hormone-secreting cells, and radiosensitivity also varies according to degree of maturation (B spermatogonia spermatozoa)
Doses of 4-6 Gy (4.000-6.000 mSv) cause temporary infertility after 1–2 months (generally lasting for at least 2 years)
For doses > 6 Gy (6.000 mSv), infertility may be permanent
DETERMINISTIC LOCALIZED DAMAGE
Female GonadsThe dose needed to cause temporary
infertility in women is higher than that needed to cause temporary infertility in men
Doses of 20-30 Gy – 20.000-30.000 mSv cause permanent infertility
DETERMINISTIC LOCALIZED DAMAGE
EyeThe damage caused by radiation occurs in the
crystalline lens at the level of the epithelial cells covering the lens
Opacities develop at the posterior pole. Over time, the confluence of these lesions leads to a total opacification of the lens, which is defined as cataract
A threshold dose was defined for the development of opacity and cataracts
DETERMINISTIC LOCALIZED DAMAGE
Estimate of the threshold dose for deterministic effects to the crystalline lens in an adult subject (ICRP 41 and ICRP 60)
Target organ and effect
Total dose equivalent received in a single exposure (Sv)
Total dose equivalent received during repeated or prolonged exposures (Sv)
Annual dose received during repeated exposures or exposures prolonged over many years (Sv a-1)
CRYSTALLINE LENS: observable opacities
0.5-2.0 5 > 0.1
VISUAL DEFICIT (cataract)
5.0 > 8 > 0.15
DETERMINISTIC LOCALIZED DAMAGE
Lack of threshold dose (precautionary hypothesis assumed for the preventive purposes of radiation protection)
The dose-effect relationship is linear without threshold
Severity is independent of dose
STOCHASTIC DAMAGES (probability-based damages)
They have long latent periods and are randomly distributed in the exposed population
The probability of appearance increases as dose increases
They were demonstrated for high doses by radiobiological experimentation and epidemiological evidence
STOCHASTIC DAMAGES (probability-based damages)
Dose-effect relationship
STOCHASTIC DAMAGES (probability-based damages)
Genetic Modifications of chromosome structure :
deletion duplication inversion translocation
Variations in chromosome number: nullisomy monosomy trisomy tetrasomy
Point mutations
STOCHASTIC DAMAGES (probability-based damages)
Somatic stochastic damage
Represented by:
Leukemias Solid tumours
The Law of Bergonié and Tribondeaux seems to apply also to this case:
Tissues with a high mitotic index seem more susceptible to neoplasia than tissues with a low mitotic index.
Somatic stochastic damage
Non-ionizing Radiations
Radiazioni Non Ionizzanti
Definition
Electromagnetic waves that:
Propagate through space, vibrating at a certain frequency (Hz) with a certain wavelength (metric units nm m).
Have an energy lower than 12 eV (minimum energy needed to turn a stable atom into an ion).
Non-ionizing Radiations
Radiazioni Non Ionizzanti
ENERGY
The energy carried by a NIR increases as itsfrequency increases:
High-energy NIRs have:
a high wave frequency a short wavelength
Low-energy NIRs have:
A low wave frequency A long wavelength
Non-ionizing Radiations
Types of NIR
NIRs in ascending wavelength order:
Optic damage: Ultraviolet radiations(UV) Visible radiations (VSBL)(400-760 nm) Infrared radiations (IR)
Microwaves Radiofrequencies Electric and magnetic fields with extremely low
frequencies (ELF) Static electromagnetic fields
Types of NIR
Laser (Light Amplification by Stimulated Emission of Radiation)
Definition
A beam of optical radiation (Ultraviolet, visible or infrared radiation):
Monochromatic
Coherent
Collimated
Laser (Light Amplification by Stimulated Emission of Radiation)
Harmful effects of Lasers
The eye is the main target organ for Laser damage, but skin can also be affected (burns), although to a smaller extent
Its penetrating power into the ocular structures varies widely depending on laser radiation wavelength
Harmful effects of Lasers
UV-B, UV-C , IR-B and IR-C laser radiations stop at the conjunctiva and cornea
UV-A laser radiations can reach the crystalline lens
VSBL and IR-A laser radiations can reach the retina.
Laser (Light Amplification by Stimulated Emission of Radiation)
Ultraviolet Radiations (UV)Invisible to the human eye
They are produced by special mercury-vapour lamps. These lamps are made of quartz and special glasses and allow filtering of electromagnetic waves with wavelengths of 115-400 nm
UV radiation can penetrate:
ordinary glassvarious types of plasticany opaque material
Ultraviolet Radiations (UV)
UV radiations are divided according to decreasing wavelength:
UV-A longer wavelength (400-315 nm) and lower energy rate
UV-B intermediate wavelength (315 -280 nm)
UV-C shorter wavelength (280-115 nm) and higher energy
Ultraviolet Radiations (UV)
Occupational Exposure
Phototherapy
Photodiagnostics
Sterilization of surfaces and environments
Photohardening of resins
Arc welding, etc.
Ultraviolet Radiations (UV)Harmful effects of UV radiation The eye and skin are the main target organs of UV
radiation The damaging effect is higher for UV-C radiation,
whereas UV-A radiation has a higher penetrating power
UV-A radiation is unable to penetrate further than the skin and crystalline lens (the retina is never reached)
The penetrating depth is greater in subjects with fair complexion, particularly albinos, who have no melanocytes no melanin, <cutaneous pigment able to absorb a part of the UV-A radiation affecting the skin, thus preventing it from penetrating deeper into the tissues
Ultraviolet Radiations (UV)
Harmful effects of UV radiation
Skin
Tanning (UV-A radiations stimulate the transfer of melanin granules to the epidermis)
Erythemas (mainly induced by UV-B and UV-C) the above-mentioned effects vary not only according to UV type, but also according to length of exposure
Skin ageing, due to loss of skin elasticity caused by UV radiation
Actinic Keratosis offers a fertile ground for the onset of skin tumours (basocellular and spinocellular carcinoma, melanoma)
Ultraviolet Radiations (UV)
Harmful effects of UV radiation
Eye
Photoconjunctivae
Photokeratitis
Opacity of the crystalline lens leading up to actinic cataract
the above-mentioned effects vary not only according to UV type (in this case, UV-B radiation is more effective), but alsoaccording to length of exposure These ocular manifestationsappear 2 to 24 hours after eye UV irradiation
Infrared Radiations (IR)
UV radiations are divided according to increasing wavelength:
IR-A shorter wavelength (760-1400 nm) and higher energy
IR-B intermediate wavelength (1400-3000 nm)
IR-C longer wavelength (3000-10000 nm) and lower energy
Infrared Radiations (IR)
Occupational Exposure
Glass processing (melting)
Smelting industry (blast furnaces)
Engineering sector (electric arc welding)
Others
Infrared Radiations (IR)
Harmful effects of IR radiation
The eye and skin are the main target organs of UV radiation
The damaging effect is higher for IR-A radiation, whereas IR-C radiation has a higher penetrating power
However, also IR-C radiation is unable to penetrate further than the skin and crystalline lens (the retina is never reached)
Infrared Radiations (IR)
Thermal EffectsEye:
• Blepharitis• Blepharoconjunctivitis• Keratitis• Posterior capsular cataract
Skin: superficial or deep burns, whose severity depends on:• Incident thermal energy• Degree of pigmentation• Efficiency of local thermoregulation phenomena
Radiofrequencies and Microwaves
Microwaves (MW)
electromagnetic waves with wavelengths ranging from 1 mm and 1 m and frequencies between 100 Khz and 300 MHz
Radiofrequencies(RF)
electromagnetic waves with wavelengths > 1 and frequencies between 300 MHz and 300 GHz
Extra-occupational Exposure
Domestic microwave ovensTelecommunications:
a. Diffusion systems (amplitude modulation aerials, TV aerials)
b. Directive links (radio link)c. Mobile telephony aerials
Radiofrequencies and Microwaves
Occupational Exposure
Workers employed in the maintenance of power plants and instruments producing high electric fields
Plastic welding and mouldingRapid wood gluing
Smelting and tempering of metalsSanitary operators using Marconitherapy
(RF) and Radartherapy (MW) devices.
Radiofrequencies and Microwaves
Thermal Effects
Temperature rise in the irradiated tissues due to faster molecular movement and consequent heat production
Hypersusceptibility of some organs:
Eye possible development of cataractTestes atrophy and fibrosis with possibility of
temporary sterilityOvaries alteration of the reproductive cycle,
increase in abortions
Radiofrequencies and Microwaves
Non-thermal Effects
Cardiovascular system: vasodilatation, hypo or hyperkinetic arrhythmias
Nervous system: irritability, depression, tremor, dizziness, sleep disorders
Endocrine system: hyperthyroidism, hypercorticosurrenalism, etc.
Radiofrequencies and Microwaves
Radiofrequencies and Microwaves Oncogenic Effects
TYPE OF TUMOUR SIGNIFICANT CORRELATION
STUDIES
GLIOMA YES Auvinen 2002
No Christensen 2005 Johansen 2002
Inskip 2001
MENINGIOMA YES _
No Christensen 2005 Johansen 2002
Inskip 2001
ACOUSTIC NEURINOMA
YES Hardell 2003
No Christensen 2004 Muscat 2002
Inskip 2001
Hardell 1999
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Sinusoidal electromagnetic fields with frequencies ranging from 30 and 300 Hz.
Any electrically powered device is a source of ELF electric and magnetic fields:
In the domestic setting, electric fields are always present regardless of whether appliances are being used or not.
On the other hand, a magnetic field is present only when appliances are turned on and current flows through them.
Occupational ExposureUse of automatic welders, arc furnaces
Induction heating systems and other widespread devices
Tempering and degasification of metals
Glass-metal welding
Sealing of plastic containers
Processing of precious metals
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Short-term Effects
Interaction with transport of Na+, k-, Ca++ ions through the membranes
Biological effects on the: Nervous system Endocrine system Cardiocirculatory system
These effects occurr in acute form when threshold values are exceeded
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Short-term Effects
In 2001, IARC (International Agency for Research on Cancer) classified ELF magnetic fields in group 2B
Possible carcinogens, which should be carefully considered for their possible carcinogenic effects in man
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Short-term Effects
In 2001, IARC (International Agency for Research on Cancer) classified ELF electric fields in group 3
Not classifiable as to their carcinogenicity to humans: substances whose carcinogenicity has not been assessed
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Long-term Effects
TYPE OF TUMOUR
SIGNIFICANT CORRELATION
STUDIES
CEREBRAL TUMOURS
Yes • Hakansson 2002• Villeneuve 2002• Van Wijngaarden 2001
No • Klaebol 2004• Sorahan 2001
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Long-term Effects
TYPE OF TUMOUR
SIGNIFICANT CORRELATION
STUDIES
CHILD LEUKEMIA
Yes • Ahlbom 2000 #• London 1991• Wertheimer e Leeper 1979
No • Ahlbom 2000 *• Verkasalo 1993• Savitz 1988
Extremely Low Frequency (ELF) Electric and Magnetic Fields
STATIC ELECTRIC AND MAGNETIC FIELDS
Occupational Exposure
Electrochemical plants (e.g. Production of aluminium)
Continuous current transport (trains, trams, underground trains)
High energy accelerators:• MNR• Particles accelerators• Nuclear reactors
Harmful Effects
Sensory group
Stress group
Genetic code group
Indirect effects
STATIC ELECTRIC AND MAGNETIC FIELDS
Sensory group
They can be associated with sensory magnetoreception, also in the case of fields of the order of the geomagnetic field, and regulate:
The navigation of migratory birds The directional sense in insects The kinetic movement of shellfish
STATIC ELECTRIC AND MAGNETIC FIELDS
Stress group Hematologic effects: leukopenia CNS: magnetophosphene
phenomenon, caused by stimulation of the retina by induced currents, and change in cerebral bioelectrical activity in high intensity fields
Delay in wound healing and tissue regeneration
Decrease in body temperature Delay in growth Interruption of the estrous cycle
STATIC ELECTRIC AND MAGNETIC FIELDS
Genetic code group
They have been hypothesized as perturbative mechanisms in proton tunneling during DNA replication, with possible errors in the genetic code
Experimental evidence is insufficient
STATIC ELECTRIC AND MAGNETIC FIELDS
Indirect Effects
Interaction with and possible malfunction of various devices:
Pacemakers Electrocardiographs Insulin pumps, etc
Interaction with external or internal ferromagnetic materials:
prostheses, clips, etc tools, gas cylinders, etc
STATIC ELECTRIC AND MAGNETIC FIELDS