Transcript Medicina del Lavoro Prof. Francesco S. Violante
Occupational Medicine Prof. Francesco S. Violante
Noise, Ionizing and Non-ionizing Radiations,
Noise
Sound =
sensation 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
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.)
Physical Characteristics
Λ = Wavelength: horizontal distance between two subsequent crests or troughs A = Amplitude of the wave: wave range maximum 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 =
of propagation (W/m 2 ) sound energy radiated by the source (acoustic power, W) per unit area perpendicular to the direction
Timbre =
refers to sound quality and is determined by the wave shape
Unit of measurement
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
Perception
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) the sound sensation into action potentials that reach the cortical acoustic areas through the acoustic nerve, determining
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:
nerve) transduction of mechanical energy (acoustic waves) into an electric signal (action potentials of the acoustic
Anatomy of the Ear
Organ of Corti
Perception
The discrimination of Corti thanks to a
sound frequency
takes place at the level of the organ of
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)
Intensity of noise: examples
Clock ticking Whispering Conversation Motor vehicles on a highway Rock concert, circular saw 20 dB 30 dB 60-70 dB 100 dB 110 dB Taking off airplane 120 dB
Occupational Exposure
Industrial sectors with noise rates frequently ≥ 85 dBA: Engineering sector Building sector Wood sector Textile sector Paper mills Food industry
Distribution of 9.368.000 Production Workers who had Noise Exposure Levels of 80 dB or greater (USA)
40 30 20 70 60 50
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)
90 80 10 0 1985 1986 1987 1988 1989
INDUSTRIA Chimica Elettricità M etallurgia Tessile e Abbigliamento Varie
1990
Source: INAIL data processed by ISPESL
1991 1992 1993 1994 1995 1996 1997 1998
Lavorazioni agricole a carattere industriale Costruzioni Legno e Affini M ineraria Trasporti
1999
Percentage trend of hearing loss cases compensated by INAIL, by occupation (“tabled” occupational diseases only)
Altre occupazioni Minatore Fabbro ferraio Tessitore Montatore Saldatore Carpentiere (e aiuto) Operatore Falegname Muratore Meccanico
0
Source: INAIL
5 10 15 20 25 30 35 40 45 50
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)
65 ed oltre 60 - 64 55 - 59 50 - 54 45 - 49 40 - 44 35 - 39 30 - 34 25 - 29 20 - 24 15 - 19 Fino a 14
0
Source: INAIL
5 10 15 20 25 30
1995-1999 1990-1994 1985-1989
Noise effects
Auditory effects
Temporary Threshold Shift (TTS) Hypoacusia due to chronic acoustic trauma Hypoacusia due to acute acoustic trauma (injury)
Extraauditory effects
Auditory effects
Temporary Threshold Shift (TTS) =
elevation of the auditory threshold as compared to rest
TTS 2 or physiological auditory fatigue
is measured 2 minutes after the end of exposure and has a duration of 16 hours
TTS 16 or pathologic auditory fatigue
is masured 2 minutes after end of exposure and has a duration of more than 16 hours
Auditory effects
Physiological auditory fatigue (TTS 2 )
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) or
hypoacusia due to chronic acoustic trauma or noise-induced hypoacusia
Example of audiometric tracing of noise-induced hypoacusia
Auditory effects
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
Hypoacusia due to chronic acoustic trauma
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 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 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
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)
Extra-auditory effects
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)
Extraauditory 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
Ionizing and Non-ionizing Radiations
Ionizing Radiations
Ionizing 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
Ionizing Radiations
Electromagnetic Radiations X rays Gamma rays Corpuscular Radiations Alpha particle Beta particle Neutrons Nrotons
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
from the skin : always harmful with internal sources; harmful for structures at less than 1 cm
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 background
Radioactivity is a natural phenomenon, we are constantly exposed to natural radiations External 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 and rays is 1, Sv and Gy for x 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)
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS
IONIZING RADIATIONS LIVING MATTER
ELEMENTARY PHYSICAL PHENOMENA
IONIZATIONS
FREE RADICALS
DIRECT AND INDIRECT ACTIONS
BIOLOGICAL EFFECTS
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS
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 IR Essential in the biological system
Direct action
Cellular 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
DETERMINISTIC DAMAGE (graded or non-stochastic damage)
● ● ● ● 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 activity inversely proportional to their degree of differentiation On the basis of this principle, a tissue radiosensitivity scale can be defined
Tissue
Linfatic tissue, hemopoietic marrow, germinal epithelium of the skin and of the small intestine
Relative Radiosensitivity
Very High Skin, other epithelial tissues (cornea, crystalline lens, mucosa of the digestive tract) High Growing bone and cartilage Salivary glands' epithelium and liver epithelium; renal and pulmonary epithelium Muscle, nervous tissue (CNS and peripheral tissue), mature bone and cartilage Moderate Medium Low
GENERALIZED DETERMINISTIC DAMAGE
Whole-Body Radiation Syndrome
Acute 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
GENERALIZED DETERMINISTIC DAMAGE
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) 100 60 Lymphocytes Granulocytes Platelets Erythrocytes 20 Cell %.
vs controls 5 10 15 20 25 Days after radiation
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 Gy It 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 Syndrome
Dose = 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
THE LITVINENKO CASE
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
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 DAMAGE
Skin
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).
DETERMINISTIC LOCALIZED DAMAGE
Male Gonads
Germinal 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 Gonads
The 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
Eye
The 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 CRYSTALLINE LENS: observable opacities Total dose equivalent received in a single exposure (Sv) Total dose equivalent received during repeated or prolonged exposures (Sv) 0.5-2.0 5 Annual dose received during repeated exposures or exposures prolonged over many years (Sv a 1 ) > 0.1
VISUAL DEFICIT (cataract) 5.0 > 8 > 0.15
STOCHASTIC DAMAGES (probability-based damages)
Lack of threshold dose radiation protection) (precautionary hypothesis assumed for the preventive purposes of 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
Somatic stochastic damage
Represented by:
Leukemias Solid tumours
Somatic stochastic damage
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.
Non-ionizing Radiations
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).
ENERGY
The energy carried by a NIR increases as its frequency increases: High-energy NIRs have: a high wave frequency a short wavelength Low-energy NIRs have: A low wave frequency A long wavelength
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
Laser (Light Amplification by Stimulated Emission of Radiation) 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.
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 glass various types of plastic any 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 nm) intermediate wavelength (315 -280 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, 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) 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 also according to length of exposure These ocular manifestations appear 2 to 24 hours after eye UV irradiation UV radiations are divided according to increasing wavelength : IR-A energy shorter wavelength (760-1400 nm) and higher IR-B intermediate wavelength (1400-3000 nm) IR-C energy longer wavelength (3000-10000 nm) and lower Occupational Exposure Glass processing (melting) Smelting industry (blast furnaces) Engineering sector (electric arc welding) Others 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) Thermal Effects Eye: • • • • 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 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 ovens Telecommunications: a. b. c. Diffusion systems (amplitude modulation aerials, TV aerials) Directive links (radio link) Mobile telephony aerials Occupational Exposure Workers employed in the maintenance of power plants and instruments producing high electric fields Plastic welding and moulding Rapid wood gluing Smelting and tempering of metals Sanitary operators using Marconitherapy (RF) and Radartherapy (MW) devices . 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 cataract Testes atrophy and fibrosis with possibility of temporary sterility Ovaries alteration of the reproductive cycle, increase in abortions Non-thermal Effects Cardiovascular system: vasodilatation, hypo or hyperkinetic arrhythmias Nervous system: irritability, depression, tremor, dizziness, sleep disorders Endocrine system: hyperthyroidism, hypercorticosurrenalism , etc. TYPE OF TUMOUR GLIOMA Oncogenic Effects SIGNIFICANT CORRELATION YES No MENINGIOMA ACOUSTIC NEURINOMA YES No YES No STUDIES Auvinen 2002 Christensen 2005 Johansen 2002 Inskip 2001 _ Christensen 2005 Johansen 2002 Inskip 2001 Hardell 2003 Christensen 2004 Muscat 2002 Inskip 2001 Hardell 1999 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 Exposure Use 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 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 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 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 Long-term Effects TYPE OF TUMOUR SIGNIFICANT CORRELATION Yes CEREBRAL TUMOURS No STUDIES • Hakansson 2002 • Villeneuve 2002 • Van Wijngaarden 2001 • Klaebol 2004 • Sorahan 2001 Long-term Effects TYPE OF TUMOUR SIGNIFICANT CORRELATION Yes STUDIES CHILD LEUKEMIA No • Ahlbom 2000 # • London 1991 • Wertheimer e Leeper 1979 • Ahlbom 2000 * • Verkasalo 1993 • Savitz 1988 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 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 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 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 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, etcUltraviolet Radiations (UV)
Ultraviolet Radiations (UV)
Infrared Radiations (IR)
Infrared Radiations (IR)
Infrared Radiations (IR)
Infrared Radiations (IR)
Radiofrequencies and Microwaves
Radiofrequencies and Microwaves
Radiofrequencies and Microwaves
Radiofrequencies and Microwaves
Radiofrequencies and Microwaves
Radiofrequencies and Microwaves
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Extremely Low Frequency (ELF) Electric and Magnetic Fields
Extremely Low Frequency (ELF) Electric and Magnetic Fields
STATIC ELECTRIC AND MAGNETIC FIELDS
STATIC ELECTRIC AND MAGNETIC FIELDS
STATIC ELECTRIC AND MAGNETIC FIELDS
STATIC ELECTRIC AND MAGNETIC FIELDS
STATIC ELECTRIC AND MAGNETIC FIELDS
STATIC ELECTRIC AND MAGNETIC FIELDS