Occupational Medicine Prof. Francesco S. Violante Noise, Ionizing and Non-ionizing Radiations,

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)


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


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


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)

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


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


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


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


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


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


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


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


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


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


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


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


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


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


Dose-effect relationship


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

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).


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


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


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.


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



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


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 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



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 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



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.


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


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 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


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

STUDIES

CEREBRAL TUMOURS

Yes • Hakansson 2002• Villeneuve 2002• Van Wijngaarden 2001

No • Klaebol 2004• Sorahan 2001


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


STATIC ELECTRIC AND MAGNETIC FIELDS


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, etc


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Occupational Medicine Prof. Francesco S. Violante Noise, Ionizing and Non-ionizing Radiations,

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