预防医学教学课件：Physical Hazards & Their Effects (2)

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1、Physical Hazards&Their Effects Physical factors abnormal meteoric condition abnormal atmospheric pressurenoise and vibration ionizing radiation non-ionizing radiation Disorders due to heat(heliosis)Noise-induced deafness Disorders due to vibrationPhysical Hazards&Their Effects（一）基本概念（一）基本概念1.声音（声音（s

2、ound）广义：凡是使人感到厌烦或不需要的声音广义：凡是使人感到厌烦或不需要的声音狭义：生产性噪声（狭义：生产性噪声（productive noise）噪声（噪声（noise）次声次声超声超声声频（声频（20 20000 Hz）Noise-induced deafness声压声压/声强增至使人耳刚能感到疼痛感觉的值声强增至使人耳刚能感到疼痛感觉的值1000Hz纯音的痛阈声压为纯音的痛阈声压为20Pa（一）基本概念（一）基本概念3.声压声压由于声波振动而对介质产生的压力（由于声波振动而对介质产生的压力（1 Pa=1N/m2）4.听阈听阈使人耳刚能引起音响感觉的声压使人耳刚能引起音响感觉的声压/声

3、强声强1000Hz纯音的听阈声压为纯音的听阈声压为20 Pa5.痛阈痛阈6.声压级（声压级（LP）为便于计算和测量而提出的概念为便于计算和测量而提出的概念 LP=20 Log （dB）PP0LP：声压级（：声压级（dB）P：被测声压：被测声压 P0：基准声压（：基准声压（1000Hz纯音听阈声压纯音听阈声压=20 Pa）（一）基本概念（一）基本概念Relative intensity of common noisesNoise level(dB)Environmental sourceHuman speech140Air raid siren 120Jet takeoff110Riveting

4、 machine 100Pneumatic hammer Shouting in ear 90Subway train Shouting at a distance of 2 ft80Vacuum cleaner 70Freeway traffic Loud conversation 50Road traffic Normal conversation 30Library Soft whisper 20Broadcasting studio 0Threshold of hearing（一）基本概念（一）基本概念（1）响度：）响度：人耳对声音强弱的主观感觉人耳对声音强弱的主观感觉7.响度和响度级

5、（响度和响度级（LP）由于能量强度相同而频率不同的声音在人耳产生的音响感觉由于能量强度相同而频率不同的声音在人耳产生的音响感觉存在差异，为使不同频率的声音产生的音响感觉能相互比较，存在差异，为使不同频率的声音产生的音响感觉能相互比较，以以1000Hz的标准声产生的音响感觉为基准，与之产生同样音的标准声产生的音响感觉为基准，与之产生同样音响感觉声音的响度均以此标准音的声压级表示，称为响度级响感觉声音的响度均以此标准音的声压级表示，称为响度级单位：方（单位：方（phon）（2）响度级：）响度级：经频率计权网络滤波后所测得的声压级经频率计权网络滤波后所测得的声压级A声级：声级：dB（A）40phon

6、 噪声卫生学评价指标（噪声卫生学评价指标（ISO）B声级：声级：dB（B）70phonC声级：声级：dB（C）100phon 总声级总声级8.声级声级（一）基本概念（一）基本概念2.Categories of productive noise Aerodynamic noise:air pump,steam whistle Mechanic noise:loom,bulldozer,ball mill Electromagnetic noise:electromotor,transformerExposed to productive noise(1)auditory system 3.Hea

7、lth effects(2)other systems Temporary threshold shift(TTS)Permanent threshold shift(PTS)Noise-induced deafnessExplosive deafness 3.Health effectsPermanent threshold shift(PTS)Prolonged repetitive exposure to hazardous noise causes irreversible decrease of hearing sensitivity.It is the result from ir

8、reversible damage to hair cells.Temporary threshold shift(TTS)Exposure to loud noise frequently causes a slight decrease in hearing sensitivity,lasting for some minutes to several hours.It is the result from reversible injury to hair cells.Auditory adaptation(15dB,several minutes)Auditory fatigue(15

9、30dB,ten hours or more)Permanent threshold shift(PTS)(Irreversible)Temporary threshold shift(TTS)(reversible)3.Health effectsHearing impairment(High frequency,30006000Hz)Noise-induced deafness(Talk frequency,5002000Hz)That is one of the occupationaldiseases which is caused by long exposure to produc

10、tive noise.Noise-induced deafness 3.Health effectsExplosive deafnessThe intensive explosion causes the serious damage in audition system,such as eardrum rupture,ossicular chain damage,as well as inner ear injuries.Tinnitus,earache,nausea,dizziness,hearing loss,deafness3.Health effects4.DiagnosisMild

11、 damageModerate damageSevere damageNoise-induced deafness2640dB4155dB5670dB7190dB5.Influential factorIntensity and frequencyExposure duration characteristics of noisesensibility and personal protectionothers 6.Prevention Control or eliminate the noise source Reduce noise spread Personal protection h

12、ygienic standard(85dB)Vibration diseaseDisorders due to vibration1.whole-body vibration tuck and bus drivers,forklift drivers,heavy equipment operators,miners 2.Hand-arm vibration(segmental vibration)tools powered by wind or by electricity,such as power saws,grinders,pneumatic drills,jackhammers;rev

13、olving tools Hand-arm vibration disease(Segmental vibration disease)Opportunities of exposure Tools powered by wind Tools powered by electricity Revolving toolsMechanism of vibration diseaseVibrationBlood vesselHyperplasia Thickening FibrosisStenosisIschemiaWhite fingerWhite fingerBlood vesselThicke

14、ning HyperplasiaClinical manifestation nerveBlood vesselMusclesBoneDiagnosis Observation subject Mild segmental vibration disease Moderate segmental vibration disease Severe segmental vibration diseaseTest of nail pressed Test of sensory Treatment Exercise therapy:Physical therapy:Nutrition therapy:

15、Medicine therapy:Surgical therapy:Whole body vibrationMotion sicknessNauseaPallorSweatingvomiting or retchingshockInfluential factorFrequency and amplitude of vibrationAcceleration of vibrationExposure durationPosition and operationEnvironmental condition Prevention Eliminate or reduce vibration Lim

16、it working hours Improve environmental conditions Personal protection Health care Occupational education and training Occupational standard Occupational Tumor Occupational Tumor*Tumors which induced by long exposure to occupational carcinogensOccupational tumorsOccupational carcinogen Factors which

17、can induce occupational tumors,including chemical,physical and biological factorsPrescribed occupational tumors*Asbestos lung cancer,mesothelioma Chloromethyl ethers lung cancer Chromate lung cancer Matters released from cokery lung cancer Arsenic lung cancer,skin cancer Benzidine occupational bladd

18、er cancer Vinyl chloride hepatic angiosarcoma Benzene leukemia Characteristics(1)Latent period Different occupational tumors have different latent periods Usually is 1225 years Onset earlier than non-occupational population(2)ThresholdPrecancerous lesions(hyperplasia,sclerosis)Tumor(3)Dose-response

19、relationship doseResponse(%)morbilitymortality(4)Liable site Sites exposed to occupational factors frequently or intensively Adjacent sites Sites far from the primary site Different sites induced by one factors Multiple tumors induced by one factors skinrespiratory system(5)Pathology type Pathology

20、type depend on the kind of carcinogen.Category Recognized carcinogens Suspected carcinogens Latent carcinogens1类：类：对对人人致癌性证据致癌性证据充分充分；2类：类：A组组:对对人人致癌性证据致癌性证据有限有限，但对，但对动物动物致癌性证据致癌性证据充分充分，B组组:对对人人致癌性证据致癌性证据有限有限，对，对动物动物致癌性证据也致癌性证据也不充分不充分；3类：类：现有证据未能对人类致癌性进行分级评价；现有证据未能对人类致癌性进行分级评价；4类：类：对人可能是非致癌物。对人可能是非致

21、癌物。IARC分类标准分类标准 Common occupational Tumor(1)Occupational tumor of Respiratory systemCrocidolite Length of service:over 10 years Smoking increase the incidence Lung cancer MesotheliomaCrocidolite Length of service:1540 yearsAsbestoslung cancer,mesothelioma(2)Occupational skin cancer The first tumor found in medical history Most tumors is induced by coal tar exposure (Polycyclic aromatic hydrocarbons)benzo(a)pyrene Precancerous lesions(3)occupational bladder cancer The length of latent period depends on the exposure intensity Smoking accelerate tumor onset Screening method:Hematuria