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I N THE NAME OF G OD Occupational carcinogens DR. M. Saraei.

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Presentation on theme: "I N THE NAME OF G OD Occupational carcinogens DR. M. Saraei."— Presentation transcript:

1 I N THE NAME OF G OD Occupational carcinogens DR. M. Saraei

2 O CCUPATIONAL CANCER 2-8%of all human cancers are due to occ. exposure to carcinogens. The most occ. cancers are completely preventable.

3 W HAT IS A CARCINOGEN ?  A carcinogen is an agent which is responsible for causing cancer.  Carcinogens may be chemical substances; physical agents, such as asbestos dust; or biological agents, such as certain viruses and bacteria  In the workplace, carcinogenic substances may be inhaled, absorbed through the skin or even ingested in some cases

4 E NVIRONMENTAL CARCINOGENS 80-90% of human cancers are environmental. 30% of cancer deaths are attributable to tobacco use, 35% to diet and less than 5% each to alcohol, occ. exposure, pollution, radiation and sexual behavior.


6 H OW BIG A PROBLEM IS OCC. C ANCER ? Mean about 2-8% of cancers associated to work place exposures. In U.S these would represent new cases of cancer each year.

7 I S THERE A SAFE LEVEL FOR EXPOSURE TO CARCINOGENS ? The carcinogen directly affects the cell,there is no safe level of exposure A safe level of exposure is difficult to define. Uncertainty about safe levels of exposure to carcinogens has resulted in the principle of keeping exposure. “as low as reasonable achievable “

8 C AN YOU PREVENT CANCER BY REDUCING A PERSON ' S EXPOSURE TO A CARCINOGEN ? In general the higher the exposure a person has to a carcinogen, the more chance they have of developing cancer. Anything that can be done to reduce a person's exposure to a carcinogen will reduce their chances of developing cancer

9 D OES SMOKING CAUSE CANCER IN THE WORKPLACE ? As well as being a significant cause of cancer in its own right, smoking has been shown to have a synergistic effect with some other carcinogens. Asbestos and smoking (multiplative) radon, arsenic, aromatic amines and crystalline silica.

10 P ROTECTING E MPLOYEES AGAINST E XPOSURE TO C ARCINOGENS Research and testing Information and training Exposure control Elimination Substitution Engineering controls Personal protective equipment

11 H ISTORY 1775: Scrotal cancer ; chimney sweeps 1895: Bladder cancer; aromatic amines 1934: Lung cancer; asbestos 1962: Lung cancer(S.C.C); chloromethylethers 1974: Liver angiosarcoma; vinyl chloride

12 CARCINOGENESIS  Stages in tumor development : - Initiation - Promotion - Progression - Metastasis

13 INITIATION Initial stage to result from irreversible change in the genetic material (DNA) of the cell. This alteration may occur spontaneously or may be caused by factors such as radiation, nickel, asbestos, beryllium, ……

14 P ROMOTION Facilitate tumor development (proliferation of the altered cell) For example: estrogen, high salt, high fat, cigarette smoke, testosterone,….

15 PROGRESSION Involve those change necessary for the development of a malignant tumor. Progression to malignancy like initiation is triggered by genetic events.

16 D ISTINCTION BETWEEN INITIATORS & PROMOTERS Initiators -Genotoxic - Carcinogenic alone - Irreversible reaction -Threshold dose -Single exposure may be sufficient to induce cancer

17 D ISTINCTION BETWEEN INITIATORS & PROMOTERS Promoters - Epigenic -Not Carcinogenic alone -Reversible effect -Threshold probably exist - Repeated exposures required

18 L ATENCY PERIOD Interval between first exposure to the agent and first clinical manifestation of the tumor. This length varies from 4-6 years to 40 years.

19 M ETHODS IN ASSESSMENT OF CHEMICAL CARCINOGENICITY Epidemiologic studies. Experimental studies in animals. Short-term test. Molecular biology

20 EPIDEMIOLOGIC STUDIES C RITERIA FOR C AUSALITY STRENGTH – magnitude of relative risk CONSISTENCY – reported in multiple studies with different circumstances BIOLOGICAL GRADIENT – dose-response validity BIOLOGICAL PLAUSIBILITY – reasonable T EMPORALITY – cause precedes effect

21 A NIMAL S TUDIES IARC requirements Good qualitative predictor Not-so-good quantitative predictor Limitations High dose exposure is needed in order to detect significance Different metabolism Different routes of administration

22 S HORT - T ERM T ESTS Provide evidence of mutagenicity Ames test, sister-chromatin exchange, DNA repair Quicker results, less expensive Correlation of results with animals/humans imperfect

23 M OLECULAR B IOLOGY  Allows assessment of exposure and possible early health effects:  Measure enzyme activity of the cytochrome P450 monooxygenase class  Measurement of DNA or Protein adducts  Measurement of protein products in the urine and serum

24 IARC CLASSIFICATION OF CARCINOGENS Class I: Human carcinogen based on sufficient positive evidence (beryllium, cadmium, strong inorganic acid mist containing sulfuric acid). Class II: Sufficient animal evidence but limited or inadequate human evidence (probable or possible carcinogens). Ex: acrylonitrile, benzidine, MMVF. Class III: Agents that are not classified. Class IV: Agents that are probably not carcinogen to humans.

25 GROUP 1: CARCINOGENIC TO HUMANS Agents and groups of agents Such as: Arsenic and arsenic compounds Asbestos Benzene Cadmium and cadmium compounds Formaldehyde Coal-tar pitches -Mixtures Soots Tobacco, smokeless Wood dust … Exposure circumstances: Boot and shoe manufacture and repair Chimney sweeping Iron and steel foundring Isopropyl alcohol manufacture (strong-acid process) Tobacco smoking and tobacco smoke

26 GROUP 2A: PROBABLY CARCINOGENIC TO HUMANS Agents and groups of agents Such as: Androgenic (anabolic) steroids Lead compounds( inorganic) Ultraviolet radiation Diesel engine exhaust High-temperature frying( emissions) Non-arsenical insecticides… Exposure circumstances: Art glass, glass containers and pressed ware (manufacture of) Carbon electrode manufacture Cobalt metal with tungsten carbide Hairdresser or barber (occupational exposure as a) Petroleum refining (occupational exposures in) Shiftwork that involves circadian disruption Sunlamps and sunbeds (use of)

27 GROUP 2B: POSSIBLY CARCINOGENIC TO HUMANS Agents and groups of agents Acetaldehyde Chloroform Cobalt and cobalt compounds DDT Magnetic fields (extremely low-frequency) Naphthalene Nickel, metallic and alloys Coffee -Mixtures Engine exhaust, gasoline Fuel oils, residual (heavy) Welding fumes … Exposure circumstances: Carpentry and joinery Cobalt metal without tungsten carbide Dry cleaning (occupational exposures in) Printing processes (occupational exposures in) Textile manufacturing industry (work in)

28 GROUP 3: NOT CLASSIFIABLE AS TO CARCINOGENICITY TO HUMANS Agents and groups of agents Caffeine Cholesterol Coal dust Ethylene Mercury and inorganic mercury compounds Talc Mineral oils, highly-refined - Mixtures Petroleum solvents Printing inks Tea… Exposure circumstances: Flat-glass and specialty glass (manufacture of) Hair colouring products (personal use of) Leather goods manufacture Lumber and sawmill industries Paint manufacture (occupational exposure in)

29 GROUP 4: PROBABLY NOT CARCINOGENIC TO HUMANS This list contains all agents evaluated as being in Group 4 to date.

30 بیماری هایی قابل غربالگری هستند که : - سیر بیماری کاملا شناخته شده باشد. - بیماری، مرحله نهفته طولانی داشته باشد. - در مرحله نهفته، درمان موثر داشته باشد. - بار بیماری در جامعه قابل توجه باشد.( بیماری، شایع باشد ) - بیماری، موربیدیتی و مورتالیتی قابل توجه داشته باشد. - تستها و آزمایشاتی که جهت انجام غربالگری آن بیماری ها بکار می روند باید مناسب باشند.

31 تستها و آزمایشاتی که جهت انجام غربالگری بیماری ها بکار می روند باید شرایط و معیارهایی به شرح زیر داشته باشند : 1- بتوانند بیماری را در مرحله نهفته و قابل برگشت و قابل علاج کشف کند. 2- حساسیت و ویژگی بالا داشته باشد. 3- در دسترس و ارزان باشد. 4- بیمار پذیرش انجام آن را داشته باشد. 5- مبتنی بر شواهد علمی و دقیق باشد.

32 M EDICAL SURVEILLANCE Surveillance is only effective if: 1. It detects pre-malignant abnormality or tumors at an early stage. 2. There is an effective intervention that reduce morbidity and mortality. 3. The screening test is sensitive and easy to perform.

33 MEASURES THAT REDUCE EXPOSURE  Producing and carrying of carcinogens inside a closed system  Measuring exposures in working atmosphere and worker ’ s biological system  Well working ventilation system if happens an emergency  PPE  Rotation  Prohibiting of smoking cigarettes

34 O CCUPATIONS AT RISK OF LUNG CANCER Asbestos (A. miners, insulation and filter material production, shipyard workers) Radon (Uranium mining, domestic exposure) CME (chemical production workers) PAHs (Rubber workers, roofers, Al. reduction workers) Chromium (chromate production). Nickel (mining) Arsenic (arsenical pesticide production and use, copper, lead, zinc smelting)

35 C LINICAL PRESENTATIONS 1. Constitutional symptoms 2. Primary Tumor 3. Intrathoracic spread 4. Asymptomatic 5. Extrathoracic spread 6. Paraneoplastic symptoms


37 P RIMARY T UMOR (30%) Cough (75%) SOB (60%) Chest discomfort (50%) Hemoptysis (35%)

38 Cough - endobronchial mass or post-obstructive pneumonia –esp concerned if new onset/changed character SOB –tumor occluding the airway Chest discomfort –intermittent/aching Hemoptysis -acute bronchitis is the common cause of hemoptysis, lung CA should always be suspected in pts >40

39 I NTRATHORACIC S PREAD (40%) Recurrent laryngeal nerve paralysis Phrenic nerve paralysis Pancoast’s tumor Horner Syndrome Chest wall invasion Pleural effusion Esophageal compression Superior vena cava obstruction

40 E XTRATHORACIC S PREAD (30%) Bone metastasis bone pain, fracture Brain mets focal neurol deficits, seizures, confusion, personality change Liver mets Adrenal gland mets Spinal cord mets

41 C OMMENTS 1. Quitting tobacco use, or not starting at all 2. Take protective measures against cancer- causing chemicals at work

42 M ESOTHELIOMA Asbestos: - Asbestos miners. - Insulation and filter material production. - Construction workers. - Roofers. - Shipyard workers.

43 C ANCER OF THE N ASAL CAVITY & S INUSES Wood and other dusts - Furniture workers - Boot and shoe manufacturing Nickel - Nickel refinery worker Chromium - Chromate pigment manufacture Isopropyl alcohol, formaldehyde - Laboratory workers - Other industry

44 C ANCER OF THE L ARYNX Asbestos -asbestos miners -insulation and filter material production. -shipyard workers  Cigarette smoking and alcohol abuse are the primary etiologic factors. Mustard gas Cutting oil Nickel Wood dust Isopropyl alcohol

45 B LADDER CANCER Naphthylamine - Textile workers( dye/pigment manufacturing) Benzidine (pigment manufacturing ) Toludine (painters) Benzidine- derived azo dyes -Chemical workers Phenacetin- containing compounds - petroleum workers. -Hairdressers.

46 H EMATOLOGIC C ANCERS - Ionizing radiation - Benzene - Ethylene oxide - Agricultural work - Cytotoxic drugs

47 L IVER Hepatitis B&C, alcohol, aflatoxins Solvents associated with hepatic fibrosis Hepatic Angiosarcoma Vinyl chloride Thorotrast Arsenic

48 S KIN CANCER UV radiation -Outdoor workers. PAHs -pigment industry workers. -Coal tar workers (fuel production) Arsenic -Arsenical pesticide production and use. -Copper, lead, zinc smelting. Ionizing radiation -Uranium miners. -Health workers.

49 A CTINIC KERATOSIS  A pre-cancerous condition of thick, scaly patches of sun-damaged skin. Also referred to as solar or senile keratosis.

50 B ASAL C ELL C ARCINOMA Three common presentations: Small, smooth, pale, or waxy shiny lump Firm, red lump A lump that bleeds or develops a crust

51 S QUAMOUS C ELL C ARCINOMA  Similar in appearance to actinic keratosis and basal cell carcinoma.

52 M ELANOMA ( THE A-B-C AND D S ) A symmetry -- The shape of one half does not match the other.

53 M ELANOMA ( THE A-B-C AND D S ) B order -- The edges are often ragged, notched, blurred, or irregular in outline; the pigment may spread into the surrounding skin.

54 M ELANOMA ( THE A-B-C AND D S ) C olor -- The color is uneven. Shades of black, brown, and tan may be present. Areas of white, grey, red, pink, or blue also may be seen.

55 M ELANOMA ( THE A-B-C AND D S ) D iameter -- There is a change in size, usually an increase. Melanomas are usually larger than the eraser of a pencil (5 mm or 1/4 inch).

56 W OMEN 25% increase in lung cancer among production workers Breast cancer tissue had 50-60% higher levels of DDT and PCB’s 38% Breast cancer increase in electrical workers (217% for telephone installers)

57 R OOFERS & ASPHALT WORKERS Stomach cancer bladder cancer skin cancer leukemia

58 F IREFIGHTERS leukemia nonHodgkin's lymphoma multiple myeloma cancers of the brain, urinary bladder, and possibly from cancer of the prostate, large intestine, and skin.

59 C ONSTRUCTION WORKERS Lung larynx oropharyngeal and nasal cancers mesothelioma

60 D RY CLEANING USING PERCHLOROETHANE 23% increase among 20-year workers esophogeal, intestinal, bladder

61 C UTTING FLUID EXPOSURE 85% increase of laryngeal cancer (also stomach)


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