Occupational Health

Nicola Magnavita

• Publisher: EDUCatt
• Year: 2019
• ISBN:
  9788893354967
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

My collaboration with the Institute for the Right to Study of the Catholic University began in 1971, December. As sometimes happens, the beginning was a very frank discussion with the Director, dr. Dino Barbavara, who had suspended the provision of the presalario to a student because the income received by his parents was 36 thousand lire a month, and not 36,500 lire as the Director would have expected. It seemed to me that the difference between 36,500 and 36,000 lire (i.e., between 18.85 and 18.59 euros) of monthly pension income for a family of three was irrelevant and that suspending the presalario was a very serious decision, which would certainly prevent the needy student to continue studying. But dr. Barbavara objected that the difference stemmed from the failure to receive family allowances and that, therefore, this could have concealed other income.
After this first heated discussion, I learned to appreciate the extreme professional scruple, honesty and mitteleuropean precision of dr. Barbavara and I began to collaborate with the Opera Universitaria in the local management of activities in favor of the right to study. In 1975, I was elected by Rome with more than 1,500 votes in favor and 7 null as student representative at the University Opera Board, and in 1976 I was re-elected to the same office by collecting votes also in Milan, Brescia and Piacenza. I thus had the honor and the burden of working as one of the 12 members of the University Opera Board of Directors under the Presidence of prof. Bolognesi, underwriting a budget of over 6 billion lire a year, entirely spent to realize the possibility of studying for everyone.
I approved, among other things, the idea of publishing books at a political price, and I was able to contribute in subsequent years to the publications of EDUCATT, with many volumes, when I was a representative of researchers in the Board of the ISU.
Now that I became the Director of the School of Specialization in Occupational Medicine at the Catholic University, I tried my hardest job, writing a booklet with my bad English.
This book is not a manual of occupational health, but only a help for students of Medicine & Surgery, who would like to allow them not to take notes during the lessons or not to photograph the powerpoint presentations with the phone, as it happens very often. I ask them the patience to bear the inevitable language errors, and indeed to point them out, so that this manuscript can become, in the future, an even more useful instrument. And I hope these lessons are the stimulus for studying the occupational medicine not only on this booklet, but on the treatises and journals of this magnificent discipline.
I would like to thank Dr. Francesco Chirico for his valuable work as proofreader of this book.

Chapter 4

INDUSTRIAL HYGIENE

4.1 Introduction

Workers can be exposed to a variety of health hazards on job site, including chemical, biological, physical, ergonomic agents.

If you are not following good hygiene practices, worker’s family members can be exposed to the same risk factors, as well. It is necessary to protect yourself and your family by knowing which health hazards may be present at your jobsite and take appropriate actions for exposure control.

What is Industrial Hygiene? Industrial hygiene is the science of anticipating, recognizing, evaluating, and controlling workplace conditions that may cause workers’ injury or illness. Industrial hygienists use environmental monitoring and analytical methods to detect the extent of worker exposure and employ engineering, work practice controls, and other methods to control potential health hazards.

OSHA and industrial hygienists are interrelated.With the Occupational Safety and Health Act of 1970, in US the Congress created the Occupational Safety and Health Administration (OSHA) to assure safe and healthful working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education and assistance. OSHA is part of the United States Department of Labor and OSH Act covers most private sector employers and their workers, in addition to some public sector employers and workers in the 50 states and certain territories and jurisdictions under federal authority.

Under the Act, OSHA develops and sets mandatory occupational safety and health requirements applicable to the more than 6 million workplaces in the USA.

Industrial hygienists also play a major role in developing and issuing OSHA standards to protect workers from health hazards associated with toxic chemicals, biological hazards, and harmful physical agents. Industrial hygienists analyze, identify, and measure workplace hazards or stressors that can cause sickness, impaired health, or significant discomfort in workers through chemical, physical, ergonomic, or biological exposures.

To be effective in recognizing and evaluating on-the-job hazards and recommending controls, industrial hygienists must be familiar with the hazards’ characteristics. Major job risks can include air contaminants, and chemical, biological, physical, and ergonomic hazards.

Some hazards to which workers can be frequently exposed at workplace inlude the following: Chemical hazards such as solids, liquids, gases and vapors, and aerosols; biological hazards such as microorganisms, insects, animals, soil, plants, water, and blood; physical hazards such as noise, vibrations, electro-magnetic fields, temperature extremes, and radiation; and ergonomic hazards including load lifting, holding, pushing, walking, and reaching.

4.2 Chemical Hazards

Harmful chemical compounds in the form of solids, liquids, gases, mists, dusts, fumes, and vapors exert toxic effects by inhalation (breathing), absorption (through direct contact with the skin), or ingestion (eating or drinking). Airborne chemical hazards exist as concentrations of mists, vapors, gases, fumes, or solids. Some are toxic through inhalation and some of them irritate the skin on contact; some can be toxic by absorption through the skin or through ingestion, and some are corrosive to human tissues.

The degree of risk faced by workers due to the exposure to any given substance depends on the nature and potency of the toxic effects and the magnitude and duration of exposure. Relevant information about risk to workers from chemical hazards and subsequent preventative measures can be obtained from the Safety Data Sheet (SDS) that OSHA’S Hazard Communication Standard and European Directives in Europe require be supplied by the manufacturer or importer to the purchaser of all hazardous materials. The SDS is a summary of the most important health, safety, and toxicological information about the chemical or the mixture’s ingredients. Other provisions of the Hazard Communication Standard require that all containers of hazardous substances in the workplace have appropriate warning and identification labels. SDS(s) are not required for asbestos, silica, lead, or and other non-manufactured chemicals, but they are recommended. Some unintended by-products of production may be hazardous, but may not be included in an SDS. For example, Carbon Monoxide (CO) is a byproduct of combustion. You may have an SDS on a gas being used, but not on the CO that is emitted. In other words, safety data sheets include information about the properties of the substance or mixture, its hazards and instructions for handling, disposal and transport and also first-aid, fire-fighting and exposure control measures. The format and content of the safety data sheets are specified in reach, which is a regulation of the European Union, adopted to improve the protection of human health and the environment from the risks that can be posed by chemicals, while enhancing the competitiveness of the EU chemicals industry.

Effects of chemical exposures may pose risk of fire and explosion hazards, as well as corrosive hazards; they may put workers at risk of developing health problems such as heart ailments, central nervous system damage, kidney and liver damage, lung damage, sterility, cancer, burns, or rashes. There are about 190,000 illnesses caused by chemical exposure annually in the US, and 50,000 deaths caused by chemical exposure annually in the US. Burns and rashes are examples of local impacts of chemical exposure. They may be reversible or irreversible. Other health problems may be the consequences of systemic impacts of chemical exposure, as such likely irreversible.

Common ways workers encounter chemical hazards are inhalation; for example, during grinding/cutting/sawing/sanding/etc., painting/spraying, cleaning, processing/manufacturing/reacting, laboratory, welding fumes, nearby construction operations there might be exposure to lead, asbestos or silica dust.

Ingestion may be a cause a cross contamination (food/water/cigarettes), or mucus contamination (particulates). Absorption (skin/eye) may determine absorption for all potential airborne exposure (for example, exposure to acids/bases/toxics in laboratory, as well as to cleaning/solvents, and product handling).

Injection may be the gateway for pressurized chemicals (hydraulics); industrial hole punching/injection processing; and sharps (needles).

Warning signs of potential chemical exposure are presence of dust, mist, smoke in the air, accumulation of particulates (dust) on surfaces, unusual tastes and/or smells, and eye, nose, throat, upper respiratory, and/or skin irritation.

Examples of symptoms due to chemical exposure are the following: Eye, nose, throat, upper respiratory tract, and skin irritation, flu-like symptoms, difficulty breathing, fatigue, loss of coordination, memory difficulties, sleeplessness, mental confusion, and other chronic effects, all depending on extent and duration of exposure. However, it should be noted that many chemicals don’t create an obvious sign or symptom of exposure, and that is why air monitoring is necessary.

For some chemical hazards our primary concern is from acute exposures (e.g., carbon monoxide (CO) leading to CO poisoning), while some have primarily chronic exposure concerns (e.g., years of silica dust exposure leading to silicosis). Some chemical exposures can have both acute and chronic exposure concerns, like benzene – which can cause narcosis from short-term exposure, and cancer from chronic exposure.

Almost anything – even water – can cause illness if taken in a large enough quantity. On the other hand, most hazardous chemicals can be used safely if the exposure is limited to the slightest exposure.

Hazard communications is essential and according to Standards on chemical risks, it should be carried out by hazard symbols and pictograms. For instance, exclamation mark states the following effects: Skin irritant, acute toxicity, narcotic effects, respiratory tract irritant. Skull and crossbones indicates acute toxicity (fatal or toxic). Health Hazard means a carcinogen, mutagenicity, reproductive toxicity effect or a respiratory sensitizer, target organ toxicity and aspiration toxicity effect.

Toxic effects depend on dose, that is given by the product of concentration (amount) and duration of exposure (time). Concentration is the amount of a given substance in a stated unit of measure. When conducting air monitoring we are determining the amount of toxin per a unit of time. Time is considered by some threshold levels such as – the OSHA Time Weighted Average (TWA) and the Permissible Exposure Limits (PEL), which are based on 8-hour time limit. Then, there is the – OSHA Ceiling limit PELs that are instantaneous threshold values. A toxic chemical may cause local effects, systemic effects, or both. For example, if ammonia gas is inhaled, it quickly irritates the lining of the respiratory tract (nose, throat, and lungs). Almost no ammonia passes from the lungs into the blood. Since damage is caused only at the point of initial contact, ammonia is said to exert a local effect. An epoxy resin is an example of a substance with local effects on the skin. On the other hand, if liquid phenol contacts the skin, it irritates the skin at the point of contact (a local effect) and can also be absorbed through the skin, damaging the liver and kidneys (systemic effects).

Most chemicals that produce toxicity do not cause a similar degree of toxicity in all organs but usually produce the major toxicity to one or two organs, they are the “target organs”. “Local Effects” are sometimes referred to as “Direct Effects”: They are irritation (dryness, redness, cracking) – fiberglass, corrosion (chemical burn) – acid, and Upper Respiratory Track infection – inhaling particles.

Substances may have systemic effects when they are absorbed into the bloodstream and are then carried to other parts of the body, where they cause their effect. These types of substances usually cause their effect in one or two target body organs. Whether or not these effects occur depends on the concentration of the chemical in the target organ. The concentration in the organ is dependent on the absorption, distribution, biotransformation, and excretion of the substance.

Hepatotoxins cause liver damage (carbon tetrachloride, nitrosamines); nephrotoxins cause kidney damage (uranium, halogenated hydrocarbons); neurotoxins cause nerve damage (mercury, lead, carbon disulphide); ematotoxins cause blood system damage (carbon monoxide, cyanides); anesthetics depress nervous system (hydrocarbons, propane, isopropyl ethers).

Many factors affect exposures, like the exposure route: Some chemicals may be highly toxic by one route but not by others. Two major reasons are the differences in absorption and distribution within the body. For example, ingested chemicals, when absorbed from the intestine, distribute first to the liver and may be immediately detoxified. Inhaled toxicants immediately enter the general blood circulation and can distribute throughout the body prior to being detoxified by the liver. Frequently there are different target organs for different routes of exposure.

Age may be important in determining the response to toxicants. Some chemicals are more toxic to infants or the elderly than to young adults. For example, children may more readily absorb lead than adults.

Race is another important factor in chemical response. For example, Asian men experience much weaker effects of codeine for same exposure than Caucasian men. The ability to be absorbed is essential for systemic toxicity to occur. Some chemicals are easily absorbed and others poorly absorbed. For example, nearly all alcohols are easily absorbed when ingested, whereas there is virtually no absorption for most polymers. For example, ethanol is readily absorbed from the gastrointestinal tract but poorly absorbed through the skin, organic mercury is readily absorbed from the gastrointestinal tract, whereas inorganic lead sulfate is not.

Metabolism, also known as biotransformation, is the changing from one configuration to another, which is a major factor in determining toxicity. There are two types of metabolism – detoxification and bioactivation. Detoxification is the process by which a chemical is converted to a less toxic form. Bioactivation is the process by which a chemical may be converted to more reactive or toxic forms.

The distribution of chemicals and their subparts throughout the body determines the sites where toxicity occurs. A major factor of whether or not a chemical will damage cells is its lipid solubility (lipids cannot be dissolved in water). If a chemical is lipid-soluble it readily penetrates cells. Many chemicals are stored in the body. Fat tissue, liver, kidney, and bone are the most common storage depots. Blood serves as the main avenue for distribution. Lymph also distributes some materials.

The site and rate of excretion is another major factor affecting the toxicity of a chemical. The kidney is the primary excretory organ, followed by the gastrointestinal tract, and the lungs (for gases). Some chemicals may also be excreted in sweat, tears, and milk.

A large volume of blood is filtered through the kidney. Lipid-soluble toxicants are reabsorbed and concentrated in kidney cells. Impaired kidney function causes slower elimination of toxicants and increases their toxic potential. For example, lead takes months to years to excrete where excess water can excrete in hours. There are interactions between multiple chemicals, which may result in several effects.

The “Additive effect” occurs when the combined effect of two or more chemicals is equal to the sum of the effect of each agent given alone.

Example: coal dust + silica dust = dust laden lungs.

The “Synergistic effect” is the situation where the combined effect of two chemicals is much greater than the sum of the effects of each agent given alone.

Example: asbestos + cigarette give a greater chance of lung cancer.

The “Potentiation effect” results when one substance that does not normally have a toxic effect is added to another chemical, making the second chemical much more toxic.

Example: isopropyl alcohol (no effect in the liver) + carbon tetrachloride, greatly increase the toxicity of carbon tetrachloride.

With regard to the “Antagonistic effect”, antagonism is the opposite of synergism and is the situation where the combined effect of two or more compounds is less toxic than the individual effects.

Example: Methanol + Ethanol = ethanol is antidote for methanol poisoning.

With respect of preventive measures, there is a hierarchy of control to be followed by employer.

The hierarchy of control is the following:

1) Eliminate the hazard (if possible);

2) Substitute hazard with safer alternative (if possible);

3) Engineer controls: Ventilation/wetting/guarding/etc;

4) Administrative: Giving breaks/cycling work to minimize exposures/training;

5) PPE: Respirators/hearing protections/face shields/gloves/boots/etc., and health surveillance.

Establishing a chemical management system that goes beyond simply complying with OSHA standards or other Regulations and strives to reduce or eliminate chemical hazards at the source through informed substitution best protects workers. Transitioning to safer alternatives can be a complex undertaking, but a variety of existing resources make it easier. Prevention has many benefits, including: Cost Savings – Reduce expenses and future risks. Efficiency – Improve performance. Industry Leadership – Invest in innovation to stay competitive. Corporate Stewardship – Advance socially responsible practices.

Engineering controls include eliminating toxic chemicals and replacing harmful toxic materials with less hazardous ones, enclosing work processes or confining work operations, and installing general and local ventilation systems. For example, replacing transfer belts with screw augers on sand movers used in hydraulic fracturing will help contain sand and reduce dust release (lowering exposure to silica).

Work practice controls alter the way in which a task is performed. Some fundamental and easily implemented work practice controls include: (1) Following proper procedures that minimize exposures while operating production and control equipment; (2) inspecting and maintaining process and control equipment on a regular basis; (3) implementing good house-keeping procedures; (4) providing good supervision and (5) mandating that eating, drinking, smoking, chewing tobacco or gum, and applying co...

Table of contents

• Preface
• OCCUPATIONAL HEALTH,HISTORY AND PRINCIPLES
• OCCUPATIONAL HEALTH SURVEILLANCE
• MEDICAL SURVEILLANCE IN PRACTICE
• INDUSTRIAL HYGIENE
• HAZARDOUS WORKERS FOR THIRD PARTIES
• BIOLOGICAL RISK.BLOODBORNE PATHOGENS
• ERGONOMICS
• ENVIRONMENTAL COMPLAINTSAND AIR QUALITY CONCERNS
• OCCUPATIONAL LUNG DISEASE
• SILICA
• LEAD
• WORK-RELATED STRESS
• PRACTICAL ACTIVITIES – MEDICAL INSPECTION OF THE WORKPLACE
• MEDICAL EXAMINATION.HOW TO VISIT A FUTURE DOCTOR
• DATA COLLECTION: THE QUESTIONNAIRES
• WHY IS THE RELATIONSHIP BETWEEN HEALTH AND WORK SO IMPORTANT FOR THE PATIENT CARE?