Chemical Exposure in the Workplace

General Definitions

1.1. Matter: Everything that has mass and occupies space is matter, and chemistry is a positive scientific discipline that examines chemical and material transformations. All matter can fundamentally exist, at least in principle, in three forms: solid, liquid, and gas. Solids are structures with definite and precise shapes. Liquids are less rigid in structure than solids and are fluid, taking on the shape of the container they occupy. Like liquids, gases are also amorphous fluids and tend to fill the volume of the environment they occupy, but unlike them, they are considered to expand without limits. Additionally, the expansion constant is the same for all gases.

1.2. Chemical Substance:

Any element, compound, or mixture found in nature, produced, arising during any process or as waste, or accidentally formed.

1.3. Hazardous Chemical Substance

1.3.1. Substances possessing one or more of the following properties: explosive, oxidising, extremely flammable, highly flammable, flammable, very toxic, toxic, harmful, corrosive, irritant, allergenic, carcinogenic, mutagenic, toxic to reproduction, and hazardous to the environment, 1.3.2. Substances that, while not falling into the classifications mentioned above, may pose a risk to workers' health and safety due to their chemical, physico-chemical, or toxicological properties and the manner of their use or presence in the workplace, 1.3.1. Substances for which occupational exposure limit values have been established.

1.4. Hazard:

The potential to cause harm or damage to a worker or workplace, whether present in the workplace or arising from external sources [1].

1.5. Risk:

The likelihood of loss, injury, or other harmful consequence resulting from a hazard [1].

1.6. Work Accident:

An occurrence in the workplace or resulting from the conduct of work that causes death or renders the body or mind permanently or temporarily disabled is called a work accident.

1.7. Near Miss:

An occurrence in the workplace that has the potential to cause harm to a worker, workplace, or work equipment but does not cause harm. For example, a brick that falls from scaffolding but does not strike anyone.

1.8. Risk Assessment:

Work that must be undertaken for the purpose of identifying hazards present in or external to the workplace, analysing and ranking the factors that lead to these hazards becoming risks and the risks arising from these hazards, and determining control measures.

1.9. Prevention:

All measures planned and taken to eliminate or reduce risks related to occupational health and safety at all stages of work conducted in the workplace.

1.10. Explosive Substance:

Substances in solid, liquid, paste, or gelatinous form that can undergo exothermic reaction with rapid gas release even without atmospheric oxygen and/or, when partly confined, spontaneously ignite with heating or ignite under specified test conditions, flashing rapidly.

1.11. Oxidising Substance:

Substances that cause significant exothermic reaction, particularly with combustible substances, in contact with other substances.

1.12. Extremely Flammable Substance:

Liquid substances with flash point below 0°C and boiling point below 15°C, or gaseous substances that can ignite in contact with air at room temperature and pressure.

1.13. Highly Flammable Substance

1.13.1. Substances that can heat up in contact with air at ambient temperature without energy application and consequently ignite, 1.13.2.Solids that ignite spontaneously on brief contact with a source of ignition and continue to burn after the source of ignition is removed; 1.13.3. Liquids with flash point below 21°C, 1.13.4. Substances that, in contact with water or humid air, emit extremely flammable gas in dangerous quantities.

1.14. Flammable Substance:

Liquid substances with flash point between 21°C and 55°C. 1.15. TLV: Threshold Limit Value. The average concentration of a chemical substance that can be worked with for 8 hours per day, 40 hours per week, without showing harmful effects to workers [2]. 1.16. TLV-TWA: Time Weighted Average. The time-weighted average chemical substance concentration that is considered not to harm the health of a worker exposed over a long period in a repeated manner to a chemical substance, working 8 hours per day, 40 hours per week [2]. 1.17. TLV-STEL: Short Time Exposure Limit. Generally intended for a period of 15 minutes and the concentration value that can cause harm to the worker such as irritation, untreatable long-term effects, or skin destruction. It is also the exposure concentration up to four times per day at intervals of 60 minutes per day, provided it does not exceed the daily TLV-TWA thresholds [2].

Figure 1. Example of a TWA graph.

1.18. TLV-C:

Ceiling. The threshold value that must not be exceeded, even instantaneously, during an 8-hour working day.

1.19. LD50:

Lethal Dose. Defines the median dose value of a toxic substance or radiation that causes the death of 50% of the test population. In toxicology, the LD50 value is used to demonstrate the acute toxicity of a chemical through ingestion or dermal absorption routes.

1.20. LC50:

Lethal Concentration. The median concentration value of a toxic substance or radiation that causes the death of 50% of the test population. In toxicology, the LC50 value is used to demonstrate the acute toxicity of a chemical through the inhalation route or in aqueous environments.

1.21. NOAEL:

No Observed Adverse Effect Level, the highest exposure level at which there is no biologically significant increase in the frequency or severity of adverse effects between the affected population and its appropriate control. Some effects may be observed at this level, but these are not considered adverse effects. NOAEL units are mg/kg bw/d or ppm for dermal absorption and ingestion routes. NOAEC is used for the inhalation route. The unit may be mg/L/6h/day. The higher the NOAEL or NOAEC values, the lower the systemic or chronic toxicity levels.

1.22. LOAEL:

Lowest Observed Adverse Effect Level, the lowest exposure level at which biologically significant increases in the frequency or severity of adverse effects are observed between the affected population and its appropriate control group. In some cases, only LOAEL can be obtained from repeated dose toxicity studies (28-day repeated dose toxicity study, 90-day repeated dose toxicity study, or chronic toxicity) and reproductive toxicity studies arising from study design. When NOAEL cannot be identified, LOAEL is also used to derive threshold safety exposure doses for humans, such as Derived No-Effect Level (DNEL). However, higher assessment factors should be applied.

1.23. Dose:

The concentration of the substance in its direction of effect. Dose = Concentration x Exposure duration

1.24. Response.

Any observable biological change in relation to the contaminant (response). 1.24.1 Must be measurable. 1.24.2. Observable adverse effect is not necessary. 1.24.3. Some minor effects may be beneficial, and adverse effects may be seen only at high doses or within critical periods.

1.25. Breathing Zone:

The half of a sphere with a radius of 10 cm, whose centre is the midpoint of the line connecting the person's ears, in front of the head [2].

1.26. Very Toxic Substances:

Substances that cause acute or chronic damage or death to human health when inhaled, ingested, or absorbed through the skin in very small quantities.

1.27. Toxic Substances:

Substances that cause acute or chronic damage or death to human health when inhaled, ingested, or absorbed through the skin in small quantities.

1.28. Harmful Substances:

Substances that cause acute or chronic damage or death to human health when inhaled, ingested, or absorbed through the skin.

1.29. Corrosive Substances:

Substances that can cause destruction of tissue upon contact with living tissue.

1.30. Irritant Substances:

Substances that are not classified as corrosive but can cause local erythema, eschar, or oedema on direct, brief, prolonged, or repeated contact with skin or mucous membrane.

1.31. Allergenic Substance (Allergens):

Substances with the property of showing excessive sensitivity when inhaled or penetrating the skin and subsequently causing manifest adverse effects upon exposure.

1.32. Carcinogenic Substances:

Substances that cause cancer or accelerate cancer formation when inhaled, ingested, or absorbed through the skin.

1.33. Mutagenic Substances:

Substances that can cause hereditary genetic damage or accelerate the occurrence of such effects when inhaled, ingested, or absorbed through the skin.

1.34. Reproductive Toxic Substance (Reprotoxins):

Substances that can cause hereditary genetic damage or accelerate the occurrence of such effects when inhaled, ingested, or absorbed through the skin.

1.35. Occupational Exposure Limit Value:

Unless stated otherwise, the upper limit of the time-weighted average concentration of a chemical substance in the air of the breathing zone of workers over an 8-hour period.

1.36. Biological Limit Value:

The upper limit of the concentration of the chemical substance, its metabolite, or a substance that determines exposure in an appropriate biological medium.

1.37. Health Surveillance:

Evaluations carried out for the purpose of determining the health status of workers in relation to their exposure to a specific chemical substance.

1.38. Biological Monitoring:

The process of measuring and evaluating substances or metabolites in tissue, secretion, faeces, inhaled air, or combinations thereof in comparative reference with appropriate standards to assess exposure and health risks. This process is a preventive action and differs from diagnostic procedures.

1.39. Gases:

An amorphous fluid that is completely gaseous in the space surrounding us at 20°C temperature and 101.1 kPa standard pressure, or has a vapour pressure greater than 100 kPa (absolute) at 50°C [3].

1.40. Compressed Gases:

Gases or gas mixtures contained in a container and having absolute pressure above 275.8 kPa at 21.1ºC temperature.

1.41. Liquids:

Substance/mixtures with vapour pressure below 100 kPa (absolute) at 20°C temperature and 101.1 kPa standard pressure, or at 50°C, or having a melting point or initial melting point at 20°C or lower temperatures at 101.1 kPa standard pressure [3].

1.42. Solids:

Other rigid substances or mixtures that do not fit the definitions of gas and liquid substances or mixtures stated above.

1.43. Vapour:

The gaseous phase of a liquid or solid substance at 20°C temperature and 101.1 kPa standard pressure; j = 10 mm (respirable).

1.44. Aerosol:

Microscopic particles dispersed in a gas medium; may be solid particles such as dust, smoke, fume, or liquid particles such as mist and spray.

1.45. Fume:

An aerosol consisting of solid particles produced by the condensation of vapours generally emitted from molten metals. The diameter of these solid particles forming the fume is generally smaller than 1.0 micron. Often, these emitted metal particles combine with oxygen in the air to form oxides. For example, cadmium oxide fume.

1.46. Smoke:

Carbon or soot particles smaller than j = 0.1 mm. These are produced as a result of complete combustion of carbonaceous materials such as coal and fuel-oil. Smoke generally consists of droplets containing particles as dry as possible. Tobacco, for example wet smoke, produces particles in the form of very small tar droplets. The particle size of tobacco smoke is approximately 0.25 micron.

1.47. Mist:

Liquid droplets suspended in air resulting from condensation of gas or liquid phase particles, or liquids dispersed in air in the form of splashing, foaming, or atomisation. In other words, mist is liquid droplets suspended in the atmosphere that will eventually become liquid. Visible to the naked eye.

1.48. Spray:

An aerosol in which liquid droplets are suspended in air, resulting from condensation of gases to the liquid phase or dispersion (e.g. splashing, foaming, or atomisation) of a liquid. For example, oil spray produced during cutting and grinding operations, acid spray produced during electroplating, acid or alkali sprays produced during surface treatment, and paint spray produced during spraying fall under this definition.

1.49. Asbestos:

A mineral consisting of fibrous silicate that is fire-resistant, resulting from the modification of tremolite which is a silicate, flexibly bendable without breaking, with a silky appearance [4].

1.50. Asbestos Removal Worker:

A worker who has completed the training programme established by the commission set up by the Ministry and obtained a course completion certificate.

1.51. Asbestos Removal Specialist:

A person to whom responsibility is given by the employer in the phase of application of operations specified within the regulation, who has completed the training programme established by the commission set up by the Ministry and obtained a course completion certificate after succeeding in the examination.

1.52. VOC:

Volatile Organic Compounds. All organic compounds other than methane that originate from anthropogenic and biogenic sources and can react with nitrogen oxides in sunlight to form photochemical oxidants [5]. Volatile Organic Compounds have aliphatic or aromatic structure, boiling temperature up to 250ºC, and are hydrocarbons that cause air pollution through atmospheric photochemical reaction. When these substances are inhaled with air, they cause many hereditary health diseases. In order to prevent health problems that may arise from the inhalation of volatile substances, VOC measurements in accordance with the standards in the OSH regulation must be carried out by employers at regular intervals.

References

[1] Law No. 6331 on Occupational Health and Safety.

[2] Regulation on Health and Safety Measures in Work with Carcinogenic or Mutagenic Substances, Article 4(d), Official Gazette 2.08.2011-28711.

[3] UN GHS Rev.7, 2017.

[4] ÇSGB, 2017, Occupational Health and Safety Application Guide for Work with Asbestos, Ankara.

[5] Air Quality Assessment and Management Regulation, Article 4(ş). Official Gazette 06.06.2008-26898.

Acknowledgement I extend my infinite gratitude to my valued friend, Chemical Engineer İlker Erdoğan, for his effort and assistance in the preparation of the course notes on "Chemical Exposure in Workplaces". Mustafa Cüneyt Gezen Lecturer Üsküdar University Textile Chemistry Engineer SEH, TMGD   İlker Erdoğan Chemical Engineer İGU (B), SDS Preparer Teknik Koruma