ela954 unit 2 - chemical and biological hazards slides

Copyright ©American Institute of Chemical Engineers 2019. All rights reserved.

1

SAChE® Certificate Program Level 1, Course 5: Laboratory Safety

Unit 2 – Chemical and Biological Hazards

Narration:

[No narration]


2

Objectives

Narration (female voice):

This is the second of five units in the Laboratory Safety course. By the end of this unit, titled

“Chemical and Biological Hazards,” you will be able to:

• List various types of toxicological hazards and common exposure limit measures;

• List various types of flammability hazards, ways in which flammability hazards are

characterized, and ways in which flammability hazards are mitigated;

• Define “chemical reactivity” and describe situations that could present a chemical

reactivity hazard; and

• Explain what a “biohazard” is, give examples of biohazards, and describe how biological

agents are classified by risk level.


3

Introduction


The previous unit in this module presented general background information on laboratory safety.

This included definitions, inherently safer design, safeguards and an introduction to the Globally

Harmonized System (GHS).

This unit will introduce hazards associated with chemical and biological materials.

Chemicals have toxic, flammable and reactive characteristics.

Biological hazards – or biohazards – represent hazards due to exposure and infection of

laboratory workers and others while working with living organisms, biological materials or

agents.

We must understand these characteristics in order to handle these materials safely.


4

SECTION 1: Toxicological Hazards

Narration:

[No narration]


5

Toxicology


Toxicology is the adverse effects of toxicants on biological organisms.

Toxicology considers the following:

• Entry of the toxicant into the worker;

• Elimination of the toxicant from the worker; and

• Toxicant effects on the worker.

Toxicants include:

• Chemical agents; and

• Physical agents, such as particles, noise, and ionizing radiation.

Toxicity is a characteristic of the toxicant related to the effect on the exposed organism.


6

Chemical Exposure Routes


Chemicals can enter workers by a number of different routes. These are shown here.

Inhalation and dermal absorption are the most significant exposure routes for laboratories.


7

Exposure Limits


Several quantities are used to determine workplace exposures to chemical vapors. These

quantities are found in Section 8 of the safety data sheet (SDS).

Typical quantities are:

• Threshold Limit Values (TLV®);

• Permissible Exposure Limits (PEL);

• Immediately Dangerous to Life or Health (IDLH):

• Acute Toxicity (Oral, LD50);

• Acute Toxicity (Inhalation, LC50); and

• Acute Toxicity (Dermal, LD50).

We’ll briefly explore each of these exposure limits on the slides that follow.


8

Threshold Limit Value (TLV®)


Threshold Limit Value – TLV® – is the maximum airborne concentration that a worker can be

exposed to over a worker’s lifetime without adverse effects.

This is only defined for workers working 8 hours per day and 40 hours per week. The TLV®

cannot be used for continuous exposures to chemicals since it assumes time away from the

chemical exposure to detoxify.


9

Source of Threshold Limit Values (TLVs®)


Threshold Limit Values are published by the American Conference of Governmental Industrial

Hygienists, a professional organization without legal authority. However, countries may use

TLVs® in their legal jurisdictions.

Several hundred TLV® values are published for common chemicals. The values are reviewed and

updated annually based on published technical information.


10

Types of Threshold Limit Values (TLVs®)

Narration (male voice):

There are three types of TLVs®:

• TLV-TWA;

• TLV-STEL; and

• TLV-C.

Click the terms for a description of each.


11

TLV-TWA (Slide Layer)

[When TLV-TWA is clicked…]

TLV-TWA is the time weighted average for a normal 8-hour workday to which nearly all workers

can be exposed, day after day, without adverse effects.


12

TLV-STEL (Slide Layer)

[When TLV-STEL is clicked…]

TLV-STEL represents short-term exposure limit. This is the maximum concentration to which

workers can be exposed for a period of up to 15 minutes continuously without suffering (1)

intolerable irritation, (2) chronic or irreversible tissue damage, or (3) narcosis of sufficient

degree to increase accident proneness, impair self-rescue, or materially reduce worker

efficiency, provided that no more than four excursions per day are permitted, with at least 60

minutes between exposure periods, and provided that the daily TLV-TWA is not exceeded.


13

TLV-C (Slide Layer)

[When TLV-C is clicked…]

TLV-C is the ceiling limit. This is the concentration that should not be exceeded, even

instantaneously.


14

Closing audio (Slide Layer)

[After all three terms are clicked…]

Several hundred TLV-TWA values are available for common materials. Fewer values are available

for TLV-STEL and TLV-C.


15

Example Threshold Limit Values (TLVs®)


Listed here are some example Threshold Limit Values.

The ppm, or parts per million, value is based on volume. For example:

• 1% = 10,000 ppm;

• 10% = 100,000 ppm; and

• 100% = 1,000,000 ppm.

Threshold Limit Values cannot be used as a relative indication of toxicity.


16

Permissible Exposure Limit (PEL)


The Permissible Exposure Limit (PEL) is another method to characterize the toxic properties of

chemicals. PELs have legal authority in the U.S. They are published by the U.S. Occupational

Safety and Health Administration (OSHA).

PEL is defined the same as TLV®. Most PELs are the same as TLVs®; however, they are not

updated as regularly as TLVs®.

Which should be used, TLV® or PEL? Most companies use the lowest of the two values. TLV® is

usually lowest and should be considered.

[Male voice]

Click the book icon if you would like to see a list of PELs published by OSHA.


17

Immediately Dangerous to Life or Health (IDLH)


The next method to characterize the toxic properties of chemicals is the IDLH which, as we

learned near the start of this unit, represents Immediately Dangerous to Life or Health.

IDLH is defined as “a condition that poses a threat of exposure to airborne contaminants when

that exposure is likely to cause death or immediate or delayed permanent adverse health effects

or prevent escape from such an environment.”


18

Immediately Dangerous to Life or Health (IDLH) (continued)


The National Institute for Occupational Safety and Health (NIOSH) has published IDLH values for

approximately 380 chemicals. NIOSH is part of the U.S. Centers for Disease Control and

Prevention (CDC).

IDLH values are available in the NIOSH Pocket Guide (NPG) to Chemical Hazards, available for

free or on-line at the website shown.


19

Example IDLH Values


This table lists some example NIOSH IDLH values. Like TLVs®, IDLH values cannot be used as a

relative indication of toxicity.


20

Other Exposure Limits


Other exposure limit values (if known) are found on the SDS in Section 11. These are:

• Acute Toxicity (Oral, LD50);

• Acute Toxicity (Inhalation, LC50); and

• Acute Toxicity (Dermal, LD50).

[Male voice]

Click each button for a brief description.


21

Oral, LD50 (Slide Layer)

[When Acute Toxicity (Oral, LD50) is clicked…]

Acute Toxicity (Oral, LD50) is the Lethal Dose (LD) which causes 50% fatalities in the target

organism. It is usually expressed as milligrams per kilogram of body weight.


22

Inhalation (Slide Layer)

[When Acute Toxicity (Inhalation, LC50) is clicked…]

Acute Toxicity (Inhalation, LC50) is the Lethal (air) Concentration (LC) which causes 50% fatalities

in the target organism. It is usually expressed in parts per million of vapor.


23

Dermal, LD50 (Slide Layer)

[When Acute Toxicity (Dermal, LD50) is clicked…]

Acute Toxicity (Dermal, LD50) is the Lethal Dose (LD) which causes 50% fatalities when applied

to the skin. It is usually expressed in milligrams per kilogram of body weight.


24

Other Exposure Limits – Typical Values


Some typical values for these exposure limits are shown here.

The target organism is frequently specified for these values. These are typically rats, mice or

rabbits.

The values are stated as milligrams of chemical per kilogram of body mass for oral and dermal

exposure and parts per million for inhalation of the chemical.


25

Goal: Minimize Chemical Exposure Limits


Despite all these published limits, you should always try to make chemical exposures as low as

possible, even if below the legal requirements.


26

SECTION 2: Flammability Hazards

Narration:

[No narration]


27

Flammability


The flammability of chemicals and other materials can result in fires and explosions in the

laboratory.


28

Fires and Explosions


What is the difference between a fire and an explosion?

The Center for Chemical Process Safety (CCPS) defines fire as "a combustion reaction

accompanied by the evolution of heat, light, and flame."

CCPS defines explosion as "a release of energy that causes a pressure discontinuity or blast

wave."

Fire is indicative of rapid exothermic oxidation with a flame. An explosion has a higher energy

release rate than fire.

It's important to recognize that a fire can trigger an explosion and vice versa.


29

Effects of Fires and Explosions


The effects of fires and explosions include injuries, fatalities, property losses and work

interruption. These effects can be the result of thermal radiation, asphyxiation, toxic products,

blast and fragments.


30

Fire Triangle


For any fire to occur, three things are necessary:

• Fuel;

• An oxidizer; and

• An ignition source.

These elements are commonly represented in this “fire triangle.”


31

Examples of Fuels, Oxidizers and Ignition Sources


Click each of the three legs of the fire triangle for examples of various types of fuels, oxidizers

and ignition sources.


32

Fuel (Slide Layer)

[When Fuel is clicked…]

Fuels can be either gases, liquids or solids. Liquids are volatized and solids are decomposed prior

to their combustion in the vapor phase.


33

Oxidizer (Slide Layer)

[When Oxidizer is clicked…]

Air is the most common oxidizer, but any oxidizer like chlorine and any chemical with oxygen

can serve as an oxidizer.


34

Ignition Source (Slide Layer)

[When Ignition Source is clicked…]

Ignition sources are very plentiful. They require a sufficient energy level to achieve ignition.


35

Preventing/Controlling Fires and Explosions


Fires and explosions can be prevented by removing any single leg from the fire triangle, for

instance, by removing the ignition source. However, ignition sources are so plentiful that it is not

a reliable control method (it’s said that ignition sources are “free” because you can have them

whether you want them or not). Grounding and bonding are typically used to reduce ignition

sources.

A more robust control method is to prevent the existence of flammable mixtures as the primary

control method while still reducing ignition sources as much as practical.


36

Lower Flammability Limit (LFL) / Upper Flammability Limit (UFL)


For flammable gases in air, there are two quantities used to characterize the flammable hazard

of the gas mixture:

• The Lower Flammability Limit (LFL); and

• The Upper Flammability Limit (UFL).

Below the LFL, the mixture will not burn because it is too lean. Above the UFL, the mixture will

not burn because it is too rich.

Both UFL and LFL are defined as volume % fuel in air. They're generally reported at room

temperature and pressure.

As the temperature increases, the LFL decreases and the UFL increases, resulting in a wider

flammability range.

As the pressure increases, the UFL increases while pressure has a limited effect on the LFL.

We'll explore this chart and labels in more detail later in this section.


37

Typical Values for LFL and UFL


Here are some typical values for lower and upper flammability limits, with units of volume

percent in air.


38

Flash Point Temperature


For flammable liquids, the flash point temperature is used to characterize its flammability. The

flash point is the temperature above which a liquid produces enough vapor to form an ignitable

mixture with air.

The flammability properties we have discussed vary with temperature and pressure. The flash

point temperature is generally reported at 1 atmosphere pressure.


39

Typical Flash Point Temperature Values


Here are typical flash point temperatures for a few liquid fuels. Note the low flash point

temperature for gasoline. This is required to ensure that automobile engines will start at low

temperatures.


40

Auto-ignition Temperature (AIT)


Another quantity used to characterize the flammability of both liquids and gases is the auto-

ignition temperature (AIT). The AIT is the temperature above which adequate energy is available

in the environment to provide an ignition source. AIT values are reported at 1 atmosphere

pressure.

[Male voice]

Watch this brief video of the use of an apparatus to determine a material’s AIT.


41

Typical AIT Values


Shown here are some typical AIT values. The experimental procedure is not very precise so great

variability is expected in reported AIT literature values. In this situation, the lowest AIT value is

used.


42

Saturation Vapor Pressure


This figure, shown previously, illustrates the relationships between all these quantities with

respect to the saturation vapor pressure curve.

Note that the LFL and UFL are typically defined at 25 °C.

The flash point temperature is the temperature at which the LFL intersects the saturation vapor

pressure curve. Finally, the AIT is the lowest temperature for an auto-ignition zone.

Again, these flammability properties vary with temperature and pressure.


43

Experimentally-determined Values


Note that the quantities used to characterize flammability – LFL, UFL, flash point temperature,

and AIT – are not fundamentally-based properties like a material’s density or heat capacity.

These quantities are determined using a particular apparatus and procedure. Thus, these

quantities are not an absolute boundary between safe and unsafe behavior and suitable safety

margins must be used.


44

SECTION 3: Reactivity Hazards

Narration:

[No narration]


45

Chemical Reactivity – Defined


In this section, we will discuss chemical reactivity. Simply stated, chemical reactivity (or

"instability") is the tendency of substances to undergo chemical change.

CCPS defines a chemical reactivity hazard as "a situation with the potential for an uncontrolled

chemical reaction that can result directly or indirectly in serious harm to people, property or the

environment. The uncontrolled chemical reaction might be accompanied by a temperature

increase, pressure increase, gas evolution or other form of energy release."


46

Some Causes of Chemical Reactivity


Chemical reactivity is very difficult to characterize! Among other causes, it can involve:

• Decomposition;

• Reactivity with other chemicals (normal and emergency situations);

• Catalyst effects;

• Contamination of reactants;

• Changes in raw material concentrations;

• Accumulation of unreacted materials;

• Equipment malfunctions (such as the stirrer, cooling, or the vessel itself);

• Improper mixing; and

• Unintended reactions.


47

Characterizing Chemical Reactivity


Chemical reactions can result in the very rapid generation of heat, gas, or other chemical

products. This can result in a very rapid temperature increase (several hundred degrees Celsius

per minute), very rapid pressure increase (many bar per minute), and very rapid generation of

flammable and toxic gases or products. These high temperatures and pressures can lead to fires,

explosions and/or toxic exposures.

It is essential to understand chemical reactivity in order to properly design, fabricate and

operate laboratory equipment safely. This could include intended reactions as well as

unintended reactions due to contamination, spilling, higher than normal temperatures, and so

on.

Chemical reactivity is difficult to characterize under a wide range of experimental conditions.


48

Chemical Reactivity Worksheet


One method to identify and characterize reactive chemical hazards is to use the Chemical

Reactivity Worksheet (CRW), a software program and database of several thousand chemicals

that can be downloaded at no cost from AIChE at the link shown.

CRW considers only binary interactions between two chemicals. It results in a chemical

compatibility matrix, an example of which is shown here. CRW also provides additional

information on the nature of the incompatibility.


49

Part 2


50

Part 3


51

SECTION 4: Biological Hazards

Narration:

[No narration]


52

Biological Hazards


In this last section we will discuss biological hazards. Biological hazards, also known as

biohazards, refer to biological substances that pose a threat to the health of living organisms,

primarily that of humans.

Shown here is the symbol used to label and identify biological hazards.


53

Biosafety


Biosafety includes the principles and practices employed to protect laboratory personnel and

the environment from exposure or infection while working with living organisms, biological

materials, or agents.

Included are any materials that may be potentially infectious. This includes recombinant DNA

research.


54

Laboratory Acquired Infections (LAI)


Laboratory Acquired Infections (LAI) can occur due to working with infectious biological agents

in clinical and research laboratories.

For bacterial LAIs:

• 76% occurred in clinical labs; and

• 8% occurred in research labs.

60% of the exposures occurred due to inhalation. Other forms of exposures include:

• Ingestion (through the mouth or nose);

• Inoculation (such as via sharp needles);

• Splashes; and

• Direct and indirect contact.


55

Biological Risk


Biological risk requires an understanding of the:

• Biology of the agent;

• Susceptibility and transmission within the host; and

• Hazards associated with equipment and procedures.

The goal is to provide the highest practical protection and the lowest potential exposure.


56

Biological Risk (continued)


The World Health Organization (WHO) has assigned four risk groups for biological agents, RG-1

through RG-4.

Click the groups for a definition of each.


57

RG-1 (Slide Layer)

[When RG-1 is clicked…]

RG-1: These are well characterized and non-pathogenic organisms or agents. They are unlikely

to cause disease in humans or animals and represent low individual and community risk. An

example is e. coli.


58

RG-2 (Slide Layer)


RG-2: These are agents of moderate hazard to personnel or the environment and are treatable.

They may cause disease but are typically not serious. They represent some individual risk but

low community risk. An example is HIV.


59

RG-3 (Slide Layer)


RG-3: These may cause serious disease and are usually treatable but are serious respiratory

agents. They represent high individual but low community risk. An example is anthrax.


60

RG-4 (Slide Layer)


RG-4: These are serious or fatal and often are not treatable. They are easily transmitted and

have high individual and community risk. Examples are the Ebola virus and any agent of

unknown risks of pathogenicity and transmission.


61

Understand the Hazardous Characteristics of Laboratory Materials Prior

to Use


As we conclude this unit, keep in mind that we must understand the hazardous characteristics of

the materials we are using in the laboratory prior to their use. This includes chemical and

biological materials.

The dominant hazardous properties of chemicals include toxicity, flammability and

reactivity/instability.

Biological agents are classified according to four risk groups, with ‘4’ being the highest risk.

We must understand how these characteristics relate to our use of these materials, including

storage, transport, experimental procedure and disposal.


62

Unit 2 Summary


We’ve reached the end of the second unit in the Laboratory Safety course. Having completed

this unit titled “Chemical and Biological Hazards,” you should now be able to:

• List various types of toxicological hazards and common exposure limit measures;

• List various types of flammability hazards, ways in which flammability hazards can be

mitigated, and ways in which flammability hazards are characterized;

• Define “chemical reactivity” and describe situations that could present a chemical

reactivity hazard; and

• Explain what a “biohazard” is, give examples of biohazards, and describe how biological

agents are classified by risk level.

In Unit 3, we’ll discuss equipment hazards. But first, please take the quiz for Unit 2 beginning on

the next slide.

ela954 unit 2 - chemical and biological hazards slides

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