Chemical Safety Lecture Notes

A comprehensive set of Q&A flashcards covering major concepts, definitions, health effects, examples, and safety practices from the Chemical Safety lecture.

What is the difference between a chemical hazard and chemical risk?

Hazard is the potential of a substance to cause damage, while risk is the probability that harm will occur under specific exposure conditions.

Approximately how many new chemicals enter the market each year?

About 1,000.

Define probability in the context of risk.

A mathematical statement about the likelihood that harm will occur from a hazard.

What does risk assessment do?

Uses statistical methods to estimate how much harm a particular hazard can cause to human health or the environment.

What is risk management?

The process of deciding whether and how to reduce a particular risk to an acceptable level.

List two cultural hazards people face.

Unsafe working conditions and poverty (others include unsafe highways, criminal assault).

Name three documented health issues common among chemists.

Shorter lifespans, higher cancer incidence, higher suicide rate (particularly females).

Give three possible health effects of chemical exposure.

Organ damage, cancer, reproductive problems (others: weakened immune system, development issues in children, allergies/asthma, blindness, death).

What is a carcinogen?

A chemical, type of radiation, or virus that can cause or promote cancer.

Define mutagen.

A chemical or form of radiation that causes or increases the frequency of DNA mutations.

Define teratogen.

A chemical that causes harm or birth defects to a fetus or embryo.

Give an example of a neurotoxin.

Lead (others: PCBs, methylmercury, arsenic, certain pesticides).

What persistent pollutant group was banned in the U.S. decades ago but only banned in the Philippines in 2004?

Polychlorinated biphenyls (PCBs).

Name one industrial pathway for arsenic contamination.

Wood preservatives (others: glass, pigments, pesticides, animal feeds, metal adhesives).

Why are lead exposures concerning in adults?

They raise the risk of high blood pressure, heart disease, kidney disease, and reduced fertility.

Which fish category should be eaten no more than three times a month due to high mercury in the Philippines?

Fresh tuna/sashimi, lapu-lapu (grouper), and sea bass.

What is the main health risk of low-level methylmercury exposure in fetuses and young children?

Brain damage.

List two main industrial sources of atmospheric mercury.

Mining and coal burning (others: various industrial processes).

What does the endocrine system regulate?

Reproduction, growth, development, learning ability, and behavior.

What is a hormonally active agent (HAA)?

A synthetic chemical that disrupts the human endocrine system.

Give two examples of HAAs.

Atrazine and bisphenol A (others: aluminum, DDT, PCBs, mercury, phthalates).

Why is BPA controversial?

Low-level exposure has been linked to brain damage, early puberty, and cancer, yet some industry-funded studies found minimal risk.

What is the precautionary response some countries have taken on BPA?

Canada and the EU banned BPA in baby bottles.

What common plasticizers are associated with reproductive problems in lab animals?

Phthalates.

State Paracelsus’ principle regarding toxicity.

"All substances are poisons; the right dose differentiates a poison from a remedy."

Define dose in toxicology.

The amount of a chemical ingested, inhaled, or absorbed through the skin.

What is an LD50?

The dose that kills 50% of test animals within a specified period (often 18 days).

What toxicity rating applies to substances with LD50 < 5 mg/kg?

Supertoxic.

Differentiate between acute and chronic chemical effects.

Acute effects are immediate or rapid reactions; chronic effects are permanent or long-lasting consequences of exposure.

Define biological magnification.

Increase in concentration of a toxin as it moves up successive trophic levels in a food chain.

Name two limitations of epidemiological studies in toxicology.

Takes a long time and people are exposed to multiple agents (others: few high-dose subjects, differing sensitivities).

Roughly what percentage of commercial synthetic chemicals have been thoroughly screened for toxicity?

About 10%.

What is pollution prevention?

Avoid releasing chemicals known or suspected to cause harm by substituting safer alternatives or recycling them within processes.

State the precautionary principle.

When reasonable evidence suggests possible significant harm, action should be taken to prevent or reduce risk even if scientific proof is incomplete.

List any three of the 'dirty dozen' persistent organic pollutants (POPs).

DDT, dioxins, PCBs (others: aldrin, chlordane, dieldrin, endrin, furans, heptachlor, hexachlorobenzene, mirex, toxaphene).

Name the five common chemical groups causing health risks highlighted in the lecture.

Acids and bases; dusts, fumes and gases; metals; pesticides; solvents.

What pH range classifies a substance as an acid?

Less than 7.

Why are strong acids or bases often dangerous when mixed with water?

Mixing releases heat that can cause burns; rule: always add acid to water (AWA).

What is a chemical burn?

Tissue damage caused by exposure to a strong acid or alkali.

Give a first-aid step for skin exposure to a corrosive acid.

Remove contaminated clothing and flush skin with water for at least 20 minutes.

What respiratory hazard can result from inhaling concentrated acid mists?

Acute inhalation injury, potentially leading to pulmonary edema or death.

Define dust in occupational hygiene.

A common air pollutant consisting of solid particles generated by processes like grinding or natural erosion.

Why are particles <2.5 µm especially dangerous?

They can travel deep into lungs and the bloodstream, posing greater health risks.

What lung disease results from inhaling crystalline silica dust?

Silicosis.

List two acute symptoms of gas exposure such as ammonia.

Mucous membrane irritation and coughing (others: vomiting, eye irritation).

Why is carbon monoxide lethal?

It binds to hemoglobin, preventing oxygen transport in the blood.

What is a fume?

Vapors, dusts, or smoke emitted during chemical transformation like reaction or heating.

Name two short-term health effects of fume inhalation.

Eye irritation and coughing.

State two heavy metals covered that are neurotoxic.

Mercury and lead (arsenic also causes neurological effects).

What tragic laboratory accident highlighted dimethylmercury’s danger?

Professor Karen Wetterhahn’s fatal exposure through latex gloves at Dartmouth in 1996.

Define pesticide.

A chemical compound used to kill pests such as insects, rodents, fungi, or weeds.

What are organophosphates primarily used for?

As components of pesticides, herbicides, insecticides, and some nerve gases.

Which first-generation synthetic insecticide metabolizes to DDE in the body?

DDT (dichlorodiphenyltrichloroethane).

What herbicide is one of the cheapest and most common in the U.S. and causes uncontrolled plant growth?

2,4-dichlorophenoxyacetic acid (2,4-D).

Explain LD50 labeling for pesticides.

Labels may show danger, warning, or caution based on acute oral or dermal LD50 values: the lower the LD50, the higher the toxicity category.

List three acute symptoms of mild pesticide poisoning.

Headache, nausea, perspiration (others: fatigue, dizziness, skin/eye irritation).

Name two chronic health effects linked to pesticide exposure.

Cancer (e.g., non-Hodgkin lymphoma) and endocrine disruption (others: infertility, Parkinson’s disease).

What mitigation measures can reduce pesticide exposure for workers?

Wearing correct PPE, following safety protocols, and using safer alternatives.

What solvent categories are based on composition?

Inorganic (carbon-less) solvents and organic (carbon-based) solvents.

Identify three subgroups of hydrocarbon solvents.

Aliphatic, aromatic, and paraffins (alkanes).

Give one example of an oxygenated solvent class.

Alcohols (others: ketones, esters, ethers, glycol ethers).

What distinguishes halogenated solvents?

They contain halogen atoms such as chlorine, fluorine, bromine, or iodine.

List two acute effects of solvent exposure.

Headache and dizziness (others: irritation, lightheadedness to unconsciousness).

Provide one chronic effect of long-term solvent exposure.

Nervous system damage (others: liver/kidney damage, cancer, skin lesions).

What is the primary route of solvent poisoning in poorly ventilated areas?

Inhalation leading to rapid lung absorption.

In the SDS, what does the NFPA diamond’s red quadrant indicate?

Fire hazard (flash point category).

Why are Safety Data Sheets essential?

They give comprehensive hazard information and safety precautions for chemical management and worker protection.

What are two required pieces of information on a Safety Data Sheet?

Hazard identification and supplier details (others: composition, first-aid measures, handling and storage).

State one key idea promoted at the end of the lecture regarding chemical safety.

Greater emphasis on pollution prevention due to the difficulty of evaluating chemical harm.

What higher-risk groups need extra protection from chemical exposure?

Children, pregnant women, seniors, people with pre-existing health conditions, and Indigenous peoples.

What is multiple chemical sensitivity (MCS)?

A condition where individuals are sensitive to a wide variety of chemicals at low exposure levels.

How can solubility affect a toxin’s behavior in the body?

Water-soluble toxins move through water systems and the body easily; fat-soluble toxins bioaccumulate in tissues and magnify up food chains.

What is an LD50 value that categorizes a substance as 'moderately toxic'?

50–500 mg per kg of body weight.

Which combustion-related gas can cause ‘silent’ asphyxiation due to being odorless and colorless?

Carbon monoxide.

During acid/base exposure, what simple safety rule prevents violent reactions?

Always add acid to water (never water to acid).

What common cleaning product contains sodium hypochlorite, a potential cause of chemical burns?

Household bleach.

Give one symptom of acute organophosphate poisoning.

Muscle twitching (others: excessive sweating, blurred vision, difficulty breathing).

What real-world event showcased the large-scale ecological damage of herbicide warfare?

The use of Agent Orange in Vietnam, causing 400,000 deaths and millions affected.

How can ventilation mitigate solvent hazards?

It dilutes airborne solvent vapors, reducing inhalation exposure.

Why is adding safety buffer zones around schools recommended concerning pesticides?

To protect children from pesticide drift from nearby farms.

What is the 'pesticide treadmill'?

A cycle where increased pesticide use leads to resistant pests, requiring stronger chemicals and causing greater harm.