PHLT 331 EXAM 1 PART 1

Absorbed Dose

Describes the amount of energy deposited per unit mass in an object or person. The units for absorbed dose are gray (Gy, international unit) and rad (rad, U.S. unit).

Exposure Dose

An exposure dose is an estimate of the amount of a chemical that enters a person’s body when the person comes in contact with the chemical.

Confounding 

The distortion of a measure of the effect of an exposure on an outcome due to the association of the exposure with other factors that influence the occurrence of the outcome

Epidemiologic Triangle

A model that describes disease transmission through the relationships between hosts, agents, and the environment.

Healthy Worker Effect

The observation that employed populations tend to have a lower mortality experience than the general population

Incidence

The number of instances of illnesses commencing, or of persons falling ill, during a given period in a specified population

Prevelance

The number of affected persons present in the population at a specific time divided by the number of persons in the population at that time—that is, what proportion of the population is affected by the disease at that time.

LD50

(lethal dose 50) The dosage (mg/kg body weight) causing death in 50% of exposed animals

Odds Ratio

The measure of association between exposure and outcome used in case-control studies

PEL

Permissible exposure limits (PELs) OSHA standards that are subject specific and that provide supporting documentation for promulgation and enforcement of occupational health regulations. They denote an allowable exposure level in the workplace air that is averaged over an eight-hour shift.

TLV

Threshold limit value (TLV) Airborne concentrations of substances that represent conditions under which it is believed that nearly all workers may be unaffected

SMR

Standardized mortality ratio (SMR): The ratio of the observed mortality in a population to the expected mortality.

SMR = (observed deaths)/(expected deaths)

Toxin

A toxic substance made by living organisms, including reptiles, insects, plants, and microorganisms

Toxicant

A poison that is made by humans or that is put into the environment by human activities. Many pesticides are toxicants.

Epidemiology

the study of the occurrence and distribution of health-related states or events in specified populations, including the study of the determinants influencing such states, and the application of this knowledge to control the problems

What does occupational health do?

Identify high-risk groups

Guide research efforts for further investigation and mitigation

What is toxicology

concerns the chemical and physical properties of poisons, their respective physiological or behavioral effects on living organisms

What does an occupational toxicologist do?

establishes exposure thresholds and reduces risk

ecological study

the units of analysis are populations or groups of people rather than individuals

case control study

Subjects who participate in the study are defined on the basis of the presence or absence of an outcome of interest. They already have it (or not) exposure is not determined for them

Experimental study

experimenter randomizes sample, controls who is exposed to a certain intervention

What kind of study is a gold standard

experimental study

What is used in cohort studies

relative risk

relative risk (formula)

risk of disease in exposed vs non-exposed

Odds ratio (formula)

odds of exposure in diseased vs. non-diseased (AD/BC)

Standardized mortality ratio (formula)

observed/ expected x100

Incidence rate (formula)

new cases/ total population at risk x multiplier

Prevalence (formula)

proportion with disease at that time

What is used in a case-control and cross sectional study

odds ratio

WHAT Hill’s criteria MUST be present everytime

temporality must be

Strength (hill’s criteria)

a strong association between exposure and outcome (ex: high odds ratio)

consistency (hill’s criteria)

association that has been observed repeatedly by different persons in different places, circumstances, and times

specificity (hill’s criteria)

association of certain outcome from a specific exposure and not from other types of exposures

Temporality (hill’s criteria)

the exposure must be observed before the outcome, and the time between exposure and outcome makes sense

Biological gradient (hill’s criteria)

existence of dose-response relationship (ex: change in dose corresponds to change in outcome)

biological plausibility (hill’s criteria)

association makes sense from the standpoint of contemporary biological knowledge

BEI (biological exposure indices)

A measure of the amount of chemical absorbed into the body. The level of exposure that the typical worker can experience without adverse health effects

coherence (hill’s criteria)

association does not seriously conflict with generally known facts of natural history and disease biology

dose

described as exposure dose, absorbed dose, administered dose, total dose

dose-response

correlative relationship between exposure and effect

threshold

lowest dose at which particular response occurs

latency

time period between initial exposure and measurable outcome

effects of mixtures

additive, antagonistic, synergistic effects can occur when exposures are combined

advantage of ecological studies

they make use of data (e.g., mortality data and census data) that have been collected routinely

disadvantages of ecological study

the difficulty of assessing the impacts of unmeasured exposures that may be related to the study outcome

ecological fallacy

a logical error in statistics and research where you wrongly assume that what is true for a group as a whole is also true for an individual member of that group

disadvantage of experimental studies

but in many instances they are difficult and expensive to perform in the work environment

prevalence (math)

#of ill/ total # at a point in time

occupations exposed to chemical

KNOW AT LEAST #

pesticides

any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest

Are pesticides just for insects?

no, they can be herbicides, fungicides, and others

solvent

a substance, usually a liquid capable of dissolving another substance

Aerosol

Small particles, usually in the range of 0.01 to 100 micrometers, dispersed in the air, which include liquid (mist) and small particles (dust)

Asphyxiant

A substance that is capable of causing death from suffocation—for example, by decreasing the capacity of the blood to carry oxygen

Antineoplastic. drug

a drug used in cancer chemotherapy

Chloracne

is a more severe form of acne [. . .].  Chloracne results from exposure to halogenated aromatic hydrocarbonsLinks to an external site. such as chlorinated dioxinsLinks to an external site. and dibenzofuransLinks to an external site.. Dioxin exposure and development of chloracneLinks to an external site. can occur occupationally or environmentally. Chloracne is the hallmark of dioxin exposure

Dioxins

A class of structurally and chemically related halogenated aromatic hydrocarbons that includes polychlorinated dibenzodioxins (PCDDs or dioxins), polychlorinated dibenzofurans (PCDFs or furans) and the “dioxin-like” polychlorinated biphenyls (PCBs)

Organic solvent syndrome

A cluster of neurologic symptoms—for example, impaired memory, confusion, restlessness, and insomnia—associated with inhalation of solvents

Sensitizer

The OSHA Hazard Communication Standard, or HCS, defines a sensitizer as “a chemical that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure to the chemical” (emphasis added).

benzene (solvent hazard)

human exposure occurs frequently; associated with leukemia and blood disorders

formaldehyde (solvent hazard)

colorless with a strong smell; KNOWN human carcinogen

tetracholoroethylene (solvent hazard)

used in dry cleaning; a LIKELY human carcinogen

2-butanone (solvent hazard)

used in coatings, paints, cleaners, and glues; causes mild irritation of the nose, throat, skin, and eyes

organophosphates (type of pesticide)

affect the nervous system by disrupting the enzyme that regulates acetylcholine, a neurotransmitter. Most organophosphates are insecticides.

Carbamate pesticides

affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter (similar to organophosphates)

Organochlorates

were commonly used in the past, but many have been since removed from the market due to their health and environmental effects and their persistence

pyrethroids

developed as a synthetic version of the naturally occurring pesticide pyrethrin. Some are toxic to the nervous system

PCB’s are

man made

PCB’s used to be used for what?

an insulating fluid in electrical components such as capacitors and transformers

Are PCB’s still used?

no, they were banned in 1979

PCB is linked to increases of what

cancer

dioxins cause what

they cause chloracne

asthmagen

Asthmagens can be divided into two separate types, namely inducers and inciters.

Inducers are substances which, on single or repeated exposure, cause a previously well individual to develop asthma.

inciters (or triggers) are substances which can cause symptoms in an individual with pre-existing abnormal airway responsiveness.

carcinogen

A substance or agent that causes cancer in mammals, including humans

dermatopathic agent

An agent that causes diseases of the skin.

Immunologic agent

An agent that affects the immune system, which forms part of the body’s natural defenses against disease

Neurological toxicant /neurotoxin

A toxic substance that is “[a]ble to produce chemically an adverse effect on the nervous system: such effects may be subdivided into two types: central nervous system effects…and peripheral nervous system effects

Pneumonoconiotic agent

An agent (e. g., inorganic and organic dusts) etiologically associated with pneumoconiosis (fibrosis of the lung)

Reproductive toxicant

Substance or preparation that produces non-heritable adverse effects on male and female reproductive function or capacity and on resultant progeny

Sensitizer

A substance that causes sensitization, which is an “immune response whereby individuals become hypersensitive to substances, pollen, dandruff, or other agents that make them develop a potentially harmful allergy when they are subsequently exposed to the sensitizing material (allergen)

Systemic toxin

A toxin that affects the body as a whole

Teratogen

Agent that, when administered prenatally (to the mother), induces permanent structural malformations or defects in the offspring

most ______ are insecticides

organophosphates