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Environmental health > Risk Assessment and Analysis > Flashcards

Risk Assessment and Analysis Flashcards

1
Q

(see risk assessment in context of agriculture)

A

(see risk assessment in context of agriculture)

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2
Q

father of toxicology who said all things are poison and nothing is without poison only the dose permits something to be not poisonous

A

Paracelsus

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3
Q

mother of toxicology; an applied toxicologists who had poisons in her jewelery which caused death to her suitors

A

Lucrezia Borgia

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4
Q

legal definition of poison

see table of ld for humans

A

chemical that has a lethal dose (LD50) less than or equal to 50 mg of chemical per kg of body weight
® 50 mg/kg is approximately ¾ tsp. for the average adult, and
about 1/8 tsp. for the average 2-year-old

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5
Q

How does dose of poison play a role in risk assessment?

A

® Relationship of dose and size: a smaller person would require a smaller dose of poison for it to be lethal, as
compared to a larger person
® Children

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6
Q

this is used for inhalation work; determined by exposing several groups of animals (e.g. rats or
mice) each to a different air concentration of chemical for a onehour
period, then they are observed for a 14-day period

A

lethal concentration 50

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7
Q

x-axis and y-axis of dose-response curve

A
  • X-axis: dose/concentration (mg/kg)

* Y-axis: response

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8
Q

How much of a particular compound kills 50% of the

population

A

LD50

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9
Q

A wider range of toxicity indicates (preferred)?

A

a narrower margin of error = need for ra

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10
Q

second part of risk assessment

A

toxicity assessment

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11
Q

This was recognised first in occupational illness

A

chronic toxicity

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12
Q

certain trades with poorer health as noted by greek physicians

A

mining, metallurgy, pottery

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13
Q

Hippocrates described what? (re: toxicity assessment)

A

severe colic in men who extracted metals (lead poisoning)

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14
Q

Poisoning which Pliny wrote about

A

mercury poisoning in miners from quicksilver mines of Spain

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15
Q

Ways of exposure to lead

A
  • Water supply – in old pipes
  • Naturally occurring lead
  • Lead as a contaminant – in air and water
  • In USA, especially the North America, lead was used in painting houses
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16
Q

Refers to the ability of a substance to do systemic damage as a result of a one-time exposure of relatively short duration

A

Acute toxicity (inversely related with LD: mgchemical/kg of body weight)

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17
Q

what does ld 0 and ld100 mean?

A
  • LD0 = no resultant deaths

- LD100 = death of the entire population

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18
Q

Refers to the harmful systemic effects produced by long-term,
low-level exposure to chemicals

A

Chronic toxicity

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19
Q

synonym for toxicity

A

hazard (more complex due to involvement of conditions of use)

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20
Q

Two components of hazard

A

• Inherent ability of the chemical to do harm by virtue of its explosiveness, flammability, corrosiveness, toxicity, etc.
• The ease with which contact can be established between
the chemical and the object of concern

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21
Q

pathway by which chemical gets into body

A

routes of exposure

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22
Q

three major routes of exposure

A

dermal entry (most common way; skin = 20 sq ft effective barier)
inhalation (2nd most common)
oral (through ingestion)

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23
Q

T or F: lungs are very effective barrier to chemicals

A

false, poor (lung surface: 750 sq ft has delicate one cell thick membrane wc allows easy passage of o2 and other harmful chemicals as well from alveolar space to blood)

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24
Q

collective term for the damage to lung surfaces caused by foreign objects

A

pneumoconiosis

causes: asbestos, silica, dust, cotton, coal, sugar cane pulp

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25
Q

Chemicals that enter body are absorbed through where?

A

GI tract (can occur from mouth to rectum; majority: SI)

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26
Q

Where is nitroglycerine usually absorbed through?

A

mucus membranes of the mouth, that is why it is taken and placed under the tongue.

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27
Q

This is absorbed rapidly in stomach as well as intestine

A

ethyl alcohol (effects seen imm.; food in stomach delays its effects)

28
Q

Other routes of entry of chemicals

A
  • Intravenously
  • Subcutaneously
  • Intramuscularly
  • Intraperitoneally
  • Intradermally
29
Q

Six kinds of toxicity when dose time and route factors are combined

A 
® Acute dermal 
® Chronic dermal
® Acute inhalation
® Chronic inhalation
® Acute oral 
® Chronic oral
30
Q

chemical that is equally toxic by all three routes of exposure

A

organophosphate pesticide parathion (highly acute toxic; exhibits cholinesterase enzyme wc deactivate choline esters)

31
Q

In OPP toxicity mech, what happens when cholinesterase is inhibited?

A

acetylcholine is not deactivated (continued stimulation of PNS)

32
Q

OTHER FACTORS THAT INFLUENCE TOXICITY OF A CHEMICAL SPECIES

A

animal models (toxicity vary among species)
age
sex

33
Q

What converts hemoglobin to methemoglobin?

A

nitrobenzene

34
Q

T or F: rats cant vomit

A

true

35
Q

T or F; in animal models, Similarities ease the process while differences require a different animal’s response to toxicity to accurately represent
man’s toxicity to a compound.

A

true

carcinogenic = cancer in animal species at any level of exposure

36
Q

use of animal data to human data dates back to 1958. Why?

A

Food Additives Amendments Act (Delaney Amendment)

37
Q

example of age affecting toxicity

A

DDT is not acutely toxic to newborn rats; however, it becomes increasingly toxic as the rats mature. Adult LD50 is 200-300mg/kg
• The organophosphate parathion is more acutely toxic to newborn rats than adult rats due to their differing capability to metabolize foreign chemicals

38
Q

The differing capability to metabolize foreign chemicals of newborn rats and mature rats is due to

A

liver microsomal enzyme system.

39
Q

example of sex affecting toxicity

A

Male rats are 10x more sensitive to liver damage than female rats from chronic exposure to DDT (sex diffs due to hormone activity)

40
Q

What can limit the difference between sex?

A

castration or hormone administration (Castrated male rats had virtually equal sensitivity to liver
damage as compared to females upon chronic exposure to
DDT)

41
Q

T or F: humans are more sensitive than test animals

A

true

42
Q

margin of safety of fda

A

100-fold (no adverse effect = 100 ppm, maximum dietary concentration= 1 ppm)

43
Q

considered the initiating event in carcinogenesis

A

mutation (change in the genetic code that result in a change of the message)

44
Q

Abnormalities in developing organisms during uterine life

A

teratogenesis

45
Q

statistics on teratogenesis

A
  • Congenital malformations in U.S.: 2 in 100 live births

* 20% of all pregnancies do not go to term as a result of spontaneous abortion

46
Q

examples of teratogenesis

A

thialidomide

diethylstilbestrol

47
Q

Prescribed between 1940 and 1970 to prevent miscarriage in high-risk pregnancies; cases of vaginal adenocarcinoma in women ages 16-20
were linked to fetal exposure through maternal DES ingestion early in the pregnancy.

A

diethylstilbestrol

1 in 1000 pregnancies were exposed

48
Q

effects of diethylstilbestrol

A
  • Females: carcinomas (vaginal, cervical), uterine abnormalities; higher risk for ectopic pregnancies, miscarriage and preterm labor and delivery
  • Males: some form of abnormal genitalia (microphallus, testicular varicoceles, hypospadias), epididymal cysts,
    undescended testes
49
Q

§ Marketed outside U.S. (1950s) as a mild sedative to combat nausea and morning sickness but withdrawn from market in 1961

A

Thialidomide

(Not all animal species tested produced reactions to thialidomide similar to humans; Risk of teratogenic effects only appear when drug is taken during a specific time period 34-50 days into preggy after beginning of last menstrual period)

50
Q

effects of thialidomide

A

Risk of ≥20% of baby with phocomelia, missing ears,deafness

51
Q

Recent uses of thialidomide

A
  • Approved treatment and control of leprosy-associated skin sores
  • Laboratory tests show its ability to inhibit HIV replication and reverse AIDS-related cachexia
  • Treatment of non-microbial aphthous mouth and throat
    ulcers
52
Q

formula for risk

A

risk = hazard x exposure

53
Q

four steps for risk assessment

A
  1. Hazard identification
  2. Toxicity assessment – dose/response
  3. Exposure assessment
  4. Risk characterization
    (sometimes: 5. Risk management, 6. Risk communication)
54
Q

see risk assessment diagram

A

see risk assessment diagram and xenobiotic exposure and lifetime risk based on employment

55
Q

see example of risk assessment

A

see example of risk assessment

56
Q

questions to ask in hazard id

A
  • What is the chemical of concern?
  • What’s been spilled, leaked, emitted, etc.
  • Does the chemical undergo transformation?
  • If transformed, which product is of most concern?
  • If mixture, which chemical is the most toxic?
57
Q

steps involved in exposure assessment

A 
• Identify hazard
• Determine likely exposure pathway
• Calculate concentration
• Calculate dose
• Determine applicable time
• Exposure Media
® Air ® Soil
® Water ® Food
58
Q

factors affecting ingestion

A

® Quantity of water ingested
§ Climate
§ Physiological factors: age, weight, gender
§ Level of physical exertion: resting, exercising, working
® Ability of the body to absorb contaminant
§ Chemical
§ Target organ
® Concentration of chemical in water

59
Q

average consumption of water by a person/day

A

2 liters

60
Q

commonly inhaled

A

water aerosols (<5 micrometers)

61
Q

transfer of chemicals through inhalation is usually through

A

showering
post bathroom time
remainder of house (miscellaneous)

62
Q

factors affecting INHALATION

A

® Concentration in air
® Physiological factors: breathing rate, age, weight, gender
® Exposure duration – hours, day
® Exposure frequency – day, week

63
Q

factors affecting INDOOR inhalation

A 
® Ventilation rate
§ Shower
§ Post shower bathroom time
§ House – geographic location
® Time per day spent in house
® Number of people in house – water use
64
Q

Factors affecting dermal absorption:

A
  • Permeability of skin to chemical in question (Unique property of chemical lipophilicity, Usually based on animal measurements)
  • Concentration of chemical – air, water
  • Duration of contact
  • Exposure media – air, water, soil
  • Exposed skin surface area (Physiological: age, weight, gender; Activity during contact)
65
Q

time averaging of toxicity includes classification into

A 
• Daily
• Yearly
• Lifetime
® 70-75 years
® Standard U.S. EPA
• Cumulative
® Total dose over entire exposure period
• Other
® Based upon exposure scenario (e.g. weekly)
66
Q

(see gen modelling principles)

A

(see gen modelling principles) basa pa gurl

Environmental health (17 decks)

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