REHS{ Registered Environmental Health Specialist}STUDY
GUIDE – 2025-2026 REGISTERED ENVIRONMENTAL HEALTH
SPECIALIST EXAM PREP WITH 250 VERIFIED QUESTIONS
AND CORRECT ANSWERS WITH MOST TESTED QUESTIONS
1. A factor or agent which increases the risk of cancer is known as a
a. teratogen
b. mutagen
c. carcinogen
d. fomite - correct answer -carcinogen
2. The four major causes of death among all age groups of Americans include all of the following
except.
a. homicide
b. accidents
c. malignant neoplasms
d. heart disease - correct answer -homicide
3. In recent years, the largest number of rabies cases were associated with
a. skunks
b. bats
c. dogs
d. raccons. - correct answer -skunks
4. Asbestosis is caused by fine silicate fibers retained in the
a. kidneys
b. lungs
c. colon
d. abdomen - correct answer -lungs
,5. An illness due to a specific infectious agent or its toxic product which is transmitted from a
reservoir to a susceptible host either directly or indirectly is called
a. an infectious disease
b. a communicable disease
c. a genetic disease
d. a noncommunicable disease - correct answer -a communicable disease
6. Rocky mountain spotted fever is spread by
a. flies
b. spiders
c. cockroaches
d. ticks - correct answer -ticks
7. Mycotoxins are poisonous chemicals produced by
a. bacteria
b. vertebrates
c. viruses
d. fungi - correct answer -fungi
8. The study of the occurrence, frequency, and distribution of disease is
a. entomology
b. biology
c. endocrinology
d. epidemiology - correct answer -epidemiology
9. Which of the following organisms are most resistant to unfavorable environmental conditions and
indicate past or possibly intermittent pollution?
a. fecal streptococci
,b. escherichia coli
c. aerobacter aerogenes
d. clostridium sporulates - correct answer -clostridium sporulates
10. Engineering controls are
a. controls that isolate or remove hazards from the work place
b. less effective than good training
c. the last option that should be considered
d. less effective than personal protection processes - correct answer -controls that isolate or remove
hazards from the workplace
11. Which of the following is not considered a satisfactory solution to the problem of chemical
contamination in
Well systems?
a. abandoning the well
b. boiling the water
c. building a new, properly constructed, drilled well - correct answer -boiling the water
12. Which of the following chemicals is most widely used to destroy microorganisms?
a. chlorine
b. copper sulfate
c. chloramine
d. hydrogen sulfate - correct answer -chlorine
13. Which of the following is not a practical method for removal of cadmium?
a. ion exchange
b. lime softening
c. reverse osmosis
d. iron coagulation - correct answer -reverse osmosis
, 14. Which of the following is not a commonly accepted method of device to prevent backsiphonage?
a. vacuum breakers
b. cross-connections
c. air gap separation
d. back pressure units - correct answer -cross-connections
15. This substance is the first product of the decomposition of organic matter. Its presence in water
usually
Indicates "fresh pollution" of sanitary significance. What is it?
a. ammonia
b. sugar
c. carbon dioxide
d. hydrogen sulfide - correct answer -ammonia
16. One of the most common reasons for the contamination of wells drilled through rock, clay, or
hardpan is
a. seepage of pollutants through soil
b. failure to seal well casings properly
c. porosity of the rock
d. use of inferior quality well casings - correct answer -failure to seal well casings properly
17. In emergencies, small quantities of water can be disinfected by boiling or using
a. aluminum salts
b. tincture of iodine
c. salt tablets
d. direct exposure to sunlight for 22 hours - correct answer -tincture of iodine
18. Back flow of nonpotable materials into the potable water system may occur by
GUIDE – 2025-2026 REGISTERED ENVIRONMENTAL HEALTH
SPECIALIST EXAM PREP WITH 250 VERIFIED QUESTIONS
AND CORRECT ANSWERS WITH MOST TESTED QUESTIONS
1. A factor or agent which increases the risk of cancer is known as a
a. teratogen
b. mutagen
c. carcinogen
d. fomite - correct answer -carcinogen
2. The four major causes of death among all age groups of Americans include all of the following
except.
a. homicide
b. accidents
c. malignant neoplasms
d. heart disease - correct answer -homicide
3. In recent years, the largest number of rabies cases were associated with
a. skunks
b. bats
c. dogs
d. raccons. - correct answer -skunks
4. Asbestosis is caused by fine silicate fibers retained in the
a. kidneys
b. lungs
c. colon
d. abdomen - correct answer -lungs
,5. An illness due to a specific infectious agent or its toxic product which is transmitted from a
reservoir to a susceptible host either directly or indirectly is called
a. an infectious disease
b. a communicable disease
c. a genetic disease
d. a noncommunicable disease - correct answer -a communicable disease
6. Rocky mountain spotted fever is spread by
a. flies
b. spiders
c. cockroaches
d. ticks - correct answer -ticks
7. Mycotoxins are poisonous chemicals produced by
a. bacteria
b. vertebrates
c. viruses
d. fungi - correct answer -fungi
8. The study of the occurrence, frequency, and distribution of disease is
a. entomology
b. biology
c. endocrinology
d. epidemiology - correct answer -epidemiology
9. Which of the following organisms are most resistant to unfavorable environmental conditions and
indicate past or possibly intermittent pollution?
a. fecal streptococci
,b. escherichia coli
c. aerobacter aerogenes
d. clostridium sporulates - correct answer -clostridium sporulates
10. Engineering controls are
a. controls that isolate or remove hazards from the work place
b. less effective than good training
c. the last option that should be considered
d. less effective than personal protection processes - correct answer -controls that isolate or remove
hazards from the workplace
11. Which of the following is not considered a satisfactory solution to the problem of chemical
contamination in
Well systems?
a. abandoning the well
b. boiling the water
c. building a new, properly constructed, drilled well - correct answer -boiling the water
12. Which of the following chemicals is most widely used to destroy microorganisms?
a. chlorine
b. copper sulfate
c. chloramine
d. hydrogen sulfate - correct answer -chlorine
13. Which of the following is not a practical method for removal of cadmium?
a. ion exchange
b. lime softening
c. reverse osmosis
d. iron coagulation - correct answer -reverse osmosis
, 14. Which of the following is not a commonly accepted method of device to prevent backsiphonage?
a. vacuum breakers
b. cross-connections
c. air gap separation
d. back pressure units - correct answer -cross-connections
15. This substance is the first product of the decomposition of organic matter. Its presence in water
usually
Indicates "fresh pollution" of sanitary significance. What is it?
a. ammonia
b. sugar
c. carbon dioxide
d. hydrogen sulfide - correct answer -ammonia
16. One of the most common reasons for the contamination of wells drilled through rock, clay, or
hardpan is
a. seepage of pollutants through soil
b. failure to seal well casings properly
c. porosity of the rock
d. use of inferior quality well casings - correct answer -failure to seal well casings properly
17. In emergencies, small quantities of water can be disinfected by boiling or using
a. aluminum salts
b. tincture of iodine
c. salt tablets
d. direct exposure to sunlight for 22 hours - correct answer -tincture of iodine
18. Back flow of nonpotable materials into the potable water system may occur by
