Environmental Health Practice Questions

Q: How is animal waste typically disposed of?

Incineration. **Explanation:** In the context of Biomedical Waste (BMW) Management, **Animal Waste** (Category 2 under the old rules, now part of **Yellow Category** waste) includes animal tissues, organs, body parts, carcasses, and fluid. **1. Why Incineration is Correct:** According to the **Biomedical Waste Management Rules (2016)**, anatomical waste—both human and animal—must be disposed of via **Incineration** or **Deep Burial** (the latter only in remote/rural areas where incineration is unavailable). Incineration is the preferred method because it involves high-temperature thermal oxidation, which reduces the organic matter to inorganic, incombustible ash. This process ensures the complete destruction of pathogens and prevents the illegal trade of animal parts. **2. Why Incorrect Options are Wrong:** * **Autoclave (B) & Microwave (C):** These are methods of **disinfection/sterilization** rather than final disposal. They are primarily used for **Red Category** waste (contaminated plastics) and **White Category** waste (sharps). While they kill microbes, they do not reduce the volume of anatomical waste or change its physical appearance, making them socially and aesthetically unacceptable for animal carcasses or body parts. **3. NEET-PG High-Yield Pearls:** * **Color Coding:** Animal waste belongs to the **Yellow Category** bag (non-chlorinated plastic). * **Temperature Standards:** A double-chambered incinerator must maintain **850°C (±50°C)** in the primary chamber and **1050°C (±50°C)** in the secondary chamber. * **Retention Time:** The gas residence time in the secondary chamber must be at least **2 seconds** to ensure complete combustion of volatile organic compounds. * **Prohibition:** Cytotoxic drugs and radioactive waste should **never** be incinerated.

Q: Which of the following statements about the pasteurization of milk is FALSE?

It causes a greater than 95% decrease in bacterial count.. **Explanation** Pasteurization is a heat-treatment process designed to make milk safe for human consumption by eliminating pathogenic microorganisms while minimizing chemical and physical changes. **Why Option C is the Correct (False) Statement:** The primary goal of pasteurization is the destruction of all pathogenic organisms. Regarding the total bacterial load, standard pasteurization (such as the Holder method or HTST) is expected to achieve a **99% to 99.9% reduction** in the bacterial count, not just 95%. A 95% reduction would be considered inadequate by public health standards. **Analysis of Other Options:** * **Option A (True):** Thermoduric bacteria (e.g., *Micrococcus*, *Bacillus*) can survive the heat of pasteurization. While they do not cause disease, they can contribute to milk spoilage. * **Option B (True):** Pasteurization is not sterilization. It is ineffective against bacterial spores (e.g., *Clostridium*, *Anthrax*), which require higher temperatures (autoclaving) to be destroyed. * **Option C (True):** *Mycobacterium tuberculosis* is the index organism for pasteurization because it is the most heat-resistant non-spore-forming pathogen. If the process kills the tubercle bacillus, it is assumed all other common pathogens (like *Salmonella* and *Brucella*) are also destroyed. **High-Yield NEET-PG Pearls:** 1. **Methods:** * **Holder Method:** 63–66°C for 30 minutes. * **HTST (High-Temperature Short-Time):** 72°C for 15 seconds (followed by rapid cooling to 4°C). 2. **Phosphatase Test:** This is the gold standard test to check the efficacy of pasteurization. If the enzyme phosphatase is absent, pasteurization was successful. 3. **Coxiella burnetii:** This is now considered the most heat-resistant pathogen in milk (causing Q fever); modern pasteurization standards are specifically calibrated to ensure its destruction.

Q: Rupture of an eardrum may occur at a noise level above:

160 dB. **Explanation:** The correct answer is **160 dB**. This question tests the physiological thresholds of the human ear in response to sound intensity (measured in decibels). **1. Why 160 dB is correct:** Noise levels are categorized based on their physiological impact. At **160 dB**, the sound pressure is so intense that it can cause immediate mechanical damage, specifically the **rupture of the tympanic membrane (eardrum)**. This level is typically associated with explosive blasts or being in extremely close proximity to a jet engine. **2. Analysis of Incorrect Options:** * **80 dB:** This is the threshold for "annoyance" or loud conversation. It does not cause immediate physical damage. * **90 dB:** This is the **Maximum Permissible Exposure** level for an 8-hour workday (as per OSHA/Indian standards). Prolonged exposure above this level leads to Noise-Induced Hearing Loss (NIHL), but not acute rupture. * **120 dB:** This is the **Threshold of Pain**. At this level, the listener experiences physical discomfort and pain in the ear, but the eardrum remains intact. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Threshold of Hearing:** 0 dB. * **Normal Conversation:** 60–65 dB. * **NIHL Character:** Typically presents as a "notching" at **4000 Hz** on an audiogram (Boiler-maker's deafness). * **Rule of thumb:** For every 5 dB increase above 90 dB, the permissible exposure time is halved (e.g., 90 dB for 8 hours, 95 dB for 4 hours). * **Temporary Threshold Shift (TTS):** Reversible hearing loss occurring at 4000 Hz; permanent damage occurs with repeated exposure.

Q: Which of the following insecticides is a natural product?

Pyrethrum. **Explanation:** The correct answer is **Pyrethrum (Option B)**. **Why Pyrethrum is the correct answer:** Pyrethrum is a potent, rapid-acting natural insecticide derived from the dried flower heads of ***Chrysanthemum cinerariaefolium***. The active principles, known as **pyrethrins**, act as nerve poisons that cause immediate paralysis (the "knock-down" effect) in insects. Because it is a natural botanical product, it is relatively non-toxic to mammals and is biodegradable, making it a preferred choice for indoor sprays and space sprays (e.g., against mosquitoes and houseflies). **Why the other options are incorrect:** * **A. Dieldrin:** This is a synthetic **Organochlorine** compound. It is highly persistent in the environment and has been largely banned globally due to its toxicity and bioaccumulation. * **C. Parathion:** This is a synthetic **Organophosphorus** compound. It is a potent acetylcholinesterase inhibitor and is highly toxic to humans, often associated with acute poisoning cases. * **D. Carbaryl:** This is a synthetic **Carbamate** insecticide. Like organophosphates, it inhibits cholinesterase but the binding is reversible. **High-Yield Facts for NEET-PG:** * **Knock-down effect:** Characteristic of Pyrethrum; it paralyzes insects almost instantly. * **Synergist:** Pyrethrum is often mixed with **Piperonyl Butoxide** to enhance its efficacy by inhibiting the insect's detoxifying enzymes. * **Synthetic Pyrethroids:** These are man-made versions (e.g., **Permethrin, Deltamethrin**) used in Long-Lasting Insecticidal Nets (LLINs). They are more stable in sunlight than natural pyrethrum. * **Paris Green:** Another high-yield "natural" related term; it is an inorganic copper-acetoarsenite compound used historically as a larvicide.

Q: What is the optimum floor space recommended per adult person in a house?

70–90 sq. ft.. ### Explanation **Concept Overview:** In Community Medicine, housing standards are defined to prevent overcrowding, which is a significant risk factor for the transmission of respiratory infections (like Tuberculosis and Influenza) and skin infestations. The **optimum floor space** is a key metric used to determine the "degree of overcrowding" in a dwelling. **Why Option B is Correct:** According to standard public health guidelines (Park’s Textbook of Preventive and Social Medicine), the recommended floor space for an adult is **70–90 sq. ft.** This space is considered sufficient to ensure adequate ventilation and maintain physical distance to minimize the spread of droplet-borne diseases. **Analysis of Incorrect Options:** * **Option A (101–150 sq. ft.):** This exceeds the minimum public health requirement. While more space is better for comfort, it is not the "optimum" standard used for assessing overcrowding in public health statistics. * **Options C & D (151–250 sq. ft.):** These values are significantly higher than the recommended threshold. In the context of national housing policies and social medicine, standards are set at the minimum functional level required to maintain health. **High-Yield Facts for NEET-PG:** * **Overcrowding Criteria:** A house is considered overcrowded if two persons over 9 years of age (of opposite sexes, not being husband and wife) must sleep in the same room. * **Space per Person (Standard Table):** * 110 sq. ft. or more: 2 persons * 90–110 sq. ft.: 1.5 persons * 70–90 sq. ft.: 1 person * 50–70 sq. ft.: 0.5 person (infant) * Under 50 sq. ft.: Nil * **Age Adjustments:** For calculation, a baby under 12 months is not counted; a child between 1–10 years counts as **half a unit** (0.5); and anyone over 10 years counts as **one unit**.

Q: What is the percentage of available chlorine in bleaching powder?

33%. **Explanation:** **Bleaching powder (Chlorinated lime)** is a chemical compound (Calcium hypochlorite) used extensively in public health for the disinfection of drinking water and sanitary disposal of waste. 1. **Why 33% is Correct:** Freshly manufactured bleaching powder contains approximately **33% available chlorine**. This "available chlorine" is the active oxidizing agent responsible for killing pathogens. Over time, bleaching powder is unstable; it loses its chlorine content when exposed to air, light, or moisture. For effective water disinfection, the powder used must have a chlorine content of at least 20% to 33%. 2. **Analysis of Incorrect Options:** * **10%:** This is too low for fresh bleaching powder. If the chlorine content falls below 20%, the powder is considered "weak" or "spent" and is generally discarded for large-scale water treatment. * **66%:** This value is associated with **High-Test Hypochlorite (HTH)** or Perchloron. HTH is a more stable, concentrated form of calcium hypochlorite containing 60–70% available chlorine. * **95%:** This concentration is not found in bleaching powder. Pure elemental chlorine gas or liquid chlorine approaches this level of purity but is not used in powder form. **High-Yield Clinical Pearls for NEET-PG:** * **Horrocks' Apparatus:** Used to estimate the dose of bleaching powder required to disinfect a specific volume of water. * **Contact Time:** For effective chlorination, the water must be in contact with chlorine for at least **30 to 60 minutes**. * **Orthotolidine (OT) Test:** Used to detect **Free Residual Chlorine** (ideal level: 0.5 mg/L after 1 hour). * **Storage:** Bleaching powder should be stored in a **cool, dark, and dry place** in airtight containers to prevent the loss of chlorine.

Question 1

How is animal waste typically disposed of?

Accepted Answer

Incineration

Answer

Autoclave

Answer

Microwave

Answer

None of the above

Question 2

Which of the following statements about the pasteurization of milk is FALSE?

Accepted Answer

It causes a greater than 95% decrease in bacterial count.

Answer

It does not kill thermoduric bacteria.

Answer

It does not kill spores.

Answer

It kills the tubercle bacillus.

Question 3

Which one of the following statements concerning Radon is NOT true?

Accepted Answer

Radon decays by alpha emission.

Answer

Radon is a single largest contributor to an individual's background radiation dose.

Answer

The most stable isotope, 222Rn, has a half-life of 3.8 days.

Answer

Radon is implicated in lung cancer.

Question 4

Rupture of an eardrum may occur at a noise level above:

Accepted Answer

160 dB

Answer

120 dB

Answer

90 dB

Answer

80 dB

Question 5

Which of the following insecticides is a natural product?

Accepted Answer

Pyrethrum

Answer

Dieldrin

Answer

Parathion

Answer

Carbaryl

Question 6

Dental fluorosis is best seen in which of the following teeth?

Accepted Answer

Central Incisors & 1st Molars

Answer

Central & Lateral Incisors

Answer

1st & 2nd Molars

Answer

Canines

Question 7

What is the optimum floor space recommended per adult person in a house?

Accepted Answer

70–90 sq. ft.

Answer

101–150 sq.ft.

Answer

151–200 sq.ft.

Answer

201–250 sq. ft.

Question 8

What is the percentage of available chlorine in bleaching powder?

Accepted Answer

33%

Answer

10%

Answer

66%

Answer

95%

Question 9

An epidemiologic study of a community shows an increased incidence of basal cell and squamous cell carcinomas in adults. These lesions are distributed predominantly on palms and soles. Analysis of groundwater pumped from wells for drinking shows increased levels of heavy metal used in pressure-treated lumber (with a greenish hue), insecticides, and herbicides. Which of the following metals is most likely implicated by this study?

Accepted Answer

Arsenic

Answer

Beryllium

Answer

Cadmium

Answer

Lead

Question 10

Disinfection of water is not required if the source is from which of the following?

Accepted Answer

Tube well

Answer

Step well

Answer

Draw well

Answer

River

Environmental Health — MCQs

Environmental Health — MCQs

On this page

Practice by Chapter

Want unlimited practice?