Environmental Health — MCQs

Environmental Health Indian Medical PG Practice Questions and MCQs

Question 621: Consider the following : 1. Magnesium Sulphate 2. Calcium bicarbonate 3. Calcium Sulphate 4. Magnesium bicarbonate Hardness of water relates to the presence of which of the above?

A. 1, 2 and 3 only
B. 2, 3 and 4 only
C. 1 and 4 only
D. 1, 2, 3 and 4 (Correct Answer)

Explanation: **Correct Answer: 1, 2, 3 and 4** **Hardness of water** is caused by the presence of dissolved multivalent metallic cations, primarily **calcium (Ca²⁺)** and **magnesium (Mg²⁺)** ions. These ions combine with various anions to form compounds that cause water hardness: - **Magnesium sulfate (MgSO₄)** - Causes **permanent hardness** (cannot be removed by boiling) - **Calcium bicarbonate (Ca(HCO₃)₂)** - Causes **temporary hardness** (can be removed by boiling) - **Calcium sulfate (CaSO₄)** - Causes **permanent hardness** - **Magnesium bicarbonate (Mg(HCO₃)₂)** - Causes **temporary hardness** **Therefore, all four compounds (1, 2, 3, and 4) contribute to water hardness.** *Why other options are incorrect:* *1, 2 and 3 only* - Incorrectly excludes **magnesium bicarbonate**, which is a significant contributor to temporary hardness *2, 3 and 4 only* - Incorrectly excludes **magnesium sulfate**, which contributes to permanent hardness *1 and 4 only* - Incorrectly omits **calcium bicarbonate** and **calcium sulfate**, which are major contributors to both temporary and permanent hardness

Question 622: The installation and usage of sanitary latrines by general public constitutes which level of prevention?

A. Disability limitation and rehabilitation
B. Early diagnosis and treatment
C. Health promotion
D. Specific protection (Correct Answer)

Explanation: ***Specific protection*** - Installation and usage of sanitary latrines is a **specific protective measure** against fecal-oral disease transmission. - This intervention specifically targets diseases like **cholera, typhoid, hepatitis A, amoebiasis, and helminthic infections** by preventing contamination of water and food sources. - Specific protection includes measures like **immunization, water purification, proper excreta disposal, food sanitation, and use of personal protective equipment** - all aimed at protecting against specific disease agents. - Proper sanitation facilities create a **physical barrier** between human excreta and the environment, preventing the spread of specific pathogens. *Health promotion* - This involves **general measures** to improve overall health without targeting specific diseases, such as health education, nutritional counseling, promotion of physical activity, and stress management. - While educating people about the importance of sanitation falls under health promotion, the actual **installation and use of latrines** is a specific protective measure. - Health promotion strengthens host defenses through lifestyle modifications and healthy behaviors. *Early diagnosis and treatment* - This is **secondary prevention** that focuses on early detection of disease through screening programs and prompt treatment to prevent progression. - Examples include mammography for breast cancer, cervical cytology for cervical cancer, and blood pressure screening for hypertension. - Not applicable to sanitary latrine installation, which prevents disease occurrence rather than detecting existing disease. *Disability limitation and rehabilitation* - This is **tertiary prevention** aimed at reducing complications from established disease and restoring function after illness or injury. - Examples include physiotherapy after stroke, cardiac rehabilitation after myocardial infarction, and limb prostheses after amputation. - Not relevant to preventive sanitation measures.

Question 623: What is the correct order of the steps in the rapid sand filtration process for water purification?

A. Alum mixing – flocculation – sedimentation – filtration (Correct Answer)
B. Sedimentation – alum mixing – flocculation – filtration
C. Alum mixing – sedimentation – flocculation – filtration
D. Flocculation – alum mixing – sedimentation – filtration

Explanation: ***Alum mixing – flocculation – sedimentation – filtration*** - This sequence represents the established steps in conventional **rapid sand filtration**, where each stage plays a crucial role in removing impurities. - **Alum mixing** (coagulation) destabilizes particles, **flocculation** consolidates them, **sedimentation** removes larger flocs, and **filtration** traps remaining fine particles. *Sedimentation – alum mixing – flocculation – filtration* - **Sedimentation** occurs *after* coagulation and flocculation, as these processes are needed to create larger, settleable particles. - Starting with sedimentation before preparing the water for efficient particle removal would be ineffective. *Alum mixing – sedimentation – flocculation – filtration* - **Flocculation** (the gentle stirring to form larger flocs) must happen *after* alum mixing (coagulation) and *before* sedimentation. - Placing sedimentation before flocculation would lead to poor particle removal as the flocs would not have fully formed. *Flocculation – alum mixing – sedimentation – filtration* - **Alum mixing** (coagulation) is the initial step to destabilize particles, which then allows for effective flocculation. - Attempting flocculation before coagulation would be ineffective as the particles would not be prepared to aggregate.

Question 624: Which of the following tests is NOT used for checking quality of pasteurisation of milk?

A. Phosphatase test
B. Coliform count
C. Orthotoluidine test (Correct Answer)
D. Standard Plate count

Explanation: ### ***Orthotoludine test*** * The **Orthotoluidine test** is used to detect residual **chlorine** in drinking water. * It is not employed to assess the quality of pasteurization in milk, which focuses on enzyme inactivation and microbial reduction. ### *Phosphatase test* * The **phosphatase test** is the most widely accepted and reliable method for checking the adequacy of **pasteurization** in milk. * It works by detecting the activity of **alkaline phosphatase**, an enzyme naturally present in raw milk that is destroyed at pasteurization temperatures. ### *Coliform count* * The **coliform count** is an indicator of **post-pasteurization contamination** or inadequate sanitation. * While not a direct measure of the pasteurization process itself, a high coliform count suggests a failure in hygiene after heating, indicating poor overall quality control. ### *Standard Plate count* * The **Standard Plate Count (SPC)**, also known as the **aerobic plate count**, measures the total number of viable microorganisms in milk. * A reduction in SPC after pasteurization indicates the effectiveness of the heat treatment in killing bacteria, making it an indirect measure of pasteurization efficiency and overall microbial quality.

Question 625: Biomedical waste from a yellow plastic bag is disposed by:

A. Incineration (Correct Answer)
B. Chemical treatment
C. Microwaving
D. Autoclaving

Explanation: ***Incineration*** - **Yellow bags** are designated for **highly infectious waste**, body parts, anatomical waste, and cytotoxic drugs. - **Incineration** is the preferred method for this waste category due to its ability to completely destroy pathogens and reduce waste volume. *Chemical treatment* - This method is typically used for **liquid infectious waste** or for disinfection of certain instruments. - It's not the primary disposal method for the solid, highly infectious waste found in yellow bags. *Microwaving* - **Microwaving** is a thermal disinfection method used for certain types of infectious waste, especially those containing plastics. - It is generally not suitable for **anatomical waste** or large quantities of highly infectious waste like those in yellow bags. *Autoclaving* - **Autoclaving** is a moist heat sterilization method primarily used for items in **red or blue bags**, such as contaminated plastics, cultures, and sharps (after shredding). - It is not the recommended disposal method for anatomical waste or cytotoxic waste collected in yellow bags.

Question 626: Waste disposal of placenta after delivery is done by

A. Incineration (Correct Answer)
B. Disposal in blue bags
C. Autoclaving
D. Microwaving

Explanation: ***Incineration*** - **Incineration** is the recommended method for disposing of anatomical waste like the placenta due to its effectiveness in destroying pathogens and reducing waste volume. - This method ensures **safe and complete destruction** of potentially infectious material, preventing environmental contamination. *Disposing it in blue bags* - Blue bags are typically used for **general non-hazardous waste** or specific categories of non-anatomical biomedical waste, not for anatomical waste like the placenta. - Disposing of anatomical waste in blue bags would violate **biomedical waste management guidelines** and pose a risk of infection. *Autoclaving* - **Autoclaving** is a sterilization method that uses steam under pressure, primarily for medical instruments and some types of infectious waste. - While it sterilizes, it does not physically destroy or reduce the volume of anatomical waste like incineration does, making it less suitable for placenta disposal. *Microwaving* - **Microwaving** is not a recognized or safe method for the disposal of anatomical waste due to its inability to reliably sterilize or destroy biological material. - It would not achieve the necessary level of **pathogen destruction** required for waste like the placenta and poses safety risks.

Question 627: As per biomedical waste management rule 2016 the metallic body implants should be discarded in which of the following?

A. Separate collection system (Correct Answer)
B. Red colored non-chlorinated plastic bag
C. Yellow colored non-chlorinated plastic bag
D. Card board box with blue colored marking

Explanation: ***Separate collection system*** - Metallic body implants, due to their nature and potential for **recycling or specific disposal methods**, are to be segregated into a **separate collection system** as per BMW Rule 2016. - This ensures they do not contaminate other biomedical waste streams and can be handled appropriately, often involving **recovery of precious metals**. *Red colored non-chlorinated plastic bag* - This category is typically for **reusable contaminated waste** such as tubing, catheters, IV sets, and urine bags, which are often plastic. - Metallic implants are not typically suitable for disposal in red bags because they are not meant for incineration or autoclaving in the same manner as these plastic items. *Yellow colored non-chlorinated plastic bag* - Yellow bags are used for **human anatomical waste**, animal anatomical waste, soiled waste, expired or discarded medicines, and **chemical waste**. - Metallic implants do not fall into any of these categories and require a different disposal method due to their material composition and potential for recycling. *Card board box with blue colored marking* - Blue or white translucent boxes/containers are designated for **sharps**, including needles, syringes with fixed needles, and blades, as well as broken or contaminated glass. - While metallic, body implants are not considered "sharps" in the same context, nor are they typically discarded in cardboard, which is unsuitable for their weight and specific disposal requirements.

Question 628: These toxic effects like abdominal colic, obstinate constipation, loss of appetite, anaemia, stippling of red cells and blue line on gums are due to exposure to:

A. Lead (Correct Answer)
B. Carbon monoxide
C. Radiation
D. Asbestos

Explanation: ***Lead*** - The constellation of symptoms including **abdominal colic**, **obstinate constipation**, **loss of appetite**, **anemia**, **stippling of red cells**, and a **blue line on the gums (Burton's line)** are classic manifestations of **chronic lead poisoning**. - Lead interferes with multiple organ systems, notably the **gastrointestinal**, **hematologic**, and **nervous systems**, causing these specific toxic effects. *Carbon monoxide* - **Carbon monoxide poisoning** primarily affects oxygen transport, leading to symptoms like headache, dizziness, nausea, and in severe cases, coma and death. - It does not cause abdominal colic, obstinate constipation, stippling of red cells, or a blue line on the gums. *Radiation* - **Radiation exposure** can lead to acute radiation syndrome with symptoms like nausea, vomiting, fatigue, hair loss, and damage to rapidly dividing cells, or long-term effects like cancer. - The symptoms described in the question are not characteristic of radiation sickness or exposure. *Asbestos* - **Asbestos exposure** is primarily associated with respiratory illnesses such as **asbestosis**, **mesothelioma**, and **lung cancer**, which develop many years after exposure. - It does not cause acute abdominal symptoms, anemia with red cell stippling, or a blue line on the gums.

Question 629: Orthotolidine (OT) test is done for determining residual free chlorine quantitatively and qualitatively. What is the colour of the solution after adding OT which indicates presence of free chlorine?

A. Blue
B. Green
C. Yellow (Correct Answer)
D. Red

Explanation: ***Yellow*** - The **Orthotolidine (OT) test** historically was used to detect and quantify residual **free chlorine** in water. - When Orthotolidine reagent is added to water containing free chlorine, it produces a **yellow color**, with the intensity of the yellow directly proportional to the amount of free chlorine present. - **Important Note:** The OT test has been **discontinued and is no longer recommended** due to orthotolidine being a **suspected carcinogen**. It has been replaced by safer methods like the **DPD (N,N-diethyl-p-phenylenediamine) test**, which also detects free chlorine but uses a safer reagent. *Blue* - A blue color is not associated with the Orthotolidine test for free chlorine. - Other water quality tests or reagents might yield a blue color for different parameters. *Green* - A green color does not indicate the presence of free chlorine in the Orthotolidine test. - It may suggest interference from other substances or mixed reactions. *Red* - A red color is not the characteristic indicator for free chlorine in the Orthotolidine test. - Red or pink colors are associated with the **DPD method** (the current standard test), which produces a pink/red color in the presence of free chlorine.

Question 630: A vital layer, also known as "Schmutzdecke" is seen in which one of the following ?

A. Air filter
B. Slow sand filter (Correct Answer)
C. Reverse osmosis filter
D. Rapid sand filter

Explanation: ***Slow sand filter*** - A vital biological layer known as **"Schmutzdecke"** or **"filter skin"** forms on the surface of slow sand filters. - This layer, composed of **algae, bacteria, fungi**, and protozoa, is crucial for effective water purification by trapping and breaking down organic matter and pathogens. *Air filter* - Air filters primarily remove particulate matter from air, not water, and do not develop a biological layer like **Schmutzdecke**. - Their mechanism involves mechanical filtration, not biological degradation. *Reverse osmosis filter* - Reverse osmosis filters use a **semi-permeable membrane** to remove dissolved solids and contaminants from water under pressure. - They operate on a physical process and do not rely on the formation of a biological "Schmutzdecke" layer for filtration. *Rapid sand filter* - Rapid sand filters primarily rely on **physical straining** and **coagulation/flocculation** for clarification, followed by backwashing to clean the filter media. - While some biological activity may occur, they do not form a distinct, vital **"Schmutzdecke"** layer as seen in slow sand filters, and their primary mechanism is different.

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