Environmental Health and Toxicology

• Due to the ozone depletion, the UV rays are filtered in the Earth's atmosphere. 
• This ray results in the development of various diseases. One of the common disorder is erythema. 
• This is a disease in which there are reddening and swelling of the skin. There is swelling of the mucous membranes. 
• There is an increase in the blood flow from the peripheral capillaries which results in inflammation.
• Thus, the correct answer is option D. 

The ozone layer in the stratosphere is useful because it absorbs the UV radiations from the sun and prevents them from reaching the earth's surface. The depletion of the ozone by the ozone-depleting substances causes the break down of the ozone resulting in the ozone depletion. Due to this, the lives on the earth's surface are exposed to the UV rays. These UV rays induce mutations in the DNA by distorting its structure, leading to the erroneous function and replication of the DNA. The uncontrolled errors at times cause uncontrolled cell proliferation, causing skin cancer.

Ozone is a triatomic gas that forms a shield or layer in the stratosphere region of atmosphere. This layer protects the living beings from harmful effects of UV-B rays of 280-320 nm. Depletion of the ozone layer can lead to an increased incidence of skin cancer.

Ozone depletion allows more harmful UV radiation to reach Earth's surface, which damages skin cells and increases the risk of melanoma (skin cancer). Ozone accumulation would have the opposite effect, while acid rain and allergens are not directly linked to skin cancer.

Ozone is an inorganic molecule. It is a pale blue gas with a distinctively pungent smell. In the environment ozone is known for its both harmful and useful effects.
Ozone present in stratosphere is useful as it act like shield and protect the earth from harmful UV-rays which can cause serious problems like skin cancer and decrease in level of photosynthesis. Ozone present in troposphere act as pollutant and have many deleterious effects. 

Therefore, the correct answer is option C.

Ozone depletion causes the harmful UV-B radiations to strike the earth surface. These radiations are capable of causing various health issues like malignant skin cancers, cataract, decreased immunity, decreased primary productivity, chlorophyll bleaching etc. 

The ever increase in the use of ozone-depleting substances like CFCs, HFCs, methyl bromide etc. will continue destroying the ozone layer in the stratosphere. The depletion of the ozone layer will result in the penetration of more UV-A and UV-B radiations to the earth surface. These radiations are strong mutagens as they distort the structure of the skin cell DNA when the skin is exposed to the UV rays. It results in skin related disorders like pigmentation, skin cancer etc. 

The exposure to the UV radiations have an ionizing and distorting effect to the body of the humans. It causes damage to the eyes by destroying the essentials of the eye-lens. The sunburn occurs due to high intensity. Skin cancer is caused due to distortion of the DNA by the formation of the pyrimidine dimers, such that the DNA cannot be replicated properly.

The atomic bomb dropped on Hiroshima in August 1945 utilized nuclear fission, which released lethal doses of ionizing radiation, causing immediate and long-term deaths from radiation sickness and cancer. The other options involved conventional warfare without nuclear weapons.

While environmental factors can influence mental health, depression is primarily classified as a psychiatric disorder with complex genetic, biological, and psychosocial causes, whereas asthma, cancer, and birth defects have well-established direct links to chemical and physical pollutants in the environment.

Overfilling the engine oil allows the rotating crankshaft to contact the oil in the oil pan, whipping it into a foam. This aerated oil contains bubbles that cannot be pumped effectively, leading to a loss of oil pressure and reduced lubrication to critical engine components.

Bacteria are single-celled organisms; while many are beneficial for digestion and food production, pathogenic bacteria can cause severe, life-threatening infections. Hormones and enzymes are essential biological molecules produced by our bodies, not external organisms that threaten us.

Diphtheria toxin is an exotoxin that binds to cell receptors, enters the cell, and inhibits protein synthesis, causing cells to stop functioning. This leads to systemic complications affecting breathing, heart rate, and kidney function.

Living in close proximity to domesticated animals allowed pathogens to jump from animals to humans, leading to many infectious diseases. While domestication required more time and led to permanent settlements, these are not primarily negative biological threats like zoonotic diseases.

Free radicals are highly reactive, unstable molecules with unpaired electrons that can damage cells, proteins, and DNA through oxidative stress.