Consider the following statements:

Other than those made by humans, nanoparticles do not exist in nature.
Nanoparticles of some metallic oxides are used in the manufacture of some cosmetics.
Nanoparticles of some commercial products which enter the environment are unsafe for humans.

Which of the statements given above is/are correct?

(a) 1 only

(b) 3 only

(d) 2 and 3

Explanation

The statements can be analyzed as follows:

Incorrect. Nanoparticles do exist naturally in the environment. Natural sources include volcanic ash, mineral springs, sulfur particles from volcanic eruptions, and nanoparticles synthesized by bacteria and other organisms.
Correct. Nanoparticles of metallic oxides like zinc oxide and titanium dioxide are commonly used in cosmetics and skincare products.
Correct. Some engineered nanoparticles released into the environment during manufacture, use or disposal of commercial products can be unsafe for humans and other organisms. They may permeate cells and cause toxicity.

Therefore, statements 2 and 3 are correct.

Nanoparticles occur naturally from sources like volcanoes, mineral springs, atmospheric reactions, plants, algae, fungi and bacteria.
Anthropogenic sources of nanoparticles include vehicle emissions, industrial processes, consumer products with engineered nanoparticles like cosmetics, textiles and medicines.
Natural nanoparticles are formed by physical, chemical and biological processes. Engineered nanoparticles are intentionally produced.
Nanoparticles have a large surface area and can be reactive, mobile and bioavailable. This makes some types toxic to living organisms.
Toxic effects of nanoparticles include inflammation, oxidative stress, DNA damage and cell death. They can permeate cells and organ barriers.
Nanoparticles require proper regulation and safety testing before commercial use to reduce risks to human health and environment.