Plastic cups were used to serve tea in trains in early days- these could be returned to the vendors, cleaned and reused. Later,Kulhads were used instead of plastic cups. Now, paper cups are used for serving tea. What are the reasons for the shift from Plastic to Kulhads and then finally to paper cups?

Explanation

### Step-by-Step Solution:

1. **Introduction to the Use of Plastic Cups**:
- In the early days, plastic cups were commonly used for serving tea in trains. They were convenient and could be cleaned and reused.

2. **Environmental Concerns with Plastic**:
- Over time, it became evident that the widespread use of plastic cups led to significant environmental issues. Plastic is non-biodegradable, meaning it does not break down naturally in the environment.
- The accumulation of plastic waste resulted in pollution, harming ecosystems and contributing to the degradation of the environment. Additionally, burning plastic releases toxic fumes, leading to air pollution.
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