Explanation:

Correct: Plastic molecules typically have longer carbon chains compared to those in LPG or diesel fuels. Plastics are made up of long chains of polymers, which are larger and more complex than the hydrocarbon molecules in fuels.

Correct: Dioxins tend to accumulate in the food chain, particularly in the fatty tissues of animals. This process is known as bioaccumulation and can lead to higher concentrations of dioxins in top predators.

Incorrect: Dioxins are environmental pollutants. They are known to be highly toxic and can cause a range of environmental and health problems.

Therefore, statements 1 and 2 are correct.