Halloween is a time for tricks and treats, but a researcher at New York University (NYU) reveals a scary truth behind seasonal candy like pumpkin-shaped Reese's peanut butter cups and M&M's Ghoul's Mix – they come at a cost of the environment and human rights.

NYU Steinhardt Associate Professor Carolyn Dimitri explains the ways in which candy is produced and consumed during the holiday season greatly impacts the climate, as well as US production systems.

Large areas of forests in the Amazon and other countries are converted into farmland to grow enough ingredients to meet the demand of candy for Halloween and other holidays such as Valentine's Day and Easter.

Deforestation involves 'slashing and burning' to clear vegetation, which results in the emission of greenhouse gasses and the loss of forests means fewer trees to absorb carbon dioxide.

In addition to negative impacts on the environment, these farms use child and trafficked labor to harvest crops.

Every Halloween, 600 million pounds of candy is sold in America, making up the overall 10 percent annual candy sales in the country – and the treats generate nearly $2 billion in sales each year.

When it comes to the impact candy has on the environment, Dimitri gives an example of her favorite treat: Pumpkin-shaped Reese's peanut butter cups.

The chocolate coated peanut butter sweets have three important ingredients: Sugar, palm oil and chocolate.

All are grown in tropical climates and on land that has been deforested.