In Guerrero, children help their parents grow poppies

Meztli has a thin black layer on the tip of her nails and her hands are a little scratched by fine blades.

"It is not dirt, it is gumpaste," she explains. "What I like the most in this town are poppies," she adds.

Her family plants poppies because "it is the only crop that gives them money". The rest, such as corn and beans, are for self subsistence, she explained on a hill at more than 2,000 meters (6,500 feet) above sea level. 

In order to extract 700 grams (1.5 pounds) of gum, used to produce opium, the family needs four months of work, and is paid 2,000 pesos (US$127). Sometimes they take the seed from the dead flowers, because buying them costs 500 pesos (US$31) per kilo.

The girl explained that now she rarely goes to the poppy plantations because now that she is bigger, she can accidentally step on the flowers and kill them. That is the reason for which children are tasked to extract the gum from the poppies by incising the pods with a razor. Each plant can be lanced up to 15 times.

Meztli, who has worked since she was five, is one of the more than three million children who work in Mexico. The Tlachinollan Human Rights Center says that instead of investing in programs to prevent planting of illegal crops, the government sends troops to the area.

According to the Drug Enforcement Administration (DEA) 42% of the heroin used in the United States is produced in Mexico and Guerrero is the main grower.