**4. Conclusions**

The GF-AAS method developed was efficient (highly sensitive and acceptable in terms of accuracy and reliability) to quantify Cd in thermoformed and biodegradable flexible films and cassava flour samples. The method is therefore reliable, with low variation coefficients, and limits of detection and quantification that indicate that the standardized method is optimal.

The concentrations that were found in the samples of thermoformed and flexible films, are below the amounts allowed for products that come into contact with food (1 mg/Kg), but, as mentioned above care needs to be taken as Cd bioaccumulation can lead to grave environmental problems.

Cd content found in thermoformed films is associated with prior contamination of the raw material (during cultivation, pretreatment, and/or transportation) or contamination derived from old machinery used for manufacturing.

This study also provides new data for food safety authorities and which broaden the existing knowledge of the contribution of raw materials in terms of Cd concentrations in biopolymers.

There is great potential in using biopolymers in packaging and food conservation, in terms of the value these materials add to agricultural activity and in helping to reduce nonbiodegradable plastics in the environment.
