**8. Radioactive waste management**

**Herbicide**

Paraquat Paraquat Bispyribac sodium

Imazamox Penoxsulam Propoxycarbazone

*Bromus tectorum*

Sodium

*Echinochloa crus-galli*

Resistant Susceptible

Resistant Susceptible

= (=) % absorbed of the total applied radioactivity, % translocate of the total absorbed, and amount of metabolites formed were similar in resistant and susceptible weeds.

(↓) values were lower in this biotype. (↑) values were higher in this biotype. NA: non-available.

Absorption, translocation, and metabolism of 14C-herbicides in resistant and susceptible weeds.

**Table 1.**

=

=

=

↑ ↓

Park et al. [37]

=

=

=

*Echinochloa crus-galli*

Resistant Susceptible

=

=

*Echinochloa crus-galli*

Resistant Susceptible

=

=

*Hordeum leporinum*

Resistant Susceptible

=

=

**Weed** *Crassocephalum crepidioides*

Resistant Susceptible

=

=

↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ =

= =

NA NA

NA NA

NA NA

NA NA

Riar et al. [8]

Riar et al. [8]

Riar et al. [8]

Preston et al. [7]

170 Herbicide Resistance in Weeds and Crops

**Biotype**

**Absorption**

**Translocation**

**Metabolism**

**Reference**

Ismail et al. [36]

The use of 14C-herbicide generates some waste that can be in the form of liquid scintillation vials, refuse, and biological waste. The volumes of the waste generated in research activities using 14C-herbicide are much smaller than those generated by reactor and fuel reprocessing operations; however, it still needs to be managed if the activity is superior of a certain threshold. This threshold will depend solely on which state of matter the waste is presented.

In Brazil, the *Comissão Nacional de Energia Nuclear* (CNEN) determines that if the solid waste activity is above 1 × 104 kBq/kg (Norm CNEN-NN-8.01, 2014) [38], it must be stored on a flask specific for radioactive solid waste storage with the international radioactive symbol. If the activity is below the same value, it can be discarded as common waste.

The liquid waste generated by the utilization of 14C-herbicide is usually in the form of scintillation solution, and since the organic solvent used in the scintillation solution is not only toxic but also water insoluble, all the radiolabeled scintillation solution must be considered radioactive waste.

Every radioactive waste must be identified with all the information about the radionuclide, including: activity, volume, physical and chemical properties.
