(6) If the analysis of a sample provided under subsection 320.28(4) demonstrates that the person has a drug in their body that is of a type that the evaluating officer has identified as impairing the person’s ability to operate a conveyance, that drug — or, if the person has also consumed alcohol, the combination of alcohol and that drug — is presumed, in the absence of evidence to the contrary, to be the drug, or the combination of alcohol and that drug, that was present in the person’s body at the time when the person operated the conveyance and, on proof of the person’s impairment, to have been the cause of that impairment.

(4) For the purpose of paragraphs 320.14(1)(b) and (d), if the first of the samples of breath was taken, or the sample of blood was taken, more than two hours after the person ceased to operate the conveyance and the person’s blood alcohol concentration was equal to or exceeded 20 mg of alcohol in 100 mL of blood, the person’s blood alcohol concentration within those two hours is conclusively presumed to be the concentration established in accordance with subsection (1) or (2), as the case may be, plus an additional 5 mg of alcohol in 100 mL of blood for every interval of 30 minutes in excess of those two hours.