Calculate an Rdf based on dose$-$response data

A rat liver pathology study was conducted over a two$-$year period on animals exposed to Aroclor $1254($Polychlorinated Biphenyl$).$ The findings are displayed below.

Dose mg$/$kg$-$d Mean

Enzyme Level Organ Wt

Change $\%$ Animals with focal necrosis

$0-$ control

$12$

$2550$

$100$

$200$

$5$

$10$

$20*$

$35*$

$42*$

$40*$

$--$

$-2\%$

$+6\%$

$+13\%*$

$+10\%*$

$+12\%$

$--$

$0$

$0$

$2$

$8*$

$*$ Significantly $($statistically$)$ different from control

The agency you work for $($based on information from the literature$)$ has made the policy decisions that an "enzyme level" value of $25$ or greater is defined as adverse and an organ weight change of $10\%$ or greater is adverse.

$1.$a$.$ Using the above table and your agency's policies, fill in the following table. The read is an example of what I am looking for in the asweres.

LEVEL Define What is the value? Explain

NOEL

No Observed Effect Level

$12$ mg$/$kg$-$d There was a statistically significant

change in mean enzyme levels at $25$ mg$/$kg$-$d but not at $12$ mg$/$kg$-$d$.$

LOEL

NOAEL

LOAEL

$1.$b$.$ Based on the information provided above which uncertainties $($Uncertainty factors$)$ would need to be accounted for in the derivation of an RfD or MRL $($Minimal Risk level$)$ from this study?

$1.$c$.$ Calculate an RfD from this study using uncertainty factors as appropriate to account for $1)$ animal$-$human extrapolation, $2)$ LOAEL to NOAEL extrapolation, $3)$ Human variability. Show your work and provide a brief explanation for the uncertainty$/$modification factors. Use your best judgement to estimate the uncertainty factors $($They should be $1,3,$ or $10)$