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1

What is the most common method of expressing concentrations in veterinary toxicology (animal tissues, feed, water, solvents, etc.)?

Part per million (ppm) on weight/weight basis

2

1 ppm =

1 mg/kg
1 microgram/gram

3

1 ppb =

1 microgram/kg

4

1 ppt =

1 ng/kg

5

ppm to percentage: 1 ppm =

0.0001%

6

How do you convert from ppm to percentage?
How do you convert from percentage to ppm?

Move the decimal point 4 places to the left
Move the decimal point 4 places to the right

7

How to make a diluted solution from a concentrated stock solution

The mL needed from the stock = (% required dilution) x (volume required in mL) / (% of the stock)

8

You want a pig feed to contain 300 ppm arsanilic acid as a growth promoter. How many grams are needed per ton?

100 g/ton = 110 ppm
300/110 = (X g/ton) / (100 g/ton)
X = 273 g/ton

9

A feed additive for piglets was added at a concentration of 220 ppm. How much is needed for 8 tons?

100 g/ton = 110 ppm
(220/110) = (X g/ton) / (100 g/ton)
X = 200 g/ton
200 g/ton x 8ton = 1.6 kg

10

Conversion from the level of drug in feed as ppm to toxicity (mg/kg)

Toxicity (mg/kg) = (ppm in feed) x (% of feed consumed daily)

11

If the toxic level of drug in feed is 50 ppm for a 20 pound pig, what is the calculated toxicity in mg/kg if 20 pounds pig eats 8% of its body weight?

Toxicity (mg/kg) = (ppm in feed) x (% feed consumed)
Toxicity = 50 x 0.08 = 4

12

Conversion from toxicity (mg/kg) to level in feed as ppm

Level in feed (ppm) = (toxicity in mg/kg) / (% feed consumed daily)

13

What is the rule for estimating dosages when exposure is based on consumption of green forage that has been sprayed?
What 2 assumptions is this rule based on?

Every animal ingests green forage that has been sprayed by a chemical at the rate of 1 lb/acre, will be approximately exposed to 7 mg/kg body weight
1) Good quality pasture will produce approx. 45 g green forage per square foot
2) Grazing animals consume 3% of their body weight green forage