Toxicology

Question 0

Threshold Limit Value (TLV)

Answer 0

airborne concentrations of substances to which it is believed that nearly all workers may be repeatedly exposed w/o adverse effects

Question 1

Gaseous Mixture TLV

Answer 1

Mixture TLV exceeded if
C(1)/T(1) + C(2)/T(2)… > 1
C: observed concentration of components
T: TLVs of components
Assumes all components have similar effects

Question 2

TLV-TWA

Answer 2

TLV Time-Weighted Average
(E(1) * T(1) + E(2) * T(2)…) / T(t)
E: exposure for that interval
T: duration of that interval
t: total
Time-weighted average, in an 8hr period in a 40-hr wk, to which nearly all workers may be repeatedly exposed w/o expected adverse effects.

Question 3

TLV-C

Answer 3

TLV Ceiling

Maximum concentration of a chemical that should not be exceeded even momentarily.

Question 4

TLV-STEL

Answer 4

TLV Short Term Exposure Limit
The maximum amount of a substance to which a person may be exposed for no more than 15 minutes w no expectation of adverse effects.

Question 5

Liquid Mixture TLV

Answer 5

TLV(mixture) = 1 / ((f(1)/TLV(1)) + (f(2)/TLV(2))…)
F(n): weight % of each liquid component
TLV(n): TLV for each liquid component in mg/m^3

Question 6

TLV Conversion

Answer 6

mg/m^3 = (TLV(ppm) *MW) / 24.45

ppm = (TLV(mg/m^3) * 24.45) / MW

MW: molecular weight