Human Health Risk Assessment for Priority Substances

Appendix D -- Definitions

Critical Effect: the effect of biological significance expected to occur at the lowest dose or concentration.

LOEL -- Lowest-observed-effect-level: the lowest dose in a toxicity study that results in an observed effect (usually one dosage level above the NOEL).

LOAEL -- Lowest-observed-adverse-effect level: the lowest dose in a toxicity study that results in an observed adverse effect (usually one dosage level above the NOAEL). (An adverse effect is a change in the morphology, physiology, growth, development or lifespan of an organism that results in impairment of its capacity to compensate for additional stress or an increase in its susceptibility to the harmful effects of other environmental influences.)

NOEL -- No-observed-effect level: the highest dose in a toxicity study that results in no observed effects.

NOAEL -- No-observed-adverse-effect level: the highest dose in a toxicity study that does not result in any observed adverse effect. (An adverse effect is a change in the morphology, physiology, growth, development or lifespan of an organism that results in impairment of its capacity to compensate for additional stress or an increase in its susceptibility to the harmful effects of other environmental influences.)

TDI -- Tolerable Daily Intake: the intake to which it is believed that a person can be exposed daily over a lifetime without deleterious effect.

Appendix E -- Reference Values for Intakes and Body Weights of Laboratory Animals

Wherever possible, values reported by the authors in the critical study are used to calculate doses on a body weight basis. Where such data are not provided, the following reference values are used:

Table 1

Reference Values For Body Weights Andintakes In Laboratory Animals¹

Species	Body Weight (kg)	Inhalation Rate (m3/day)	Water Consumption (L/day)	Food Consumption (g/day)	Dose Conversion (1 mg/m3 in air Equals X in mg/kg b.w./day)	Dose Conversion (1 ppm (mg/L) in water Equals X in mg/kg b.w./day)	Dose Conversion (1 ppm in food Equals X in mg/kg b.w./day)
Mouse	0.032	0.042	0.0062	42	1.33	0.20	0.13
Rat	0.352	0.114	0.052	182	0.31	0.14	0.05
Hamster	0.142	0.132	0.032	122	0.93	0.21	0.09
Guinea Pig	0.842	0.402	0.202	342	0.48	0.24	0.04
Rabbit	3.82	2.02	0.412	1862	0.53	0.11	0.05
Rhesus Monkey	8.02	5.42	0.532	3202	0.68	0.07	0.04
Dog	122	4.32	0.612	3002	0.36	0.05	0.03
Cat	1.53	0.753	0.155	1685	0.50	0.10	0.11
Pig	805	--	5.55	2,2505	--	0.07	0.03

1. In most cases, values have been rounded to two significant figures.
2. Calabrese and Kenyon (1991).
3. Flecknell (1987). (Values are averages of the ranges reported).
4. Calculated from the minute volume of 220 mL/kg b.w. reported by Flecknell (1987).
5. Canadian Council on Animal Care (1980-1984). (Values are averages of the ranges reported).

References

CALABRESE, E.J. AND KENYON, E.M. (1991). Air Toxics and Risk Assessment. Lewis Publishers, Inc., Chelsea, Michigan, 612.

CANADIAN COUNCIL ON ANIMAL CARE (1980-1984). Guide to the Care and Use of Experimental Animals. Volumes 1 and 2. Ottawa, Ontario.

FLECKNELL, P.A. (1987). Laboratory Animal Anaesthesia. An Introduction for Research Workers and Technicians. Academic Press, Toronto, 118-132.