Ratio of toxicant exposure (estimated or measured) to a reference value regarded as corresponding to a threshold of toxicity: if the total hazard quotient from all toxicants to a target exceeds unity, the combination of toxicants may produce (will produce under assumptions of additivity) an adverse effect. RT hazard, pollutant, toxic substance.
The ratio of a single substance exposure level over a specified time period (e.g., sub-chronic) to a reference dose for that substance derived from a similar exposure period.
is used to measure potential human health hazards from noncarcinogenic substances. The HQ is the ratio of the daily intake of a specified noncarcinogenic substance during a specified time period over (divided by) a reference dose for a similar time period. If the HQ exceeds one, the possibility exists for systemic toxic effects. HQ = Daily intake/Reference dose.
the ratio of a single contaminant exposure level over a specified time period to a reference dose for that contaminant derived from a similar period. [Source: Virginia Voluntary Remediation Regulations, 9 VAC 20-160-10
An indicator of health hazard obtained by dividing the average daily dose by the Reference Dose (RfD)
The ratio of the level of exposure of a single hazardous substance in a single medium over a specified time period to a reference dose, which represents a safe level, derived for a similar time period.
The ratio of estimated site-specific exposure to a single chemical from a site over a specified period to the estimated daily exposure level, at which no adverse health effects are likely to occur.
The ratio of an exposure level to a substance to a toxicity value selected for the risk assessment for that substance (e.g., LOAEL or NOAEL).