Lifetime average daily dose

The ADD is the dose rate averaged over a pathway-specific period of exposure expressed as a daily dose on a per-unit-body-weight basis (US-EPA 1997). The ADD is used for exposure to chemicals with noncarcinogenic or nonchronic effects. Eor compounds with carcinogenic or chronic effects, the lifetime average daily dose (LADD) is used. The LADD is the dose rate averaged over a lifetime. The C refers to the concentration of the contaminant in inhaled air. The ED refers to the total time an individual is exposed to an air pollutant. 

The doses from exposure are characterized by distributions. For each possible dose level, these distributions quantify the probability that an individual in a specified population or subpopulation will receive that dose level as a result of exposure to atrazine and simazine through drinking water ingestion, dietary consumption, herbicide handling, or a combination of these potential exposure routes. For chronic toxic endpoints, the traditional (default) dose metric summarizing a lifetime of exposure is the lifetime average daily dose (LADD). Distributions of LADDs have been determined, and the corresponding distributions of the MOEs are presented herein. 

Lifetime average daily dose (LADD) is the total dose of a specified substance an individual receives in a lifetime, divided by the total number of days in that lifetime. The LADD is frequently expressed on a per unit body weight basis (e.g., mg/kg/d). 

The potential for non-carcinogenic health effects associated with exposure of local residents to POPs in locally consumed food items and the ambient air was evaluated by calculating the relevant HQ for individual POPs. The HQ was defined as the ratio of the estimated lifetime average daily dose (LADD) of POPs from dietary (Table 7.6) and inhalation... 

Figure 4 Relative contribution by exposure route to predicted dose Estimated population lifetime average daily dose of arsenic for children exposed to chromated copper arsenate (CCA)-treated wood playsets and decks in warm climate regions (from Zartarian et al., 2006).

In the Monte Carlo approach, there are no inherent limitations on the complexity of the exposure equation, the number of component variables, the probability distributions for the variable components, or the number of iterations. This freedom from limitations is especially useful in simulating the distributions of a lifetime average daily dose (LADD) for the different exposure scenarios considered herein. As its name suggests, a LADD is the average over all of the days in an individual s lifetime of the dose of a chemical (e.g. atrazine, simazine, or both) received by that individual in those days as a result of his or her exposure from one or more exposure pathways (e.g. water, diet and herbicide handling). Because the exposure equation can explicitly consider each day individually, the values of the equation s variable components can vary from day to day and have different distributions for different ages. The length of an individual s lifetime can also vary from individual to individual. 

Monte Carlo techniqnes allow the distributions of the LADDs for the combined exposure pathways for atrazine or simazine to be appropriately determined. It has been assumed herein that it is appropriate to add the absorbed doses from each route (ingestion, inhalation and dermal) and each pathway (drinking water, diet and herbicide handling) together. Thns, the LADD distribntion is the distribution among individuals of the lifetime average of the sum of the individual s daily doses from the different exposnre pathways and routes. The individual s lifetime average daily doses from the different pathways and rontes are summed, and then the distribution of these snms in a popnlation or snbpopnlation is determined. 

Lifetime average daily dose (LADD) Dose that is averaged over an individual s lifetime, taking into account the frequency, duration and intensity of exposure events. LADDs are usually expressed in units of mg/kg/d (USEPA,... 

In contrast to acute or short-term estimates of exposure, for purposes of chronic or long-term exposure and risk assessments, such as evaluation of potential lifetime excess cancer risk, regulatory agencies typically set the averaging time at that of an average lifetime (e.g., 70 or 75 years times 365 days year ) to obtain the lifetime average daily dose. 

ADI Acceptable daily intake LADD Lifetime average daily dose... 

New dose metrics should be used that incorporate age or time dependence on the dose level rather than a lifetime average daily dose or its analog for a shorter time period... 

Because it is a probability, risk is expressed as a fraction, without units. It takes values from 0 (absolute certainty that there is no risk, which can never be shown) to 1.0, where there is absolute certainty that a risk will occur. Values between 0 and 1 represent the probability that a risk will occur.16 We say that the lifetime cancer risk from carcinogen A at an average daily dose of B is one in 100000 (0.000 01) if this number is accurate, it means that one of every 100000 people exposed to carcinogen A at a lifetime average daily dose of B will develop cancer over a lifetime. The probability also describes the extra risk incurred by each individual in that exposed population. 

To assess a carcinogen, doses are usually averaged over a lifetime and are presented as lifetime average daily doses (LADDs), even though exposure does not... 

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