Exposure response function

Assessment of Exposure-Response Functions for Rocket-Emission Toxicants (1998) Review of a Screening Level Risk Assessment for the Naval Air Facility at Atsugi, Japan (Letter Report) (1998)... 

Assessment of Exposure-Response Functions for Rocket-Emission Toxicants (1998)... 

The second step when determining impacts is the hazard assessment [28]. During the hazard assessment, the impact caused by the exposure to a substance is determined [30]. This is often done using in vitro or in silico testing. The results of the hazard assessment are often presented as dose-response functions. 

Exposure calculation to the emission calculations involving impact of emissions on humans and ecosystem of the emissions means the impact calculation of the dose from the increased concentration. The impact calculation is followed by calculation of impacts (damage in physical units) from this dose, using a dose-response function. The impact of WEEE substances on health and the environment is location specific and is based on conditional, that is to say the way the WEEE is taken care of. Hence, the exposure assessment relates to the population and the ecosystem being exposed to the externalities. 

According to Spadaro and Rabl [41], damage costs of IQ decrement is likely the dominant part of the total damage costs of Pb. The dose-response function has been quite well characterized for Pb, for example by Schwartz [48] in a meta-analysis, who found that the IQ decrement is 0.026 IQ points for a 1 pg/L increase of Pb in blood. Spadaro and Rabl identified two possible ways of linking blood levels of lead to exposure. One of the methods connects incremental exposure of Pb in air to... 

Combining the dose-response function with the exposure/blood level relations, Spadaro and Rabl [41] derived two possible characterization factors of 0.268 and 0.59 IQ points decrement per kg emitted Pb. 

Intraspecies Because the species used was the most sensitive to monomethylhydrazine toxicity and the most closely related to humans, an uncertainty factor of 3 is justified. A factor of 3 was used. Although the mechanism of toxicity is uncertain and sensitivity among individuals may vary, the exposure-response relationship is steep, suggesting limited variability in the toxic response to methylhydrazine. Furthermore, it is likely that acute toxic responses are, at least initially, a function of the extreme reactivity of methylhydrazine. The interaction of the highly reactive monomethylhydrazine with tissues (e.g., pulmonary epithelium) is not likely to greatly vary among individuals. 

If a nonlinear dose-response function has been determined, it can be used with the expected exposure to estimate a risk. If an RfD or RfC is calculated, the hazard can be expressed as a Hazard Quotient (HQ), defined as the ratio of an exposure estimate over the RfD or RfC, i.e., HQ = Exposure/(RfD or RfC). 

Figure 2.3. Dose-response graph for drinking wine. Dose-response function for difficulty in walking and number of glasses of wine consumed. This is an idealized curve, but it illustrates the principle that at low doses (i.e. few glasses) there is little response, then an increasing response to a maximum response. Note that this figure does not take into consideration body weight or any other variables such as gender or frequency of exposure (i.e. time between drinks).

Mutti, A., A. Mazzucchi, P. Rustichelli, G. Frigeri, G. Arfini, and I. Franchini. 1984. Exposure-effect and exposure-response relationships between occupational exposure to styrene and neuropsychological functions. Am. J. Ind. Med. 5(4) 275-286. 

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