Mean exposure value

Normally, the geometric mean exposure value is used, with an operator weight of 65 kg and a time period of a typical work day (5 hours) in the EEC calculation. When this is done, the safety factor for application of cyromazine on potatoes is 40. For comparison, the values by the EEC method for individual operators are presented in Table 4. All operators had large safety factors. The values were a6000 by the U.S. EPA method. In the EEC method, any AOEL value greater than 1 is considered acceptable, as the actual safety factor is built into the calculation. The U.S. EPA factors followed the same pattern of high and low values as the EEC results. 

Arithmetic mean exposure value for entire Seychelles cohort. 

The mean exposure limit value for 3-methyl-1-butanol in the air of workplaces was set at 100 ppm in 1984 by the ACGIH (135). Standards have not been set for the other alcohols (135). 

Based on their data, Zimmerli et al u estimated the mean exposure of Swiss adults to HAAs to be 5 ng (kg b.m.) 1 d, comparing this with values of about 2 ng (kg b.m.) d 1 obtained for elderly Swedes and for a US subgroup. They went on to estimate the theoretical cancer risk due to such an intake by extrapolation of the results of long-term animal experiments as 10 4, i.e., one additional tumour induced in a population of 10k individuals exposed during their entire lifespan. For comparison, the comparable risk due to naturally occurring radioactive potassium is 10 3 and the risk of dying by lightening in Switzerland is 10 4 to 10 5. 

FIGURE 3 Overall mean flux values of 17P-estradiol across human vaginal, colonic, and small intestinal mucosa, as determined by flow-through diffusion cells. Flux values (7) were calculated as / = Q/(At), where Q is quantity of 17P-estradiol crossing mucosa (in dpm), A is mucosa area exposed (in cm2), and t is time of exposure (in min). SEM standard error of the mean. (Reprinted with permission from P. van der Bijl and A. D. van Eyk, International Journal of Pharmaceutics, 261,147-152, 2003. Copyright 2003 by Elsevier.)... 

The program provides sensitivity analyses for each stochastic parameter, in which mean exposures or doses as a function of the value of a selected stochastic parameter are depicted and analyzed. 

When calculating chronic dietary exposure, the deterministic models use point values for both food consumption and residue concentration, thereby yielding a point estimate of dietary exposure. In the US, the initial chronic dietary exposure estimate is the Theoretical Maximum Residue Contribution (TMRC) and is analogous to the Theoretical Maximum Daily Intake (TMDI) used to estimate chronic dietary exposure in the EU. Both the TMRC and the TMDI are relatively conservative estimates of dietary expostire. The TMRC is calculated as the product of the mean consumption value and the US pesticide tolerance [6]. In the EU, the TMDI is calculated as the product of the mean consumption value and the Maximum Residue Limit (MRL) [7]. The objective of both calculations is essentially identical to calculate an estimate of the central tendency of the dietary exposure. Both calculated values use the central tendency dietary exposure estimate as the estimate of chronic (long-term) dietary exposure and calculate it using mean consumption data and the maximum residue permitted on the commodity. 

Changes in plasma-ChE activity in dosed and control animals are shown in Table 4. Over the course of the study, plasma-ChE activity levels in dosed and control animals appear to be more stable than RBC-AChE activity. It was reported that plasma-ChE activity was decreased by about 55% in dosed females at week 7, and by 37.5% in dosed males at week 3. Mean plasma-ChE activity in the female controls exhibited a slow increase over the 13-week test period (from 1743 lU/L at week -1 to 2891 lU/L at week 13). A similar response was seen in the two lowest dose groups of females. In males, mean plasma-ChE activity in controls was lower than preexposure levels (401 lU/L at week -1) at all weeks except week 3 (413 lU/L). In the dosed groups of males, mean plasma-ChE levels were lower than pre-exposure values at all sampling times. Statistical analysis of the plasma-ChE activity indicated that mean values were significantly lower than controls in the mid- and high-dose females at weeks -1, 1, 3, and 7 but not at week 13, and in the high-dose males at weeks 3 and 7. 

Indoor (mean) concentrations for benzene range from 8.2 to 17 pgm. Typical values for indoor as well as for outdoor environments were up to 5 pg m For formaldehyde mean indoor concentrations reach values up to 92pgm, while typical values for outdoor air concentrations of 4pgm are reported. Indoor/outdoor (I/O) ratios, based on typical air concentration levels, of 2 and of 50 for benzene and formaldehyde, respectively, are calculated. Daily exposure estimates are based on the assumption that people spend 90% of its time in indoor environments and 10% outdoors. For benzene daily personal exposures vary between 108 and 177pgm for 24h periods, 20% lower than the mean exposures estimated for European citizens. For formaldehyde personal exposures range from 1080 to 2000 pgm over 24 h, rather similar to European exposure estimates. 

First the data were examined for variability. The convenient measure of noise to signal (standard deviation divided by the mean) yielded values which were quite large for a large number of carbon steel exposure tests. Due to this variability and the typically short exposure times, carbon steel was not examined in greater detail. Single year exposures of zinc plates indicated that the relative variability was 3O/S for marine sites, 20% for rural sites, and 10 for industrial sites. The marine sites had the highest... 

Airborne levels of total and respirable manganese were obtained using personal samplers and were not available for years prior to 1997. Using the arithmetic mean of samples collected in 12 different job categories, exposure was estimated for the years prior to 1997. Cumulative exposure values for each worker... 

We and others have reported a series of studies in ammonium perchlorate production workers who are exposed intermittently to perchlorate, resulting in urine perchlorate values of up to 40 mg daily, and in normal volunteers given 3—3 5 mg perchlorate daily for 2 weeks or 0.5 and 3mg daily for 6 months (Lawrence et al, 2000, 2001 Greer et al., 2002 Gibbs et al., 1998 Braverman et al, 2005, 2006). Thyroid function studies, including serum TSH, thyroxine (T4), free T4, and total triiodothyronine (T3), were not affected by perchlorate exposure in the plant or perchlorate administration to normal volunteers, despite a decrease in the thyroid uptake of at the higher exposures. Despite a mean exposure of 3 years to high levels of perchlorate in the production workers, no abnormalities of the thyroid evaluated by ultrasound were detected compared to a nonexposed local population (Braverman etal., 2005). 

There are times when a researcher wants to estimate the mean y values for multiple X values simultaneously. For example, suppose a researcher wants to predict the logio microbial counts (y) at times 1, 10, 30, and 40 sec after the exposures and wants to be sure of their overall confidence at a = 0.10. The Bonferroni procedure can again be used for Xi, X2,..., simultaneous estimates. y ha/2r,n-T) Sy (mean response), where r is the number of x, values estimated y = bo + bix, for i = 1, 2,. .., r simultaneous estimates... 

As a result of the Eleventh Circuit Court of Appeals decision (AFL-CIO versus OSHA), OSHA s permissible exposure level for tetrachloroethylene, which was lowered to 25 ppm in 1989, was returned to 100 ppm (OSHA 1993). Based on human exposure data, Stewart etal. (1981) concluded that a TLV of 100 ppm contained no safety factor for individuals more susceptible to the subjective and neurological symptoms of tetrachloroethylene. Based on human data, the ACGIH (ACGIH 1995) TLV-TWA is 25 ppm. The geometric mean exposure of dry cleaning machine operators was 22 ppm (Ludwig et al. 1983), a value close to the ACGIH TLV-TWA. 

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