Roughness dose effect

Ferguson and Bowman 1990 Gilbert and Rice 1987 Hopper et al. 1986 Krasovskii et al. 1979 Levin et al. 1988 Massaro and Massaro 1987 Overmann 1977 Rice 1985a). It appears that animals are affected at roughly the same blood lead levels as humans. Measured neurotoxic effects in animals include significantly delayed motor function and reflexes, decreased performance on learning tasks, and impaired spatial discrimination. Additional animal studies are needed to investigate the neurotoxic effects of subchronic inhalation exposures to establish external dose-effect relationships. 

Diaryl derivatives with a hydroxyl group at another site in the alkylene chain are represented by BRL 14342 (78). Some structural relationship with (76) and (77) may be seen in this compound, which is currently undergoing tolerance and EEC studies in human volunteers. The results suggest that (78) is a potent nondepressant CNS-active drug [220]. The compound is a 60 40 mixture of the two possible diastereoisomers (racemates ), which are of approximately equal activity [220]. It is stated that the (—)-isomer shows fewer peripheral anticholinergic effects than the (+)-form. The (+)-isomer is more active than the (—)-isomer in the reserpine reversal test at low doses, but the 2 isomers have roughly equal effects in tests on prevention of reserpine-induced hypothermia [221]. Because (78) has 2 chiral centres it is not clear if the optically active compounds are sin e diastereoisomers or mixtures of 2 of them. 

For radiation doses <0.5 Sv, there is no clinically observable iacrease ia the number of cancers above those that occur naturally (57). There are two risk hypotheses the linear and the nonlinear. The former implies that as the radiation dose decreases, the risk of cancer goes down at roughly the same rate. The latter suggests that risk of cancer actually falls much faster as radiation exposure declines. Because risk of cancer and other health effects is quite low at low radiation doses, the iacidence of cancer cannot clearly be ascribed to occupational radiation exposure. Thus, the regulations have adopted the more conservative or restrictive approach, ie, the linear hypothesis. Whereas nuclear iadustry workers are allowed to receive up to 0.05 Sv/yr, the ALARA practices result ia much lower actual radiatioa exposure. 

In exposures by inhalation of airborne materials, the dose is the concentration multiplied by the time (CT), and is roughly a constant for any given material and specified effect. The CT value can be used to provide a rough approximation of other combinations of concentration and time which would have about the same effect. Although this concept must be used very cautiously and cannot be applied at extreme conditions of either concentration or time, it is most important in setting limits for airborne contaminants and physical agents in respect to environmental exposures. The worker is exposed for various periods of time, day after day, to the... 

Radiation adversely affects limb regeneration of amphibians, alters DNA metabolism, and increases the frequency of chromosomal aberrations and liver lesions (Table 32.25). In some species of amphibians and reptiles, as in many mammals, mortality rates after acute exposure to radiation do not stabilize within 30 days — effectively invalidating the conventional LD50 (30-day postexposure) value. In the rough-skinned newt (Taricha granulosa), for example, the minimal LD50 dose at 200 days after irradiation was 2.5 Gy, compared with 350 Gy at 30 days (Willis and... 

I predicted vindication, but darned if the five charts he picked at random didn t prove to be less than convincing. The TRIs matched up only roughly with the doses. Henry said very little, but I got his message and elected to retreat to the safer ground of conventional statistics. In the end, estimates of effectiveness came out about the same, but the psychologists had at least won a minor victory. 

Fig. 11 This subject was one of 8 volunteers who participated in Project Dork, previously described in Chapter 14. Performance scores dropped rapidly when physostigmine was withheld, but returned to near normal when resumed. Heart rate responded similarly. Total amount of physostigmine given was roughly 100 mg (expressed as oral dose equivalent). Note that physostigmine by injection is approximately 50% more effective than by the oral route (i.e., 2 mg i.m. 3 mg p.o.)...

Goodman noted that the usual textbook estimates of the lethal dose of atropine (and scopolamine) are undoubtedly too low. With respect to scopolamine, for example, he found 9 cases that survived scopolamine doses of 225-267 mg, 3 cases that survived 324-384 mg and 2 who survived 500 mg.. (Abood also reported personal observation of two recoveries from large oral doses of scopolamine 350 mg and 500 mg, respectively.) These doses are close to the highest reported lethal range for atropine. Since scopolamine has about 7x the potency of atropine centrally, but roughly equal potency peripherally, one can infer that death from belladonnoid drugs is probably due to a peripheral effect - most likely cardiotoxicity. 

The principal effects of carbon tetrachloride in humans are on the liver, the kidneys and the central nervous system. These effects are apparent following either oral or inhalation exposure, and limited data indicate they can occur after dermal exposure as well. All of the effects seen in humans except renal injury are demonstrable at roughly comparable exposure levels in animals, although there are some variations in susceptibility between species that are likely to be related to differences in metabolism. No studies were located regarding reproductive and developmental effects in humans after exposure to carbon tetrachloride. In rats, carbon tetrachloride was not shown to adversely affect reproduction or development. Studies with both mice and rats suggest that sufficiently high doses of carbon tetrachloride may increase the risk of liver tumors in exposed humans. 

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