Acute Effects on Humans

In studies of acute effects on humans caused by exposure to Pb, nephrotoxic effects as well as gastrointestinal effects have been observed [40], Encephalopathy can affect both children and adults. Acute encephalopathy has been shown to increase the incidence of neurological and cognitive impairments. 

Acute Effects on Animals and Humans Due to the poor solubility of thorium and the low radiotoxicity of natural thorium, no acute effects on humans are reported. Cases of severe pneumoconiosis have been described in photoengravers working with rare earth elements/thorium electrodes. 

Future Research Needs. It is obvious that studies on toxicity and carcinogenicity of lipid oxidation products, as they occur in food, are in their infancy. It is still not established that any of these compounds constitute a threat to public health. It is certain that, at the levels normally encountered in foods, acute effects on humans would not be seen. The chronic area remains an enigraa. It is known that levels of MA in foods have been overstated by the TBA test. Extensive studies are urgently needed to quantify free MA directly by HPLC (32). Further investigations are also necessary to determine more fully the toxicity of MA. 

What effects does it have on humans and other animals Well, the acute effects on humans (e.g., workers in the DDT-manufacturing plants) are not lethal. It gives headache and fatigue. In an eagerness to promote the DDT s usefulness, some advocates demonstrated its non-toxicity by drinking a cocktail of DDT. The effect was slight. DDT, however, is chemically toxic for human just as for flies and worms, but the differences in body size and physiology make the toxic effects of DDT appear different. We will talk about subtler and, perhaps, more serious effects of DDT later. 

After the use of a chemical becomes widespread, new deleterious effects on human health may be observed. In such situations, the occupational limit values will have to be modified. Usually the OELS tend to decrease when more information on the toxicity of a chemical is obtained. Knowledge of the specific features of various chemicals is thus extremely important for planning ventilation of industrial premises. It is important to be especially aware of those chemicals that may cause long-term effects without causing any acute effects. There are also compounds such as isocyanates that are extremely irritating at concentrations as low as 0.5 ppm. However, some workers may become sensitized to isothiocyanates at a concentration of 10 ppb, and therefore this has to be taken into consideration when planning the industrial ventilation. Thus, one has to plan against compounds that can cause serious health effects at concentrations at which their presence cannot be observed by the human senses, i.e., irritation or odor. 

Hammond, B. R., B. R. Wooten et al. (2001). Carotenoids in the retina and lens Possible acute and chronic effects on human visual performance. Arch. Biochem. Biophys. 385(1) 41—46. 

As well as NONOates, other NO donors also showed anticancer activity independently. Sodium nitroprusside (SNP), a metal-NO complex, showed cytotoxic effects on the cells of some patients with malignant lymphoma (ML), acute myelocytic leukemia (AML) or chronic myelomonocytic leukemia (CMMoL), but not with multiple myeloma [109]. SNP and cytosine arabinoside (Ara-C) did not share the drug resistance. Interestingly, SNP had no effect on lymphocytes of healthy volunteers. These results suggest that SNP has an anti-tumor effect on human hematological malignant cells. 

To test the irritancy potential of substances, two tests which can reliably distinguish between skin corrosives and noncorrosives are endorsed by the European Centre for the Validation of Alternative Methods (ECVAM). The testing procedures are based on the transcutaneous electrical resistance (TER) measurements of rat skin and on a human skin model. Both test systems [141-145] will be briefly outlined below. Nevertheless, these tests are not suited for the group of mild irritants which do not induce an acute effect on the barrier function. For those substances, new markers need to be evaluated. First results are available for heat shock protein 27 where higher levels were observed in skin models after exposure to mildly irritating chemicals [146, 147]. 

The following summary of acute effects in humans is based primarily on a review of the charts in the clinical files at Edgewood. Like many clinical records, these vary greatly in extent of detail, ranging from sketchy and Incomplete notes or one-line summaries to records that could serve as models for research documents. Independent chart reviews by NRC scientists provided some cross-checks on... 

This review of acute effects on volunteers Is based on clinical records at Edgewood. When the cannablnold studies began at Edgewood In November 1958, much less was known about the pharmacology of DMHP than about the pharmacology of phencyclidine (SNA). The studies of the DMHP series In humans spanned the period from 1958 through 1968, with concentration In 1963-1966. 

Figure 5.1. The interplay between time and adaptational options occurs in human as well as in animal evolution of physiological systems. The acute and acclimation effects on human hypoxia response physiology can be readily evaluated. However, adaptations requiring generations of time of course cannot be studied by direct manipulations in humans. All workers in this area therefore rely upon comparing human lineages adapted to hypobaric hypoxia in different regions of the world and for different time periods. Two such groups that have extensively studied in this manner are Quechuas and Aymaras from the Andes, and Sherpas and Tibetans from the Himalayas. See chapter 1 for further discussion of time and adaptation options.

It is quite clear that traditional risk assessment and risk management approaches are not working sufficiently well in the field of chemicals policy, in particular not in cases of high uncertainty. The traditional approach could hardly deal with the early chemical problems, characterised by evident impacts such as acute effects, and is even less effective in the present situation, with globalised flows of articles that contain hazardous chemicals and the resulting complex chemical cocktail, which may cause diffuse but significant adverse effects on human health and the environment. 

Acute-Duration Exposure. There are reports on the health effects resulting from acute exposure of humans and animals to benzene via the inhalation, oral, and dermal routes. The primary target organs for acute exposure are the hematopoietic system, nervous system, and immune system. Acute effects on the nervous system and immune system are discussed below under Neurotoxicity and Immunotoxicity. Information is also available for levels that cause death in humans (e.g., Cronin 1924 ... 

Lane SD, Cherek DR, Tcheremissine OV, Lieving LM, Pietras CJ. Acute marijuana effects on human risk taking. Neuropsychopharmacology 2005 30 800-9. 

Chronic exposure to benzyl alcohol would presumably produce effects similar to those from acute exposure. No other industrial illness is known from benzyl alcohol. No reproductive effects on humans are known. 

Formaldehyde-induced effects on human pulmonary function variables including forced vital capacity (FVC), forced expiratory volume in 1.0 seconds (FEV, q), peak expiratory flow rate (PEFR), and forced expiratory flowrate between 25 and 75% FVC (FEFRoj,, ), have not been found as consistently as symptoms of eye and nose irritation at acute exposure levels in the range of 0.4-3 ppm. In controlled exposure studies, no statistically significant exposure-related effects on lung function measurements were found in 10 healthy subjects exposed to up to 2 ppm for 3 hours (Kulle et al. 1987 Kulle 1993),... 

---