Solvent exposures history

The most obvious effect of stereoregularity in polymers concerns their crystallizability and hence the potential existence of a melting transition with a concomitant heat of fusion. It is generally accepted that with one or two possible exceptions (eg. polyvinyl alcohol), substantial stereoregularity is required to permit crystallization in vinyl polymers and, indeed, the appearance of a melting transition is sometimes adopted as a crude assay of synthetic procedures. It should be noted, of course, that the absence of a fusion transition cannot in itself be taken as evidence for atacticity, since thermal and solvent exposure history strongly influence the extent of crystallization in isotactic and syndiotactic systems. For example, isotactic polystyrene (T = 240°C) can be bulk annealed to yield material with a degree %f crystallinity (x. ) between 0.4 and 0.5, and... 

Some new work has been done here which shows the effects of solvents exposure. A new study illustrates a simple method of detoxification using heat chamber depuration (sauna), and raises awareness in the practice of medicine of the importance of taking an environmentally oriented historical approach. The connection between symptoms of chronic degenerative diseases and environmental and/or nutritional factors is missed in many cases due to lack of obtaining an environmentally oriented medical history. Taking such a history and dealing with the cause of illness using avoidance and/or appropriate therapy is preventive and cost-effective for both the patient and society (Krop, 1998). 

Chester AC, Levine PH The natural history of concurrent sick building syndrome and chronic fatigue syndrome. J Psychiatr Res 31 51-57,1997 Cone J, Suit TA Acquired intolerance to solvents following pesticide/solvent exposure in a building a new group of workers at risk for multiple chemical sensitivities. Toxicol Ind Health 8 29-39,1992... 

A susceptible population will exhibit a different or enhanced response to Stoddard solvent than will most persons exposed to the same level of Stoddard solvent in the environment. Reasons include genetic make-up, developmental stage, health and nutritional status, and chemical exposure history. 

In a case-control study of pesticide factory workers in Brazil exposed to methyl parathion and formulating solvents, the incidence of chromosomal aberrations in lymphocytes was investigated (De Cassia Stocco et al. 1982). Though dichlorodiphenyltrichloroethane (DDT) was coformulated with methyl parathion, blood DDT levels in the methyl parathion-examined workers and "nonexposed" workers were not significantly different. These workers were presumably exposed to methyl parathion via both inhalation and dermal routes however, a dose level was not reported. The exposed workers showed blood cholinesterase depressions between 50 and 75%. However, the baseline blood cholinesterase levels in nonexposed workers were not reported. No increases in the percentage of lymphocytes with chromosome breaks were found in 15 of these workers who were exposed to methyl parathion from 1 week to up to 7 years as compared with controls. The controls consisted of 13 men who had not been occupationally exposed to any chemical and were of comparable age and socioeconomic level. This study is limited because of concomitant exposure to formulating solvents, the recent history of exposure for the workers was not reported, the selection of the control group was not described adequately, and the sample size was limited. 

Toxicity/symptoms nervous system, reproductive system, and death General facts long history of use (alcohol), high volatility of solvents results in inhalation exposure to vapors... 

A nested case-control study within a cohort of rubber workers in the United States was performed to examine the relationship between exposure to solvents and the risk of cancer (Checkoway et al., 1984 Wilcosky et al., 1984). The cohort consisted of 6678 male rubber workers who either were active or retired between 1964 and 1973. The cases comprised all persons with fatal stomach cancer (n = 30), respiratory system cancer (z7 = 101), prostate cancer ( = 33), lymphosarcoma (n = 9) or lymphocytic leukaemia (z7 = 10). These sites were chosen because they were those at which cancers had been found to be in excess in an earlier cohort analysis (McMichael et al., 1976). The controls were a 20% age-stratified random sample of the cohort (z = 1350). Exposure was classified from a detailed work history and production records. An association was observed between exposure for one year or more to carbon tetrachloride and lymphocytic leukaemia (odds ratio (OR), 15.3 / < 0.0001, based on eight exposed cases) and lymphosarcoma (OR, 4.2 p < 0.05, based on six exposed cases) after adjusting for year of birth. The relative risk associated with 24 solvents was examined and levels of exposure were not reported. [The Working Group noted that overlapping exposures limit the ability to draw conclusions regarding carbon tetrachloride.]... 

Olsson and Brandt (1980) carried out a hospital-based case-control study of Hodgkin s disease and chemical exposures in Lund, Sweden. Twenty-five consecutive male cases aged 20-65 years were included. Two neighbourhood-matched controls were selected for each case from the Swedish population register. Interviews with study subjects focused on their detailed job history, and in particular exposure to solvents. Interview data were supplemented with visits to employers in some cases. Four of the cases and none of the controls had been exposed to xylene. All exposed cases were also exposed to other solvents. [The Working Group noted the opportunity for information bias, since the interviewer was not blind to disease status or to the study objectives ]... 

IV. Diagnosis is based on a history of exposure and clinical presentation. Many chlorinated and aromatic hydrocarbon solvents may cause identical symptoms. 

IV. Diagnosis is based on the history of exposure and the presence of characteristic muscarinic, nicotinic, and CNS manifestations of acetylcholine excess. There may be a solvent odor, and some agents have a strong garlicky odor. 

One of the most influential innovations in the history of LbL technology so far must be LbL assembly on a colloidal particle with subsequent hoUow capsule preparation [220-223]. In the first decade of LbL technology, researchers regularly assembled films on a flat solid support of visible dimensions. However, the mechanism of the LbL assembly does not exert any limitations on the size of supports or their shape. Therefore, LbL assembly on microscopic solid surfaces dispersed in solution is reasonable, opening the way to fabrication of both three-dimensional structures and nano/micro-sized objects through the LbL process. As shown in Fig. 8, the concept of the assembly is simple. LbL films are assembled sequentially on a colloidal core in a similar way to conventional LbL assembly on a flat plate. Dissolution of the central particle core upon exposure of the particles to appropriate solvents then results in hollow capsules. 

---