Toxic concentrations

Health nd Safety Factors. Isophorone is considered moderately toxic by ingestion and skin contact. Some rat tumor formation evidence has been found (264), but no demonstration as a human carcinogen has been proven. Isophorone is considered an Environmental Protection Agency (EPA) priority pollutant, and has a permissible acute toxicity concentration of 117, 000 ///L to protect freshwater aquatic life, 12, 900 ///L to protect saltwater aquatic life, and 5, 200 ///L to protect human life (265). Isophorone is mildly toxic by inhalation, but because of its low volatiUty it is not a serious vapor hazard. 

Toxic Constituents. The seed coat of European beechnut contains an unidentified toxic substance that makes the feeding of beechnut cake to certain farm animals ha2ardous (47). A toxic concentration (up to 4000 ppm) of barium found in some Bra2il nut kernels (30,48) has been reported to... 

Fig. 1. Blood—drug concentration curve used to determine bioavailabiLitv and bioequivalence. C is the maximum dmg concentration in the blood and corresponds to some The AUC (shaded) represents the total amount of orally adininistered dmg the time from points A to B represents dmg onset, from points B to D, the duration MEC = minimum effective concentration MTC = minimum toxic concentration and TI = therapeutic index.

Health and Safety Factors. Animal-feeding studies of DMPPO itself have shown it to be nontoxic on ingestion. The solvents, catalyst, and monomers that are used to prepare the polymers, however, should be handled with caution. Eor example, for the preparation of DMPPO, the amines used as part of the catalyst are flammable toxic on ingestion, absorption, and inhalation and are also severe skin and respiratory irritants (see Amines). Toluene, a solvent for DMPPO, is not a highly toxic material in inhalation testing the TLV (71) is set at 375 mg/m, and the lowest toxic concentration is reported to be 100—200 ppm (72). Toxicity of 2,6-dimethylphenol is typical of alkylphenols (qv), eg, for mice, the acute dermal toxicity is LD q, 4000 mg/kg, whereas the acute oral toxicity is LD q, 980 mg/kg (73). The Noryl blends of DMPPO and polystyrene have PDA approval for reuse food apphcations. 

The chronic aquatic effects which relate silver speciation to adverse environmental effects were studied on rainbow trout eggs and fry. The maximum acceptable toxicant concentration (MATC) for silver nitrate, as total silver, was reported to be 90—170 ng/L (43). Using fathead minnow eggs and fry, the MATC, as total silver, for silver thiosulfate complexes was reported as 21—44 mg/L, and for silver sulfide as 11 mg/L, the maximum concentration tested (27). 

Health, Safety, and Environmental Factors. Sulfur dioxide has only a moderate acute toxicity (183). The lowest pubHshed human lethal concentration is 1000 ppm for 10 months. The lowest pubHshed human toxic concentration by inhalation is 3 ppm for 5 days or 12 ppm for 1 hour. The lowest pubHshed human lethal concentration is 3000 ppm for 5 months. In solution (as sulfurous acid), the lowest pubHshed toxic dose is 500 flg/kg causing gastrointestinal disturbances. Considerable data is available by other modes of exposure and to other species NIOSH standards are a time-weighted average of 2 ppm and a short-term exposure limit of 5 ppm (183). 

The toxicity of many bleaching chemicals is also reflected in observed effect doses and concentrations. These measures include lowest pubHshed toxic concentration (TC q), concentration that is lethal to 50% of a specified population (LC q), lowest pubHshed lethal dose (LD q), and dose that is lethal to 50% of a specified population (LD q). Some relevant values of these are Hsted in Table 3. 

Exposure to metal carbonyls can present a serious health threat. Nickel carbonyl is considered to be one of the most poisonous inorganic compounds. However, the toxicological information available on metal carbonyls is restricted to the mote common, commercially important compounds such as Ni(CO)4 and Ee(CO). Other metal carbonyls are considered potentially dangerous, especially ia the gaseous state, by analogy to nickel and iron carbonyls. Data concerning toxicological studies on a few common metal carbonyls are Hsted ia Table 6 (185). Additional toxicity data are OSHA personal exposure limits (PEL) for Ee(CO) this is 8 h at 0.1 ppm, whereas for the much more toxic Ni(CO)4 it is 8 h at 0.001 ppm, with a toxic concentration TCLq low (of 7 mg/m ) for human inhalation. 

A relatively small number of studies have reported on the effects of cumene on plants, fish, and other organisms. Studies of the effects of cumene on fresh and saltwater fish indicate the lowest reported toxic concentration (LC q) for fishes was 20 to 30 mg/L (18). The solubiUty of cumene is about 50 mg/L (19). Among invertebrates, the lowest reported concentration that was toxic to test organisms was 0.012 mg/L after 18 hours (20). The only available data on the effect of cumene on aquatic plants indicate that the photosynthesis of several species was inhibited at concentrations from 9 to 21 mg/L (19). 

Toxic Volatile Ratio of Equilibrium Vapor Concentration over the Acute Substances Toxic Concentration (in ppm) is greater than 1000... 

Table 16.13 Toxic concentrations of heavy metals to rainbow trout...

EMGRESP is a source-term and dispersion emergency response screening tool for calculating downwind contours with a minimum of user input and computational expense in the event of a release of a hazardous chemical. The program provides hazardous contaminant information, calculates toxic concentrations at various distances downwind of a release, and c" the... 

Do I need the airflow or turbulence quantities at certain locations, or are toxic concentrations needed ... 

Failure of the metal can be the most important effect of a corrosive water, but other eff ts may arise from small concentrations of metallic ion produced by corrosion. A natural water passed through a lead pipe may contain a toxic concentration of that metal with copper there is a greater tolerance from the toxicity point of view but staining of fabrics and sanitary fittings may be objectionable. With iron, similarly, discoloration of the water may be unpleasant and may cause damage to materials being processed. 

The solubility (or insolubility) of different vitamins is of concern in nutrition. Molecules of vitamins B and C contain several —OH groups that can form hydrogen bonds with water (Figure 10.3). As a result, they are water-soluble, readily excreted by the body, and must be consumed daily. In contrast, vitamins A, D, E, and K, whose molecules are relatively nonpolar, are water-insoluble. These vitamins are not so readily excreted they tend to stay behind in fatty tissues. This means that the body can draw on its reservoir of vitamins A, D, E, and K to deal with sporadic deficiencies. Conversely, megadoses of these vitamins can lead to very high, possibly toxic, concentrations in the body. 

Dtug interactions can cause serious problems in clinical practice especially when the affected dmg has the potential to be highly toxic. Furthermore, pharmacokinetic interactions are clinically important if the affected dmg has a narrow therapeutic range (i.e. small difference between the minimum effective concentration and the toxic concentration Fig. 1) and a steep concentration-response curve (i.e. significant alterations in pharmacological and/or adverse effects caused by small changes in blood concentration). 

The results of metabolism studies with laboratory animals and livestock indicate that endosulfan does not bioconcentrate in fatty tissues and milk. Lactating sheep administered radiolabeled endosulfan produced milk containing less than 2% of the label. Endosulfan sulfate was the major metabolite in milk (Gorbach et al. 1968). A half-life of about 4 days was reported for endosulfan metabolites in milk from survivors of a dairy herd accidentally exposed to acutely toxic concentrations of endosulfan endosulfan sulfate accounted for the bulk of the residues detected in the milk (Braun and Lobb 1976). No endosulfan residues were detected in the fatty tissue of beef cattle grazed on endosulfan-treated pastures for 31-36 days (detection limits of 10 ppm for endosulfan, 40 ppm for endosulfan diol) the animals began grazing 7 days after treatment of the pastures. Some residues were detected in the fatty tissue of one animal administered 1.1 mg/kg/day of endosulfan in the diet for 60 days. No endosulfan residues were... 

An alternative to most of these mechanisms is the existence of efficient efflux systems, so that toxic concentrations of the drug are not achieved. There are three major families of proton-dependent multidrug efflux systems (1) the major facilitator superfamily, (2) the small multidrug resistance family, and (3) the resistance/nodulation/cell division family (Paulsen et al. 1996). It should be emphasized that several of these systems are involved not with antibiotic efflux but with, for example, acriflavine, chlorhexidine, and crystal violet. An attempt is made only to outline a few salient features of the resistance/nodulation/cell division family that mediates antibiotic efflux, and these are given in Table 3.3 (Nikaido 1996). They consist of a transporter, a linker, and an outer membrane channel. 

Weber FJ, S Isken, JAM de Bout (1994) Cis/trans isomerization of fatty acids as a defence mechanism of Pseudomonas putida strains to toxic concentrations of toluene. Microbiology (UK) 140 2013-2017. 

The tolerance of the strains to high concentrations of pentachlorophenol—S. chlorophenolica appears to be less sensitive than M. chlorophenolicus (Miethling and Karlson 1996). This may be attribnted to the ability of the cells to adapt their metabolism to avoid synthesis of toxic concentrations of chlorinated hydroquinones, and is consistent with the low levels of these metabolites measnred in the cytoplasm of cells metabolizing pentachlorophenol (McCarthy et al. 1997). Inocnla have also been immobilized on polyurethane that, in addition, ameliorates the toxicity of chlorophenols (Valo et al. 1990). 

A toxicant concentrate, emulsifying agent which leaves little to be desired... 

RESPONSE We do not understand all there is to know about the mechanisms of MPTP neurotoxicity, but it seems to involve MPP+, which is potentially cytotoxic to all cells but that attains toxic concentrations after MPTP administration only in cells that concentrate MPP+. Dopamine apparently is not involved in the neurotoxic effects of MPTP. I am attracted to the idea that dopamine itself may be involved in the etiology of Parkinson s disease, that dopamine neurons may be at risk because of the nature of their neurotransmitter. 

Such growth of sulphate reducing bacteria is responsible for the most commonly noticed malodour associated with emulsion paint spoilage. Hydrogen sulphide levels in paint have never been shown to have reached toxic concentrations, but even very small... 

Maximum allowable toxicant concentrations (MATC) of cadmium to sensitive species of freshwater teleosts... 

Maximum acceptable toxicant concentration values (MATC) for toxaphene and aquatic organisms, based on exposure for the entire or most of the life cycle... 

Table 1.4 Maximum Allowable Toxicant Concentrations (MATC)... 

Table 2.5 Maximum Acceptable Toxicant Concentration (MATC) Values for Hexavalent and Trivalent Chromium to Aquatic Life Based on Life Cycle or Partial Life Cycle Exposures... 

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