Indicators limited information

No studies were located regarding excretion of methyl parathion in humans following inhalation exposure. The limited information available from human case studies indicates that the chemical s metabolites are rapidly excreted primarily in the urine in humans following oral (Morgan et al. 1977) or dermal (Ware et al. 1974, 1975) exposure and in animals following oral (Hollingworth et al. 1973) or dermal (Abu-Qare et al. 2000) exposure. 

This may be due, in part, to the limited information on toxic effects associated with such exposures. If additional information becomes available indicating adverse health effects of long-term exposures, then studies examining methods for mitigating the effects of such exposures would become a data need. 

Immunotoxicity. Limited information is available regarding the effects of endosulfan on the human immune system. However, specially designed studies using rats indicate that both humoral and cellular immune responses are depressed by ingested endosulfan at doses that do not induce any overt signs of toxicity (Banerjee and Hussain 1986,1987). In vitro studies support the possibility that endosulfan affects immune system function (Das et al. 1988). These results demonstrate that immunotoxicity may be a more sensitive end point of endosulfan-induced toxicity than other end points, and humans may be at risk for adverse immune effects following exposure to endosulfan. An intermediate-duration oral MRL was derived based on the observation of depressed immune responses (Banerjee and Hussain 1987). 

The ACC/AHA recommends that P-blockers be initiated in all patients with NYHA FC I to IV or ACC/AHA stages B through D heart failure if clinically stable.1 To date, only three p-blockers have been shown to reduce mortality in systolic HF, including the selective prantagonists bisoprolol and metoprolol succinate, and the non-selective pr, p2-, and arantagonist carvedilol.29 33 The positive findings should not be extrapolated to be indicative of a class effect, as bucindolol did not exhibit a beneficial effect on mortality when studied for HF, and there is limited information with propranolol and atenolol. 

In this respect it is also interesting to note that in bioaccumulation it is found that the concentration of toxicant in the tissues and particularly in some of its organs such as kidney, liver and opercle, increases with both concentration in the water and exposure time. Measurement of toxicant levels in tissues or organs provide an indication of the amount of exposure to toxicants that the creature has suffered over a period of time. Only limited information is yet available relating concentrations of toxicant in tissues and the onset of ill health or mortality. This is clearly an area where much further work remains to be done. 

Limited information was presented in an abstract indicating that 1,3-DNB caused mild eye irritation in rabbits, whereas 1,3,5-TNB caused severe irritation no further details were provided (Desai et al. 1991). 

Limited information is available on lethal amounts of PBBs in animals. In general, dosing regimen and magnitude affect response. The lack of decreased survival in some studies does not necessarily indicate low toxicity because observation periods may not be sufficient to observe effects that develop slowly. 

In summary, the limited information currently available indicates that a pumping system guaranteed to meet the 40-ppm discharge specification is not available. However, hydrocyclooe technology for liquid/liquid separation is still in its infancy. It is considered that an acceptable combinatioa of pumps, valves, and hydrocydones is achievable to overcome the current low-pressure limitation. 

Limited information was located regarding possible interactions of DEHP with other chemicals in humans. Urinary measurements of the monoester metabolites of seven common phthalates in 289 adults from the U.S. population, determined using the selective and sensitive analytical approach discussed in Section 3.8.1 (Biomarkers Used to Identify or Quantify Exposure to DEHP), showed detectable levels of monoethyl phthalate (95th percentile concentration, 3,750 ppb), monobutyl phthalate (294 ppb), monobenzyl phthalate (137 ppb), 2-ethylhexyl phthalate (21.5 ppb), cyclohexyl phthalate (8.6 ppb), isononyl phthalate (7.3 ppb), and octyl phthalate (2.3 ppb), reflecting exposure to DEHP, dibutyl phthalate, benzyl butyl phthalate, di-(2-ethylhexyl) phthalate, dicyclohexyl phthalate, di-isononyl phthalate, and dioctyl phthalate, respectively (Blount et al. 2000a). Considering evidence such as this which indicates that co-exposure to multiple phthalates can occur, as well as the likelihood that many of these compounds exert effects via a common mechanism of action, there is a potential for interactions between DEHP and other phthalate esters. 

For the Pb6(OH)g4+ solution the changed Pb-Pb peak shape at 3.85 A and two additional Pb-Pb peaks at, 6.4 and 7.1 A, indicate a more complex structure, which cannot be unambiguously derived from the limited information in the RDF. Crystals can be prepared, however, which contain discrete Pb60(0H)64+ units with the structure shown in Fig. 30 (227). Theoretical peaks calculated for the Pb framework in this structure are in complete agreement with the peaks in the RDFs (Fig. 30), which proves that the structure of the complexes are the same in solution and in crystals. Raman spectroscopic measurements are consistent with this interpretation. 

Bioavailability from Environmental Media. No studies were located regarding the bioavailability of acrolein from environmental media. Since acrolein has been detected in ambient air and in food and beverages (ppb levels), it is important to determine if acrolein can be absorbed by humans from environmental samples. However, the chemical structure of acrolein makes it a highly reactive molecule, which presumably is why its effects are, for the most part, restricted to the area of exposure (i.e., respiratory system for inhalation exposure or localized skin damage for dermal exposure). The limited information available regarding absorption parameters of acrolein in experimental animals indicates that acrolein is easily retained in the respiratory airways however, virtually no information is available regarding absorption by the gastrointestinal tract or skin. Therefore, based on the data available, it is likely that inhalation of contaminated air will result in irritation of the eyes and respiratory tract. 

The most direct information concerning compliance with Dempsey s rules is found in Figure 5 where the experimental x2 values are compared with computed results. Again, the dealuminated x=.17 sample (i) exhibits total randomization under Loewenstein s restrictions, while the other samples indicate limited compliance with Dempsey s rules. 

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