P-Nitrophenol in urine

Total p-nitrophenol in urine End of shift at end of workweek 5 mg/g creatinine Ns... 

In order to reach a conclusion when and how and, and to some extent, how much of a particular insecticide was administered, the form and quantity in which the insecticide exists in different tissues and in blood and urine may give valuable clues. Indeed, an intelligent deduction is also based on the knowledge of metabolic pathways and formation of other derivatives. Thus, as parathion is excreted in the urine ultimately as p-nitro-phenol, urinary p-nitrophenol levels may indicate the extent of exposure to parathion ). In cases of mild and moderate exposure, the excreted p-nitrophenol in urine was found to be of the order of 0.057 to 0.322 mg. percent. In severe and fatal cases of poisoning by parathion, the level of p-nitrophenol in urine was from 0.16 to 1.16 mg. percent. para-Nitrophenol thus is rapidly excreted in urine and no longer detected 48 hours after the exposure to the pesticide. 

Total p-nitrophenol in urine Cholinesterase activity in red cells Pentachlorophenol (PCP)... 

Biomarkers of Exposure and Effect. The presence of p-nitrophenol in urine serves as a satisfactory biomarker of nitrobenzene exposure. Because nitrobenzene metabolites, nitrosobenzene and phenylhydroxylamine, bind to hemoglobin in the blood of rats and mice, the presence of these hemoglobin adducts in human blood may also serve as biomarkers of nitrobenzene exposure. More information on this possibility would be useful. 

Salmowa J, Piotrowski J, Neuhorn U. 1963. Evaluation of exposure to nitrobenzene Absorption of nitrobenzene vapour through lungs and excretion of p-nitrophenol in urine. Br J Ind Med 20 41-46. 

CranmerM. 1970. Determination of p-nitrophenol in human urine. Bull Environ Contam Toxicol... 

According to Trautman (16), PNA was converted almost exclusively to p-nitrophenol in the mouse with 24 hours, nearly all of which was excreted in the urine as glucuronide, sulfate, glucoside, and unextractable products the mouse tissue retained only about 1% of the original dose. By comparison, the sea urchin metabolized PNA slowly p-nitrophenol and its conjugates accounted for only about 6% of the metabolites and most of the remainder (90%) was p-anisidine (p-methoxyaniline) and its N-acetyl derivative. 

Barr DB, Turner WE, DiPietro E, McClure PC, Baker SE, Barr JR, et al. Measurement of p-nitrophenol in the urine of residents whose homes were contaminated with methyl parathion. Environ Health Perspect 2002 110(Suppl 6) 1085-91. 

The presence of p-nitrophenol in the urine can be used to indicate exposure to nitrobenzene (Ikeda and Kita 1964). Measurement of p-nitrophenol, however, cannot be used to determine the level of nitrobenzene exposure or if harmful effects can be expected to occur. The nitrobenzene metabolites, nitrosobenzene and phenylhydroxylamine, have been found to bind with hemoglobin in the blood of... 

As part of the Third National Health and Nutrition Evaluation Survey (NHANES III), the Environmental Health Laboratory Sciences Division of the Centers for Disease Control, will be analyzing human urine samples for p-nitrophenol and other phenolic compounds. Since p-nitrophenol is a major metabolite of nitrobenzene, the presence of p-nitrophenol in the urine can be used to indicate exposure to nitrobenzene. These data will give an indication of the frequency of occurrence and background levels of these compounds in the general population. 

Bradway, D. E., and Shafik, T, M. Parathion Exposure Studies. Gas Chromatographic Method for the Determination of Low Levels of p-Nitrophenol in Human and Animal Urine... 

Determination of p-Nitrophenol in Human Urine by Gas Chromatography 173rd Natl. Mtg., ACS, New Orleans,... 

Roan CC, Morgan DP, Cook N, et al. 1969. Blood cholinesterases, serum parathion concentrations and urine p-nitrophenol concentrations in exposed individuals. Bull Environ Contam Toxicol 4 362-369. 

Ingestion of alcohol aggravates the toxic effects of nitrobenzene. In general, higher ambient temperatures increase susceptibility to cyanosis from exposure to methemoglobin-forming agents." p-Nitrophenol and p-aminophenol are metabolites of nitrobenzene, and their presence in the urine is an indication of exposure."... 

In humans, an oral dose of 3-5mg/kg is usually fatal. In a study of 115 workers exposed to parathion under varying conditions, the majority excreted significant amounts of p-nitrophenol (a metabolite of parathion) in the urine, whereas only those with heavier exposures had a measurable decrease in blood cholinesterase. Measurement of urinary p-nitrophenol can be useful in assessing parathion absorption in occupational or other settings. ... 

Guidotti, M., Ravaioli, G., and Vitali, M. 1999. Total p-nitrophenol determination in urine samples of subjects exposed to parathion and methyl para-thion by SPME and GC/MS. J. High Resolut. Chromatogr. 22 628-630. 

In the case of pesticides which are not ChE inhibitors, exposure is measured by the analysis of blood and/or urine for the active ingredient or its metabolites. Baseline levels of pesticides and/or metabolites are not usually determined, with the exception of methyl bromide. In this case, a blood sample is taken to check for bromide ion before fumigators use the pesticide. Blood and urine tests are run only in the case of spills or other accidents to assist in identifying the cause of poisoning or to monitor workers in a workplace. Paraquat, chlorinated hydrocarbons, mercury, p-nitrophenol, and dinitrophenol are examples of pesticides or metabolites of pesticides that have been found in the urine of exposed workers. 

A reentry study 12 hr after application in Arizona cotton, exposing volunteers to methyl parathion, ethyl parathion, or monocrotophos for 5 hr produced no clinical signs of poisoning. However, cholinesterase depression averaged 147., and both ethyl-and methyl-parathion were found in the blood as well as p-nitrophenol (PNP) in the urine. These workers were not judged in jeopardy as cholinesterase depression was less than 307. and the PNP excretion was less than 4 mg following exposure (22). 

TJarathion, methylparathion, EPN (O-ethyl-O-p-nitrophenyl phenyl- phosphonothioate), and chlorthion all contain the p-nitrophenol radical (abbreviated PNP), which is excreted in the urine and sweat of per-... 

Urinary p-nitrophenol concentrations were obtained by the Elliott (3) method and a thin layer chromatography method. To compare these two methods, duplicate analyses were run on 45 urine samples with levels of PNP (measured by Elliott) ranging from 0.10 to 11.3 p.p.m. In both methods the urine was hydrolyzed with concentrated hydrochloric acid and heated. The benzene-ethyl ether extracts were made and either tested as described by Elliott (3) or evaporated, resuspended in ether, and applied to silica gel plates for chromatographic separation. Kidney concentrations were obtained from a weighed, hydrolyzed, benzene-ethyl ether extract of homogenized kidney (5 to 10 grams) and treated by the Elliott procedure (3) for urinary assay. 

Another product of esterase cleavage is p-nitrophenol (PNP), which is generated in the human body by the degradation of parathion, parathion-methyl and parathion-ethyl. Some methods for the determination of PNP in urine are summarized in Table 9.5. PNP can, for example, be determined in the urine of occupationally exposed subjects by means of GC-ECD. Sample preparation involves acid hydrolysis, extraction with diethyl ether, derivatization with diazoethane and purification on silica gel columns. The LOD was 20 pg L with a recovery of 85-98%. This method has also been used in a study on selected pesticide residues and metabolites in urine from a survey of the US general population.In the context of another survey study, a more complicated technique to detect PNP in urine has recently been used by Hill et involving GC-MS-MS with positive chemical ionization after derivatization with l-chloro-3-iodopropane. The authors also used this method for the determination of the metabolite TCP and 10 other analytes in urine.Sample preparation involved hydrolysis with p-glucuronidase, several extraction steps using different solvents and purification by SPE (silica gel column). The LOD was 1 pg L with an inter-assay RSD... 

Urinary excretion rates of p-nitrophenol were found in 7 volunteers who had inhaled 6 ppm nitrobenzene for 6 hours (Salmowa et al. 1963). The rate of urinary elimination varied considerably from individual to individual, but showed a general dose dependence at 1 to 6 ppm nitrobenzene. In general, excretion was most rapid during the first two hours and then leveled off. In some cases, p-nitrophenol could be detected for as long as 100 hours after exposure to 6 ppm for 6 hours. In a 47-year-old woman who had been occupationally exposed to nitrobenzene for 17 months, p-nitrophenol and p-aminophenol were found in the urine (Ikeda and Kita 1964). 

After oral exposure to nitrobenzene, the major route of excretion is the urine. In most cases of human poisoning, the metabolites excreted in the urine are p-aminophenol and p-nitrophenol (Myslak et al. 1971 Von Oettingen 1941). Five days after oral administration to rats, Albrecht and Neumann (1985) found 65% of the administered dose (25 mg/kg) in the urine and 16% in the feces. 

Uri ne Measure p-nitrophenol metabolite in urine No data No data No data Ikeda and Kita 1964... 

Biological monitoring of exposure to nitrobenzene may be performed by determining the total p-nitrophenol (a metabolite of nitrobenzene) in the urine. -Nitrophenol is reduced to p-aminophenol by treatment with zinc and HCl. p-Aminophenol is further treated with phenol to convert to indophenol, the absorbance of which is determined by a spectrophotometer. The amount of nitrobenzene absorbed, E, may be calculated as follows (Piotrowski 1967) ... 

Blood Cholinesterase, Serum Para-thion Concentrations, and Urine p-Nitrophenol Concentrations in Exposed Individuals Bull. Environ. Contam. Toxicol. 4(6) 362-369 (1969) CA 72 77892m... 

This improvement can be readily seen when compared to single electrode detection shown in Fig. 2. Here the determination of p-nitrophenol (PNP) has been undertaken in human urine extracts by both dual electrode detection and single oxidative mode detection. The oxidative mode detection trace is characterised by large number of co-eluting peaks which obscure the retention time expected for PNP. However, hy DED a relative clean trace is recorded. The presence of PNP in the fortified urine extract can be readily recorded. 

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