Chlorpyrifos toxicity

Li, W.F., Furlong, C.E., Costa, L.G. (1995). Paraoxonase protects against chlorpyrifos toxicity in mice. Toxicol. Lett. 76 219-26. 

Auerberry, T, T, Burnett, W. T and Chambers, J, E. (1997). Age-related differences in parathion and chlorpyrifos toxicity in male rats Target and nontargel esterase. scasiiivity and cytochrome P450-mediatcd metabolism. Toxicol. Appl. Pharmacol, 147,411-418. 

Qiao, D, Seidler, F. J, and Slotkin, T. A. (2(X)5). Oxidative mechanisms eontribuiing to the developmental neurotoxicity of nicotine and chlorpyrifos. Toxical. Appl. Pharmacol., 2(16, 17-26. 

Y. Jin-Clark, M.J. Lydy, K.Y. Zhu, Effects of atrazine and cyanazine on chlorpyrifos toxicity in Chironomus tentans (Diptera Chironomidae), Environ. Toxicol. Chem. 21 (3)... 

Schimmel SC, Gamas RE, Patrick JM, et al. 1983. Acute toxicity, bioconcentration and persistence of AC 222,705, benthiocarb, chlorpyrifos, fenvalerate, methyl parathion and permethrin in the estuarine environment. J Agric Food Chem 31 104-113. 

It is important to emphasize that the initial metabolites after hydrolysis may be both toxic and sometimes resistant to further degradation. Examples include nitrophenols, whose degradation is discussed in Chapter 9, Part 5 and 3,5,6-trichloropyridin-2-ol (Feng et al. 1997), which is produced by the hydrolysis of chlorpyrifos (0,0-diethyl-0-[3,5,6-trichlo-2-pyridyl]phosphorothioate). 

Official Soviet science considered that OPPs did not remain in the soil for very long, and the products resulting from its decay were of low toxicity [21, 30]. In fact trichlotfon, for example, decays slowly in acid soils. It more actively dehydrochlorinates in alkaline media, but it then forms highly toxic dichloifos [33]. Parathion may remain in soil for up to 16 years [34]. Cases are known when phosalone and chlorpyrifos remain in soil for up to two years [3, 20]. Methyl parathion and trichlorfon were detected in the Kilmez region of the Kirov Oblast in an underground chemical repository 20 years later [3]. 

The purpose of this chapter is not to discuss the merits, or lack thereof, of using plasma cholinesterase inhibition as an adverse effect in quantitative risk assessments for chlorpyrifos or other organophosphate pesticides. A number of regulatory agencies consider the inhibition of plasma cholinesterase to be an indicator of exposure, not of toxicity. The U.S. Environmental Protection Agency, at this point, continues to use this effect as the basis for calculating the reference doses for chlorpyrifos, and it is thus used here for assessing risks. 

In 1985, Berteau and Mengle (1985) of the California Department of Health Services and Maddy of the Department of Food and Agriculture conducted a preliminary review of pesticides used indoors. They noted several cases (six) from the Pesticide Illness Surveillance system in which illness was reported after structural pest control. Hypothetical exposure estimates for infants, children, and adults following label use for propoxur, DDVP, and chlorpyrifos were sometimes greater than toxic levels. In 1987, Berteau et al. (1989) reiterated the concern about the potential magnitude of indoor exposures, particularly for children. 

Chemicals degraded by WRF include pesticides such as organochlorines DDT and its very toxic metabolite DDE [8, 9] and organophosphate pesticides such as chlorpyrifos, fonofos and terbufos [10] polychlorinated biphenyls (PCBs) of different degrees of chlorine substitution [11-13], some even to mineralization [14, 15] diverse polycyclic aromatic hydrocarbons (PAHs) in liquid media and from contaminated soils or in complex mixtures such as creosote [16-18] components of munition wastes including TNT and its metabolites DNT [19-23], nitroglycerin [24] and RDX [25]. 

Acute toxicities of chlorpyrifos to selected species of aquatic invertebrates and hshes... 

Moore, M.T., D.B. Huggett, W.B. Gillespie Jr., J.H. Rodgers Jr., and C.M. Cooper. 1998. Comparative toxicity of chlordane, chlorpyrifos, and aldicarb to four aquatic testing organisms. Arch. Environ. Contam. Toxicol. 34 152-157. 

Formulations of chlorpyrifos include emulsifiable concentrates, wettable powders, granules, pellets, microencapsulates, and impregnated materials. Suggested diluents for concentrates include water and petroleum distillates, such as kerosene and diesel oil. Carrier compounds include synthetic clays with alkyl/aryl sulfonates as wetting agents (Table 14.1). Little information is available to assess the influence of various use formulations on toxicity, dispersal, decomposition, and bioavailability. Chemical and other properties of chlorpyrifos are summarized in Table 14.2 and Figure 14.1. 

Table 14.3 Acute Toxicities of Chlorpyrifos to Selected Species of Aquatic Invertebrates and Fishes (Values are in micrograms of chlorpyrifos per liter of medium [ g/L] fatal to 50% in 96 h.) ...

Table 14.3 (continued) Acute Toxicities of Chlorpyrifos to Selected... 

Table 14.6 Dietary Toxicity of Chlorpyrifos to Selected Species of Birds...

Dermal application routes are also toxic. Some deaths were recorded in turkeys from dermal treatments of 15 to 20 mg chlorpyrifos/kg BW (Schlinke etal. 1969). Higher levels applied to feathers killed turkeys within 8 h (Marshall and Roberts 1978). Newborn piglets (Sus spp.) were especially more sensitive than those 30 to 36 h old to cutaneous applications of chlorpyrifos ... 

Develop suitable replacements for chlorpyrifos in mosquito control programs. These replacement compounds should exhibit a relatively long half-life in aquatic environments while avoiding the broad-spectrum toxicity typical of chlorpyrifos to large numbers of nontarget organisms. 

Goodman, L.R., D.J. Hansen, G.M. Cripe, D.P. Middaugh, and J.C. Moore. 1985b. A new early life-stage toxicity test using the California grunion (Leuresthes tenuis) and results with chlorpyrifos. Ecotoxicol. Environ. Safety 10 12-21. 

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