Department of Entomology


Robert Kriegerucr entomology

Cooperative Extension Specialist

Location: Chapman 10
Tel: (951) 827-3724
E-mail: bob.krieger@ucr.edu


Research Specialization - Identification and movement of pesticides and other chemical residues from environmental compartments to children and adults. Indoor, turf, and agricultural settings have been included. In agriculture this research has supported development of exposure-based field entry times, as opposed to adverse effect based entry times that were extensively used prior to implementation of the risk assessment process. Effective entry times require accurate human pesticide exposure data and clear definition of work tasks so that short-term and long-term exposures can be considered. We will continue to investigate the relationship between surface chemical exposures including dislodgeable foliar and surface residues on turf or agricultural crops or indoor pesticide residues in homes. Transfer and human bioavailability of residues will be studied by urine biomonitoring. We expect to explore chemical transferability of chemical residues with respect to chemical (active ingredients as well as spray adjuvants) as well as from physical characteristics (absorption, particularly cuticular waxiness in the case of plants and nylon carpets).


BS Chemistry/Biology 1967
Pacific Lutheran University, Tacoma, WA
PhD Ins.Toxicology. Ins. Chemistry, Bio-Chem, Physiology 1970
Cornell University


2006 - Entomological Society of America Pacfic Branch, Distinguished Award in Extension
2005 - Society of Toxicology Public Communications Award
2005 - American Chemical Society International Award for Research in Agrochemicals
2004-2005 - Non-Senate Distinguished Research Award
1998 - Centinela Chapter Research Award, California Association of Nurserymen

Research Area

Extension toxicology Human chemical encounters Chemical risk assessment 


Williams R. L., C. E. Bernard, M. Bigelow-Dyk, J. H. Ross, R. I. Krieger. 2008 Measurement of transferable chemical residue from nylon carpet using the California Roller and a new Mega-California Roller. Submitted to J. Environ. Science Health Part B. 43: 675-679.

Krieger, R. E. 2008. Aldrin Epoxidation and Dihydroisodrin Hydroxylation As Probes Of In Vivo and In Vitro Oxidative Metabolic Capability Of Some Caterpillars. Pest Management Science. Pest Manag. Sci. 64: 622-627.

Sanchez, C. A., B. C. Blount, L. Valentin-Blasini, S. M. Lesch, R. I. Krieger. 2008. Perchlorate in the Feed-Dairy Continuum of the Southwestern United States. J. Agric. & Food Chem. 56: 5443-5450.

Sanchez, C. A., L. Barraj, B. C. Blount, C. Scrafford, L. Valentin-Balsini, K. M. Smith, R. I. Krieger. 2008. Perchlorate Exposure from Food Crops Produced in the Lower Colorado River Region. J. Exp. Sci. Environ Epidem. 5: 1-10.

Woodrow, J. E., J. N. Seiber, J. S. LeNoir, R. I. Krieger. 2008. Determination of MITC in Air Downwind of Fields Treated with Metam Sodium by Sub-Surface Drip Irrigation. J. Agric. Food Chem. 56: 7373-7378.

Sanchez, C. A., B.C. Blount, L. Valentin-Blasini, R. I. Krieger. 2007. Perchlorate, Thyiocyanate, and Nitrate in Edible Cole Crops (Brazxica sp.) Produced in the Lower Colorado River Region. Bull. Environ Contam Toxicol. 79: 655-659.

Sanchez C.A., K. S. Crump, R. I. Krieger, N. R. Khandaker ,J. P. Gibbs. 2006. Perchlorate and itrate in leafy vegetables of North America. Environ. Science Tech. 39: 9391-9397

Sanchez, C., R. I. Krieger, N. R. Khandaker, L. Valentin-Blasini, B. C. Blount. 2006. Potential Perchlorate Exposure fro Citrus sp. Irrigated with Contaminated Water. Analytica Chimica Acta. 567: 33-38.

Sanchez, C. A., R. I. Krieger, L. Valentin-Blasini, B. C. Blount, and N. R. Khandaker. 2006. Perchlorate Accumulation and Potential Exposure from Durum Wheat Irrigated with Colorado River Water. Journal of ASTM International. Online Vol 3: 7.

Barton, H. A., T. P. Pastoor, K. Baetcke, J. E. Chambers, J. Diliberto, N. G. Doerrer, J. H. Driver, C. E. Hastings, S. Iyengar, R. Krieger, B. Stahl, C. Timchalk. 2006. The acquisition and application of absorption, distribution, metabolism, and excretion (adme) data in agricultural chemical safety assessments. Critical Reviews in Toxicology, 36: 9-35.

Sanchez, C. A., R.I. Krieger, N. Khandaker, R.C. Moore, K.C. Holts and L.L. Neidel. 2005. Accumulation and perchlorate exposure potential of lettuce produced in the lower Colorado River Regions. J. Agric. & Food Chem. 53: 5479-5486.

Dowling, K.C., L.E. Blanco R., I. Martinez M., A. Aragon B., C.D. Bernard and R.I. Krieger. 2005. Urinary 3, 5, 6-tricholoro-2-pyridinol Levels of chlorpyrifos applicators and small farm families in Nicaragua. Bul. Environ. Contam. Toxicol. 74: 380-387.

Gerry, A.C., X. Zhang, G. Leng, A.D. Inman, and R I. Krieger. 2005. Low pilot exposure to pyrethrin during ultra low volume (ULV) aerial insecticide application for control of adult mosquitoes. Journal of the American Mosquito Control Association. 21: 291-295.

Krieger, R.I. 2005. Reviewing some origins of pesticide perceptions. Outlooks on Pest Management. 16: 244-248.

Gerry, A.C., X. Zhang, T. Walker, S. Frederickson, M. Metzger, R. Hu, R.I. Krieger. 2005. Worker exposure to diazinon during flea control operations in response to plague epizootic. Bull. Environ. Contam. Toxicol. 74 (2): 391-398.

Williams, R. L., L. S. Aston, R. I. Krieger. 2004. Perspiration increased human pesticide absorption following surface contact during an indoor scripted activity program. J. Exposure Anal Environ Epidemiol 14: 129-136.

Krieger, R. I., T. M. Dinoff, and X. Zhang. 2003. Octachlorodipropyl Ether (S-2) Mosquito Coils are Inadequately Studied for Residential Use in Asia and Illegal in the United States. Environmental Health Perspectives. 111: 1439-1442.

Williams, R. L., C. E. Bernard, and R. I. Krieger. 2003. Human exposure to indoor residential cyfluthrin residues during a structured activity program. Journal of Exposure Analysis and Environmental Epidemiology. 13: 112-119.

Duggan, G. Charnley, W. Chen, A. Chukwudebe, R. Hawk, R. I. Krieger, J. Ross, and C. Yarborough. 2003. Di-alkyl phosphate biomonitoring data: assessing cumulative exposure to organophosphate pesticides. Regulatory Toxicology and Pharmacology 37: 382-395.

Williams, R. L., M. R. Oliver, S.B. Ries, R.I. Krieger, 2003. Transferable Chlorpyrifos Residue from turf grass and an empirical transfer coefficient for human exposure assessments. Bulletin of Environmental Contamination and Toxicology. 70: 644-651.

Krieger, R.I., P. Brutsche-Keiper, H.R. Crosby, A.D. Krieger. 2003. Reduction of Pesticide Residues of Fruit Using Water Only or Plus Fit fruit and vegetable wash. Bulletin of Environmental Contamination and Toxicology. 70: 213-218.

Krieger, R. I., T. M. Dinoff, R. L. Williams, and X. Zhang. 2003. Preformed Biomakers in Produce Inflate Human Organophosphate Exposure Assessements. Environmental Health Perspectives. 111: A688 (Letter).

Krieger, R.I., T.M. Dinoff, R.L. Williams, X. Zhang and L. Aston. 2003. Pesticide Counts. Chemical and Engineering News (Letter), May 19,7-8.

Krieger, R I. 2002. Unintended and unavoidable human pesticide exposures. Journal of Environmental Monitoring. 4: 61N-65N.

Williams, R. W., C. E Bernard, R. I. Krieger. 2002. Influence of moisture on chemical transferability from nylon carpet. Bull Environ Contam Toxicol 69(3): 436-443.

Krieger, R. I. 2001. Handbook of Pesticide Toxicology (2nd edition; Assoc. Eds. J. Doull, D. Ecobichon, D. Gammon, E. Hodgson, L. Reiter and J. Ross) Academic Press. San Diego, CA, pp. 1908.

Bernard, C.E., H. Nuygen, D. Truong, R.I. Krieger. 2001. Environmental Residues and Biomonitoring Estimates of Human Insecticide Exposure from Treated Residential Turf. Arch. of Environ Contam. And Toxicol. 41:237-240.

Ross, J. H., Jeffrey H. Driver, Roger C. Cochran, Thomas Thongsinthusak and Robert I. Krieger. 2001. Could Pesticide Toxicology Studies be More Relevant to Occupational Risk Assessment? Ann. Occup. Hyg., No. 1001, 45: S5-S17.

Krieger, R.I., C.E. Bernard, T.M. Dinoff, J.H. Ross and R.L. Williams. 2001. Biomonitoring of Persons Exposed to Insecticides Used in Residences. Ann. Occup. Hyg., No. 1001, 45: S143-S153.

Williams, R.L., C.E. Bernard, R.I. Krieger. 2001. Child-like Mannequin for Observation and Measurement of Spray Drift Deposition for Pesticide Exposure Assessment. Bull. Environ. Contam. Toxicol., 67: 179-186.

Krieger, R. I., C. E. Bernard, T. M. Dinoff, L. Fell, T. Osimitz, J. H. Ross, and T. Thongsinthusak. 2000. Biomonitoring and whole body cotton dosimetry to estimate potential human dermal exposure to semivolatile chemicals. J. Exposure Analysis & Environ. Epidemiol. 10: 50-57.

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