UC Riverside

The fate and distribution of DDA [2,2-bis(4-chlorophenyl)acetic acid, CAS No.:83-05-6], a water-soluble DDT [1,1,1-trichloro-2,2-di(4-chlorophenyl) ethane, CAS No.: 50-29-3] metabolite and its potential role in environmental surveillance and biomonitoring was investigated.

An analytical method for urinary DDA detection using pentafluorobenzyl bromide derivatization in human urine was developed (LOQ 10 ppb). Repeat of a 1946 human oral DDT study showed rapid DDA excretion in urine. Urine biomonitoring of Indoor Residual Spraying (IRS) program applicators demonstrated significantly higher DDA levels during spraying season (59 µg/L) than 1-month post-season (11 µg/L) and indicated low DDT exposure. DDA levels of applicators were similar to those of general U. S. population during earlier periods of DDT use. DDE does not form DDA. DDA analysis is sensitive, specific and technically simple and adaptable for measurement of low level DDT exposures in applicators or residents where DDT is used in IRS.

DDA is a fecal chemical biomarker of DDT exposure in chickens based upon DDT feeding studies (10 to 3000 ppm) in White Leghorn and ISA Brown hens. . Dose-dependent, rapid DDA excretion was observed. Blood and egg yolk DDTs (DDT/DDE/DDD) reflected body burden. Chlortetracycline HCl (~20 mg/kg drinking water) showed gut microflora contributed to DDA formation. Chicken feces from previous IRS treated areas indicated low background levels of DDTs and DDA. Chickens may be used as a sentinel species in monitoring current environmental DDT exposure.

DDTs are present in the sediments of Southern California Bight (SCB). Only ~10% of total DDTs discharged into the SCB are accounted for using available monitoring data (sediment, water, and biota). DDE is the dominant contaminant and analysis of white croakers and gull and brown pelican feces yielded no evidence of current DDT exposure based upon DDA residues. DDA was detected in SCB sediment (up to 76 µg/kg dry weight). DDT and DDD levels at the primary wastewater outfall indicated substantial potential for DDT transformation to DDA. Still culture of SCB sediment revealed rapid DDA formation following DDT fortification. DDA formation may be important in the natural recovery of SCB and provide important insight into resolution of the DDT mass balance.