Toxicity reduction evaluation, toxicity identification evaluation and toxicity tracking in direct toxicity assessment.
Toxicity reduction evaluations (TREs) in the River Esk and Lower Tees Estuary were based on the approach described by USEPA, but adapted to tackle the specific problems of the two sites. A combination of toxicity tracking and toxicity identification evaluation (TIE) was used at both locations to enhance the understanding of source and type of toxicants present. The assessment of toxicity at Langholm focussed on pesticides present in the sewerage network. The TIE programme indicated that the most likely toxic agents within the effluent were the organophosphate pesticides diazinon and to lesser extent propetamphos, although these did not account for all of the observed toxicity. The exact source of these toxicants was not clear although toxicity tracking identified two potential candidates. The TRE undertaken on the discharge to the lower Tees utilised high-throughput methods with standard test organisms to generate toxicity information throughout a complex sewerage network. The toxicity tracking information was used in conjunction with TIEs to identify a number of key sources of toxicity. Substantial toxicity was associated with a currently untreated industrial effluent. Chemical analysis and TIE highlighted cyanide as the likely toxicant in this effluent and its possible significance in the final discharge.
AstraZeneca, Brixham Environmental Laboratory, Freshwater Quarry, Brixham Devon TQ5 8BA, UK. matt.hutchings@brixham.astrazeneca.com
Matt
M
Hutchings
Ian
I
Johnson
Elaine
E
Hayes
Andrew E
AE
Girling
John
J
Thain
Kevin
K
Thomas
Rachel
R
Benstead
Graham
G
Whale
Joy
J
Wordon
Ruth
R
Maddox
Phillip
P
Chown
D000818:Animals; D003486:Cyanides / Q000032:analysis / Q000633:toxicity*; D003621:Daphnia; D003976:Diazinon / Q000032:analysis / Q000633:toxicity*; D004784:Environmental Monitoring; D007306:Insecticides / Q000032:analysis / Q000633:toxicity*; D018570:Risk Assessment; D012606:Scotland; D012722:Sewage / Q000737:chemistry; D018675:Toxicity Tests / Q000379:methods*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity
D003486:Cyanides; D007306:Insecticides; D012722:Sewage; D014874:Water Pollutants, Chemical; D003976:Diazinon