Human health risks associated with contaminants in Southland waters A review Prepared for Environment Southland October 2019 Prepared by: Jennifer Gadd For any information regarding this report please contact: Jennifer Gadd Aquatic Chemist Urban Aquatic Environments +64-9-375 2058 [email protected] National Institute of Water & Atmospheric Research Ltd Private Bag 99940 Viaduct Harbour Auckland 1010 Phone +64 9 375 2050 NIWA CLIENT REPORT No: 2019320AK Report date: October 2019 NIWA Project: ENS19101 Quality Assurance Statement Reviewed by: Juliet Milne Formatting checked by: Emma Hope-Ede Jonathan Moores Approved for release by: Regional Manager - Auckland © All rights reserved. This publication may not be reproduced or copied in any form without the permission of the copyright owner(s). Such permission is only to be given in accordance with the terms of the client’s contract with NIWA. This copyright extends to all forms of copying and any storage of material in any kind of information retrieval system. Whilst NIWA has used all reasonable endeavours to ensure that the information contained in this document is accurate, NIWA does not give any express or implied warranty as to the completeness of the information contained herein, or that it will be suitable for any purpose(s) other than those specifically contemplated during the Project or agreed by NIWA and the Client. Contents Executive summary ............................................................................................................. 6 1 Introduction .............................................................................................................. 9 1.1 Background ............................................................................................................... 9 1.2 Scope ......................................................................................................................... 9 1.3 Sources of information ........................................................................................... 10 1.4 Report outline ......................................................................................................... 10 2 Human health risk assessment ................................................................................. 11 2.1 Risk assessment concepts ....................................................................................... 11 2.2 Exposure media, pathways and routes ................................................................... 11 2.3 Receptors for contaminants in waterways ............................................................. 13 2.4 Risk assessment framework for this report ............................................................ 13 3 Sources of contaminants to Southland waterways and estuaries ............................... 15 3.1 Agriculture .............................................................................................................. 15 3.2 Forestry ................................................................................................................... 18 3.3 Horticulture ............................................................................................................. 19 3.4 Industries ................................................................................................................ 19 3.5 Municipal activities ................................................................................................. 22 3.6 Diffuse and unknown sources ................................................................................. 27 3.7 Summary ................................................................................................................. 27 4 Hazards of contaminants of concern ......................................................................... 29 4.1 Persistence, mobility, and bioaccumulation ........................................................... 29 4.2 Toxicity of identified contaminants ........................................................................ 33 4.3 Reference doses, slope factors, guidelines and standards ..................................... 37 5 Risks associated with contaminants in groundwater ................................................. 40 5.1 Exposure routes for groundwater .......................................................................... 40 5.2 Presence of contaminants in Southland groundwater ........................................... 41 5.3 Risk assessment for ingestion of groundwater ....................................................... 47 6 Risks associated with contaminants in surface water ................................................ 49 6.1 Exposure routes for surface waters ........................................................................ 49 Human health risks associated with contaminants in Southland waters 3 6.2 Presence of contaminants in Southland surface waters ........................................ 50 6.3 Risk assessment for ingestion of surface waters .................................................... 54 7 Risks associated with contaminants in aquatic biota ................................................. 55 7.1 Consumption of fish, shellfish and other aquatic biota .......................................... 55 7.2 Presence of contaminants in Southland fish, shellfish and other aquatic biota .... 55 7.3 Risk assessment for consumption of biota ............................................................. 59 8 Knowledge gaps ....................................................................................................... 61 8.1 Sources of contaminants ........................................................................................ 61 8.2 Hazards ................................................................................................................... 61 8.3 Groundwater ........................................................................................................... 61 8.4 Surface water .......................................................................................................... 62 8.5 Aquatic biota ........................................................................................................... 62 9 Summary ................................................................................................................. 63 10 Acknowledgements ................................................................................................. 65 11 Glossary of abbreviations and terms ........................................................................ 66 12 References ............................................................................................................... 68 Tables Table 2-1: Exposure media and routes for contaminants. 11 Table 2-2: Risk ranking based on contaminant concentrations and the number of possible receptors. 14 Table 3-1: Dissolved contaminants in leachate from the New River Estuary Landfill. 24 Table 3-2: Contaminants in treated wastewater discharge from Invercargill City’s Clifton WWTP. 25 Table 3-3: Summary of sources of contaminants in the Southland region. 28 Table 4-1: Persistence, mobility and likely fate of toxic contaminants in waterways. 31 Table 4-2: Carcinogenic classifications. 33 Table 4-3: Human health effects of inorganic contaminants potentially present in Southland waterways. 34 Table 4-4: Human health effects of POPs potentially present in Southland waterways. 35 Table 4-5: Human health effects of pesticides potentially present in Southland waterways. 36 Table 4-6: Reference doses, carcinogenic slope factors, national drinking water standard MAVs (MoH 2018) and FSANZ guidelines for food (MLs) for contaminants of potential interest in Southland waterways. 38 Table 5-1: Towns and localities in Southland using groundwater for reticulated drinking water supply. 40 4 Human health risks associated with contaminants in Southland waters Table 5-2: Metals detected in Southland groundwater through monitoring by Environment Southland. 41 Table 5-3: Contaminant concentrations measured in groundwater near pesticide dumps in Southland. 45 Table 5-4: Pesticides detected in Southland wells during national and specific surveys. 46 Table 5-5: Summary of contaminant hazards and potential exposure in the Southland region through use of groundwater as a drinking water source. 48 Table 6-1: Towns and localities in Southland using surface water for reticulated drinking water supply. 49 Table 6-2: Total metals measured in stream water in Invercargill City. 50 Table 6-3: POP concentrations in surface waters of Southland. 52 Table 6-4: Summary of contaminant hazards and potential exposure in the Southland region through use of surface water as a drinking water source. 54 Table 7-1: Mean concentration of trace elements measured in biota in Southland. 56 Table 7-2: Summary of trace elements measured in watercress in Wellington and Canterbury. 56 Table 7-3: Summary of organochlorine concentrations measured in biota in Southland. 57 Table 7-4: Summary of anticoagulant residues (maximum concentrations in mg/kg wet weight) in Southland aquatic biota. 59 Table 7-5: Summary of contaminant hazards and potential exposure in the Southland region based on consumption of aquatic biota. 60 Table 9-1: Summary of contaminants present (or potentially present) in Southland groundwater, surface water and aquatic biota. 63 Table 9-2: Summary of relative risks of contaminants through the consumption of groundwater, surface water and aquatic biota in