PETITIONED PUBLIC HEALTH ASSESSMENT
ALASKA PULP CORPORATION
SITKA, SITKA COUNTY, ALASKA
Theresa Kilgus, Lead Health Assessor
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Exposure Investigation and Consultation Branch
Susan Moore, Toxicologist
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Exposure Investigation and Consultation Branch
Concurrence:
Richard Kauffman, Regional Representative
Agency for Toxic Substances and Disease Registry
Office of Regional Operations, Region
Marie Patterson, Community Involvement Specialist
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Community Involvement Branch
Dianne Drew, Health Educator
Agency for Toxic Substances and Disease Registry
Division of Health Education and Prevention
Safe Drinking Water Act
ATSDR Methods Summary
Glossary
The municipal water system in Sitka is regulated under the Safe Drinking Water
Act (SDWA). The purpose of the SDWA is to protect the public from contaminated
drinking water. The SDWA requires EPA to identify contaminants in drinking water
which may have an adverse effect on people's health and to specify a maximum
contaminant level (MCL) for those contaminants where feasible [1]. The MCL is
the National Primary Drinking Water Standard. Dioxin is one of the 83 contaminants
that are required to be regulated. However, the City of Sitka has a state-wide
waiver that is approved by EPA. The EPA's MCL for dioxin is 30 ppt. These standards
are to be met by all public water systems. The SDWA also requires EPA to set
standards for filtration and disinfection of drinking water. The National Primary
Drinking Water Regulations require systems relying on surface waters like Blue
Lake to use disinfection and to use filtration unless stringent standards are
met for microbiological contaminants, turbidity, and protection of surface water
used by the system [2]. To avoid filtration the Sitka municipal water system
must [1] :
1) | use disinfection and provide redundant disinfection capacity or an automatic shut-off if residual disinfectant levels drop to low; |
2) | must maintain disinfectant levels and operating conditions sufficient to inactivate 99.9% of Giardia lamblia cysts and 99.99% of viruses [3]; |
3) | establish and maintain an affective watershed control program; |
4) | verify the watershed and disinfectant programs through annual state inspections; |
5) | prevent any outbreaks of waterborne disease; and |
6) | comply with total coliform and trihalomethane MCLs. |
The watershed control program must 1) characterize the watershed hydrology and land ownership; 2) identify watershed characteristics and activities which may have an adverse effect on source water quality; and 3) monitor the occurrence of activities which may have an adverse effect on source water quality [4].
To ensure these requirements are met, an annual on-site inspection of the City of Sitka's public
water system is conducted by a consultant certified by the State of Alaska. Up to this time, the
water system has met all requirements [5].
REFERENCES
Randle, RV. Chapter 4, Safe Drinking Water Act in Environmental Law Handbook, 11th Edition. Government Institutes, Inc. 1991, Rockville, Maryland.
Williams, SE. Chapter 7, Safe Drinking Water Act in Environmental Law Handbook, 13th edition, editor Thomas F.P. Sullivan, Government Institutes, Inc. 1995, Rockville, Maryland.
18ACC 80.532. Disinfection requirements for systems avoiding filtration.
City and Borough of Sitka, Alaska Public Works Department Water Division. Watershed Control Program, Blue Lake Drinking Water Supply. Submitted as part of the Avoidance Criteria of the U.S. Environmental Protection Agency Surface Water Treatment Rule 40 C.F.R 141.71 Safe Drinking Water Act. June 1992.
City and Borough of Sitka. Report on 1997 Annual onsite Inspection of City of Sitka Public Water System To Satisfy Annual Report Requirements for Avoidance of Filtration. December 1, 1997.
Toxic Equivalency Factors(TEFs) and Toxic Equivalents (TEQs)
Toxic Equivalency Factors (TEFs) were developed by EPA and have been used by regulatory
agencies world-wide to estimate the potential health effects of exposure to dioxin like chemicals.
TEFs were derived from subchronic studies in mice using enzyme induction as an endpoint.
These values will be used to predict the relative potency of mixtures of these chemicals to induce
immune suppression, oxidative stress and enzyme induction in mice and enzyme induction,
thyroid hormone alterations and reproductive and developmental toxicity in rats.
The number and arrangement of the chlorine substituents determines the toxicity of dioxin congeners. The toxicity of individual congeners varies 1000-fold, which complicates the risk assessment of these compounds when found in the environment. A further complication is that dioxins are present along with dibenzo furans, polychlorinated biphenyls, and other halogenated aromatic compounds in complex mixtures.
To simplify the task of assessing the risk resulting from exposure to complex mixtures of dioxins and related compounds, Toxic Equivalency Factors (TEFs) were developed. TEFs are measures of toxicity determined relative to 2,3,7, 8-TCDD, which is given a TEF of 1.0. The 7 most toxic dioxins congeners, and the ten most toxic dibenzofuran congeners, have been assigned TEF values ranging from 0.5 to 0.001. The remaining 193 dioxins and dibenzofurans are less toxic and are thought to contribute comparatively little to the toxicity of a complex mixture. They have been assigned a TEF value of 0. When isomer-specific data are available, the concentration of each dioxin and dibenzofuran congener containing the 2,3,7, 8-substitution pattern is multiplied by its respective TEF, and the products are summed to generate a single value called the "2,3,7, 8-TCDD Toxic Equivalent (TEQ)". A review of environmental and mechanistic consideration which support the development of TEFs has recently been published.
While many research groups have utilized TEF approaches, the World Health Organization
suggests that "the use of [2, 3, 7, 8] TCDD equivalents must be regarded as an interim procedure
for the measurement of the toxicity of environmental samples, in the absence of long-term
toxicity data on specific PCDD [polychlorinated dibenzo-p-dioxin] isomers and mixtures of these
compounds." Because of the many gaps in the data at present, the use of TEFs is considered to
be imprecise, but the best that is available to date.
Reference for Glossary:
http://atsdr1.atsdr.cdc.gov:8060/glossary.html
APPENDIX B - List of Figures & Tables
Figures:
Figure 1: Blue Lake Vicinity Map
Figure 2: Alaska Pulp Company Intro Map
Figure 3: Blue Lake Topographical Map
Figure 4: Blue Lake Water Supply Overall System Schematic
Figure 5: Sediment Sampling Locations for Blue Lake
Figure 6: Dioxin Furan Results for Sediment Samples [1]
Tables:
Table 1: Turbidity in City of Sitka Water Supply 1992-1996
Figure 1. Blue Lake Vicinity Map
Figure 2. Alaska Pulp Company Intro Map
Figure 3. Blue Lake Topographical Map
Figure 4. Blue Lake Water Supply Overall System Schematic
Figure 5. Sediment Sampling Locations for Blue Lake
Figure 6. Dioxin Furan Results for Sediment Samples
| |||||
1992 | 1993 | 1994 | 1995 | 1996 | |
Jan | 2.0/1.0 | 0.4/0.2 | 8.4/3.1 | 0.56/0.37 | 0.4/0.22 |
Feb | 1.2/0.5 | 0.8/0.3 | 3.3/2.3 | 1.14/0.4 | 1.28/0.19 |
Mar | 1.1/0.6 | 0.5/0.3 | 1.9/2.0 | 0.98/0.4 | 1.2/0.41 |
Apr | 0.7/0.5 | 0.6/0.3 | 1.5/0.9 | 0.91/0.54 | 2.2/0.9 |
May | 0.9/0.6 | 0.6/0.3 | 0.5/0.4 | 1.3/0.63 | 1.7/0.4 |
Jun | 0.7/0.5 | 0.6/0.3 | ND | 0.9/0.47 | 2.12/0.3 |
Jul | 1.2/0.4 | 0.3/0.2 | 0.6/0.3 | 0.4/0.22 | 4.8/0.38 |
Aug | 1.6/0.5 | 0.5/0.3 | 0.6/0.3 | 2.57/0.35 | 1.4/0.6 |
Sept | 1.2/0.4 | 10.0/0.4 | 43.0/0.6 | 0.61/0.44 | 18.0/0.6 |
Oct | 1.2/0.5 | 10.0/4.1 | 8.0/2.0 | 0.88/0.32 | 17.0/4.16 |
Nov | 1.1/0.5 | 45.0/2.7 | 2.4/1.0 | 0.3/0.22 | 3.31/1.2 |
Dec | 1.7/0.3 | 12.8/6.1 | 1.2/0.7 | 0.4/0.24 | 3.49/1.2 |
a Turbidity is shown as the hi/low for the month. |