Ecological relevance of pesticide residues in Alberta surface waters : an evaluation based on toxicity testing

50 Pages·2001·6 MB·English

by  HydroQual Laboratories Ltd

Ecological Relevance of Pesticide
Residues in Alberta Surface Waters:
An Evaluation Based on
Toxicity Testing
A
w^:jHyd-roQusa! ^ Environment
Digitized by tine Internet Arcliive
in 2015
https://archive.org/details/ecologicalrelevaOOhydr
Ecological Relevance of Pesticide Residues in
Alberta Surface Waters: An Evaluation Based on
Toxicity Testing
Prepared for:
Alberta Environment
Water Management Division
Water Sciences Branch
10*^ Floor, Oxbridge Place
Edmonton, Alberta
Canada T5K 2J6
Prepared by:
HydroQual Laboratories Ltd.
#3, 6125 12th Street S.E.
Calgary, Alberta
Canada T2H 2K1
March 30*^ 2001
Pub No. T/675
ISBN: 07785-2445-0 (Printed Edition)
ISBN: 07785-2446-9 (On-line Edition)
Web Site: http://www3.gov.ab.ca/env/info/infocentre/publist.cfm
Disclaimer
This study was funded by Alberta Environment. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use. The author, not
the publisher is responsible for the conclusions and opinions expressed.
Any comments, questions, or suggestions regarding the content of this document may
be directed to:
Science and Standards Branch
Alberta Environment
4*^ Floor, Oxbridge Place
9820 -106*^ Street
Edmonton, Alberta T5K 2J6
Phone: (780) 427-5883
Fax: [phone]
Additional copies of this document may be obtained by contacting:
Information Centre
Alberta Environment
Main Floor, Oxbridge Place
9820-106*^ Street
Edmonton, Alberta T5K 2J6
Phone: [phone]
Fax: [phone]
Email: [email protected]
SUMMARY
Low concentrations (ng/L to fig/L range) of many different pesticides are present in Alberta
surface waters. The environmental significance of the presence of low levels of pesticides is
unclear particularly because water quality guidelines (if a vailable) apply only to single compounds
and not mixtures. The objective was to assess the toxicity of pesticide mixtures to species
representative of major trophic levels in aquatic systems. Pesticides were selected based on the
frequency of detection in Alberta surface waters, relative concentration, and availability of
information (toxicity data).
The study was conducted in three phases. The first phase involved range fmding tests to compare
species sensitivities and establish treatment levels for tests to derive endpoints based on measured
pesticide levels (Phase II). The most sensitive species was carried forward to Phase III testing of
pesticide mixtures.
The tests were done with nine technical or reagent grade chemicals (2,4-D, MCPA, MCPP,
dicamba, bromoxynil, picloram, imazamethabenz, lindane, and diazinon) and four commercial
formulations (MCPA, MCPP, diazinon and chlorpyrifos). The commercial formulations were not
carried forward to Phase II and III. The testing included:
> Microbes
■ Estrogenic activity with the YES assay (Yeast Estrogen Screening assay)
■ Genetic induction potential (SOS-Chromotest)
■ Bacterial luminescence (light output at 15 minutes)
> Plants
■ 72 h algal grov^h inhibition test
■ 7 d duckweed growth inhibition test
> Invertebrate
■ 7 d Ceriodaphnia dubia survival and reproduction test
> Vertebrate (fish)
■ 7 d fathead minnow survival and growth test
The tests were conducted on a water-accommodated fraction (i.e., solution containing the
compound in excess of the maximum water solubility).
The pesticides were not genotoxic and exhibited no estrogenic activity. These two assays were
not carried forward into Phase II and III. The concentrations of each herbicide required to ehcit a
response in the other test species were substantially higher than the median and mean levels
measured in surface waters (mg/L range as compared to ng/L and ng/L range). However, the
effects of the two insecticides on Ceriodaphnia and fathead minnows were at concentrations near
those levels found in surface waters.
Ecological Relevance of Pesticide Residues in Alberta Surface Waters: An Evaluation Based on Toxicity
Testing i
The effects of the pesticides were also consistent amongst the test species. The insecticides
lindane and diazinon and the herbicide bromoxynil were the most toxic. Ceriodaphnia was the
most sensitive test species.
Mixtures of the seven herbicides had no adverse effects on survival and reproduction in
Ceriodaphnia when administered at concentrations of 0.01 and 0.1 mg/L. Similar results were
obtained for a mixture of the two insecticides (lindane and diazinon).
The fmdings suggest that the pesticide residues measured in surface waters of Alberta are at levels
that have no adverse effects on species representative of major trophic levels in aquatic systems. It
should be noted that the final tests were done with reagent and technical grade materials added to
laboratory dilution water. Degradation products, metabolites, and differences in water quality
conditions could affect the availability and toxicity of the chemicals. Further, there is a need to
address other related issues such as the bioaccumulation and biomagnification of these substances
in aquatic ecosystems, and impacts of peak runoff events.
Ecological Relevance of Pesticide Residues in Alberta Surface Waters: An Evaluation Based on Toxicity
Testing ii
TABLE OF CONTENTS
SUMMARY i
LIST OF TABLES iv
LIST OF FIGURES iv
1,0 INTRODUCTION 1
2.0 METHODS 2
2.1 Test Substances 2
2.2 Biological Tests 3
2.2.1 Microbial Tests 3
2.2.1.1 YES Assay 3
2.2.1.2 SOS-Chromotest. 4
2. 2. 1. 3 Bacterial Luminescence 5
2.2.2 Plant Tests 5
2. 2. 3 Invertebrate Test - Survival and Reproduction in Ceriodaphnia 6
2.2.4 Vertebrate Test - Survival and Growth of F athead Minnow. 7
2.3 Full Tests and Tests on Mixtures 7
3.0 RESULTS AND DISCUSSION 8
3.1 Phase I: Range Finding Tests 8
3.1.1 Test Results. 8
3.1.1.1 Microbes 8
3.1.1.2 Plants 9
3. 1. 1. 3 Invertebrates 9
3 J . 1.4 Vertebrates 9
3.1.2 Other Test Data 9
3.2 Phase U: Derivation of Endpoints 10
3.3 Phase HI: Tests on Mixtures 1 1
4.0 CONCLUSIONS AND RECOMMENDATIONS 13
4.1 Phase I: Range Finding Tests 13
4.2 Phase U: Derivation of Endpoints 13
4.3 Phase ID: Tests on Mixtures 14
4.4 General Conclusions and Study Limitations 14
4.5 Recommendations 14
5.0 REFERENCES 16
6.0 TABLES 17
7.0 FIGURES 33
Ecological Relevance of Pesticide Residues in Alberta Surface Waters: An Evaluation Based on Toxicity
Testing ill
LIST OF TABLES
Table 1 Test Organisms and Endpoints 18
Table 2 Test Substances 19
Table 3 a Selected Physical and Chemical Properties of Pesticides Included in the Assessment
20
Table 3b Selected Physical and Chemical Properties of Pesticides Included in the Assessment
(cont'd) 21
Table 4 Range Finding Test Results Summary (Phase I): T est Concentrations (mg/L) Giving a
50% Change in the Response Variable (LC50, EC50, and IC50) 22
Table 5 Range Finding Test Results Summary (Phase I): H ighest Concentration (mg/L) Tested
that had No Observed Effect (NOEC) on the Measured Response 23
Table 6 Observations on Water-accommodated Stock Solutions 24
Table 7 Effect of a Co-solvent on Toxicity of 2,4-D to Luminescent Bacteria 24
Table 8 Changes in Potency of Stock Solutions Over Time (Bacterial Luminescence) 25
Table 9 Full Test Results Summary (Phase II): Test Concentrations (mg/L) Giving a 50%
Change in the Response Variable (LC50, EC50, and IC50) 26
Table 10 Full Test Result s Summary (Phase II): Highest Concentration (mg/L) Tested that had
No Observed Effect (NOEC) on the Measured Response 27
Table 1 1 Test Results Summary (Phase III): Effects of Herbicide Mixtures on the Survival and
Reproduction of Ceriodaphnia 28
Table 12 Test Results Summary (Phase III): Effects of Insecticide Mixtures on the Survival and
Reproduction of Ceriodaphnia 29
Table 13a Nominal and Actual Concentrations of Pesticide Stock Solutions for Phase 1 30
Table 13b Nominal and Actual Concentrations of Pesticide Stock Solutions for Phase II and III
31
Table 13c Nominal and Actual Concentrations of Pesticide Mixture Solutions (Phase III) 32
LIST OF FIGURES
Figure 1 Project Overview 34
Ecological Relevance of Pesticide Residues in Alberta Surface Waters: An Evaluation Based on Toxicity
Testing iv
1.0 INTRODUCTION
Low levels of many different pesticides are regularly detected in samples from Alberta surface
waters (AENV, unpublished data). The environmental significance of these findings is u nclear
particularly because water quality guidelines (if a vailable) apply only to single compounds and not
mixtures. There are few published studies on the environmental effects of pesticide mixtures
administered at low concentrations (i.e., |ig/L range).
The objective of this study was to assess the ecological relevance of pesticide mixtures in Alberta
surface waters. An ecosystem approach was selected incorporating organisms representative of
major trophic levels in aquatic systems (Table 1). T he tests were conducted under defined
laboratory conditions following standard Environment Canada test methods. These methods were
designed to assess potential impacts of substances and conditions on selected life forms present in
aquatic systems. Additional tests were included to assess potential genotoxicity and to screen for
estrogenic effects.
The test species and endpoints are summarized in Table 1 and include microbes, plants, an
invertebrate, and a f ish. The approach includes both acute (survival) and chronic effects (growth
and reproduction). Microbes are an integral component of aquatic ecosystems. They convert
chemical energy into biomass (decomposition and cycling of nutrients) and serve as a m ajor food
source for invertebrates. Plants convert chemical energy and light into biomass and serve as a
food source for invertebrates and fish. Invertebrates feed on plants, microbes, and detritus and are
preyed upon by fish and other invertebrates. Effects detected at any one level could indicate
potential impairment of ecosystem structure and function. This would warrant further analyses to
determine what constituent or condition caused the effect.
The study was conducted in three phases as outlined in Figure 1 .
I. Range Finding Tests
II. Derivation of Endpoints
III. Tests on Mixtures
Ten pesticides (7 h erbicides and 3 insecticides) were included in the initial screening phase (Table
2). These compounds were selected based on the following criteria:
• Frequency of detection in surface waters,
• Concentration in surface waters versus guidelines for the protection of aquatic life, and
• Lack of available toxicity information.
The objective of Phase I w as to determine the relative potencies of each compound to the selected
test species. The pesticides and tests carried forward to Phase II were selected based on results
from Phase I. The tests with mixtures were done with the most sensitive organism (Phase III).
Ecological Relevance of Pesticide Residues in Alberta Surface Waters: An Evaluation Based on Toxicity
Testing 1
2.0 METHODS
The methods apply to all three phases of the project where appropriate.
2.1 Test Substances
Seven herbicides and three insecticides were included in Phase I o f the study (Table 2). The
herbicides are listed based on the frequency of detection and concentration in surface waters. In
other words, 2,4-D was detected more frequently and at higher concentrations than all other
herbicides. The insecticides were included in Phase I l argely because of a lack of information on
the toxicity of these materials to aquatic life forms.
Reagent grade or technical grade material was obtained for all herbicides and two insecticides
(lindane and diazinon). The percentage of active ingredient in the reagent or technical grade
formulations is g iven in Table 2. . T able 3 a and 3b present selected physical and chemical
properties of each pesticide. Reagent grade 2,4-D, MCPA, bromoxynil, picloram, and lindane
were purchased from Sigma. BASF Corporation provided technical grade MCPP and dicamba.
Cyanamid Crop Protection, Canada (now BASF Corporation) provided a 5 g s ample of technical
grade imazamethabenz for the study. A sample of diazinon (technical grade) was provided by
Novartis Crop Protection Inc. (now Syngenta). Clopyralid could not be obtained from a
manufacturer and was not included in any of the testing.
Commercial formulations of two herbicides (MCPA, MCPP) and the insecticides diazinon and
chlorpyrifos were also included in the initial range fmding tests. These formulations contain
solubilizing agents and the concentrations of the active ingredient far exceed the water solubility.
These products were included in Phase I o f the study for:
• Comparative purposes (formulation to reagent or technical grade material),
• Lack of access to the active ingredient, and
• Cost of the active ingredient.
The tests were conducted on water-accommodated fractions of the pesticides. The chemicals or
commercial formulation were made up in litre volume with deionized water to a f mal nominal
concentration of 1,000 mg/L (wt/vol). The solutions were shaken once or twice daily (bottles
inverted and shaken) for one week and then allowed to settle for two days before test initiation.
Reagent grade MCPA and MCPP, and technical grade dicamba went into solution (clear).
Commercial formulations of diazinon and chlorpyrifos formed milky white suspensions. The other
reagent and technical grade chemicals did not fully dissolve. The solid remained on the bottom of
the bottle. The concentration in solution was believed stabilized by the presence of excess material
on the bottom of the bottle (water-accommodated).
One stock solution was prepared for all tests in Phase I, a nd another set was prepared for
Phases II and III.
Ecological Relevance of Pesticide Residues in Alberta Surface Waters: An Evaluation Based on Toxicity
Testing 2