The following generally accepted parameters have been developed to determine the concern level for a chemical in the environment. These parameters are a subgroup of the parameters in a methodology developed for the Ministry of the Environment for assessing the relative environmental hazards of chemical contaminants. The magnitude of the score assigned to each parameter reflects the level of concern arising from that property of a chemical.
Range of scores: 0-10 for all parameters a. to c.
Range of scores: 0-10 for all parameters a. to g.
- Acute Lethality
- Sub-Lethal Effects on Non-Mammalian Animals
- Sub-Lethal Effects on Plants
- Sub-Lethal Effects on Mammals
In addition to the numerical value assigned to a parameter, various symbols are used to indicate special concerns regarding the source of, or confidence in, the underlying data:
a) Insufficient Information for Scoring (*)
The insufficient data (*) tag is used where there are no data for a particular parameter or exposure route available, following a search of bibliographic databases. Any individual oral, inhalational, dermal or aquatic score and tag fields are left blank if no information for them is available after a search of factual databases and reference texts.
b) Limited Data (L)
The limited data (L) tag is used when the data available is of limited scope.
c) Worst-Case Designation (W)
The worst-case tag (W) is used when a score is based on data obtained from a study reporting an unusual endpoint or using a route of administration which would overestimate the hazard. (W)-tagged scores may decrease when additional data becomes available during a subsequent detailed assessment.
d) Questionable Data (Q)
The questionable-data tag (Q) is used to indicate that the data used does not fully match the criteria description, was obtained from situations of questionable relevance to the Ontario environment, or is otherwise questionable due to deficiencies in study or analytical methodology. (Q)-tagged scores may increase or decrease when additional data becomes available during a subsequent detailed assessment.
e) Estimated Data (E)
The estimated data tag (E) is used when a value is derived from a model such as a QSAR or fugacity model. In most cases this type of data is acceptable only if "real" data is absent. An exception is in scoring persistence [see section III(1b), below].
Only a single tag is to be assigned to a score. The order of precedence is: Q = W > E > L. For example, if a score is based on estimated data and also warrants a (W) tag, the tag assigned would be (W).
These "tags" may be taken into consideration when the chemical is reviewed.
1. Environmental Behaviour Parameters
|10||Three or more media each contain > or = 5% of the total amount released or substance is inorganic and is adsorbed to particles <10um in diameter when released.|
|7||Two media each contain > or = 5% of the total amount released.|
|4||No one medium contains > 95%, and only one medium contains > or = 5% of the total amount released.|
|0||Any single medium contains > 95% of the total amount released.|
|10||Half-life greater than 100 days|
|7||Half-life of more than 50 but less than or equal to 100 days|
|4||Half-life of more than 10 but less than or equal to 50 days|
|0||Half-life of less than or equal to 10 days|
Types of Data Preferred - Biodegradation data best reflecting the conditions in the ambient environment is preferable over data derived from studies using media such as activated sludge. The order of preference is:
environmental data (e.g. river die-away, half-life in soils) > some shaker flask studies > QSAR estimates > BOD.
When QSAR results in the form "t1/2 > x" are used for scoring, the score is assigned as if t1/2=2x.
If data from the studies mentioned above are available, scoring is not based on other types of studies even if they represent a worst-case. If preferred data is not available, the obtainable data is used and a (Q) tag is assigned.
Limited Database - When data on persistence are available for one medium only, an (L) tag is assigned.
|7||>500 - 15000||>4.0 - 6.0|
|4||>20 - 500||>2.0 - 4.0|
|0||< or = 20||< or = 2.0|
Use of Log P in the Absence of BCF Data - When log P values are used in the absence of bioaccumulation factors (BCFs) for scoring bioaccumulation, an (L) tag is assigned.
Use of BCFs for Unusual Species -
When bioaccumulation is scored on the basis of a BCF for an unusual species, e.g. an aquatic organism other than a freshwater fish, a (Q) tag is assigned.
2. Toxicity Parameters
|10||< or = 0.5||< or = 0.5||< or = 1.5||< or = 0.1|
|8||>0.5 - 5||>0.5 - 5||>1.5 - 15||>0.1 - 1|
|6||>5 - 50||>5 - 50||>15 - 150||>1 - 10|
|4||>50 - 500||>50 - 500||>50 - 500||>10 - 100|
|2||>500 - 5000||>500 - 5000||>1500 - 15000||>100 - 1000|
Route of Administration (Terrestrial Species) - When acute lethality is being scored, the score is based on intravenous, subcutaneous or intraperitoneal route data only if oral, dermal or inhalational route data are not available. A (W) tag is assigned in these cases, and scores are determined by using the oral LD50 criteria.
Aquatic Toxicity Ratings -
Saltwater Studies -
Scoring Acute Lethality in the Absence of LD50/LC50s -
|SCORE||AQUATIC ORGANISMS||TERRESTRIAL ORGANISMS|
|10||EC50 < or = 0.02 mg/L;
OR MATC < or = 0.002 mg/L;
OR NOAEC < or = 0.0002 mg/L
in different genera.
|Adverse effects at < or = 1 mg/kg for sub-chronic exposure OR < or = 0.5 mg/kg for chronic exposure, in different genera.|
|8||EC50 < or = 0.02 mg/L;
OR MATC < or = 0.002 mg/L
OR NOAEC < or = 0.0002 mg/L
in one genus only.
|Adverse effects at < or = 1 mg/kg for sub-chronic exposure OR < or = 0.5 mg/kg chronic exposure, in one genus only.|
|6||EC50 0.02 - <0.2 mg/L;
OR MATC 0.002 - <0.02 mg/L;
OR NOAEC 0.0002 - <0.002 mg/L.
|Adverse effects at >1-10 mg/kg for sub-chronic exposure OR >0.5-5 mg/kg for chronic exposure.|
|4||EC50 0.2 - <2 mg/L;
OR MATC 0.02 - <0.2 mg/L;
OR NOAEC 0.002 - <0.02 mg/L.
|Adverse or non-adverse effects at >10-100 mg/kg for sub-chronic exposure OR >5-50 mg/kg for chronic exposure.|
|2||EC50 2 - <20 mg/L;
OR MATC 0.2 - <2 mg/L;
OR NOAEC 0.02 - <0.2 mg/L.
|Adverse or non-adverse effects at >100-1000 mg/kg for sub-chronic exposure OR >50-500 mg/kg for chronic exposure.|
|0||EC50 > or = 20 mg/L;
OR MATC > or = 2 mg/L;
OR NOAEC > or = 0.2 mg/L.
|Adverse or non-adverse effects at > or = 1000 mg/kg for sub-chronic exposure exposure, > or = 500 mg/kg for chronic exposure.|
|SCORE||MEDIUM**||< or = 5
* Effects considered: Reduction in growth, total biomass or photosynthesis
Water - mg/L
Air - mg/m3
Soil - mg/kg
|10||< or = 0.1||< or = 0.3|
|8||>0.1 - 1||>0.3 - 3|
|6||>1 - 10||>3 - 30|
|4||>10 - 100||>30 - 300|
|2||>100 - 1000||>300 - 3000|
* Criteria are based on data from exposures of 90 days or more in duration; Refer to NOTES below if data from studies of this duration are not available.
Route of Administration -
Duration of Study -
Estimating NOAEL when only LOAELs are available -
Limited Database -
When a sublethal effects score is based on only one piece of data or on data for only one species, an (L) tag is assigned.In cases where only LOAELs are available, or in cases where some studies give LOAEL figures lower than the NOAELs reported in other studies, scores are based on the lowest LOAEL divided by a safety factor of 10, and are tagged (Q).The criteria are based on data from exposures of 90 days or more in duration. If such data is lacking, the results of shorter-term studies are used, tagged as questionable data (Q), and scored based on a modification of the data as described below. The rationale for this is that over a shorter period of time, higher concentrations of a toxin may be tolerated by an organism than over a extended period. The order of preference is > or = 90 days, 28-89 days, <28 days duration. If data from studies of 28 to 89 days exposure duration are used, the data values are divided by 10. If data from studies of less than 28 days exposure duration are used, the data values are divided by 100.When sublethal effects are being scored, the score is based on intravenous, subcutaneous and intraperitoneal route data only if oral, dermal or inhalational route data are not available. A (W) tag is assigned in these cases, and scores are determined using the oral exposure criteria.
|10||Teratogenic effects observed without overt maternal toxicity at maternal exposures < or = 0.1 mg/kg/day during organogenesis, or equivalent exposure*|
|8||Teratogenic effects observed without maternal toxicity at maternal exposures >0.1 - 1 mg/kg/day during organogenesis or equivalent exposure|
|6||Teratogenic effects or developmental anomalies observed at maternal exposures >1 - 10 mg/kg/day during organogenesis or equivalent exposure|
|4||Teratogenic effects or developmental anomalies observed at maternal exposures >10 - 50 mg/kg/day during organogenesis or equivalent exposure|
|2||Teratogenic effects or developmental anomalies obsreved at maternal exposures >50 - 1000 mg/kg/day during organogenesis or equivalent exposure|
|0||No terata observed, or observed only at maternal exposures of > or = 1000 mg/kg/day or equivalent exposure|
* Equivalent exposure by inhalation or dermal routes, assuming effects by dermal exposure would occur at comparable doses to oral exposure. Total dose via inhalation is to be converted to an approximate daily oral dose equivalent by the use of appropriate factors (e.g. ppm-to-mg/m3 conversion factor and physiological standards such as: a 60 kg adult human respires 20 m3 of air per day; a 275 g female rat respires 0.17 m3 of air per day).
|10||Conclusive evidence of mutagenicity or genotoxicity in recognized prokaryotic or eukaryotic test systems at exposure levels not producing overt toxic effects (in vivo and in vitro eukaryotic data are positive or are absent).|
|8||Evidence of clastogenic effects (general DNA damage, strand breaks, sister chromatid exchange), intercalations or crosslinks but no evidence of increased incidences of mutations or direct interactions with genetic material|
|6||Does not interact directly with DNA, but interferes with cellular mechanisms such as DNA synthesis and DNA repair. Effects may be observed at exposure levels associated with overt toxicity unrelated to genetic effects|
|4||Mutagen/genotoxin in prokaryotic systems only; in vitro eukaryotic data exist, and the results are negative.|
|2||Mutagen/genotoxin in vitro only; in vivo data exist, and the results are negative.|
|0||No evidence of mutagenic or genotoxic effects in an adequate battery of test systems.|
Absence of Eukaryotic and/or In Vivo Data -
Limited Database -
When the score is based on only one piece of data or on data for only one species strain, an (L) tag is assigned.If positive prokaryotic in vitro (e.g. Ames Salmonella) assays are available, but positive or negative eukaryotic or in vivo data are absent, a score of 4 is assigned, with a (Q) tag. A (Q) tag is also given when a score of 6 or greater is assigned in the absence of in vivo data (i.e. in the case of positive eukaryotic in vitro assays).
|10||Direct acting human carcinogen or potential human carcinogen (based on animal bioassay data) with evidence of direct interactions with genetic material; acts as an electrophile or direct alkylating agent, produces DNA adducts, induces cell transformation, etc.|
|8||Indirect acting (epigenetic) human carcinogen or potential human carcinogen (based on animal bioassay data) with evidence that it does not interact with genetic material.|
|6||Carcinogenic in animal bioassay tests at levels of exposure shown to saturate enzymes involved in the metabolism of the compound or at exposure levels shown to cause histopathological lesions known to predispose animals to the development of cancers at sites where the lesions are observed (e.g., ATPAse deficient liver foci in rodents). Adequate evidence must be available demonstrating that no interactions occur with genetic material and that the chemical does not induce cell transformation.|
|4||Positive tumorigenic agent (benign tumours) in humans or animals. Evidence must be available of lack of interactions with genetic material. Includes chemicals that act solely as promoters and those that cause cell transformation in vitro without evidence in other systems.|
|2||Tumorigenic in only one animal species and negative in other(s) (all studies considered adequate).|
|0||Not tumorigenic in an adequate animal bioassay in at least two species and must not interact with genetic material.|
Limited Database -
When the score is based on only one piece of data or on data for only one species strain, an (L) tag is assigned.
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Effluent Monitoring Priority Pollutants List (EMPPL)
|The minimum parameter scores leading to promotion of a substance to the EMPPL are:|
|Sublethal Toxicity, non-mammals||6|
|Sublethal Toxicity, plants||6|
|Sublethal Toxicity, mammals||6|
* A persistence score equal to or greater than 7 alone does not cause promotion to the EMPPL, but may support promotion based on other parameters.
When only LDLo or LCLo data are available, the data are scored as if they were for LD/LC50s and a (W) tag is assigned. When only LD100 or LC100 data are available, the data are scored as if they were for LD/LC50s and a (Q) tag is assigned.Freshwater species studies are preferred over saltwater studies. If an aquatic LC50 score must be based on a saltwater study (i.e. no freshwater data exist), a (Q) tag is assigned.When an overall acute lethality score is based only on an "aquatic toxicity rating" range, an (L) tag is assigned.