The Globally Harmonized System for the Classification and Labelling (The GHS) - Implementation of the GHS in Canada

Pest Control Products

Table 2: How hazards are identified and communicated in the GHS and for Pest Control Products

Flammable Gases

Comments: For any pressurized pest control product with a flame projection, the statement "Do not use in presence of open flame or spark" is required under the "Precautions" heading on the secondary panel of the label. All pressurized products require a statement regarding a maximum storage temperature. Products with a flame projection of >90 cm are not generally acceptable for registration, unless they are designed to be used >90 cm from the target.

Flammable Aerosols

Comments: For any pressurized pest control product with a flame projection, the statement "Do not use in presence of open flame or spark" is required under the "Precautions" heading on the secondary panel of the label. All pressurized products require a statement regarding a maximum storage temperature. Products with a flame projection of >90 cm are not generally acceptable for registration, unless they are designed to be used >90 cm from the target.

Gases Under Pressure

Comments: PMRA does not require a measure of the pressure in pressurized containers. All pressurized pest control products require a statement regarding a maximum storage temperature.

Flammable Liquids

Corrosive to Metals

Comments: PMRA requires information on the corrosivity of end-use products, unless a reasonable explanation of a lack of corrosivity is provided, e.g. lack of extreme pH, lack of reaction with container material.

Acute Toxicity

Regarding the labelling of acute health hazards, the following paragraphs describe (1) differences between the GHS and PMRA's current approach and (2) PMRA's proposal for labelling acute health hazards according to the GHS. Overall, the symbols for lower hazard pesticides and border shapes as well as the signal words would change. The use of a single symbol border shape (square on point) would replace the current three border shapes (octagon, square on point, inverted triangle).

Acute toxicity is one criterion used to ensure that the more hazardous products are not available in the DOMESTIC market class and that highly hazardous products are limited to the RESTRICTED market class. Market class LD₅₀ cut-off values have been established for acute oral and dermal toxicity, but not for inhalation toxicity. There is, however, a provision that no special precautions or equipment (e.g. respirator) should be needed to mitigate hazard for a product destined for use in a domestic setting.

Under the GHS, mixtures are classified according to the same criteria as substances when data are available for the complete mixture and classification will always be based on that data. When data are not available for the complete mixture, bridging principles are then applied. If this approach is not viable, the GHS specifies methods to estimate the acute toxicity of a mixture based on a formula that sums the contribution of each hazardous ingredient. Pesticide petitioners usually produce test data on the active ingredient (substance) as well as the end-use products (mixture) or they bridge to other similar products in order to identify acute hazards and determine the appropriate hazard labelling.

Acute Toxicity: Oral

* GHS criteria for inclusion in Category 5 for oral, dermal and inhalation toxicity:

• indication of significant effect in humans
• any mortality at Category 4
• significant clinical signs at Category 4
• indication from other studies

Comments: Oral Toxicity LD₅₀ Cut-off Values for current market classes: Commercial Class > 50 mg/kg; Domestic Class > 500 mg/kg.

Because the GHS cut-off value for oral toxicity for Category 4 is slightly lower than PMRA's current cut-off value for eligibility in the DOMESTIC market class (300 mg/kg body weight vs. 500 mg/kg body weight), it may be beneficial for PMRA to lower its cut-off value for eligibility in the DOMESTIC market class to that of the GHS in order to maintain correspondence with thresholds for symbol and signal word requirements under the GHS. Under the GHS, pesticides with LD₅₀ values between 301 - 500 mg/kg body weight would meet the GHS criteria to be labelled as "WARNING Harmful if swallowed" and carry the ! hazard symbol instead of "DANGER POISON" and the Skull and Crossbones symbol currently required by the PMRA. In 1998, the PMRA performed an in-house analysis of acute oral toxicity data to gain a sense of the potential impact of this change. The assessment was based on a cut-off value of 200 mg/kg body weight (value under consideration at that time) and revealed that approximately 8% of pesticides bearing a COMMERCIAL market class designation could be considered eligible for the DOMESTIC market class by virtue of a change in cut-off values from 500 mg/kg body weight to 200 mg/kg body weight. The number potentially impacted by use of the 300 mg/kg body weight value would be less. The remainder of DOMESTIC market class products which currently display the signal words (and accompanying symbols) "WARNING POISON" and "CAUTION POISON" would now require the ! symbol under the GHS as well as the signal word "WARNING". The signal words "WARNING May be harmful if swallowed" would be required for products in Category 5 (LD₅₀ 2000 - 5000 mg/kg body weight) which would represent a change from the current PMRA approach (no hazard labelling).

Acute Toxicity: Dermal

Comments: Acute dermal toxicity LD₅₀ cut-off values for current market classes: Commercial Class > 100 mg/kg; Domestic Class > 1000 mg/kg.

For dermal toxicity under the GHS, Category 4 products (LD₅₀ 1000 - 2000 mg/kg body weight) would be labelled with the GHS hazard symbol (!) and the signal words "WARNING Harmful in contact with skin", instead of the skull and crossbones symbol and current PMRA signal words "CAUTION POISON". The signal words "WARNING May be harmful in contact with skin" would be required for products in Category 5 (LD₅₀ 2000 - 5000 mg/kg body weight) which would represent a change from the current PMRA approach (no hazard labelling).

Acute Toxicity: Inhalation - Dusts & Mists

Comments: Restricted Class & Commercial Class Pesticides - no specific criteria defined; Domestic Class - there is no LC₅₀ cut-off value, however, the inhalation hazard must be sufficiently low that they can be safety used without special precautions or equipment.

The PMRA utilizes LC₅₀ values to determine the appropriate hazard level as well as accompanying symbol for labelling purposes. PMRA does not require hazard labelling for pesticides with acute inhalation LC₅₀ values exceeding 2 mg/l. As with other hazard classes with different GHS cut-off values than PMRA has used, this difference will represent a classification challenge for PMRA and pesticide registrants.

GHS Categories 1 and 2 correspond in terms of both LC₅₀ cut-off values as well as hazard symbol with the higher levels of inhalation hazard currently identified by PMRA (LC₅₀ <0.5 mg/l). Therefore, under the GHS, the skull and crossbones symbol would be retained for these highly toxic pesticides. Under the GHS, pesticides currently meeting the criteria for inclusion in Category 2 would require a change to their labels (from WARNING to DANGER). Likewise, in view of differences between cut-off values currently used by the PMRA hazard level identification with those established under the GHS, pesticides currently carrying the signal word CAUTION would fall within either GHS Category 3 or 4 and require either DANGER or WARNING , respectively, depending upon the LC₅₀ value.

Many pesticides exist in a physical form which allows for the generation of dust, mists or aerosols when conducting acute inhalation toxicity testing. There are some pesticides, however, which exist in solid or liquid form but under conditions of use (e.g. fumigants) liberate volatiles or gases when in contact with water or other materials. The acute inhalation hazard classification would be based on the liberated gas which represents the active form of the pesticide. There are currently no specific classification criteria for gases and vapours, however, these pesticides would be restricted in use and the label would stipulate the requirement for the use of personal protective equipment to mitigate any inhalation hazard.

Market Classes

PMRA's current cut-off values for acute toxicity of products in the DOMESTIC market class are an oral LD₅₀ > 500 mg/kg body weight and a dermal LD₅₀ > 1000 mg/kg body weight. These values correspond to current thresholds for symbol and signal word requirements. As a result, DOMESTIC market class products currently bear the WARNING POISON or CAUTION POISON symbol and signal words, or no symbol or signal words at all. The acute oral and dermal toxicity of current DOMESTIC market class products correspond fairly well with GHS Categories 4 and 5. PMRA does not require hazard labelling for pesticides with acute oral or dermal LD₅₀ values exceeding 2000 mg/kg body weight (corresponding to GHS Category 5).

On the basis of acute oral LD₅₀, the current COMMERCIAL market class pesticides (LD₅₀ 50 mg/kg body weight) would correspond with GHS Category 3 or higher. On the basis of acute dermal LD₅₀, these products would correspond with GHS Category 2 or higher. Under the GHS, the most toxic COMMERCIAL market class pesticides would maintain the Skull and Crossbones symbol and signal word DANGER which currently appear on these products.

Highly toxic pest control products with acute oral LD₅₀ < 50 mg.kg or acute dermal LD₅₀ < 100 mg/kg are currently restricted to the RESTRICTED market class. Under the GHS, the acute toxicity hazard of such products would be Category 1 or Category 2 and these products would be labelled with the Skull and Crossbones symbol and signal word DANGER which currently appear on these products.

Skin Corrosion/Irritation

Current PMRA criteria are based on physical-chemical properties as well as biological response data (largely animal data). However, the criteria for both are not integrated and occasionally consultation with PMRA is required to determine appropriate hazard labelling. Signal word assignment is based on the biological response as well as the physical-chemical properties. However, the criteria for symbol selection as outlined in the Pesticide Registration Handbook take into account physical-chemical properties only. The PMRA would likely classify a pesticide as a skin corrosive if results from eye irritation testing demonstrate a corrosive response.

The PMRA and the GHS utilize the Draize scale of scoring (maximum of 8-points for skin reactions - 4 points for erythema/eschar response and 4 points for oedema response) . However, the PMRA criteria are based on the average Draize scores for both erythema/eschar and oedema whereas the GHS criteria are based on the average Draize scores for either erythema/eschar or oedema. There are slight differences between the Draize score ranges used by the PMRA and those identified by the GHS, however, the classification outcome is not expected to differ to any significant extent.

With the adoption of the GHS, there would be an integration of physical-chemical properties and biological response data for selection of appropriate hazard symbol and signal word. The more irritating pesticides which, on the basis of animal Draize tests, currently require a signal word only (DANGER, WARNING or CAUTION), would now require a symbol (!) under the GHS and the words WARNING Causes mild skin irritation.

The GHS criteria to classify a chemical as Corrosive (Skin Category 1A, 1B, 1C) appear to encompass PMRA's current criteria for requiring the signal word CORROSIVE on a pesticide label, i.e. >1% mineral acids or alkalis, organic acids, solid chlorine; >10% liquid chlorine; pH <2 or > 11.5. Three current levels of corrosion hazard would compress into one GHS category. Likewise, the PMRA currently requires the corrosive symbol for liquid pesticides containing 1 - 10% available chorine. Under the GHS, these pesticides would likely be classified as Corrosive (Skin Category 1). Consideration of GHS Skin Category 2 (reversible effects) may be justified, but would require supporting documentation.

Serious Eye Damage/Eye Irritation

* PMRA will consider use of DANGER EYE IRRITANT for pesticides with Maximum Average Scores >50 - 80 if the response is severe (i.e. opacity) but does demonstrate complete recovery within the study observation period

** The treated eye of each animal is scored using the standard Draize scale (cornea, iris, and conjunctival effects). These values are converted to an overall individual animal score based on a 110 point Draize rating scale. These converted animal scores are averaged for each of the 24, 48, and 72 hour observation periods. The observation period at which the average score is highest is then compared against either the Draize (1944) rating guide or Kay and Calandra rating guide (1962) to determine the appropriate level of eye irritation hazard.

Current PMRA criteria are based on physical-chemical properties as well as biological response data (largely animal data). However, the criteria for both are not integrated and occasionally consultation with PMRA is required to determine appropriate hazard labelling. Signal word assignment is based on the biological response as well as the physical-chemical properties. However, the criteria for symbol selection as outlined in the Pesticide Registration Handbook are based on physical-chemical properties only. The PMRA would classify a pesticide as an eye corrosive if results from skin irritation testing demonstrate a corrosive response. Therefore, pesticides meeting the criteria for classification as corrosive to skin on the basis of physical-chemical properties would also be considered corrosive to the eye and the label would carry the signal words DANGER CORROSIVE TO EYES.

There are slight differences between the animal test scoring approach used by the PMRA and that of the GHS, however, these differences are not anticipated to impact the classification outcome to any significant extent.

The PMRA currently requires signal words to designate three levels of eye hazard: one for irreversible effects (DANGER CORROSIVE TO EYES) and two levels for reversible effects (WARNING EYE IRRITANT, CAUTION EYE IRRITANT). The GHS includes 3 comparable levels. Under the GHS, pesticides producing irreversible effects to the eye would be Category 1 (irreversible effects) and labelled with the corrosive symbol and signal words DANGER Causes severe eye damage". Pesticides which produce reversible eye effects would be Category 2 and, depending on the time required to reversal of effects, could be classified as Category 2A (within 21 days) or Category 2B (within 7 days). Under the GHS, pesticides currently labelled as CAUTION EYE IRRITANT would probably be in Category 2B with the signal words WARNING Causes eye irritation. No hazard symbol would be required for Category 2B.

Skin Sensitization

The potential for skin sensitization is assessed by the PMRA and the hazard is communicated via the label phrase " POTENTIAL SKIN SENSITIZER". However, no hazard symbol or signal word is used to enhance the communication of this hazard. PMRA currently applies this approach to both pesticide active ingredients (substances) and formulated products (mixtures). Under the GHS, pesticides meeting the criteria for skin sensitization would require a symbol (!) as well as a signal word (WARNING) in addition to the text "May cause an allergic skin reaction".