FAQ: Health effects of pesticide used at Charles H. Hulse Public School


(via Ottawa Public Health)

1. What insecticides were used at Charles H. Hulse Public School?
Two insecticide products were used at Charles H. Hulse Public School on April 11, 2015. The products were GARDEX 1% Baygon Residual Insecticide AND KONK 400 Residual Insecticide Spray with Baygon. Both products contained a carbamate insecticide (propoxur). There was 1-2% propoxur in the products used. One product was applied from an aerosol can; the other as a liquid spray.  Most of the material applied was not propoxur, it consisted of a variety of liquids that act as solvents or carriers for the propoxur. The other components of the product applied included a mixture of isopropanol and paraffin solvents.

The insecticide was applied by an experienced, licensed pest control operator that has a contractual agreement with the Ottawa-Carleton District School Board (OCDSB) to provide pest control services. Health Canada is confirming the composition of the product through samples obtained by swabbing the classroom surfaces and taking a product sample from the applicator.  As of April 22, no results are available.

2. What is Propoxur?
Propoxur was introduced in the late 1950’s and has been available as an “unrestricted pesticide” for use by both consumers and commercial businesses in many countries, including Canada. It is used in different forms in different parts of the world, including sprays, wettable powder, room “foggers”, insect traps and tapes, and in flea & tick collars for pets.

3.  I heard that this may be an unapproved pesticide or that Health Canada has changed the label instructions on where this pesticide can be used. Is that true?
The pesticide propoxur is approved for use in Canada;  until recently, it was registered for use at a wide variety of sites including: structures (indoors and outdoors), transportation vehicles (for example, boats, ships, trucks, trains), on companion animals, in human habitat and recreational areas (for biting fly and mosquito control) and in residential outdoor areas.

Recently, the indications for use of the product changed on the label. The previous label indicates that propoxur may be applied by both ground and aerial means, using mist blowers, foggers and ultra-low volume application equipment to control mosquitoes and other biting flies. Cats and dogs are treated using slow release pet collars. Propoxur is also applied to other sites using pressurized spray cans, hand held and backpack sprayers, and paste applicators by professional applicators and casual users such as home owners.

In April 2014, Health Canada (HC) released the results of its re-assessment of propoxur. The reassessment indicated that some of the previously permitted uses might not meet target levels of safety for humans. Specifically, the HC re-assessment indicated that after indoor application, children might have excessive exposure to propoxur residues through breathing and hand-to-mouth contact.  The assessment also indicated exposure to surfaces in the building or to the perimeter of buildings after application could exceed target cancer risks levels.

As a result of the reassessment, Health Canada changed the label requirements. To protect residents and residential applicators; all indoor domestic-class products (except bait trays) were to be phased out and commercial-class products could no longer be applied to indoor residential use sites, including homes, schools, public buildings, day care facilities, motels, hotels, passenger areas of trains, buses or airplanes, and other indoor locations where children may be exposed. Use in pet collars was eliminated and some additional requirements were included on the label to protect workers applying propoxur.

The pesticide application at Charles H. Hulse Public School was consistent with the instructions on the old label but was not consistent with the new label.

4. Where was the insecticide sprayed in the school building?
OPH was advised that the insecticide was applied in Room 120 (daycare) and the washroom in room 113 as well as the staff washroom.

5.  What are the expected potential health impacts of the chemical from exposures?
Typical symptoms of overexposure to propoxur include excessive sweating and salivation, watery tearing eyes, pinpoint pupils, headache and abdominal cramping, vomiting and diarrhea. Twitching small muscles, malaise and muscle weakness may also occur. A life-threatening poisoning is signified by loss of consciousness, incontinence, convulsions and respiratory depression.

Propoxur is quickly eliminated from the body, so the ill effects resolve within hours of removing the exposure. Long term effects in humans from an acute exposure have not been documented.

The carrier liquids include isopropanol and paraffin. These substances may have a characteristic smell of alcohol or hydrocarbons. They can both be irritating to the airways and mucosal membranes but are not associated with long term harm in low concentrations.

Isopropanol inhalation is associated with irritation of the eyes, nose, and throat. Some people also experience headache and dizziness. Even at lower doses, people may find the odor and sensation objectionable. If someone drank or consumed a large quantity, there could be more severe effects, such as vomiting, diarrhea, confusion, and incoordination.

Paraffin is an irritant to airways. Mists or sprays are not usually harmful to the worker applying the product.

6. What could have caused the symptoms reported by some of the staff and students at the school?
Symptoms reported such as burning eyes, scratchy or irritated throat and/or skin and headache were reported in greater than 50% of a sample of those who reported symptoms the week of April 13th. Less commonly reported symptoms included nausea, sweating, weakness, clumsiness, vomiting, diarrhea, and confusion. Of those interviewed, some had consulted family doctors or walk-in clinics. None who had these symptoms visited an emergency department or was hospitalized. Some of the reported symptoms were not consistent with exposure to a chemical.

Irritation of the eyes, nose and throat reported are more consistent with exposure to the solvents components of the products that were applied rather than the propoxur itself.  Most of the material applied included paraffin solvents and isopropanol. Prolonged exposure to these solvents can result in symptoms such as skin rashes, itching, dryness and redness while repeated high exposures can lead to headaches, dizziness, confusion and loss of coordination, many of which were reported here.

Based on the information currently available, it is more plausible that that the solvents caused the symptoms rather than a toxic pesticide exposure.

7. Are there long-term effects that may occur?
No long-term health impacts to staff and children who were at the school or daycare are anticipated.  Steps have been taken to remove residues of propoxur and the solvents they were mixed with that may have remained after the application on April 11 and prevent ongoing exposure.

Ongoing exposure to propoxur in the general Canadian population also occurs through diet, however, Health Canada indicated that levels are not likely to result in adverse effects on health.

8. Have reproductive effects been reported?
There was no evidence of increased susceptibility of the young in reproduction or developmental toxicity studies. When pregnant animals were given tablets of propoxur, effects on the developing fetus were only observed at doses that caused death in the mother.

9. Will there be any air quality testing done?
The Ontario Ministry of the Environment and Climate Change (MOECC) has been assisting the response, and is performing air testing at the school.  Any environmental test results obtained by OPH or partner investigation agencies will be shared with those exposed.  The testing is not specific for the pesticide and conclusions about ongoing exposure will be made based on cleaning and detection of odour.

10. How and why was OPH involved?
OPH is mandated under the Ontario Health Protection and Promotion Act to investigate reported health hazards in our community and notify appropriate government agencies that may also have mandates around health hazards such as the MOECC and the Ministry of Labour (MOL).

OCDSB and OPH are in regular contact on health-related issues. OPH was informed about a cockroach problem at this school in March 2015 by the MOECC as parents had contacted them with concerns about the use of a pesticide in the daycare. OPH investigated and found no health concerns among the daycare staff for themselves or children at that time.

This month, OPH was notified by the school late Tuesday April 14, 2015 that there were concerns about a pesticide application at Charles H. Hulse Public School. On the same evening, the MOECC notified OPH of the pesticide application at the school.  OPH investigated the next morning, advised cleaning and ventilation, and have been back to the school every day with representatives from the MOL, MOECC and HC.  The school board informed OPH that they were taking extra precautions and relocated the daycare into the gym away from affected area.

On Wednesday, April 15, an OPH inspector visited the school and recommended additional ventilation and thorough cleaning. According to information since provided by the school to OPH on April 17, OPH has been advised that 30 students and 7 staff had been absent from school most likely related to this event.

A health symptoms assessment was done on Saturday, April 18th to determine if the symptoms being reported and the severity of the symptoms could be related to the pesticide application at the school. A sample of students who were absent in the week of April 13th or had bee removed from school by a parent, as well as teachers who had reported symptoms were called.

Common symptoms that are potentially related to chemical exposure were reported but other symptoms were also reported that are not consistent with chemical exposure as noted above.

On Sunday, April 19, 2015, OPH conducted an inspection of the school building to determine if appropriate cleaning had taken place and if any odours that could cause adverse health impacts among the staff and students still persisted. Based on that inspection, OPH was satisfied at that time with the improvement in the air quality and the description of the cleaning procedures that were used at the school location. OPH took into account a report from the Ministry of Labour that stated similar conclusions.

On Monday, April 20, Ottawa Public Health learned an odour had re-emerged at the school location. As well, some school staff who returned to the school location on Monday, April 20 experienced recurring symptoms. The recurring symptoms resulting from the exposure appear as previously reported – reversible health effects, such as itching of the eyes and skin, sweating, and headaches. Since Monday, April 20, OPH has been involved in further joint inspections and recommendations to remove the presence of the chemicals applied.

11. Is there anything further that can be done to eliminate the odour
Following joint inspections with other agencies several suggestions and recommendations have been made to improve the odours and potential health hazard at the school and daycare.  These measures include but are not limited to:

  • changing the carbon filters on the mobile air scrubbers in the daycare
  • closing the daycare doors so the odour doesn’t spread
  • installing carbon filters on the building HVAC system
  • discarding all products that were stored in drawers such as food wrap, diapers, etc.
  • ventilating the room to the outdoors via open windows

12. I (or my child) experienced symptoms related to this chemical application but I haven’t been contacted by OPH? Why hasn’t anyone contacted me?
OPH received contact information for the school staff and students who were absent during the week of April 13-17 or who experienced symptoms related to the pesticide application. Telephone interviews of a sampling of school staff and parents and guardians of children who either reported illness or were absent during the week of April 13-16, 2015 have been conducted. No further survey is planned because the data OPH has collected has given us an idea of the severity of the symptoms and of a possible link to the exposure.

13. If people think they are still having symptoms what should they do?
If students or staff experience any new or recurring symptoms which they believe are associated with a health hazard at the school, they should consider seeking medical attention and are asked to advise OPH at 613-580-6744. Staff of the daycare or school can contact the Ontario Ministry of Labour at 1-800-267-1916.

14. How will further information be shared?
OPH will continue to liaise with the OCDSB and the Andrew Fleck Childcare Services and these agencies will share OPH information directly with staff and parents of children who attend the school and daycare.

OttawaStart Staff



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