Health Canada has determined that there is no health concern associated with eating berries (e.g. blueberries, raspberries) sprayed during forestry applications. This applies to large quantities of berries eaten at one time, or smaller amounts over a longer period of time.
Pesticide regulations are always developed applying a precautionary principle; that is to say, the intent is always to minimize both direct and inadvertent human exposure, as much as possible, within the context of the intended use of the pesticide product. Glyphosate herbicide has many food uses for which acceptable Maximum Residue Limits (the amount of residue of a pesticide which may lawfully be present in or on a food crop) have been established.
The PMRA, like all major regulatory agencies all over the world, derive Reference Doses, which define levels of a pesticide residue to which an individual can be exposed over a single day (acute) or over a lifetime (chronic) with no significant adverse health effects. Generally, dietary exposure to glyphosate from food and water is acceptable if it is less than 100% of the acute reference dose or chronic reference dose (the Reference Dose is also commonly known as the Acceptable Daily Intake or ADI). The PMRA has estimated potential acute (short term) and chronic (long term or lifetime) dietary exposures to glyphosate from residues of glyphosate and relevant metabolites in both treated crops, and from drinking water. Exposure to different subpopulations, including children and women of reproductive age, were considered. The acute dietary exposure estimate (from both food and drinking water) at the 95th percentile represents 31% of the acute reference dose (ARfD) for females 13-49 years of age and ranges from 12% to 45% of the ARfD for all other population subgroups. The PMRA estimate indicates that the sum of exposure from dietary sources and from water represents only one eighth to one half of an exposure level not expected to be associated with adverse health effects. The PMRA also estimated that chronic dietary exposure for the general population represents 30% of the acceptable daily intake (ADI). Chronic exposure estimates for population subgroups range from 20% of the ADI (for adults aged 50 years or older) to 70% of the ADI (for children 1-2 years old). The PMRA concluded that acute and chronic dietary risks from exposure to glyphosate are not of concern (PMRA, 2015).
Glyphosate forestry products are also used in agricultural settings and it is therefore expected that the exposure to glyphosate from food products (i.e., fruits and vegetables from direct treatment with glyphosate) will cover potential exposure from inadvertent residues in berries following a forestry use. The potential inadvertent exposure from consumption of berries is therefore not of concern (PMRA, personal communication).
In April 2015, the PMRA released their latest review of glyphosate and declared that the weight of evidence indicates that glyphosate does not present unacceptable risk to human health. The full PMRA glyphosate review can be found here or please visit here for a summary version of the full PMRA review.