On Aug. 16, Health Canada’s Pest Management Regulatory Agency proposed to ban all outdoor uses of [the neonicotinoids] clothianidin and thiamethoxam …. because of an unacceptable risk to aquatic insects ….
…. PMRA scientists concluded:
- The threshold to protect 95 percent of all aquatic invertebrates from chronic exposure to clothianidin is 0.0015 ug/L, or 1.5 [parts per trillion]
[T]he U.S. [EPA] uses 50 [parts per trillion] as the acceptable, chronic exposure to the neonic.
“The PMRA chronic reference value for clothianidin of 1.5 [parts per trillion] … is more than an order of magnitude lower (more sensitive) than the US EPA’s unbound reference value of [50 parts per trillion],” the PMRA says ….
What is a part per trillion?
- A 747 airplane can hold almost 50,000 gallons of fuel. One part per billion is about four drops of liquid mixed into the fuel …. One part per trillion would be about half a drop of oil in a super tanker carrying six million gallons of oil.
“In Bayer’s opinion, that is the critical issue,” said Paul Thiel, vice-president of innovation and public affairs with Bayer Crop Science in Canada. “The chronic endpoint value, 1.5 parts per trillion, is … overly conservative.”
Christy Morrissey of the University of Saskatchewan has come up with significantly higher thresholds for chronic risk to aquatic insects such as mayflies and midges. The PMRA said in its report that Morrissey’s number is 35 parts per trillion for neonic exposure.
Read full, original article: Neonic threshold called ‘overly conservative’