The federal government's No. 1 hunting ground for environmental offenders isn't deep in the mists of the boreal forest - it's in the back rooms of Canada's neighbourhood dry cleaners.
The pursuit of violations linked to a toxic chemical commonly used in dry-cleaning machines now makes up nearly a quarter of all inspections by Environment Canada enforcement officers.
In just a few years, the number of inspections to sniff out offences related to handling perchloroethylene - sometimes called tetrachloroethylene or PERC - has more than doubled.
Environment Canada warns that human exposure to high concentrations of PERC can inflict a host of health issues, including eye irritation, memory loss and even liver and kidney damage.
The department says PERC primarily enters the environment through the atmosphere, where it can damage plants, but it can also find its way into water systems, putting aquatic creatures at risk.
Between 2005-06 and 2008-09, Environment Canada conducted more inspections for PERC than anything else. The substance remains legal in Canada, but users must follow regulations and keep machines in good condition.
"It has been a focus of our attention over the past four or five years," said Manon Bombardier, head of Environment Canada's enforcement bureau.
"The rate of non-compliance in that sector is particularly high because of the high turnover rate of owners of those facilities.
"They change hands very quickly and to re-educate the new owners that the regulations exist and (that) there are requirements takes some time."
PERC inspections soared to 1,230 in 2007-08 from 446 in 2004-05. There were 1,032 inspections in 2008-09, the most recent data available on the department's website.
"Sometimes when we do inspections we get there and the company is unaware of the regulations and the requirements, so often they're in violation," Ms. Bombardier said.
"Some are minor violations, others are more significant."
A few years ago, California began phasing out the chemical and a statewide ban will come into effect in 2023.
Toronto Public Health, which released a 2007 report on PERC, describes the chemical as "probably carcinogenic."
It has recommended that Toronto gradually eliminate its use at dry-cleaning operations, particularly those that share residential buildings.
In its report, the health authority was also critical of Ottawa's PERC regulations, which it said "are not based on the most stringent measures that can be taken to protect the public from exposure."
Toronto Public Health also wants the federal government to strengthen its tetrachloroethylene regulations by eliminating the use of PERC in dry cleaning in Canada by the earliest date possible.
The president of the Eastern Canadian Laundry and Drycleaners Association welcomes the boost in inspections to ensure the environment is well-protected.
But Nick Mazzoli says the chemical shouldn't be banned.
Mr. Mazzoli said PERC is less of a concern today because newer dry-cleaning machines emit fewer emissions and do a better job of containing spills.
"It's not like it's as potent as everybody makes it out to be now, because things have changed over the years," Mr. Mazzoli said from his office in Concord, Ont.
"There's a lot of chemicals out there that are toxic, not only PERC.
"Gasoline's very toxic and we've got (a gas station) on every corner - I understand it's even worse than PERC."
Mr. Mazzoli said there are several alternatives to PERC, which isn't used as widely today as it once was in the dry-cleaning industry.
But he said it remains a critical solvent for businesses that can't immediately afford to replace machines with newer models - many of which range in price from $40,000 to $90,000.