INDUSTRIAL CHEMICALS – KNOWN CARCINOGEN (IARC 1)
4,4′-Methylenebis (2-chloroaniline) is a synthetic chemical that occurs as tan coloured pellets or flakes. It has a faint amine odour, very low solubility in water, and may explode when heated. It is generally referred to as MOCA, but may also be called bisamine, MBOCA, or MCA. There are numerous other synonyms and product names; see Hazardous Substances Data Bank (HSDB) for more information.
MOCA has been classified by the International Agency for Research on Cancer (IARC) as Group 1, a known human carcinogen. It was first classified as a Group 2A carcinogen in 1987, but was re-classified as Group 1 in 2008 based on strong genotoxic mechanistic evidence. MOCA’s Group 1 classification was reaffirmed under IARC’s review of Group 1 carcinogens in 2012. In experimental animals, MOCA causes liver, bladder, and lung cancer.
Additionally, when MOCA is inhaled or ingested it can cause cyanosis (blue coloration of lips, fingernails or skin), as well as confusion, dizziness, headache, nausea, abdominal pain, unconsciousness, and convulsions. Chronic exposure can also cause blood disorders.
Regulations and Guidelines
|Canadian Jurisdictions||OEL (ppm)|
|Canada Labour Code||0.01 [sk]|
|AB, BC, MB, NB, NL, NS, PE||0.01 [sk]|
|QC||0.02 [sk, em]|
|NT, NU, SK||0.01 [sk]
|Other Organizations||OEL (ppm)|
|ACGIH 2020 TLV||0.01 [sk, IFV]|
ppm = parts per million
sk = easily absorbed through the skin
stel = short term exposure limit (15 min. maximum)
em= exposure must be reduced to the minimum
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value (8 hour maximum)
IFV = inhalable fraction and vapour
Canadian environmental guidelines and standards*
|Ontario Ambient Air Quality Objective||24 hour: 10 μg/m3||2016|
|BC’s Contaminated Sites Regulation, BC Reg 375||Sets soil standards for:
Agricultural and low density residential sites: 15 μg/g
Urban park and high density residential soil: 30 μg/g
Commercial and industrial soil: 350 μg/g
Drinking water standard: 0.5 μg/L
*Standards are legislated and legally enforceable, while guidelines (including Ontario ambient air quality criteria) describe concentrations of contaminants in the environment (e.g. air, water) that are protective against adverse health, environmental, or aesthetic (e.g. odour) effects
μg/m3 = micrograms per cubic metre
μg/g = micrograms per gram
μg/L = micrograms per liter
|Environment Canada’s National Pollutant Release Inventory||Reportable to NPRI if manufactured, processed, or otherwise used at quantities greater than: 10 tonnes.||2016|
|Health Canada||DSL – high priority substance with intermediate potential for exposure||2006|
DSL = domestic substances list
MOCA was not included in other Canadian government guidelines, standards, or chemical listings reviewed.
As of 2005 in Canada, MOCA was primarily used as a curing agent for polyurethane prepolymers. These prepolymers were used to make specialized, castable polyurethane products such as industrial tires and rollers, shock absorption pads, conveyor belting, sport boots, roller skate wheels, cameras, computers, electrical components and wear-resistant industrial products. Newer information on Canadian uses was not found.
Canadian Production and Trade
MOCA is not manufactured in Canada. However, polyurethane products and epoxy resins are.[33,34,35,36] Given that MOCA is used in conjunction with these processes, it is likely used in Canada. In 2000, Canadian imports of MOCA ranged from 100,000 to 1,000,000 kg. In Ontario, approximately 84,000 and 70,000 kg of MOCA were used in 2011 and 2012, respectively. Two companies that manufacture polyurethane and rubber products in Canada reported the release or disposal of MOCA in 2017.
No export or import data on MOCA was included in the TradeMap database.
Environmental Exposures Overview
MOCA is not a naturally-occurring chemical, so any found in the environment is from industrial releases or spills.[32,41] Sources of environmental exposure include dermal exposure to contaminated soil and ingesting root vegetables grown in contaminated soil.
Para-occupational exposures may occur in family members of workers exposed to MOCA.
Trace amounts of unreacted MOCA may be present in some plastic products, however because MOCA has a high molecular weight and low volatility, exposure in consumers is expected to be very low.
No household products are listed as containing MOCA in the Consumer Product Information Database from the United States.
A search of Environment Canada’s National Pollutant Release Inventory (NPRI) database yielded the following results on current potential for exposure to MOCA in Canada:
|Released into Environment||0.003 t||Plastic product manufacturing, rubber product manufacturing (2 facilities)|
|Disposed of||0.046 t|
|Sent to off-site recycling||None|
t = tonne
The most important route of occupational exposure to MOCA is dermal absorption, followed by inhalation and ingestion.
The main occupations exposed to MOCA include workers involved in its manufacture and in producing polyurethane and epoxy where MOCA is used as a curing agent.[1,6] MOCA has been detected on a number of workplace surfaces in MOCA and polyurethane production plants, which suggests potential dermal exposure for workers.[6,41] In a polyurethane factory, MOCA was detected in the air in areas where it was melted and used, indicating that chemical mixers and moulders would have the highest inhalation exposure to MOCA.
CAREX Canada has not prioritized MOCA for exposure estimate development. This is because there is a lack of exposure monitoring data in the Canadian Workplace Exposure Database on which to base an estimate.
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