Methanol Listed on Prop 65 List, Methanol in Fruit and Vegetables Linked to Pectin

As of March 16, 2012 Methanol was added to the Prop 65 list as a reproductive hazard. According to OEHHA ,Methanol occurs naturally in fruits and vegetables. Methanol is also formed when fruits and vegetables are physically prepared for consumption by slicing, chopping, pureeing and juicing. The production of free methanol in all these instances is the result of reactions in pectin, a principal component of plant cell walls and the middle lamella between them. Pectin is heteropolysaccharide contained in the primary cell walls of terrestrial plants. It is produced commercially as a white to light brown powder, mainly extracted from citrus fruits, and is used in food as a gelling agent particularly in jams and jellies. It is also used in fillings, medicines, sweets, as a stabilizer in fruit juices and milk drinks, and as a source of dietary fiber. Pectin will break down to methanol when the plant cell walls and middle lamellae are disrupted, as can happen through physical processes of food preparation. Methanol is also produced when pectin is digested after eating fruits and vegetables, but OEHHA does not believe that the pectin that is activated by chopping and slicing will increase over the amount that is produced during digestion.

In addition to the notice that methanol is now on the Prop 65 list, OEHHA released the Interpretive Guideline No 2012-01  that indicates that methanol resulting from Pectin in Fruits and Vegetables is considered to be Naturally Occurring under section 25501 of Prop 65 and thus not required to comply with the Prop 65 warning requirements. The interpretation leaves the door open as to whether pectin that is added to products is subject to Prop 65. The text of the exemption which excludes levels of these chemicals that occur naturally in food without addition by human activity, may be a hard standard to meet.


OEHHA has also proposed regulatory levels for the consumption of methanol both by ingestion and inhalation. The numbers although they appear to be high on their face, Maximum Allowable Dose Levels for methanol of 47,000 micrograms per day for inhalation and 23,000 micrograms per day for ingestion are not. Based on the numbers derived from the pectin interpretation,  fresh orange juice may have methanol concentrations as high as 80 ppm. At that concentration the Prop 65 MADL level is arguably reached with just ten ounces of juice.


Comments may still  be transmitted to OEHHA on these proposed MADLs until April 30, 2012.

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Nate - April 18, 2012 11:00 AM

Is exposure to methanol from other natural occurrences such as machining wood exempt from Proposition 65 similar to exposure to methanol in foods prepared from fruits and vegetables?

Good question, naturally ocurring defense only applies to Food.

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