Maine public safety officials have responded to an unprecedented number of incidents involving the manufacture of methamphetamine, officials said Tuesday.

Public Safety Commissioner John Morris said the Maine Drug Enforcement Agency responded to 86 meth incidents in the first six months of 2016, compared to 56 responses for all of 2015.

Morris said more than half of the agency’s responses have been to meth dump sites where plastic soda bottles that were used to make meth were discarded. Of the total number of responses from the MDEA this year, 44 have been to dump sites, usually along roads or at other outdoor locations. By comparison, MDEA responded to 20 meth dump sites last year.

Morris said that the discarded soda bottles, often still containing the residue of meth-making, are dangerous.

The Maine Department of Public Safety is cautioning anyone picking up discarded bottles along the road to be aware of the danger. If a bottle has white residue inside or other material that does not look like soda, or the bottle is enlarged from its normal size, call police and don’t pick it up.

Methamphetamine is made by mixing common household ingredients, with the key component being the nasal decongestant pseudoephedrine.

Morris said most of the MDEA’s meth lab and dump site responses this year have been in Aroostook and Penobscot counties.

The cost to gather and process evidence from the sites averages $3,000 for a meth lab and $500 for a dump site, according to the MDEA.

In 2009 Maine had a single meth lab response, but the numbers have climbed in recent years, with 20 MDEA meth responses in 2013, and 37 in 2014.