Comment pubs.acs.org/est
Re-Emergence of Emerging Contaminants
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registered each day. Registrations currently comprise 89 million organic and inorganic substances and 65 million sequences. Even antibiotic resistance gene (ARG) sequences could become listed as “emerging contaminants” in the future. EPA simply cannot keep pace with the lists. Their budget is in decline and the list grows exponentially. New contaminants (and old contaminants presenting new problems) emerge almost daily. Oil and gas companies use dozens of unknown and unregulated chemicals in tens of thousands of fracking operations annually for shale gas in the U.S. alone. Incredibly, these companies are exempt from scrutiny under the Safe Drinking Water Act by congressional edict in 2005, even though fracking wells penetrate through drinking water aquifers. Faulty well casings may allow direct contamination of aquifer units with these chemicals. For better or worse, our commerce is producing innovative, challenging new compounds for biological pesticides, novel pharmaceuticals, and nanomaterials. Biological toxins, antibiotic resistance genes and new waterborne pathogens may become known as emerging contaminants in the next decade. Climate change, drought, and dwindling groundwater supplies means that direct potable reuse for drinking water is increasing worldwide. As such, new disinfection processes are being adopted which generate a plethora of novel disinfection byproducts (DBPs) for EPA to consider each year. Unfortunately the treatment process of choicereverse osmosis by high pressure membranespasses small concentrations of low molecular weight, neutral organic molecules (e.g., nitrosodimethylamine (NDMA), new halogenated DBPs like iodoacetate, and other halonitro-compounds) which are persistent and of possible health significance. Some contaminants are new and emerging, while others are the same old stuff in new clothes. EPA still struggles with what to do about dioxin and perchlorate after decades of risk assessment. States are beginning to independently regulate chemicals like 1,4-dioxane, PFCs, flame retardants, BPA, MTBE, neonicotinoids, and hormones used in animal agriculture because EPA cannot complete the review and come to a conclusion in a timely fashion. We need comprehensive reform of the Toxic Substances Control Act of 1976 to streamline this process and allow EPA to review and regulate chemicals in commerce more efficiently and rapidly. Much has changed since 1976. We have new approaches to high throughput testing and in-silico modeling that could provide preliminary guidance. The risk management paradigm needs to become more tiered, sleeker, and faster. And EPA requires greater authority to demand rapid testing data from industries in critical risk situations, not a voluntary testing program like the HPV. We can do better.
istory repeats itself. That certainly seemed true on August 2 when Toledo, Ohio lost their water supply from Lake Erie to a bloom of cyanobacteria and its toxin microcystin. Five hundred thousand people were without water. I thought Lake Erie was dead in the 1960s, not 50 years later in 2014? Did we not solve this problem thanks to massive (and expensive) action taken in the decades following the 1972 Clean Water Act? We successfully restricted phosphate in detergents, reduced phosphorus in the effluent from wastewater treatment plants, and drastically cut industrial discharges. But now, this old toxin (microcystin) from an ancient organism (cyanobacteria) has emerged again. It is due to nonpoint sources of agricultural runoff and more severe storms (climate change) carrying large loads of nutrients to fuel record blooms. Back to the future. Another episode of historic recurrence took place on January 9 near Charleston, West Virginia when 7500 gallons of the coal washing solvent, 4-methylcyclohexanemethanol (MCHM), was accidentally released from a storage tank adjacent to the Elk River. This time, 300 000 people were without drinking water. What’s interesting about the case is not the emergence of a “new” chemical, rather an old unregulated substance causing a new problem near the intake for a drinking water supply. Should not somebody suspect that an old storage tank could leak and a spill containment system could fail? (Think Bhopal.) MCHM is not a high production volume (HPV) chemical, so it is not on the Toxic Substances Control Act (TSCA) list to be tested by industry under EPA’s HPV Voluntary Challenge program. Instead, MCHM underwent premanufacture testing of a preliminary nature. The chemical is not discharged to wastewater at the plant, so there was not a NPDES permit required. It is not on the Safe Drinking Water Act Candidate Contaminant List (CCL3), so no primary drinking water standard exists for it or is contemplated. In fact, there was very little literature available on the aquatic or human toxicity of MCHM at all. It is apparently not acutely toxic because allowable chronic daily intake in one animal study was 100 mg/ kg per day, which means that a 70 kg adult could ingest a teaspoonful daily without serious health effects. (But you would smell a lot like licorice.) There’s still plenty of emerging compounds out there. TSCA inventory contains about 84 000 contaminants registered for commercial use. Only 2400 of those are HPV chemicals (more than one million lbs produced per year) that require detailed toxicological testing. Of those, 267 chemicals remain on the “orphan” list and are yet to be sponsored for testing. These include some suspicious candidates like methyl chlorobenzene, creosote, coal tar, and trichloracetaldehyde. But the most comprehensive list of chemicals is from our own American Chemical Society. The Chemical Abstracts Service (CAS) has established registry numbers for all new chemicals (CAS RN) reported in the literature and patents. These are not necessarily in commercial use and most will not get there. But the growth of the list is eye-popping with approximately 15 000 new chemicals and biological sequences © 2014 American Chemical Society
Jerald L. Schnoor,* Editor-in-Chief Published: September 12, 2014 11019
dx.doi.org/10.1021/es504256j | Environ. Sci. Technol. 2014, 48, 11019−11020
Environmental Science & Technology
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AUTHOR INFORMATION
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[email protected]. Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS. The authors declare no competing financial interest.
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dx.doi.org/10.1021/es504256j | Environ. Sci. Technol. 2014, 48, 11019−11020
