Chromium - Exposing The Element

Thanks to the hit movie Erin Brockovich, most people have at least heard about chromium VI - more properly called "hexavalent chromium" - and those who have heard about it probably do not want it in their drinking water. What is it? Chromium is the 11^th most-abundant, naturally occurring, metallic element found in water, soil and rock. Chromium is used for making steel and other alloys, bricks in furnaces, and dyes and pigments, and for chrome plating, leather tanning and wood preserving. It is a necessary human nutrient. Chromium has three main forms, chromium (0), trivalent chromium (chromium III) and hexavalent chromium (chromium VI). Chromium III is a necessary dietary supplement at trace concentrations, is a stable compound and occurs naturally in the environment. Chromium (0) does not occur naturally. Chromium VI is an inhalation carcinogen and "questionable" ingestion carcinogen. The United States Environmental Protection Agency (EPA) classified chromium VI as a human carcinogen by inhalation, however, it also then stated it was not a carcinogen when ingested and increased the maximum contamination level (MCL) from 50 parts per billion to 100 parts per billion. To date, EPA, IARC, NTP and DHS say there is no compelling evidence nor identification of chromium VI as a carcinogen when ingested in drinking water. One of the reasons for the strong lack of concern about ingestion is that the body's stomach acids convert chromium VI to chromium III internally and chromium III poses no health risk. There is no published study finding that a cancer risk exists for ingesting chromium VI in drinking water at the current concentration limits of 100 parts per billion federal and 50 parts per billion state. The general population can be exposed to chromium through the air, water, soils and food.

However, the movie Erin Brockovich prompted legislation to regulate chromium VI as there is no federal standard specifically governing the amount of chromium VI allowable in drinking water. At the federal level, Democratic Senators Barbara Boxer of California and Harry Reid of Nevada have introduced legislation, Senate Bill S698, that would require the National Academy of Sciences to study the health effects of chromium VI, and based on the findings of that study, to propose a MCL under federal law. Currently, federal regulations call for a maximum of 100 parts per billion of total chromium in drinking water. The Boxer-Reid legislation would, for the first time, establish separate standards for chromium III and its toxic cousin, chromium VI.

At the state level, there is no MCL for chromium VI in drinking water. The Office of Environmental Health Hazard Assessment and the California Environmental Protection Agency (OEHHA) in February 1999, set a Public Health Goal (PHG)¹ for total chromium of 2.5 parts per billion with 2 parts per billion for chromium VI, reduced from 50 parts per billion.² The PHG is not an enforceable standard but one strongly considered by DHS in setting MCL's, which DHS will be doing. Senate Bill 2127 mandates DHS to determine levels of risks of chromium VI in drinking water by January 1, 2002. Senate Bill 351 requires DHS to provide a progress report to the legislature on developing a chromium VI drinking water standard by January 1, 2003, and to adopt a primary drinking water standard by January 1, 2004.

Remediation

On January 1, 2001, the Department of Health Services added chromium VI to the list of unregulated chemicals for which monitoring is required by vulnerable community and non-transient, non-community water systems. Systems shall complete the required monitoring and report to DHS by December 31, 2002. So far, pump and treat, physical concrete barriers and excavations of contaminated soils are the remediation treatment options. Chromium has been detected in at least 386/1,777 NLP sites. The Toxic Chemical Release Inventory (EPA) listed 929 industrial facilities that produced, processed, or otherwise used chromium in 1998. EPA regulates chromium and its compounds under the Clean Water Act, CERCLA, RCRA, SARA and TSCA.

Litigation

While lawsuits may be filed, the absence of scientific data to support ingestion of chromium VI as a health hazard should stem the proliferation of these lawsuits. Additionally, the lack of a federal or state standard is significant because of the legal presumptions that come into play against entities who can be shown to have violated a statute or regulation. Clearly, if no such standard or regulation exists, a powerful argument for liability has been taken away from both governmental regulators and private plaintiffs. Finally, there are grave problems in accurately testing for chromium VI in drinking water because: (i) few labs conduct the test due to complexity and expense, (ii) accurate detection levels are difficult to obtain, and (iii) 24-four-hour turn around time on test results are necessary to prevent contamination.

Because accurate detection of tracer amounts of chromium VI is so difficult, there is very little information on current levels of chromium VI in the water supply. Extensive monitoring studies by the Metropolitan Water District of Southern California from 1998 to the present have shown relatively low levels of chromium VI - much less than 1/2 of one part per billion. These results are orders of magnitude below the federal standard for total chromium (100 parts per billion), the more stringent California standard for total chromium (50 parts per billion), and the 2.5 parts per billion standard for chromium VI that was adopted as a PHG in 1999 by the OEHHA.

No significant progress has been reported on the Boxier-Reid bill since its introduction earlier this year. Thus, it remains to be seen whether the momentum of an Oscar winning movie can translate into a controversial new federal standard applicable to the drinking water of every American.