The payment was the largest tort injury settlement in U. The animal study does not prove that people in Hinkley contracted cancer from drinking the tainted water. But it does resolve the debate over whether the contaminant is capable of causing some types of cancer. The national standard is ppb.
Because of the cancer uncertainty, California has had a tumultuous history of setting water standards to protect people from chromium. In , after the Hinkley case, California set a water guideline, called a Public Health Goal, of 2.
It was based on a study in Germany that found stomach tumors in animals that drank the substance. However, the U. EPA rejected that study as flawed and determined there was no evidence it was carcinogenic in water. The debate focused on whether hexavalent chromium is neutralized in the stomach by gastric acids that turn it into Chromium III, an essential nutrient.
California officials, seeking to resolve the controversy, asked the National Toxicology Program to conduct animal tests. In addition, chromium caused mouth cancers, and infiltrated the cells of many organs, including livers and pancreatic lymph nodes. Chromium is widely used in metal plating, stainless steel production , wood preservation and textile manufacturing. It has been detected in 30 percent of drinking water sources in California, at levels mostly under the existing 50 ppb state standard, according to the state health department.
Some of the rats and mice developed malignant intestinal tumors when fed doses as low as 57, ppb— times higher than the Hinkley water levels—for up to two years, Hooth said. The higher the dose, the more cancers found among the animals. When setting a standard, scientists use high animal doses to extrapolate to a lower dose designed to protect people from a year lifetime of exposure.
Water standards are usually designed to keep the cancer risk to one case in every million or , people. In sensitized workers, contact with even small amounts can cause a serious skin rash. Safety and Health Topics Hexavalent Chromium. Hexavalent Chromium. Health Effects Highlights. Hexavalent Chromium Hazards in Bridge Painting. Controlling Hexavalent Chromium Exposures during Electroplating. Controlling Hazardous Fume and Gases during Welding.
Related Safety and Health Topics Pages. Chromium Toxic Metals. In a recent article using data from the National Toxicology Program NTP of the National Institutes of Health, hexavalent chromium was identified as 'likely to be a carcinogen to humans' with an estimate of the cancer potency to humans equal to 0. At the cellular level, Cr VI is a highly active carcinogen [ 3 , 4 ].
A key issue is whether Cr VI ingested through the oral route, converts to trivalent Chromium Cr III which does not cross the cell membrane that easily before entering a living cell [ 5 ]. A recent study [ 6 ] revealed that rats and mice exposed to Cr VI -contaminated drinking water developed gastrointestinal abnormalities, including oral and intestinal tumors.
An earlier study [ 7 ] also found an increased incidence of benign and malignant combined forestomach neoplasms in mice orally exposed to Cr VI , whereas a more recent publication [ 8 ] presented a physiologically based model of chromium kinetics according to which non reduced hexavalent chromium after oral exposure could be metabolized in the red blood cells, liver, kidney and bone.
Because areas characterized by high Cr VI concentrations in drinking water are relatively uncommon, human epidemiologic studies are scant. One of the most cited and controversial studies analyzing the effects of oral exposure to Cr VI on population cancer mortality rates was conducted near a chromium smelting plant in the Liaoning Province, China [ 9 ].
Elevated mortality rates for total cancer, lung cancer, and stomach cancer were noted. These data were re-analyzed and re-evaluated by other investigators [ 10 , 11 ]; their re-analysis supported the conclusions of the original study [ 12 , 13 ]. However, a different study [ 14 ], comparing the same exposed villages to those of nearby areas, concluded that on average, the mortality rates for lung, stomach, and total cancer were not statistically different.
Thus, based on ecologic studies and animal studies, one could hypothesize that several organs could be targets of chromium carcinogenicity including the liver, kidney, bladder, gastrointestinal tract, the hematopoietic system and even bone. Therefore, the goal of this study was to examine the cancer mortality in an area of Greece, historically satisfying its potable needs with a Cr VI -contaminated aquifer. The Oinofita municipality Figure 1 is situated 50 km north of Athens, Greece and is comprised of four villages that were initially rural but transformed into industrial areas in the early s.
In , a ministerial decision gave permission for depositing processed industrial waste in the Asopos river, which runs through Oinofita. This decision, furthered by a presidential decree in , permitted free disposal of processed liquid industrial waste into the river. Map of the Oinofita municipality study area in Greece.
Panel A: Oinofita municipality lies at the border of the Voiotia with the Attica prefecture. The high industrial concentration near Asopos river can also be observed. The Oinofita industrial region is located within Voiotia prefecture at the border of Attica prefecture that includes the capital city of Athens.
Due to the proximity to Attica, the number of industries in the Oinofita region increased precipitously after , when a new law imposed restrictions on the establishment of various industries within Attica. According to the Technical Chamber of Greece [ 15 ], in , there were about industries operating in the Oinofita area, of which generated liquid industrial waste. Initial concerns were raised after Oinofita area citizens complained about the discoloration and turbidity of their drinking water.
Regular protests ensued from the s onward. In , the Ministry of Environment, Regional Planning and Public Works of Greece imposed fines on 20 industries for disposing industrial waste with high levels of hexavalent chromium into the Asopos river. However, as of yet, there are no limits set by any international body for Cr VI. In , the California Environmental Protection Agency proposed a public health goal level of 0.
Since , three independent sets of hexavalent chromium measurements are available for the Oinofita area. According to official Oinofita municipality authorities, in early the main drinking water supply of Oinofita was diverted to receive water from Mornos lake reservoir which is part of the drinking water supply network of the city of Athens.
To the best of our knowledge, there are no systematic measurements of Cr VI before In order to identify these individuals, we first obtained electronic records of all persons ever since legally registered in the municipality. Greek municipality records are maintained in family units. At the time of marriage a new record is created for the couple, and their children are included in that same record.
In case of divorce, two new records are created and children may be included in either of the parents' records. Thus, it was essential for our study design to exclude individuals registered in the Oinofita municipality but living outside the municipality. The municipality records provide the information of whether a person is a permanent resident or has moved outside the municipality.
Thus we selected persons fulfilling both criteria "a" and "b" to include in the study design. The original file with municipality records of Oinofita contained 13, records referring to a total of individuals.
We merged the information of all records on each person into a single record per individual for the analysis. Therefore, the resulting cohort was comprised of individuals. The beginning of follow up period for each individual was set as either a January 1, for individuals registered in the municipality before this date, or b the date of registration in the municipality for those registered after January 1, The end of the follow up was set as either a the date of death or the date of deletion from the records because of registering to another municipality before December 31, , or b December 31, The dates of death were cross-checked with the corresponding death certificates of each individual, which were obtained from the local vital statistics registry and from burial records of the local church.
The cause of death was coded using the four-digit ICD-9 classification system by a physician P. For the few eight persons who had changed municipality and then re-registered in the Oinofita municipality during the study period, we counted only the person years during which they were formally registered in the municipality.
We calculated person years, stratified by gender, age in five year groups , and calendar year. We also calculated observed deaths for all causes, overall cancer, and site specific cancers, stratified by gender, age, and calendar year. The expected number of deaths was calculated based on mortality statistics of the entire Voiotia prefecture, in which Oinofita municipality belongs to.
Voiotia prefecture includes 20 municipalities, and had an average population size of approximately , during the years of interest. We chose Voiotia prefecture, because of the similar geographical, population density, socioeconomic, and ethnic origin characteristics of the population.
The population statistics for Voiotia, as well as the cause specific deaths coded from original death certificates , stratified by gender, age, and calendar year, were provided by the Hellenic Statistical Authority. Hence, we were able to calculate the corresponding all cause and cause specific mortality rates by gender, age, and calendar year for the Voiotia prefecture.
Standardized Mortality Ratios SMRs were computed, stratified by age in five-year age groups , gender and calendar year, by dividing the observed number of deaths with the expected number of deaths multiplied by The expected deaths were obtained by multiplying the corresponding person years with the age-gender-year and cause specific mortality rate of the Voiotia prefecture population.
In the analysis, we reduced the four-digit ICD-9 code to a three-digit level classification system similar to what is used by the Hellenic Statistical Authority [ 19 ]. Tests of linear trend were performed under the Chi-square distribution [ 22 ], after computing cause specific SMRs adjusted for age and gender for each year of follow up.
The reason was to use years of follow up as a proxy to exposure level dose. Although municipality records do not specify the village in which each individual resides, we obtained this information from the death certificates. Thus, we were able to calculate proportional mortality ratios PMRs adjusted for age and gender of cause specific deaths versus all deaths, for specific Oinofita villages compared to those of the Voiotia prefecture. The number of total deaths, cancer deaths, and persons years total and within each age group , stratified by gender and calendar year are presented in Table 2.
The person years were decreasing as a function of time, showing and person years in and , respectively. Thus, the rate at which persons exit the cohort surpasses the corresponding entry rate. Furthermore, it is interesting to note that in there were more cancer deaths than ever before 18 compared to as observed in previous years.
A total of deaths were observed, of which were cancer related Table 3. These figures i. There were eight observed deaths of the hepatobiliary system, and more specifically: six primary liver cancers, one bile duct, and one gallbladder.
Furthermore, elevated SMRs were noted for several other cancer sites, including cancers of lip, oral cavity and pharynx, stomach, female colon, female breast, prostate, and leukaemia, but did not reach statistical significance Table 3. Tests for linear trend performed after grouping the period specific SMRs into 3 time intervals, i.
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