Review of Cancer Rates in the Vicinity of Chrome Crankshaft Company and J and S Chrome Plating Company
J&S CHROME PLATING
BELL GARDENS, LOS ANGELES COUNTY, CALIFORNIA
The Environmental Health Investigations Branch (EHIB) of the California Department of Health Services (CDHS) has prepared this public health consultation under a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR). This health consultation presents information on cancer rates in the areas that could have been affected by exposures from two former chromium-plating facilities, Chrome Crankshaft, Inc., and J&S Chrome Plating, located adjacent to each other, in Bell Gardens, Los Angeles County, California.
Specifically, this consultation addresses the question of whether there are more cases of cancer in the area near the Chrome Crankshaft and J&S Chrome Plating facilities than would be typically expected.
The review of cancer rates in the areas potentially exposed to Chrome Crankshaft and J&S Chrome Plating emissions found no excess childhood cancer in any area. Nor did the review find excess cancer among adults who live in the census tracts downwind of the facilities (City of Downey). Similarly, no excess cancer was found in any group of Hispanics, either males or females. Rates of cancer for non-Hispanic white adults in Bell Gardens near the facilities varied. Rates of cancer in the immediate area where the facilities are located were lower than expected for white males, but white females had slightly higher than expected rates of lung cancer. In other parts of Bell Gardens located farther from Chrome Crankshaft and J&S Chrome Plating, higher rates of cancer, including lung cancer, were noted among white males and females.
Scientific studies of workers exposed to high levels of chromium have found such exposure increases their chances of lung cancer. Because measurements of chromium in the air near the Chrome Crankshaft and J&S Chrome Plating facilities were much lower than typical workplace levels, it seems unlikely that increased cancer rates would have been caused by exposure to chromium from Chrome Crankshaft and J&S Chrome Plating. Also, the geographical pattern of excess cancer could not be associated with the location of the two facilities. If chromium from Chrome Crankshaft and J&S Chrome Plating had been responsible for the excess cancer, the incidence would be expected to be highest in the area near the facilities.
There are a number of reasons why it is difficult to tell from this type of review whether specific exposures caused cancer in a community. It is possible that other factors, such as emissions from other facilities, chromium workers residing in the neighborhood, or other risk factors contributed to the elevated cancer rates in some areas. For example, because smoking is such a strong risk factor for lung cancer (85% of lung cancer is caused by cigarette smoking), and information on smoking is not available, it is not possible to attribute the excess in lung cancer that occurred in some areas to exposure to Chrome Crankshaft and J&S Chrome Plating. Thus, it is not possible to determine if any of the cancers were caused by exposure to chemicals from Chrome Crankshaft and J&S Chrome Plating, by something else (such as smoking), or by chance.
EHIB has an agreement with ATSDR to conduct public health assessment activities at hazardous facilities throughout California, including Chrome Crankshaft and J&S Chrome Plating. These facilities are located in Bell Gardens, California, within the County of Los Angeles. In conducting the public health assessment, CDHS evaluated whether any contaminated water or air from these facilities could affect or could have affected the community, or may affect the community in the future. This information is summarized in reports on the water (1) and air (2).
The Chrome Crankshaft facility is located at 6845 Florence Place, and operated from 1963 to 1999 (Figure 1) (3). J&S Chrome Plating is adjacent to Chrome Crankshaft, at 6863 E. Florence Place, and operated from 1953 to 1991. Because of contamination of the soil and groundwater resulting from their operations, Chrome Crankshaft and J&S Chrome Plating are currently under investigation by the Department of Toxic Substances Control (DTSC) of the State of California and the Los Angeles Regional Water Quality Control Board. These facilities released chromium into the air through smokestacks on their roofs. DTSC has directed both sites to initiate remedial and clean-up activities. J&S Chrome Plating began remedial work in 1992. Chrome Crankshaft is presently implementing remedial operations. DTSC is overseeing the site investigation and cleanup of both Chrome Crankshaft and J&S Chrome Plating, as well as cleanup of an adjacent property, Downey Vendors Industrial Property. The Downey Vendors building is constructed on property that was originally purchased from Chrome Crankshaft, but its business does not involve the manufacture or use of hazardous materials (4).
CDHS obtained the cancer incidence rates from the University of Southern California Cancer Surveillance Program, the designated cancer registry for Los Angeles County. This registry has been collecting information on all cancer diagnoses in Los Angeles County since 1972, thus allowing this type of analysis to be performed. Cancer incidence data have been collected under California Public Health Foundation Subcontract 050H-8709. The subcontract is supported by CDHS as a part of its statewide cancer-reporting program as mandated by California Health and Safety Code Section 210 and 211.3.
The Chrome Crankshaft site is bordered to the north by an empty lot and to the east by the J&S Chrome Plating facility (3). Residential areas are located south and west of the facilities (Figure 1). The Suva Elementary and Intermediate Schools are located at 6740 East Suva Street, adjacent to the Chrome Crankshaft facility (Figure 1). A chain-link fence separates the western boundary of the Chrome Crankshaft facility from the eastern boundary of the Suva Elementary School. Other industrial facilities are located northwest of Suva Street.
In this area, the wind blows primarily from the west or southwest (3). This is the "predominant wind direction." This also means that most of the time the wind is not blowing from the facilities toward the schools. In general, concentrations of contaminants in the air are highest in the area near where they are released, and then become lower farther from that point. How this happens exactly (in what pattern the contaminants disperse) depends on wind speed and direction.
This review examines cancer rates in three census tracts in Bell Gardens, two census tracts in Downey, and one in Commerce (Figure 1). Census tracts are specific geographical areas defined in the United States Census. The Bell Gardens census tracts reviewed are 5340, 5342, and 5339. Chrome Crankshaft and J&S Chrome Plating are located in census tract 5340. CDHS reviewed Downey census tracts 5507 and 5508 because they are downwind of the two facilities. The Commerce census tract 5323.01 is included only in the analysis of cancer among children; some children in Commerce travel by bus to attend Suva Intermediate School. There were differences between the Bell Gardens and Commerce census tracts in terms of the average socioeconomic status (income and educational level) of the residents. The average income and educational level of residents in the Bell Gardens census tracts was lower than the average for residents in the Downey census tracts.
Approximately 42,000 persons live in the City of Bell Gardens (5). In the 1990 census, the ethnic makeup was 87% Hispanic (includes white Hispanics), 10% white (not Hispanic), <2% Native American, <2% Asian/Pacific Islander, and <1% African American. Eighteen percent of the total population was under the age of 18, and 36% was age 65 or over. The two census tracts from Downey (5507 and 5508) included a total of approximately 11,000 persons. The ethnic composition was 26% Hispanic, 80% white, <1% Native American, 1% African American, and 8% Asian/Pacific Islander. Twenty-three percent of the population was under the age of 18, and 18% was 65 or over. Also according to the 1990 Census approximately 8,000 persons resided in the census tract studied in Commerce (5323.01). Hispanics accounted for 88% of the population, and 23% of the total population was under the age of 18.
The Suva Elementary and Intermediate Schools, located by the facilities, have a combined student population of approximately 2,800. Suva Elementary School includes kindergarten through 4th grade, with a total of 1,070 students. Suva Intermediate School includes 5th through 8th grade, with a total of 1,785 students (6).
Cancer is a major health concern raised by those who reside in areas surrounding the Chrome Crankshaft and J&S Chrome Plating sites. Concerns include cancer in children and young adults and cancers in teachers and staff in the Suva Elementary and Intermediate Schools. Other health concerns, such as the safety of the drinking water, are addressed by separate public health assessment activities (1).
ATSDR and CDHS recognize that infants and children may be more sensitive to chemical exposures than adults in communities with contamination in their air, soil, water, or food. This sensitivity is the result of many factors. First, children may have higher exposures to environmental toxins than do adults because pound-for-pound of body weight, children drink more water, eat more food, and breathe more air than do adults (7). Second, children's bodies are rapidly growing and developing; they could sustain permanent damage if exposures occur during critical growth stages. For example, a child's lungs and body might respond differently to chromium exposure than would an adult's. Still, at this time there is inadequate information in the scientific literature to address children's sensitivity to chemical exposures, and additional data on children's health is needed to fill this gap.
Chromium is an element that occurs naturally in rocks, animals, and plants (8). It has several forms, including chromium (III), which is an essential human nutrient in small amounts. Chromium (VI), also known as hexavalent chromium, is primarily a man-made form produced by industrial processes (and is the more toxic form of chromium). Chromium (VI) has been determined to be a known human carcinogen (can cause cancer) by the inhalation route of exposure (8).
In reviewing a site, CDHS considers whether any of the contaminants from the facility could have reached nearby residents. CDHS attempts to determine whether residents could have come in contact with any chemicals, such as by touching or eating contaminated soil, breathing contaminated air, or drinking contaminated water. A chemical cannot cause a health problem if a person does not come in contact with it.
CDHS determined that the main route by which people in the community could have been exposed to chemicals is through past releases into the air from Chrome Crankshaft or J&S Chrome Plating (2). (The drinking water has been reviewed, and no elevated levels of chromium or other contaminants were found (1).)
Past air sampling and estimates of levels based on what was emitted from smokestacks provide an indication of how much chromium was in the air in the community. In 1987 air sampling for chromium found hexavalent chromium at 0.058 micrograms/ cubic meters (ug/ m3) in a Bell Gardens city park (Table 1) (9). Follow-up air sampling a year later found levels of hexavalent chromium on the Suva School property ranging from 0.023-0.43 ug/m3, although in some samples the amount of chromium was too low to be detected (3). Also in 1988, requirements for more strict emissions were issued (9). In 1991, J&S Chrome Plating closed (3), but the South Coast Air Quality Management District renewed Chrome Crankshaft's permit to operate when Chrome Crankshaft added improved air emissions control devices (10). In 1998, air sampling found hexavalent chromium had greatly decreased; the highest sample at that time was 0.0011 ug/ m.3 (3). These levels are all lower than ATSDR's health-based comparison values for assessing chemical exposures, which are explained in greater detail below.
Estimates of past amounts of chromium (VI) in the area have also been made using information about how much was released and weather information (2). During the years before reduced air emissions, the average annual concentrations of chromium (VI) were estimated to range between 0.00016 to 0.01516 ug/m3, dropping to 0.00001-0.00017 ug/m3 thereafter (2). These numbers are all below ATSDR's health-based guidelines for reviewing levels of chemicals called "minimal risk levels," or "MRLs." MRLs are estimates of the amount of exposure that is likely to be low enough as to not be a health risk to humans. Because non-cancer health effects can occur at lower levels than those that cause cancer, MRLs are based on potential health problems that are not cancer. MRLs have an additional built-in margin of safety, in that they are purposely set below a level at which an actual health effect has been observed. The MRL for inhalation risk of hexavalent chromium (VI) is 1.0 ug/m3(8).
The respiratory system is the main system that would be affected by breathing chromium. Over 30 studies were located which noted excesses in lung or respiratory system cancers among people who work with chromium (8). Seven additional studies were located in which an excess of lung or respiratory cancer was not found, although some of these included workers who had shorter exposure periods (11,12). Finally, some studies only involved exposure to chromium (III), not chromium (VI) (13,14).
A few studies of chromium exposure in workers found elevations of cancers other than lung cancer. Several studies found elevated nasal cavity/sinus cancer (15,16,17). One study found elevated bladder cancer among a group of African American workers (15). Two studies also suggested elevated stomach cancer, although the findings were somewhat weak (18,19). One study in former Czechoslovakia found an elevation of oral cavity cancer among electroplating workers who were exposed to high levels of chromium (20).
Only a few studies have been made of residents near chromium facilities, and they did not find that residents suffered ill effects. A study of 810 lung cancer deaths in Sweden found no association between such cancers among residents and the local ferrochromium alloy industries (21). Similarly, studies in the People's Republic of China did not find consistent associations between cancer and exposures from an alloy plant that smelted chromium (22). These processes are different than chrome plating, and this may result in somewhat different types of exposures than what people might receive from chrome plating exposures.
Some health studies also had measurements of chromium levels (Table 1). Information from these studies suggests that starting at concentrations of about 200 ug/m,3 workers began to have increased risks of lung cancer (23,24). This concentration is over 400 times higher than the highest measurement ever found at Suva schools (9), and over 1 million times higher than the highest estimated annual average level of chromium (VI) near the Suva schools after emission controls were installed (2). Often studies found an association between chromium and lung cancer at higher levels, such as 500 or even 2,000 ug/m3 (24,25,26). Some health effects other than cancer were found at lower exposure levels (Table 1).
The measured ambient air levels of chromium near the Chrome Crankshaft and J&S Chrome Plating facility were much lower than the levels that have been found in workers to be associated with an increased risk of lung cancer. Thus, it seems unlikely that increased cancer rates would have been caused by residential exposure to airborne emissions from Chrome Crankshaft and J&S Chrome Plating.
The available information suggests that it is unlikely that cancer would have increased in the neighborhood as a result of exposure to emissions from these facilities. Nevertheless, the community members were very interested in learning the rates of cancer in the area and whether there was any excess cancer, especially childhood cancer. This review was conducted to address their concerns. CDHS chose to look for lung cancer because it is the only cancer type consistently associated with chromium exposure. CDHS also looked at cancer rates overall (this is all cancers combined). Additionally, because lung cancer almost never occurs in children, CDHS reviewed childhood cancers overall. CDHS was unable to assess whether there was an excess of cancer specifically among teachers or staff of Suva schools, as this review uses data from the cancer registry that are based on residence rather than worksite.
Although incidence of and mortality from many cancers have been decreasing in California, cancer overall is still the second leading cause of death (27). According to current rates, one of every two men and two of every five women will develop some form of cancer in their lifetimes (27). This means that cancer will affect about 1/3 of all California residents. And the older someone becomes, the more likely it is that he or she will eventually get cancer. Breast cancer is the most common cancer among women, and prostate cancer is the most common cancer among men.
Lung cancer is the second most common cancer for both men and women (27). According to current rates, 1 of 12 men will develop lung cancer, but this risk is 10 to 20 times higher among smokers. It is estimated that 85% of lung cancer is caused by cigarette smoking (not including exposure to smoke from others).
Although cancer is much less frequent among children than adults, it is second only to accidents as the leading cause of death among children (28). Leukemia (of which there are a number of types) is the most frequent cancer among children, followed by cancers of the central nervous system (brain and spinal cord), and lymphomas.
When and where cancer occurs depends partly on chance. Information is, however, available about how cancer develops. Cancer is a slow process, generally requiring years or even decades. The process of cancer can be started by a causative agent, which might be one factor among many. These agents could include radiation (29), chemical exposures (30,31), viruses (32), or possibly bacteria (33,34). But there must also be a pathway by which this agent can reach someone. This could be through the air, through water or food, or through sexual transmission. Additionally, the agent has to exert an effect that causes a biological change in the person's body. The exposure must also last long enough for harm to occur.
There are many different types of cancers, and different cancers have different causes. For example, in the body there are natural hormones that play a role in whether someone gets cancer (35,36). For example, breast cancer is related to hormonal functions such as early onset of menstruation and when a woman bears children (37,38,39). Exposure to sunlight is a factor in skin cancer (40). Drinking alcohol can be the cause of some cancers, such as liver cancer (41). Some cancers are caused by viruses (32); cervical cancer is caused by a virus that is sexually transmitted (42).
Cancer does not generally result from one exposure or influence (43). Instead, there are usually several factors that work together to cause cancer. In lung cancer, several possible factors might make a person more or less likely to get lung cancer: 1) smoking cigarettes, 2) having a genetic susceptibility to cancer, 3) exposure to another agent that can cause cancer, such as asbestos, and/or 4) having a poor diet (44). But in many cases why a person gets cancer is unknown.
To determine whether there are more cases of cancer occurring in an area than would typically be expected, it is important to know some information about the people in the area. This information includes:
- the number of residents in the area,
- the ages of residents,
- the sex of residents,
- the race of residentsfor purposes here, individuals are considered either Hispanic or white (these are not overlapping categories), and
- the education and income level of residents.
To calculate a cancer rate, it is necessary to know the number of people in the area. The number of cancer cases depends greatly on the population. Thus in a small town, fewer cancers would be expected than in a large city.
Age is important because people at various ages are more or less likely to get certain cancers. In general, the older a person is, the more likely it is that they will get cancer. Thus cancer rates will be higher in populations with a greater proportion of elderly persons.
Men are more likely to get certain cancers, and women are more likely to get other cancers (45). Some of these differences are due to hormones; some are due to differences in behavior. For example, more men than women smoke, so men as a group are more likely to get lung cancer (44).
Persons of different ethnic and racial backgrounds get cancer according to different patterns (46). As with differences between men and women, some of the difference in cancer patterns between race and ethnic groups have to do with biological differences, and some patterns have to do with lifestyle. For example, some cancers increase among immigrants from less-developed countries when they move to more developed countries such as the United States and change their diet (47).
Cancer patterns also differ among groups with different education and income levels. This occurs for a variety of reasons. For example, women who have relatively more education and income have higher rates of breast cancer than other women. This is because breast cancer is thought to be at least partly caused by the natural hormones in a woman's body (48). These hormones change during pregnancy and while a woman is nursing a baby. Because women with more education and income are more likely to have children later in life (as a result of being in school longer), they are exposed to their bodies' own natural hormones in a different pattern than women who become pregnant and nurse their children when they are younger. This makes those women who have children later in life more likely to have breast cancer than women who have children earlier in life. Also, on average, persons with less education and income are more likely to be smokers (49)one reason this group has higher rates of lung cancer.
The cancer registry does not, however, have information on how many people in the community smoked cigarettes. This would be very helpful information in studying lung cancer, given that most lung cancers are caused by smoking. Thus, if an increased number of lung cancers is found in this community analysis, it will not be possible to determine if this is due to more people smoking, or because of other factors.
A cancer incidence rate (CDHS might refer to this as "cancer rate" in the remainder of the document) is the number of new cases of cancer that occur in a particular area compared with all persons who lived in that area for that time period. Each cancer is counted only one time. If someone gets cancer one year and still has it the next year, that person is not counted a second time when the cancer cases are checked for the second year. On the other hand, if someone gets one type of cancer one year, and gets a new cancer the next year, each cancer is counted separately.
Rates generally take into account the age, race, and sex of the population. It is also helpful to take into account the education and income level of people in the area as well, if this information is available.
Using rates (rather than a simple count of persons with cancer) is helpful as a way to compare cancer patterns in different areas, or to see if cancer rates increase or decrease over time. Just knowing the total number of cancers for California from year to year does not reveal whether the rate of cancer is increasing or decreasing. Changes in the number of persons with cancer might simply be caused by more people moving to or leaving California. But a rate can help point out changes that would not be identified by only counting the number of cancer cases without accounting for the number of people in an area. For example, if it is known that 75 out of every 100,000 persons in California got lung cancer in one year, and the next year 50 persons out of every 100,000 persons got lung cancer, then this shows that the rate of lung cancer (i.e., the number of new cases in a population for a certain time period) is going down.
To estimate the cancer rate for a particular area, the cancer registry first considers the rate for a large group of people, such as the rate for the state of California overall, or the rate for a large region. This rate is then used to estimate how many people would be expected to have cancer in this specific area. This is called the "expected" number of cancers. This review uses the rates for the Los Angeles area to calculate the estimates of expected rates used in this analysis. An example using California to explain how expected rates are calculated is given below.
To calculate an expected rate of cancer for a particular area under study, one can use information on the total number of persons with lung cancer in California and the total number of persons in California (27). If 50 new cases of lung cancer develop each year for every 100,000 people in California and the particular city being studied has 200,000 people, then the number of expected cancers for that particular city would be 100 cancers because 200,000 is 2 times as large as 100,000, and 50 cancers are typically expected among any 100,000 persons in California. The cancer rate analysis also takes into account the age, race, and sex of the people in the area being evaluated. This is important because if the population includes many elderly persons, more cancers (and different cancers) would be expected than if the population was mainly young families and children.
After the cancer registry determines the expected number of cancers, it checks to see exactly how many cancers did occur during the time period in the place being evaluated. Then the cancer registry compares these numbers to see if there is more cancer than would be expected.
Another important aspect of predicting the expected number of cancers concerns the need to estimate this information. It is impossible to predict an exact number of cancers. The number will vary due to the many different, often unknown factors affecting cancer. Thus, when the cancer registry estimates the number of cancers expected for an area, it estimates the approximate number of cancers that would be expected.
It might be helpful to think of comparing the unknown aspects of cancer occurrence to the variability of a tossed coin. If one tosses a coin 100 times, the coin would be expected to land approximately 50 times on heads and 50 times on tails. Still, it would not be surprising if the coin did not land exactly 50 times on each side, but instead landed 45 times on heads and 55 times on tails. Because there are so many factors that are unknown, and because cancer occurrence is somewhat random, it is not possible to predict exactly how many cancers are expected to occur in a certain population. Because of this variability, a range of numbers is calculated, and it is expected that the actual number of cancers will be within that range. The numbers for the range are calculated mathematically, based on how much variability is found in the rates in the larger group and how large of a sample is being studied. These numbers show the range that would be expected, given that some natural variability can occur by chance. If the actual number seen is greater (or less) than this range, this indicates that the chance of this result occurring just by normal variability is less than a certain standard (in this case less than a 5% chance). In other words, there is less than a 5% chance of a certain number of cancers (a number outside this range) occurring just by chance.
For example, when it is estimated that about 100 cancers would be expected in the earlier example of a city of 200,000, a range would be given, such as 80 - 120. This means that although about 100 cancers are expected, the number might be within the range of 80 and 120.
Thus, to determine whether the number of cancers is different from what would be expected, one checks to see if the actual number of cancers that occurred is greater than the high number of the range, or whether it is lower than the low number in the range. In this case, one would check if the number is either less than 80 or greater than 120. If, for example, 130 cancers occur, this number of cancers is greater than the number that would have been expected by chance.
As discussed in the section above, there are many reasons for the number of cancers that could occur in a particular area at a particular time period. This random variability means that there could be a higher or lower number of cancers in a particular area just due to chance. For example, if one calculates the rates of lung cancer in census tracts in Los Angeles, because there are so many census tracts, by chance some are likely to have greater than expected lung cancer rates. And the more rates one calculates, the greater the chance that an elevated rate of some kind will appear. For this health consultation CHDS looked at cancer rates in some census tracts in California. Because of random variability and chance, the rates in some of those census tracts might be elevated. But if such elevated rates appear, it is not possible to determine whether it is by chance or whether some other factor or factors caused additional cancers in that census tract.
CDHS incorporated several considerations into its decision of which areas to analyze within the Bell Gardens area. First, CHDS selected certain areas based on whether persons in those areas could have been exposed to air emissions from Chrome Crankshaft or J&S Chrome Plating. CDHS took into account how far air contaminants would have been carried from the site, and included the downwind areas (primarily in Downey).
Another reason CDHS chose certain geographical areas was because the cancer rates are based on specific geographical areas defined in the United States Census, called "census tracts." CDHS chose the census tracts that best fit the areas that were of greatest concern, specifically the areas that might be exposed to air contaminants.
To form Areas 1 and 2 for the analysis of all cancers and lung cancer (Figure 1), CDHS grouped the census tracts together according to how close they were to Chrome Crankshaft and J&S Chrome Plating: Area 1 being the closest, and Area 2 being not as close. According to the estimates of concentrations of chromium (VI) in the area, these levels quickly decrease the farther the distance from the site, with most exposure contained within Area 1 (please refer to the CDHS/ATSDR health assessment for a more complete discussion of this topic (2)). The areas studied in the childhood cancer analysis are slightly different, and are described in the childhood cancer analysis section (section K.a. of this document).
In selecting the time period, CDHS chose all years for which the Cancer Surveillance Program had information. J&S Chrome Plating began operations in 1953; thus a period of 19 years separates exposure and the start of cancer review (1972). Also, because it takes several years for new cases of cancer to be identified and recorded with the Cancer Registry, information up to the current year is not available (the available years are 1972-1997).
a. Area 1 (Closest to the Facilities)
This area consists of two census tracts. The first census tract is the one in which the facilities are located (5340, Bell Gardens) (Figure 1). The second is the census tract immediately downwind (5507, Downey). These two census tracts were different from each other in terms of the average socioeconomic status (income and educational level) of the residents. The average income and educational level of residents in the Bell Gardens census tract (5340) was lower than the average for residents in the Downey census tract (5507).
b. Area 2 (not as Close to the Facilities)
This area includes three census tracts near the facilities, but not as close as Area 1 (5342 and 5339, Bell Gardens; 5508, Downey). Compared to Area 1, Area 2 would have received very little exposure. Nevertheless, it is included because at least some chromium would have been expected to reach parts of these census tracts. The first two census tracts are in the city of Bell Gardens, and west of the facilities. Because the wind comes from the west, most of the time the wind from Chrome Crankshaft and J&S Chrome Plating does not blow in this area. The third census tract is in Downey. The two Bell Gardens census tracts (5342 and 5339) have the same average income and education level. The average income and educational level of residents in the Bell Gardens census tracts (5342 and 5339) was lower than the average for residents in the Downey census tract (5508).
CDHS looked at all childhood cancers combined in children. This part of the review is not separated by whites and Hispanics, because the number of children in the analysis was much smaller than the number of adults.
Of the several census tracts in this analysis, one area was included that approximately represents the City of Commerce. Children from that area travel by bus to attend Suva Intermediate School, which is immediately adjacent to the sites.
The areas included:
- The census tract in which the facilities were located (Bell Gardens census tract 5340),
- The downwind census tract, located in Downey (Downey census tract 5507), and
- The census tract in which children live who attend Suva Intermediate School, which includes the area of Commerce where children live and travel by bus to Suva Intermediate School (Bell Gardens census tract 5339, and Commerce census tract 5323.01).
b. Analysis of all Cancer Types Combined, General Population, 1972-1997
The analysis approach to the general population is slightly different from that for children. Because the general population is much larger than the number of children, it is possible to look at rates by different groups. CDHS looked at rates of all cancer types combined among males, females, whites, and Hispanics. The rates in the census tracts in Downey are calculated separately from the census tracts in Bell Gardens because the populations are quite different in terms of education and income level. This analysis was conducted for the following areas (see Section J for a more detailed description):
- Area 1, closer to the facility (census tracts 5340 and 5507), and
- Area 2, not as close to the facility (census tracts 5342, 5339, 5508).
c. Analysis of Lung Cancers, General Population, 1972-1997
CDHS looked at rates of lung cancer among the same groups studied as in the analysis for all cancer types combined: males, females, whites, and Hispanics. The areas chosen also parallel the analysis for all cancer types combined:
- Area 1, closer to the facility (census tracts 5340 and 5507), and
- Area 2, not as close to the facility (census tracts 5342, 5339, 5508).
For Figures 2-6, cancer rates are shown using graphs. Each the bar represents the range of cancers that would occur in this population based on typical regional cancer rates. The dark line represents the number of cancers that actually occurred. To read the graph, check whether the dark line falls within the bar. If the dark line is inside the bar, it means the actual number of cases was what we would expect. If the dark bar is farther to the right of the bar, it means the actual number of cancers found was greater than what would be typically expected. If the dark line falls to the left of the bar, then that means the actual number of cancers that occurred was less than what would typically be expected.
a. Childhood Cancer Rates (all Cancers Combined) (Figure 2)
Cancer rates were reviewed among children from 0 - 19 years of age. Children of all races were included in this review. Each bar, on Figure 2 represents a different group of children in a different geographical area. None of the cancers reviewed for children exceeded expected levels.
For the census tract where the facilities are located (5340), the expected range and the actual number of male and female children with cancer are represented by the top two bars of the graph. Because the range for the expected number of cancers in males is between 2 and 14, and the actual number of cancers is 7, this is within the expected range. The same is true for other areas examined, including the other census tracts in Bell Gardens and in Commerce (5339 and 5323.01). Childhood cancer in the census tract in Downey that is directly downwind of the facilities was also evaluated (5507), and the number of cancers found was within the range that was expected. However, because the number of cancers was fewer than five, to protect confidentiality, the exact number of cancers is not reported, and thus is not shown on the graph. In summary, the review of cancer rates found no excess of childhood cancer in any census tract near the Chrome Crankshaft and J&S Chrome Plating facilities.
b. All Cancer Types Combined, Area 1, General Population (Figure 3)
Rates of all cancer types combined were examined in Area 1which includes the census tract in which the facilities are located (5340) and the census tract downwind of the facilities (5507). The analysis found no excess cancer for any group of persons: males, females, Hispanics or whites. The number of cancers that actually occurred was within the expected range, except that among white males in the census tract in which Chrome Crankshaft and J&S Chrome Plating are located, the rate of cancer was somewhat lower than expected (5340).
c. All Cancer Types Combined, Area 2, General Population (Figure 4)
The next part of the analysis examined the cancer rates in Area 2, which includes the areas close to the facilities, but not as close as Area 1 (5342 and 5339, Bell Gardens; 5508, Downey). Most groups in these census tracts had no more cancer than would be expected. However, within the census tracts in Bell Gardens that are not as close to the facilities as in Area 1, white males, and to a lesser extent, white females, had rates of cancer (all types of cancer combined) that were higher than what would be expected. No excesses were found in any group of Hispanics. No excess of cancer was found in the Downey census tract (5508) in any group of persons.
d. Lung Cancers, Area 1, General Population (Figure 5)
Rates of lung cancer were examined in Area 1, the area closest to the facilities (5340 and 5507). The analysis found that residents of the census tract in Downey had no more cases of lung cancer than expected. White male residents of Bell Gardens in the census tract in which the facilities were located (5340) had fewer lung cancers than would be expected, but white female residents in this census tract had slightly more lung cancers than would be expected. Hispanic females did not have enough lung cancers to report, and the number of lung cancers in male Hispanics was not above what would be expected.
e. Lung Cancers, Area 2, General Population (Figure 6)
The analysis of lung cancer in Area 2, which includes the areas close to the facilities, but not as close as Area 1 (5342 and 5339, Bell Gardens; 5508, Downey), was similar to the findings for all cancer types (Section L.c. above). Downey residents had no more lung cancer than would be expected. However, within the census tracts in Bell Gardens that are not as close to the facilities as in Area 1, white males and white females had rates of lung cancer higher than what would be expected. Most groups of Hispanics had too few cancers for the data to be included on the graph.
No excess cancer was found in children in any geographical area studied. No excess cancer was found in any group of Hispanics (males or females in any areas). Similarly, in the area downwind of the facilities (in Downey), cancer rates were what would be expected under usual circumstances.
Rates of cancer for non-Hispanic adult white males and females in Bell Gardens near the facilities varied. Rates of cancer overall and lung cancer in the immediate area where Chrome Crankshaft and J&S Chrome Plating are located were lower than expected for white males, but white females had slightly higher than expected lung cancer. In parts of Bell Gardens not as near to Chrome Crankshaft and J&S Chrome Plating, however, higher rates of all cancers combined and lung cancer were noted among white males and females.
A number of limitations make the cancer rate review less informative than one might wish. Unfortunately, these limitations could prevent recognition of a relationship which, in the midst of multiple cancer causes, might exist but be too small to detect. There is no information on whether someone smoked, which is important because tobacco exposure accounts for most lung cancer. Also, because there is only information on where someone lived at the time of diagnosis, it is not possible to know whether a former Bell Gardens or Downey resident might have been diagnosed with cancer after moving away and was therefore not included in the cancer registry. On the other hand, cancer cases that occurred among persons who just recently moved to the area would be included, even though their cancers would have developed while they were living elsewhere. Although the cancer registry contains nearly all cancer cases, it is not absolutely complete. Also, the rates are based on information from the census, and if the population count is inaccurate, the rate will be inaccurate. For example, if not every resident is included in the census count in an area, the rate of cancer will look higher than it would otherwise.
In hypothesizing that chromium in the air could have contributed to excess cancer, it would be expected that the excess cancer would be found in the area where people could have received the most exposure. This would include the census tract where Chrome Crankshaft and J&S Chrome Plating are located. However, the findings were not consistent in this census tract. White males had significantly lower than expected rates of cancer (that is, the rate of all cancers combined) and lower than expected lung cancer specifically, but white females had slightly higher rates of lung cancer. Nor was excess lung cancer found downwind in the Downey census tracts, the other area that would be most likely to have relatively greater exposure to chromium. Instead, higher rates of cancer were found upwind of the sites. These findings do not associate Chrome Crankshaft and J&S Chrome Plating specifically with a pattern of excess cancer. It is possible that air contaminants from other sources could have contributed to lung cancers in the area.
Regarding the number of cancers overall for some areas of Bell Gardens, it should be pointed out that lung cancers are the second most common cancer. Thus because lung cancers are included in the calculation of cancers overall, the elevation in the number of lung cancers would contribute to raising the rate of cancers overall.
Another possible explanation for an increase in lung cancer rates could be that workers in the chromium facilities were also residents in the neighborhood, and could have received their exposures at their worksite rather than from the community's ambient air. If the exposures were only among workers, this would not explain why there was an excess of lung cancer among females as well (unless there were many female chromium workers, which is not known).
It is also possible that more smokers or heavier smokers lived in the Bell Gardens census tracts that had greater than expected lung cancer. As previously stated, information on smoking habits of individuals was not available for the cancer review. The cancer rates in these Bell Gardens census tracts were compared to other census tracts which include residents with similar income and education, thus the smoking patterns would be expected to be similar.
As also noted earlier, it is not possible to know definitively why some cancer rates were increased. These differences could be due to unknown factors or to chance variation.
No excess cancer rates that could be attributed to the facilities were found. Because the ambient air levels in the community near Chrome Crankshaft and J&S Chrome Plating were much lower than those found to cause lung cancer in workers, it is unlikely that cancers among residents were caused by exposure to these facilities. Also, the geographical pattern of excess cancer is not associated with the location of the two facilities. Nevertheless, some residents could have been at higher risk because of unknown factors such as high individual susceptibility. It is also possible that other factors, such as emissions from other facilities or chromium workers residing in the neighborhood, contributed to these lung cancers. Lastly, it is possible that these differences are due to other factors or to chance.
Currently, Chrome Crankshaft and J&S Chrome Plating are not in operation and do not pose an apparent public health hazard. Given this situation, CDHS would not anticipate any change to this assessment. However, as with any site, it is the policy of CDHS and ATSDR to reevaluate the need for follow up if future data should suggest human exposure to hazardous substances at levels of public health concern.
The Public Health Recommendations and Actions Plan (PHRAP) contains a description of actions regarding this site taken, to be taken, or under consideration by ATSDR and CDHS. The purpose of the PHRAP is to ensure that this health consultation not only identifies public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposures to hazardous substances in the environment. CDHS and ATSDR will follow up on this plan to ensure that actions are carried out. The plan summarizes completed and ongoing actions. No new recommendations are needed at the present time to protect public health.
- CDHS conducted community interviews to document community concerns (2000).
- CDHS wrote a health assessment addressing water quality in areas surrounding the Chrome Crankshaft and J&S Chrome Plating sites (produced in 2001) and historical air emissions in areas surrounding the facilities (Public Comment Draft to be released in 2003).
- CDHS has worked with a group of community and other stakeholders to assist in the public health activities at the site.
- CDHS is conducting a health study focusing on potential non-cancer respiratory health effects of air emissions from the facilities. A final report should be available in 2003.
Sumi Hoshiko, M.P.H.
Environmental Health Investigations Branch
California Department of Health Services
Marilyn C. Underwood, Ph.D.
Environmental Health Investigations Branch
California Department of Health Services
COMMUNITY RELATIONS COORDINATOR:
Tivo Rojas, M.P.H.
Impact Assessment, Contractor to the
Environmental Health Investigations Branch
California Department of Health Services
ATSDR REGIONAL REPRESENTATIVES:
William Q. Nelson
Regional Representatives, Region IX
Agency for Toxic Substances and Disease Registry
ATSDR TECHNICAL PROJECT OFFICER:
Tammie McRae, M.S.
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch, State Programs Section
The Review of Cancer Rates in the Vicinity of Chrome Crankshaft Company and J&S Chrome Plating Company Health Consultation was prepared by the California Department of Health Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was prepared.
Tammie McRae, MS
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.
Chief, State Program Section, DHAC, ATSDR
|Occupational Studies||Concentrations in the air, ug/m3 chromium VI(unless otherwise specified)|
|Lung cancer (25)||500 to 2,000|
|Lung cancer (26)||500 to 1,500|
|Lung cancer (24)||250 to > 6,000
(soluble chromium, assumed to be primarily Cr-VI)
|Lung cancer (50)||413.0|
|Lung cancer (50)||218.0|
|Non-cancer health effects: stomach irritation ulcer (51)||5.0|
|Non-cancer health effects: nosebleed, damage to inside of nose, stomach cramps, ulcers (51)||4.0|
|Non-cancer health effect: nasal membrane thinning (52)||2.0|
|Measurements in Bell Gardens|
|1987, 1 air sample in park near Suva schools
(Error! Bookmark not defined.)
|1988, Suva schools, highest sample of 19 air samples (4 were too low to be measured)(9)||0.430|
|1998, Suva schools, weekday, highest sample of 8 (3 were too low to be measured)(3)||0.0011|
|1998, Suva schools, weekend, 4 samples(3)||All samples too low to be measured|
|Estimated Annual Averages in Bell Gardens|
|1963-1990, highest estimate(2)||0.01516|
|1963-1990, lowest estimate(2)||0.00016|
|1991-1999, highest estimate(2)||0.00017|
|1991-1999, lowest estimate(2)||0.00001|
Note: The form of chromium varied in different studies; some studies had PbCrO4, ZnCrO4, or CrO3.
Figure 2. Observed number and expected range of all childhood cancer cases near Chrome Crankshaft, 1972-1997. [Areas closer (census tract 5340): and areas not as close + school bus areas (census tracts 5339, 5323.01)]
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