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PUBLIC HEALTH ASSESSMENT

FRONTERA CREEK
RIO ABAJO, HUMACAO COUNTY, PUERTO RICO


RESUMEN EN ESPAÑOL

El sitio de la Lista Nacional de Prioridades (NPL) Caño Frontera no es un peligro a la saludpública, debido a la falta de una exposición actual a contaminantes relacionados al sitio. ElMercurio en el suelo y en el aire pueden haber causado pequeñas contracciones en los músculos,de algunos individuos en la planta industrial de Technicon, antes del 1990. Es posible que elmetileno de cloruro en el aire, aunque no está relacionado con el sitio del Caño Frontera, hubiesecausado pequeños cambios en el higado o en los riñones, o la disminución leve y reversible en lavisión o en la audición de los individuos que vivieron y trabajaron en el área del Caño Fronteradurante el periodo del 1983 al 1985. Sin embargo, esta conclusión acerca de la metileno decloruro no se puede asegurar por las dificultades en indentificar niveles de exposición a metilenode cloruro en el área del Caño Frontera, tanto como los problemas con la evaluación de latoxicidad del metileno de cloruro.

La conclusión de la Agencia para Sustancias Tóxicas y Registro de Enfermedades (ATSDR) sebasa en el análisis de datos sobre el medioambiente y niveles de mortandad, tanto comopreoccupaciones de la comunidad en este sitio. Este análisis indica que la contaminaciónrelacionada con el sitio del Caño Frontera se limita al mercurio en el suelo, el sedimento, y el aireen una planta industrial (Technicon), y el sedimento de la zanja de Technicon. Aúnque no estárelacionado con el sitio, el arsénico en el suelo en dos locales industriales, aligual que el metilenode cloruro en el aire se detectó a niveles más altos de los que se considera normal en elmedioambiente.

La contaminación con mercurio, a lo cual fueron expuestos los residentes que vivían antes enCiudad Cristiana, no se relacionaba con el sitio del Caño Frontera. El análisis de los datos sobrelos niveles de mercurio en la sangre de 290 residentes de Ciudad Cristiana, conducido por laATSDR, indica que el nivel promedio fue de 3.9 ug/dl. La fuente major de este mercurioprobablemente proviene del pescado con procedencia local. Los niveles de mercurio en elpescado del área del Caño Frontera son típicos para Puerto Rico. Sin embargo, los pescadores delCaño Frotera consumen grandes cantidades de pescado cada día, lo cual puede resultar en unaexposición elevada al mercurio.

Las concentraciones del mercurio en la sangre no alcanzaron el nivel de 20 ug/dl, dondeempiezan a manifestarse los efectos nocivos en la salud por la exposición a este típo de mercurio.Sin embargo, efectos nocivos en la salud en los bebes adentro del vientre de las mujeres puedenhaber ocurrido donde los niveles de mercurio en la sangre fueron más de 4.0 ug/dl. Alrededor de27 de las 64 mujeres de una edad conceptíva que fueron examinadas (42%) tuvieron niveles demás que 4 ug/dl. Los niños (25%) expuestos a estos niveles de mercurio en el vientre maternoempezaron a hablar y caminar más tarde que los niños no expuestos. No se sabe si estos atrasosson permanentes o reversibles. A niveles maternos entre 4-20 ug/dl, no se observaron eféctosmás graves como el atráso mental, la ceguera, la sordera, microencephalia, y perlesía cerebral.

El equipo técnico de la ATSDR se asegurará que los ex-residentes de Ciudad Cristiana y losprofesionales de cuidado de salud del área alrededor de Humacao reciban información adicionalsobre la toxicidad del mercurio.

SUMMARY

The Frontera Creek National Priorities List (NPL) site is not a public health hazard based on alack of current exposure to site-related contaminants. Mercury in the soil and air may havecaused slight muscle tremors prior to 1990 for a few individuals at the Technicon facility. It ispossible that methylene chloride in the air, though not site-related, may have caused slightchanges in the liver and kidney or mild reversible decreases in vision and hearing in individualswho both worked and lived in the Frontera Creek area during the period between 1983 - 1985. However, this conclusion about methylene chloride is uncertain because of difficulties inidentifying methylene chloride exposure levels for the Frontera Creek area and in evaluating thetoxicity of methylene chloride.

The Agency for Toxic Substances and Disease Registry's (ATSDR) conclusion is based on itsreview of environmental and health outcome data, and community health concerns for this site. This review indicates that site-related contamination is restricted to mercury in soil, sediment,and air at one industrial facility (Technicon) and sediment from the Technicon ditch. Though notrelated to the NPL site, arsenic in the soil at two industrial locations; and methylene chloride inthe air were detected above background levels.

While not site-related, the former residents of Ciudad Cristiana were exposed to mercury. ATSDR's review of blood mercury data for about 290 Ciudad Cristiana residents indicates thatthe average blood mercury level was 3.9 micrograms of mercury per deciliter of blood (µg/dl). The major likely source for this mercury was local fish. The mercury levels in Frontera Creekarea fish are typical for Puerto Rico. However, Frontera Creek area fishermen eat large amountsof fish per day which could result in increased mercury exposure.

Individual blood mercury concentrations were not above the 20 µg/dl level where health effectsappear to begin for this type of mercury exposure. However, health effects might have occurredin the unborn babies of mothers whose blood mercury levels were above 4.0 µg/dl. About 27 ofthe 64 (42%) women of child-bearing age tested had levels above 4.0 µg/dl. Some (perhaps25%) children with maternal blood mercury levels of 4 - 20 µg/dl would have walked later than19 months or talked later than 26 months. It is not known whether those developmental delayswould be temporary or permanent. At maternal levels of 4 - 20 µg/dl, more severe effects suchas mental retardation, deafness, blindness, microcephaly (small brain), and cerebral palsy are notobserved.

ATSDR staff will ensure that the former Ciudad Cristiana residents and Humacao area healthcare professionals receive additional information on the toxicity of mercury.

BACKGROUND

In this public health assessment, the Agency for Toxic Substances and Disease Registry(ATSDR) evaluates the public health significance of the Frontera Creek National Priorities List(NPL) site in Humacao, Puerto Rico Figure 1, Appendix F). More specifically, ATSDRreviewed available environmental and health outcome data, and community health concerns todetermine whether adverse health effects are possible. In addition, this public health assessmentwill recommend actions to reduce, prevent, or further identify the possibility for site-relatedadverse health effects. ATSDR, in Atlanta, Georgia, is one of the agencies of the U.S. PublicHealth Service. ATSDR is required by the Superfund law (Comprehensive EnvironmentalResponse, Compensation, and Liability Act of 1980 [CERCLA] as amended by the SuperfundAmendments and Reauthorization Act of 1986 [SARA]) to conduct public health assessments ofhazardous waste sites proposed for the National Priorities List (NPL).

This site was placed on the NPL in 1983 and was first evaluated by the Centers for DiseaseControl and ATSDR in 1985; that document is considered a public health assessment (1). Considerable additional environmental and other data have become available since thatdocument was issued. In addition, specific guidance on developing public health assessmentshave been devised (2). For those reasons, this new public health assessment was conducted.

A. Site Description and History

Industrial development of the Frontera Creek area began in 1970 and will be described further inthe Demographic, Land Use, and Natural Resource Use portion of this section. Environmentalconcerns about the site first surfaced in 1977, with reports of an alleged connection between thedeaths of 30 cows and contaminants in Frontera Creek (3,4). An investigation by the Puerto RicoEnvironmental Quality Board (EQB) concluded that lindane discharged into Frontera Creek byone of the area industries was the probable cause of the deaths. This study also identifiedelevated levels of mercury in another facility's effluent and in Frontera Creek surface water andsediment. The discharges of lindane were stopped and subsequent investigations by EQB andEPA focused on mercury contamination. All discharges of waste water into Frontera Creek fromarea industries ceased in 1979, when all facilities were connected to a waste water treatmentplant.

Ciudad Cristiana, a residential development of about 480 homes near the Frontera Creek areaindustries, opened in 1979 (Figure 2, Appendix F) (3). In 1984, residents of Ciudad Cristianabegan to report health effects (irregular heart beat, upset stomach, rashes, headaches, andnervousness) that they associated with mercury or other chemicals in the subdivision. Inresponse to those concerns, the incoming Governor of Puerto Rico directed EQB in January 1985to investigate the possible contamination at Ciudad Cristiana. In February 1985, EQB sampledsoil from 33 locations at 5 Ciudad Cristiana homes for mercury and found levels above 1,000parts per billion (ppb) at half of the 33 locations (4). This discovery led the Puerto RicoDepartment of Health (PRDH) to test urine from Ciudad Cristiana residents for mercury (1). Ofthe 795 residents tested, 21 had levels of mercury above 40 micrograms/liter (µg/l). Levels ofmercury in urine greater than 40 µg/l are considered to be abnormal or above background. However, only three of these were considered high enough by PRDH to be termed a healthconcern (i.e., above 150 µg/l). Additional soil sampling by EQB in March 1985 found that 16 of47 homes had levels above 1,000 ppb with a high of 12,975 ppb (4). As will be described,subsequent sampling by EPA put the validity of both rounds of soil sampling by EQB in 1985very much in doubt.

In March 1985, the Governor ordered the relocation of the residents of Ciudad Cristiana based onEQB's soil sampling and the PRDH's urine results (3). Evacuation of Ciudad Cristiana wascompleted in May 1985.

However, sampling of Ciudad Cristiana soils in March and April 1985 by EPA, at the request ofEQB, did not identify elevated mercury levels (3,4). A review of the various soil sampling data,dated July 30, 1985, was done by ATSDR and the Centers for Disease Control and Prevention(CDC) (1). The review strongly criticized EQB's sampling. Based on EPA's results, theATSDR/CDC report concluded that the mercury levels did not present a threat to public health. In December 1985, EQB's soil samples with the highest reported mercury levels, were split andanalyzed by EPA and EQB (4). Both agencies' laboratories found that mercury levels were notelevated and were within what was considered "background" levels.

Technicon, the facility which had been identified as having discharging mercury in its effluent, agreed to perform a remedial investigation (RI) in 1986 (4). Their study focused on a wide rangeof contaminants including mercury. This comprehensive RI found that, except for the Techniconfacility, soil mercury levels at Ciudad Cristiana and the rest of the Frontera Creek area werewithin the normal or background levels for Puerto Rico.

The builders of the Ciudad Cristiana subdivision sued the Commonwealth of Puerto Rico forover $12 million to recover the money lost by the evacuation of the development (5). TheCommonwealth lost the case (including an appeal to the U.S. Supreme Court in 1989) becausethey were unable to demonstrate a health hazard due to mercury. The overall cost to theCommonwealth for this case and relocating the former Ciudad Cristiana residents has beenestimated to be over $50 million.

In 1989, EQB and PRDH agreed in writing with EPA that there was not, nor had there been amercury problem at Ciudad Cristiana (6). In June 1991, it was concluded in an ATSDR HealthConsultation that the mercury levels reported in the final remedial investigation of the FronteraCreek site do not represent a health threat, except for the levels at the Technicon facility (7).

However, concern about mercury-linked health problems continues to be expressed by formerCiudad Cristiana residents (8). One environmental group has identified Frontera Creek as aforgotten NPL site (9).

In 1992, the Mayor of Humacao proposed renovating Ciudad Cristiana.(1) Renovation of severalhomes has been completed and approval for reoccupation is pending.

B. Site Visit

ATSDR staff visit the site for which a public health assessment is being developed. Typically,ATSDR staff tour the site and the surrounding residential area; solicit community healthconcerns; meet with representatives of EPA, state and local health and environmental agencies,and local public officials; and identify relevant environmental and health outcome data. Thisportion of the Background section identifies when site visits were made, who conducted them,and any specific observations made during the site visit. Other information obtained during sitevisits will be described in the appropriate section of the public health assessment.

Two site visits have been made of the Frontera Creek site. A site visit emphasizing a site tourand a file search was made on May 20-23, 1991. A second site visit to identify communityhealth concerns was made on January 11-15, 1993.

On the first site visit, Dr. John Crellin and Ms. Rosalyn Lee (ATSDR/Atlanta) met withrepresentatives of EPA and PRDH. A search was also made of EPA's files on Frontera Creek. On the site tour, it was observed that the Technicon facility was fenced and entry was restricted. The areas of Technicon contaminated with mercury were covered with grass or asphalt andmarked with warning tape.

On the second site visit, Dr. John Crellin, Mr. Antonio Quiñones, and Dr. Mark Rodriguez(ATSDR/Atlanta), and Arthur Block (ATSDR Region II) held two day-long public availabilitysessions, and a public meeting (10). In addition, those ATSDR staff were conducted on a tour ofthe site by representatives of EPA and the former residents of Ciudad Cristiana. The informationobtained during this site visit will be described in the Community Health Concerns section (p. 8)and evaluated in the Health Outcome Data and Community Health Concerns Evaluation sections(p. 30 and p. 35).

C. Demographics, Land Use, and Natural Resource Use

This portion of the public health assessment identifies the demographic characteristics (i.e., age,sex, and racial make-up), commercial use, and natural resource utilization (fishing, hunting,boating, swimming, ground and surface water, etc.). The demographics of an area can indicatewhether the population of the area has more than the normal portion of individuals (i.e., veryyoung or old) who might be more sensitive to a chemical. Industries in the site area couldrepresent another potential source of exposure to toxic substances. A specific natural resourceuse such as eating fish or crabs could be a significant way for area residents to be exposed.

Demographics

Humacao is a community estimated in 1986 to have a population of 50,800 (4). A significantportion of the adult population of Humacao are employed at the facilities in the Frontera CreekIndustrial Park.

The peak population at Ciudad Cristiana is estimated to have been about 1,500, but thepopulation was reportedly dropping in 1984 due to concern about increased illness (11). Many ofthe original residents of Ciudad Cristiana (in English - Christian City) were members of aProtestant group (12). The residents of Humacao and the former Ciudad Cristiana residents areculturally Hispanic and racially are mostly white.(2)

Land Use

Prior to 1970, the primary use of the Frontera Creek area was agriculture (4). From the 1930'sthrough the 1970's, the three Frontera and the Mandri lagoons (north of Frontera Creek) werepumped dry to permit sugar cane and coconut production and cattle grazing in the lagoon areas. During this period, the lower portion of Frontera Creek (see Figure 1) was canalized. In 1979 thepumping ceased, allowing the lagoons to refill and be repopulated with fish. This lagoon areaincluding Mandri Canal, which is between Ciudad Cristiana and the Caribbean Sea, has beendesignated as a wildlife refuge, and is managed by the Puerto Rico Department of NaturalResources.

From 1970-1980, an industrial park, with 13-15 facilities including several pharmaceuticalcompanies, was developed in the Frontera Creek area (Figure 1, Appendix F) (4). The toxicsubstances reported to have been used in those facilities are described in Tables 24 and 25 ofAppendix E. Toxic substance releases by area facilities are described in the Toxic ChemicalRelease Inventory (TRI) portion of the Environmental Contamination and Other Hazards section.

There are several residential developments within one mile of the Frontera Creek industrial park(Figure 1). The closest, Ciudad Cristiana, which was evacuated in 1985 as described on page 4,is directly across the highway from the industrial park. There are two residential areas, RioAbajo and Santa Teresa, to the west of the industrial park. A development of mostlyvacation/weekend residences, Villa Palmira, lies on the Caribbean Sea just north of the mouth ofFrontera Creek. Bajandas and Los Perros are on the coastal hills north of the industrial park.

Natural Resource Use

The major natural resource uses are the grazing of cattle and fishing. There are pasture landswhere cattle were observed grazing to the east and west sides of the industrial park and to theeast and south of Ciudad Cristiana (10). Fish and shellfish are caught in the Mandri Canal, bothFrontera Lagoons, and Frontera Creek (4). The most commonly caught fish are tilapia and tarponand the most common shellfish are blue crab. Mandri Canal and Southwest Frontera lagoon aresome of the most productive fisheries in Southeastern Puerto Rico, but Frontera Creek is one ofthe least. A survey of the former residents of Ciudad Cristiana indicates that about 10% of theresidents ate fish and crabs from the area.(3)

Most of the water used in the Humacao area is obtained from the Humacao River, especiallywater supplied to residences (4). Squibb and several other facilities in the Frontera Creek areaobtain at least some of their process water from four groundwater wells. Ciudad Cristiana wason the municipal water supply line that utilized Humacao River water. In general, the groundwater in the Humacao area is of relatively poor quality and of limited productivity.

D. Health Outcome Data

Health outcome data are used in a public health assessment to help identify whether there ishigher than expected amount of adverse health effects in the area around the site. For theFrontera Creek NPL site, the health outcome data pertinent to this public health assessment,based on community health concerns, included analyses of human tissues for mercury and othercontaminants, and information on cancer, lupus, asthma, and birth defects. Developmentaldefects and cancer were identified as biologically plausible outcomes. The rationale for theirselection will be described on page 31.

The only quantitative data available were blood mercury analyses and cancer incidence. However, for reasons that will be explained on page 31, cancer incidence data were notevaluated. Information was also available on self-reported illnesses and symptoms for formerCiudad Cristiana residents. The self-reported data and the blood mercury results are evaluated onpages 32 and 34 in the Health Outcome Data Evaluation section.

COMMUNITY HEALTH CONCERNS

Community health concerns were obtained through two public availability sessions and a publicmeeting (10). The health concerns identified are described below.

Community Concerns obtained during Public Availability Sessions

Public availability sessions were held in the Vista Hermosa subdivision of Humacao on January13 and January 15, 1993 (10). About 250 of the 261 families at Vista Hermosa formerly lived atCiudad Cristiana. Information was obtained on perceived site-related health problems for 448individuals by requesting data on each member of the interviewee's family. Interviews wereconducted on a one-to-one basis with all but 3 or 4 of the interviews in Spanish. Nearly all tookplace at the home of the leader of the former Ciudad Cristiana residents group; a few were doneat the interviewee's home. One hundred twenty former residents were interviewed. Someindividuals brought medical records which were reviewed by ATSDR staff. The results of thoseinterviews are described and evaluated on page 32 of the Health Data Outcome Evaluationsection.

The major non-health concerns were uncertainty about housing in the future, legal title of CiudadCristiana property, and poor service by all levels of government (10).

Community Concerns identified during Public Meeting

At the request of the former residents, a public meeting was held on January 14, 1993 (10). ATSDR staff explained what the components of a public health assessment (PHA) were, thepurpose of the site visit, the review process for a PHA, and why a PHA was being done. Themeeting was conducted mostly in Spanish. The concerns identified were (10):

  • How can ATSDR conclude that the soil mercury levels in the Ciudad Cristiana are typicalfor the southeast region of Puerto Rico?

  • Why is ATSDR planning to use the blood mercury data in the public health assessment,whereas these data were considered unacceptable by ATSDR in 1986 and 1988?

  • What, if any, are the health consequences associated with the blood mercury levelsidentified in former Ciudad Cristiana residents?

  • What, if any, is the health risk posed by past and present air emissions from the industrialpark?

Those are addressed in the Community Health Concerns Evaluation section (p. 35).

1. Personal communication with Jose Font of EPA's Caribbean Field Office during the January1993 and August 1994.

2. Observations made during January 1993 site visit.

3. Personal communication with Jose Sepulveda Rivas, the leader of the former CiudadCristiana residents group.


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