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PUBLIC HEALTH ASSESSMENT

VEGA BAJA WASTE DISPOSAL SITE
RIO ABAJO WARD, VEGA BAJA, PUERTO RICO


Discussion

Findings and results for lead levels in soil

PREQB and EPA collected surface and subsurface soil samples in July and August 1996, and May 1997. Approximately 200 samples were collected from 137 properties. The level of lead in the top two inches of soil ranged from 7 parts per million (ppm) to 26,300 ppm, while the level of lead in subsurface soil ranged from 18 ppm to 2,540 ppm. Background soil samples showed lead levels ranging from 7 ppm to 81 ppm. Forty-five of the properties contained lead levels in soil greater than 400 ppm (EPA 1996).

Children, especially pre-school children, might be exposed to lead when they accidentally swallow soil and dust that cling to their hands. Such exposure could increase blood lead levels and might cause harmful effects in some children. Possible harmful effects could be a slight decrease in measures of intelligent quotient, decrease in hearing, and changes in enzyme function in the blood (ATSDR 1993; Steele, et. al. 1990).

ATSDR and PRDOH worked jointly to develop a public health implication statement (PHIS) for each residence where EPA and PREQB collected soil samples. A PHIS is a confidential report to the people at each residence that explains the public health significance of environmental data collected from that residence. Since a PHIS is confidential, a sample of an English and Spanish version with the personal identifiers removed is shown in Appendix C. The Vega Baja team mailed residents their PHIS on 20 March 1997, so they could receive the PHIS before the first poster session held on 8 and 9 April 1997.

As a follow up to the PHIS, ATSDR released a health consultation in January 1998 concerning lead contamination of residential soil at the Vega Baja Waste Disposal Site (see appendix D). The team coordinated the release of this consultation just prior to the second poster session held 15 January 1998. In the consultation, ATSDR concluded that the level of lead in certain properties on the site is a public health threat to children because of long-term exposure to lead in soil. At the 15 January 1998, poster session, ATSDR presented a summary of the health consultation to the residents and provided them with Spanish and English versions of the health consultation.

Findings and results for garden produce

The Vega Baja team determined that the results of the garden produce samples from the first sampling event in June 1996 were not reliable. Working with officials from the U.S. Food and Drug Administration (FDA) in the winter of 1997, the team developed a collection protocol for fruits and vegetables and agreed to use the FDA's analytical protocol to ensure reliable results (see appendix F.) In May 1997, PREQB sent the second round of fruit and vegetable samples to the FDA for analysis.

The Vega Baja team evaluated the levels of lead in and on garden produce from the second sampling event and determined that the lead levels were not a public health threat. The team shared the results and its conclusions with the residents in a fact sheet prepared for the second poster session held on 15 January 1998.

Findings and results for blood lead tests in children

The PRDOH conducted a voluntary blood lead survey in December 1996, collecting approximately 70 venipuncture blood samples from children ages one to six years who live on or near the site. The blood lead levels of the children tested showed levels up to 5.7 micrograms lead per deciliter blood (µg/dL) with an average of 1.9 µ/dL (Deseda, Carmen, M.D., communication, 1996). The blood lead results are below the Center for Disease Control and Prevention's level of concern of 10 µg/dL. Therefore, the children tested are not likely to experience harmful effects from lead.

PRDOH sent confidential letters to the parents whose children were tested for lead and shared statistical results with the community in the first poster session on 8 and 9 April 1997. In addition, ATSDR reported a summary of the statistical results in its Health Consultation for Residential Soil dated 5 January 1998 (see Appendix D.)

In April 1998, the PRDOH collected an additional 37 venipuncture blood samples from children ages 1 to 6 years old who live in Brisas del Rosario. Blood lead levels ranged from less than 0.6 micrograms per deciliter (µg/dL) to 8.4 µg/dL (Deseda, Carmen, M.D., communication, 1998). No blood lead levels exceeded CDC's level of concern for blood in children of 10 µg/dL (CDC 1997). The blood lead results from December 1996 and April 1998, which included all of the preschool children in the community, show that no immediate actions are necessary to stop exposure to lead in soil.

Numerous epidemiological studies have shown a positive correlation between lead in soil and lead in blood (ATSDR 1993; Steele et al. 1990). The studies showed an increase of 1 to 8 µg/dL of blood lead in young children living in residential areas with lead-contaminated soil for every 1,000 ppm lead in soil. The variation in blood lead values is a factor of the source of lead, the type of lead, the size of the lead particles, the degree of contact with contaminated areas, the concentration of lead, and the behavior of children. Because of these epidemiological studies, ATSDR believes that elevated soil lead levels in Brisas del Rosario might increase blood lead levels in the future for some children living in lead-contaminated yards. That increase in blood lead levels might cause harmful neurological, audiological, and hematological effects in some children.

On 6 and 7 August 1998, ATSDR, EPA, and PREQB held a public availability session for the residents of Brisas del Rosario. ATSDR explained to the residents the following points (see Appendix E for a fact sheet):

  • The blood lead results show that none of the children tested in December 1996 and April 1998 are at risk of lead poisoning,
  • The blood lead results show that no immediate actions are necessary to stop exposure to lead in soil,
  • The blood lead results cannot be used to decide that elevated soil lead levels are safe in the future, and
  • ATSDR considers that while the elevated level of soil lead in certain properties is not a problem now, the lead levels could be a problem in the future for some children.

Findings and results for tapwater samples

In August 1996, EPA collected 17 tapwater samples from 16 houses in the Brisas del Rosario community. Tapwater water in the community is supplied by a local municipality. The analytical results showed that no chemicals were present at levels that could cause harmful effects. The level of trihalomethanes slightly exceeded the Safe Drinking Water Act's Maximum Contaminant Level (MCL) of 100 µg/L (micrograms per liter) for trihalomethanes. PREQB officials informed the municipal water authority and is working with them to ensure that chlorination procedures are followed properly so as to reduce trihalomethanes below the MCL.

Educational Activities

The Vega Baja team used poster sessions, one-on-one conversations, update reports, handouts, PHIS's, and a health consultation to educate residents about the activities and public health decisions made for the site.

Poster sessions with the residents were held April 1997, January 1998, and August 1998. During the April 1997 poster session, the team set up four poster stations. As residents entered the church where the stations were set up, they first viewed PREQB's poster showing an aerial photograph of the site in 1970 when most of the land was undeveloped and an areal photograph of the site in 1990 showing the housing development that has taken place. PREQB officials also described historical information about the site. At the second poster station, PRDOH officials summarized statistics of the blood lead survey they conducted in December 1997. The residents then moved to the third poster station, where ATSDR officials, with PREQB officials serving as interpreters, described the team's conclusions about the health hazard posed by lead in soil at the site. Residents also learned about the status of the team's investigation into garden produce and were told actions they could take to reduce exposure to lead (see appendix G.) At the last poster station, EPA described the Superfund process and informed the residents about EPA's activities that could take place next at the site (see appendix H.) The team also handed out an update report (see appendix I) that described the status of the activities being conducted by EPA, PREQB, PRDOH, and ATSDR.

About two weeks before the April 1997 poster session, ATSDR and PRDOH sent a PHIS to each residence where EPA and PREQB collected soil samples (see appendix C.) ATSDR and PRDOH sent out 111 PHIS's that informed the residents about the public health significance of lead levels in their yard.

The Vega Baja team also held a second poster session in the community on 15 January 1998, to inform the residents of the results of (A) the fruit and vegetable analysis, (B) the release of ATSDR's health consultation about lead in residential soil, and (C) EPA's activities. For the two days before the poster session, teams of ATSDR, EPA, and PREQB officials visited the residents who had yards with elevated soil lead. The purpose of the visits was:

A) to invite them to the poster session,
B) to discuss with them EPA's planned activities, and
C) to get permission for EPA to conduct remedial activity on their property.

The Vega Baja team also released an update report to the residents during the January 15 poster session (see appendix J) describing the results of the team's investigation into fruit and vegetables, additional soil lead analysis, and ATSDR's health consultation about lead in soil.

In addition, EPA released a fact sheet to the residents during the January 15 poster session describing the work activities that EPA plans to do in the community because of ATSDR's health consultation about lead levels in soil (see appendix K).

During the August 1998 poster session, ATSDR explained to residents that since the blood lead results on children were below CDC's level of concern, no immediate actions were necessary to stop exposure. ATSDR explained also that the level of lead in certain properties might be a problem in the future and for that reason still considered soil lead levels in some properties a public health threat (see Appendix E.) At that time, EPA also explained to the residents their plans for further characterizing the site and for addressing properties with soil lead levels that were a public health threat.

ATSDR Child Health Initiative

To ensure that the health of the nation's children is protected, ATSDR has implemented an initiative for each investigation to protect children from hazardous waste. ATSDR achieved that initiative at the Vega Baja site by evaluating the effect that lead in soil might have on the children living in Brisas del Rosario. In fact, possible exposure to lead in some children was the driving force behind ATSDR's, EPA's, PREQB's, and PRDOH's activities at the site.

To ensure that children living on the site did not have elevated blood lead levels, PRDOH conducted two blood lead screening surveys during the Vega Baja team's investigation of the site. The screening surveys took place in December 1996 and April 1998. No children were found to have blood lead levels above CDC's level of concern.

In addition to the blood lead surveys, ATSDR and the Vega Baja team evaluated the potential for lead exposure in children from contaminated soil. That evaluation prompted ATSDR to issue a health consultation declaring lead-contaminated soil at the site a public health threat because of possible lead exposure in children. The health consultation recommended that EPA and PREQB take actions to stop exposure to lead-contaminated soil.

Community Health Concerns

During its investigation, the Vega Baja team met frequently with residents of Brisas del Rosario. Residents asked the following questions.

  1. Question: Is it safe to eat garden produce?

    Answer: Yes. The Vega Baja team evaluated the levels of lead in and on garden produce and determined that the lead levels were not a public health threat.

  2. Question: Is the lead in yards harmful?

    Answer: Yes. Children, especially pre-school children, who live in yards with elevated levels of lead in soil might be exposed to lead when they accidentally swallow soil and dust that cling to their hands. Such exposure could increase blood lead levels and might cause harmful effects in some children. Possible harmful effects could be a slight decease in measures of intelligent quotient, decrease in hearing, and changes in enzyme function in the blood.

    While no children were found to have elevated blood lead levels, ATSDR concluded that lead levels in certain yards remains a public health threat because of the possibility that some children's blood lead levels might increase in the future should exposure not be stopped.

A major focus of ATSDR's investigation at the Vega Baja site involved developing and using enhancement activities to improve working relationship with community members as well as federal and state agencies. ATSDR identified several enhancement goals during its investigation and those goals are discussed in appendix L.

Actions Taken to Meet CERCLA

Section 104(i)(6)(A) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended [42 U.S.C. 9604(i)(6)(A)] requires ATSDR to conduct certain activities while investigating hazardous waste sites. Those activities are shown below:

1) determine the nature and extent of environmental contamination,
2) evaluate potential pathways of human exposure,
3) determine the demographics (size and susceptibility) of people being potentially exposed,
4) determine the health hazard posed by contaminants at a site, and
5) conduct a comparison of morbidity and mortality data when necessary.

ATSDR's participation in the Vega Baja team with EPA, PREQB, and PRDOH allowed ATSDR and the team to determine the nature and extent of chemical contamination at the Vega Baja Waste Disposal Site. From environmental data already collected by EPA and from sample designs developed by the Vega Baja team, ATSDR and EPA identified the chemical of concern to be lead contamination in soil. ATSDR also identified the pathway of human exposure as accidental ingestion of lead-contaminated soil by young children, particularly pre-school children. Exposure occurs because soil and dust containing lead will cling to the hands of children, who inadvertently swallow lead and soil when they put their hands in their mouth. From the fruit and vegetable data collected by the team, ATSDR, EPA, and PREQB were able to rule out the garden produce pathway.

The demographics of the community consisted of approximately 400 Hispanic adults and 300 Hispanic children living in approximately 225 homes. Approximately 85 preschool children lived in yards with elevated lead levels in soil and might be exposed to lead by putting their hands in their mouths.

The population is too small to compare morbidity and mortality data. The PRDOH, however, was able to conduct a blood lead survey to ensure that children had blood lead levels less than CDC's level of concern of 10 µg/dL.



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