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PUBLIC HEALTH ASSESSMENT

T. H. AGRICULTURE AND NUTRITION COMPANY
FRESNO, FRESNO COUNTY, CALIFORNIA


CONCLUSIONS

Based on the information reviewed, the California Department of Health Services (CDHS) and the Agency for Toxic Substances and Disease Registry (ATSDR) conclude that when the THAN facility was in operation it likely posed a public health hazard to nearby residents that inhaled air emissions from the site. From 1969 to 1981, the local air pollution control district received numerous odor and health complaints from nearby residents. These complaints were most likely due to the processing of two sulfur-containing compounds with low odor threshold impurities present in the formulations. It is difficult to assess the level of health impact from this exposure pathway because insufficient air monitoring data is available. Several studies have documented similar odor-related complaints and acute health symptoms in communities located near agricultural fields where sulfur-containing cholinesterase-inhibitor pesticides have been applied. It is not known whether these compounds may be associated with long-term health effects because there is very little toxicological information about these compounds. Given the work practices that resulted in the odiferous chemicals migrating off-site, the possibility exists that other chemicals with higher odor thresholds also migrated off-site.

When the facility was in operation, the site was a public health hazard to on-site workers not wearing adequate respiratory protection. The California Occupational Safety and Health Administration (Cal OSHA) documented work conditions that exceeded the allowable air concentrations for worker exposure to diphenamid, trifluralin, and nuisance dust during DeFend formulation. Although the employees were wearing respirators, on one of the visits, THAN was cited for supplying the wrong respirator filters and for the employees incorrectly wearing the respirators. Exposure to trifluralin and diphenamid may have resulted in non-cancer health effects and trifluralin exposure may have resulted in a minimal increased cancer risk to the employee. The inadequate worker safety practice suggests that it is possible that the process workers were exposed to any number or all of the chemicals that were handled at the facility.

Additionally, when the facility was in operation, the site may have posed a public health hazard to THAN workers who were exposed through dermal contact and incidental ingestion to the contamination in the on-site surface soil. In three surface soil samples taken on site, the only contaminants detected were DDT and DDE. However, the subsurface soil is contaminated with many chemicals at levels above health comparison values. Workers exposed to DDT and DDE in soil at the site may experience noncancer health effect, and those who may have been exposed for 13 years may have a moderate increased cancer risk.

The site did pose and still poses a public health hazard to those people (resident, off-site workers, Temperance Kutner school children) that used or use a contaminated well for domestic purposes. Most of the private wells downgradient of the site are contaminated with DBCP and nitrates. Chloroform (18 private wells), 1,2-dichloroethane (21 private wells), dieldrin (10 wells), lindane (1 well), -HCH (13 wells) has been detected in certain downgradient private wells at levels of health concern. DBCP, chloroform, and nitrates have been detected at levels of health concern in the Temperance-Kutner school. Since 1988 when THAN first provided for bottled water and then for the extension of the municipal water system to 64 homes and the elementary school located southwest of the site, the exposures through use of contaminated groundwater should no longer be occurring for those residents and schoolchildren. THAN continues to monitor private wells at the fore edge of the plume, and when contamination appears, take the well off-line and provide municipal water to the residence. If the resident uses the contaminated well, they may be exposed to unaccepatable levels of contamination.

There is inadequate toxicological information, especially about noncancer health effects, to evaluate the health impact of the low-level, long-term exposures that may have occurred. Additionally, little is known about exposure to multiple compounds. However, those residents whose wells were contaminated with chemicals other than DBCP and nitrates may have, based on what is known, a slight to minimal increased lifetime cancer risk because of past exposure to chloroform, 1,2- dichloroethane, dieldrin, and -HCH. Residents who used water from wells contaminated with DBCP, but not other chemicals, may have a low increased cancer risk. A health study would not be able to detect this increased cancer risk because of the small number of people that were exposed.

Nearby residents who drank or showered with the contaminated groundwater posed a number of health concerns. Significant scientific gaps limit a complete understanding of the human health impact to residents living near the site. Many reported health effects (headaches, nausea, vomiting, diarrhea, skin inflammation, heart/blood system effects, and liver changes) are associated with some of the chemicals present in groundwater, but the effects usually are associated with much higher levels than those found in the groundwater used by the people. Reproductive changes have been associated with DBCP exposure. Immunological and neurological changes are not easily evaluated because of little toxicological information on how the groundwater contaminants may affect those processes upon exposure. A number of compounds in the groundwater are thought, based on animal studies, to be carcinogenic; thus, a slight increased cancer risk may exist for people exposed to those compounds.

In addition to the site's contribution to the groundwater contamination, an area-wide DBCP and nitrate problem exists because of previous agricultural practices in eastern Fresno County. DBCP, as a probable human carcinogen, poses an increased cancer risk to those people with on-going exposure. The nitrate in the groundwater may cause methemoglobinemia (change in blood that results in discoloration of the skin and mucous membranes and other serious effects) in infants who drink the contaminated water.

As has been documented in this public health assessment, the on- site soil is still contaminated with a variety of chemicals. Because there are no longer people working at the facility and the low likelihood that someone would trespass onto the property, this was not considered an exposure pathway that currently exists. However until this soil is cleaned up it does pose a threat if chemicals spread to the groundwater, if the site is used for other purposes in the future, or if the contaminated soil migrates off-site via fugitive dust generation.

Cancer incidence (1988-1991) in the two census tracts surrounding the site does not appear to be unusual and is very similar to that seen for Fresno County as a whole. The birth defect rate (1986-1991) in the zip code area surrounding the site is comparable to the rate for the rest of Fresno County and the rest of the state. Several epidemiological surveys that evaluated cancer and reproductive outcomes as a result of exposure to the area-wide, DBCP-contaminated groundwater have been inconclusive.

Community concern is very high, and the people are frustrated that no one has acted on their requests for an epidemiological study or some other health-related activity.

PUBLIC HEALTH RECOMMENDATIONS AND ACTIONS

The Public Health Recommendations and Action Plan (PHRAP) for the THAN site contains a description of actions taken, to be taken, or under consideration by CDHS and ATSDR. The purpose of the PHRAP is to ensure that this public health assessment not only identifies public health hazards, but provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The CDHS and ATSDR will follow-up on this plan to ensure that it is implemented. The recommendations address the actions to protect public health, additional site- characterization information, obtaining additional health information; and conducting public health actions. CDHS and ATSDR do not have regulatory authority but will work with regulatory agencies to address these recommendations. Some of the recommendations may be or may have been acted on by a regulatory agency such as DTSC or U.S. EPA. CDHS and ATSDR are currently exploring ways to implement the recommended health actions.

Actions Completed:

  1. CDHS and HARP recommended site-specific community education. CDHS conducted a community meeting regarding site issues in February 1995. At the same time, CDHS issued a fact sheet that summarized the findings of this public health assessment.

  2. CDHS and HARP recommended site-specific health provider education. CDHS staff in conjunction with the TK Neighbors in Action have developed health provider education packet including that were delivered to every household in December 1995. These packets are designed to be taken by the community member to their health care provider so as to inform the provider of exposure related to the site and toxicological information regarding the chemicals used at the site.

  3. CDHS and ATSDR recommend that steps be taken to reduce the potential migration of contaminants into the groundwater from the soil. Under DTSC's direction, THAN has already remediated many areas of subsurface soil contamination and placed groundcover such as asphalt, to keep any remaining chemicals from migrating to the groundwater via rain water.

  4. CDHS and ATSDR recommend maintaining periodic monitoring of the private wells in the area that may be potentially affected and to provide an alternative water source if wells become contaminated with site-associated chemicals. Under DTSC's direction, THAN conducts a periodic (annually, semiannually, or quarterly depending upon the well) sampling of private wells in and on the edge of the groundwater contamination plume. According to DTSC, THAN is responsible for providing an alternative water source to those residences if a private well would become contaminated with site-associated chemicals. Such was the case in 1995 when three houses along East Harvey Street were connected to municipal water system by THAN after the discovery of several hits (below drinking water standards) of site- associated chemicals.

Actions Planned:

  1. A further health statistics review is indicated. (HARP) CDHS will be reevaluating the cancer registry data using the Geographical Information System (GIS). This will be developed in the form of a health consultation and is expected to be completed in the spring of 1996. The health consultation will be shared with the community.

  2. CDHS and ATSDR recommend that action be taken so as ensure that the contaminated soil will not migrate off-site through fugitive dust generation. This is proposed in accordance with a draft remedial action plan for this site.

  3. Institute groundwater remediation to reduce the spread of the contamination. THAN has been directed by DTSC to clean- up the groundwater. It is expected that this may begin in the spring 1997.

  4. Implement deed and building restrictions to prevent future development on the site until contamination has been reduced to levels below health concern. Deed restrictions are expected to be a part of the Record of Decision (ROD) that will be signed sometime in 1996.

  5. When activities occur on-site that involve disturbing contaminated soil, appropriate protective clothing and respiratory protection should be worn by workers. This site is being cleaned-up under the CERCLA regulation which requires that workers involved in site investigation or remediation be trained in proper hazardous waste site protocol and follow specific OSHA regulations that are designed to protect the worker. These regulations have been followed in the past and DTSC and CDHS will continue to ensure that such activities are followed in the future.

  6. Conduct air monitoring during any site-activities that involve disturbing contaminated soil. This site is being cleaned-up under the CERCLA regulation which requires that precautions be taken to protect nearby workers and residents during site investigation and remediation. These precautions would include air monitoring. Air monitoring has been conducted in the past when soil disturbances were occurring on-site and DTSC and CDHS will continue to ensure that such activities are followed in the future.

  7. Evaluation of effectiveness of health provider education packet and six-month follow-up with providers who received the packet.

Recommendations for Further Action:

  1. CDHS, with the high level of community concern in mind, recommended the establishment of a registry or a similar procedure for long-term follow-up of people accidentally exposed to pesticides at hazardous waste sites. The inquiry was reviewed by ATSDR's Division of Health Studies. The subregistries of the ATSDR National Exposure Registry are composed of persons with documented exposure to certain chemicals. At this time subregistries have been created for persons with documented exposure to trichloroethylene, benzene, dioxin, and chromium. A subregistry for pesticide expsure has not been established at this time, but all chemicals are continuously reviewed for inclusion. Pesticides represent a broad group of chemicals, and a subregistry for non-specific pesticide exposures would not provide the chemical-specific information on health effects that registries are designed to provide.


PREPARERS OF REPORT

Environmental and Health Effects Assessor:

Marilyn C. Underwood, Ph.D.
Staff Toxicologist
Environmental Health Investigations Branch
California Department of Health Services

Community Relations Coordinator:

Jane Riggan, M.S.W.
Public Health Social Work Consultant II
Environmental Health Investigations Branch
California Department of Health Services


ATSDR REGIONAL REPRESENTATIVES

William Nelson
Gwendolyn Eng
Regional Services, Region IX
Office of Regional Operations


ATSDR TECHNICAL PROJECT OFFICER

Richard R. Kauffman, M.S.
Toxicologist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch, State Programs Section



CERTIFICATION


This T.H. Agriculture & Nutrition Co., Inc., public health assessment was prepared by the California Department of Health 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 public health assessment was begun.

Richard R. Kauffman, M.S.
Technical Project Officer
State Programs Section (SPS)
Superfund Site Assessment Branch (SSAB)
Division of Health Assessment and Consultation (DHAC)
ATSDR

The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health assessment, and concurs with its findings.

Richard Gillig
for Director, DHAC, ATSDR


REFERENCES

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