Evaluation of Exposures 

to Pesticides and 

Parasitic Vectors During 

Inspection of Imported 

Aquatic Plants

Srinivas Durgam, MSPH, MSChE, CIH

Carlos Aristeguieta, MD, MPH

Health Hazard Evaluation Report

HETA 2008-0070-3112

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Los Angeles, California

July 2010

Department of Health and Human Services

Centers for Disease Control and Prevention

Workplace

Safety and Health

 National Institute for Occupational 

Safety and Health

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific 

facility evaluated and may not be universally applicable. Any recommendations made are not to be 

considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE 

reports are available at http://www.cdc.gov/niosh/hhe/
The employer shall post a copy of this report 

for a period of 30 calendar days at or near 

the workplace(s) of affected employees. The 

employer shall take steps to insure that the 

posted determinations are not altered, defaced, 

or covered by other material during such 

period. [37 FR 23640, November 7, 1972, as 

amended at 45 FR 2653, January 14, 1980].
Health Hazard Evaluation Report 2008-0070-3112 Page i

Appendix A

Report Abbreviations.......................................................................ii

Highlights of the NIOSH Health Hazard Evaluation............ iii

Summary .............................................................................v

Introduction..........................................................................1

Assessment.........................................................................3

Results.................................................................................4

Discussion ...........................................................................7

Conclusions.........................................................................9

Recommendations...............................................................9

References ........................................................................12

Contents

Acknowledgments and Availability of Report.....................19

Methods.............................................................................14

Occupational Exposure Limits and Health Effects.............15

Acknowledgments

Appendix B
Page ii Health Hazard Evaluation Report 2008-0070-3112

μg Microgram

μg/m3 Micrograms per cubic meter of air

ACGIH® American Conference of Governmental Industrial Hygienists

APHIS Animal and Plant Health Inspection Service

BHC Benzene hexachloride

CDC Centers for Disease Control and Prevention

CFR Code of Federal Regulations

DDD Dichlordiphenyldichloroethane

DDE Dichlorodiphnyldichloroethylene

DDT Dicholordiphenyltrichloroethane

EPA Environmental Protection Agency

FOH Federal Occupational Health

GA General area

HHE Health hazard evaluation

LOD Limit of detection

MDC Minimum detectable concentration

NAICS North American Industry Classification System

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PBZ Personal breathing zone

PEL Permissible exposure limit

PPE Personal protective equipment

PPQ Plant Protection and Quarantine

REL Recommended exposure limit

SOP Standard operating procedure

STEL Short term exposure limit

TLV® Threshold limit value

TWA Time-weighted average

USDA U.S. Department of Agriculture

WEEL Workplace environmental exposure level

Abbreviations
Health Hazard Evaluation Report 2008-0070-3112 Page iii

Highlights of the

NIOSH Health

Hazard Evaluation

The National Institute 

for Occupational Safety 

and Health (NIOSH) 

received a health hazard 

evaluation request 

from a management 

representative of the 

U.S. Department of 

Agriculture, Animal and 

Plant Health Inspection 

Service (APHIS) in 

Riverdale, Maryland. The 

requestor was concerned 

about potential hazards 

from inspecting imported 

aquatic plants at Plant 

Protection and Quarantine 

stations throughout the 

United States. No health 

effects among APHIS 

employees were listed in 

the request.

What NIOSH Did

● We evaluated the Los Angeles Plant Protection and 

Quarantine station in September–October 2008.

● We observed the plant inspection process, employee work 

practices, and personal protective equipment use.

● We tested the air and work surfaces for pesticides.

● We talked to employees about their work and health.

● We reviewed a previous surface wipe sampling report, injury 

and illness records, and standard operating procedures.

What NIOSH Found

● We did not detect pesticides in the air or on surfaces. 

Because of these findings, we did not identify a need for 

respiratory protection during routine plant inspections.

● Some employees tried to detect pesticides on the plants by 

smelling them.

● The written respiratory protection program required the 

use of respirators for specific tasks such as welding and 

fumigation. However, the program did not provide guidance 

for worksite-specific procedures such as the chemical dip 

process.

● Employees regularly wore disposable gloves when inspecting 

imported plants.

● Employees did not report work-related symptoms. They were 

aware of the potential hazards from disease-carrying insects 

and snails found in aquatic plant shipments.

● We found no recorded injuries or illnesses.

● Inspecting imported aquatic plants poses a potential risk of 

parasitic and bacterial infection.

What Managers Can Do

● Revise the written respiratory protection program to provide 

worksite-specific guidance. The written program should 

identify job tasks and job locations that require respiratory 

protection and note the level of protection.

● Include the list of disease-carrying snails in the APHIS Safety 

and Health Manual. This list should be updated periodically.

● Communicate any changes that are made to standard 

operating procedures and other written materials that 
Page iv Health Hazard Evaluation Report 2008-0070-3112

Highlights of the

NIOSH Health

Hazard Evaluation

(continued)

guide employees in their daily job duties. These changes 

should be shared with employees through written and oral 

communication.

What Employees Can Do

● Continue to wear disposable gloves and use absorbent pads 

such as newspapers when inspecting imported plants.

● Do not smell the plants for pesticides during inspection.

● Wash hands thoroughly prior to eating, drinking, smoking, 

and after removing gloves.

● Wear a face shield along with safety glasses and long sleeve 

lab coats if work activities pose a splash hazard.
Health Hazard Evaluation Report 2008-0070-3112 Page v

Summary

NIOSH received a 

management request 

to evaluate employee 

exposures during 

inspection of imported 

aquatic plants. None of 

the 20 pesticides that 

were analyzed for were 

detected in air or on 

surfaces. Employees 

did not report workrelated health symptoms. 

We recommend that 

employees continue 

to use PPE such as 

disposable gloves and 

long sleeve lab coats 

when inspecting imported 

plants.

In January 2008, NIOSH received an HHE request from a 

management representative of the USDA APHIS in Riverdale, 

Maryland. The requestor was concerned about potential hazards 

from aquatic plant inspections conducted at PPQ stations 

throughout the United States. No health effects among APHIS 

employees were listed in the request. The APHIS PPQ station in 

Los Angeles, California, was chosen for evaluating exposure risks 

resulting from disease-carrying insects and pesticides because it has 

a high volume and frequency of imported aquatic plant shipments.

On September 29–October 3, 2008, we made a site visit to the 

APHIS PPQ station in Los Angeles, California. We met with 

management and employee representatives and observed work 

processes, practices, and workplace conditions. We collected 

PBZ air samples and surface wipe samples to evaluate pesticide 

exposures. We talked to employees about their work and related 

symptoms. We reviewed APHIS wipe sampling records, the OSHA 

Form 300 Log of Work-Related Injuries and Illnesses for 

2005–2008, and other pertinent records.

We did not detect the 20 pesticides we analyzed for in the air 

or on surface wipe samples. No work-related symptoms among 

APHIS PPQ inspectors were reported. Our findings indicated 

that respiratory protection is not needed during routine 

inspection of imported plants. The written respiratory protection 

program required respirators for specific tasks such as welding 

and fumigation. However, the program lacked guidance for 

worksite-specific procedures such as the chemical dip process, 

and employees were uncertain about when respirators were 

needed. Employees used disposable gloves when conducting plant 

inspections and knew the potential hazards from disease-carrying 

insects found in aquatic plant shipments. We found a potential 

risk of contracting a parasitic or bacterial infection from splashes 

with contaminated water when inspecting aquatic plants.

We recommend revising the written respiratory protection 

program to provide worksite-specific guidance including the type 

of respirator needed and job tasks that require respirator use. 

Employees should continue to wear disposable gloves, clear face 

shields along with safety glasses, and long sleeve garments such 

as lab coats to further minimize the potential for inadvertent 

exposure to pesticides and disease-carrying insects. Employees 

should also continue to use newspapers or other absorbent pads 
Page vi Health Hazard Evaluation Report 2008-0070-3112

Summary (continued)

to absorb residual contaminated water when inspecting imported 

aquatic plants.

Keywords: NAICS 926140 (Regulation of Agricultural Marketing 

and Commodities), plant inspection, aquatic plants, snails, pesticides, 

PPE
Health Hazard Evaluation Report 2008-0070-3112 Page 1

Introduction

In January 2008, NIOSH received an HHE request from a 

management representative of the USDA APHIS in Riverdale, 

Maryland. The requestor was concerned about potential hazards 

from aquatic plant inspections conducted at PPQ stations 

throughout the United States, specifically contact with pesticides 

and disease-carrying snails and insects. No health effects among 

APHIS employees were listed in the request. Plant inspections are 

conducted at APHIS PPQ stations throughout the United States. 

The APHIS PPQ station in Los Angeles, California, was chosen as 

a suitable site for evaluating exposure risks resulting from diseasecarrying insects and pesticides because it has a high volume and 

frequency of imported aquatic plant shipments.

On September 29–October 3, 2008, we made a site visit to the 

APHIS PPQ station in Los Angeles, California. We met with 

management and employee representatives and observed work 

processes, practices, and workplace conditions. We also spoke 

with employees about their work and whether they experienced 

symptoms they related to workplace exposures. We collected 

PBZ air samples and surface wipe samples to evaluate pesticide 

exposures. We held a closing conference with management and 

employee representatives on October 3, 2008, to summarize site 

visit activities and provide preliminary recommendations.

Background 

USDA APHIS is responsible for protecting U.S. agriculture from 

foreign pests and diseases. APHIS PPQ employees inspect imported 

cut flowers (roses, chrysanthemums, carnations, etc.), produce 

(fruit and vegetables), and live plants (dry land and aquatic). 

The objectives of the imported commodity inspections are to 

ensure that plants and produce are free of disease and infestation 

(snails, insects, and noxious weeds) and are not an endangered or 

threatened species. This inspection is required prior to releasing 

the products into U.S. trade markets. APHIS PPQ inspectors not 

only look for plant diseases, but also for vectors of human diseases, 

and can serve as quarantine personnel. Aquatic plants arrive in 

the United States through five main port cities, with the largest 

quantity of aquatic plant shipments arriving through Los Angeles, 

Seattle, and Miami. The APHIS PPQ facilities in these cities 

reportedly ranged from antiquated to state-of-the-art, although 

plans are in place to build new facilities to replace old ones, 

including the Los Angeles facility.
Page 2 Health Hazard Evaluation Report 2008-0070-3112

Introduction 

(continued) Aquatic plants are imported from nurseries all over the world. 

Plants can come from state-of-the-art USDA-certified facilities or 

from brackish backyard ponds. Review of aquatic plant shipment 

inspection records from January 1–December 31, 2007, indicated 

that shipments arrived from Southeast Asian countries such as 

Singapore, Thailand, and Indonesia, as well as Costa Rica, the 

Netherlands, and Guatemala. Exporters are not required to label 

or provide information about whether a plant shipment has been 

treated with a pesticide.

Seven inspectors (four full-time and three part-time) worked at the 

PPQ station in Los Angeles during our evaluation. The standard 

inspection service is from 8:00 a.m.to 4:30 p.m., Monday through 

Friday. Because of the perishable nature of the imported material, 

on-call service is available 24 hours a day, including weekends. PPQ 

inspectors and management representatives constitute a five-person 

health and safety committee.

Plant Protection and Quarantine 

Inspection Process

Import brokers bring the plants to the PPQ facility for inspection. 

When an imported plant shipment arrives, U.S. Customs and 

Border Protection personnel issue a provisional release to the 

importers on the condition that the plants are approved by the 

PPQ inspectors. The import broker or freight forwarder then 

initiates the request for an inspection. Inspection time per 

shipment ranges from 30 minutes to 1 hour depending on the size 

of the shipment and experience with the particular commodity 

(a representative sample of the shipment is inspected). Daily logs 

note the size of the shipment, plant type, country of origin, and 

the name of the exporter. During inspections, there is considerable 

handling of the plants, including vigorous shaking of the plants 

over an examination table to dislodge insects and snails onto the 

examination table. Aquatic plants are mostly individually packaged 

and are kept moist to prevent plants from perishing during transit. 

Plants suspected of disease upon initial visual examination are 

closely examined using a magnifying glass; samples are collected 

and examined further under a stereo microscope by the PPQ 

inspector, who may take the sample to a biologist for confirmation. 

After passing inspection, the plants are released to the importer. 

If a shipment does not pass inspection (insect infestation or plant 

disease is detected), the broker has the option of returning the 
Health Hazard Evaluation Report 2008-0070-3112 Page 3

Introduction (continued)

Assessment

entire shipment to the country of origin, destroying the plants in a 

gas-fired incinerator, treating the plants offsite at a methyl bromide 

fumigation station, or treating the infestation at the PPQ station 

using appropriate chemicals. The on-site treatment of plants is 

referred to as a “chemical dip” process.

At the Los Angeles PPQ station, PPQ inspectors oversee 

contractors responsible for cargo fumigation as well as brokers 

conducting on-site treatment using the chemical dip process.

Previous NIOSH HHEs 

In 1995–1996, NIOSH investigators conducted two evaluations 

at the APHIS PPQ station in Miami, Florida, to evaluate the 

potential for employee exposure to pesticides during inspection 

of imported plants. Both evaluations found pesticide residue on 

foliage and determined that PPQ inspectors were at risk for skin 

exposure to pesticides. Pesticides were not detected in air samples 

collected during either evaluation; therefore, respiratory protection 

was not recommended. Disposable glove use was recommended 

at all times during inspection. The investigators concluded that 

human senses such as smell and presence of visible residue should 

not be used to determine whether PPE should be worn [NIOSH 

1997a, 1997b].

We observed the inspection process for imported plants, noted 

PPE availability and use, and observed housekeeping practices. 

PPQ inspectors inspected aquatic plants on October 2 and 3, 

2008. Imported plants can contain a variety of residual pesticides, 

the specifics of which are not known to PPQ inspectors [NIOSH 

1997a, 1997b]. Therefore, our air and surface wipe samples were 

analyzed for 20 common pesticides, including isomers of these 

compounds, using a gas chromatograph with a mass spectrometer 

detector according to EPA Method TO-10A. Chromatogram 

peaks for all the eluted chemicals were also identified and their 

identities confirmed from the spectral library. We collected seven 

PBZ and five GA full-shift air samples to assess pesticide exposure 

during the plant inspection process. We also collected 15 surface 

wipe samples for pesticides, including 13 from three work tables 

and two from high contact surfaces (the viewfinder and focusing 

knobs of two different microscopes). Details on the air and surface 
Page 4 Health Hazard Evaluation Report 2008-0070-3112

Assessment (continued)

Results

wipe sampling methods used in this evaluation are described in 

Appendix A; a discussion of occupational exposure limits and 

health effects for pesticides is in Appendix B.

We interviewed employees informally about symptoms that may 

have been related to their workplace exposure and any concerns 

about workplace exposures. We also reviewed the following 

documents:

● Industrial hygiene report assessing the presence of pesticides 

in plant shipments at the San Juan airport conducted by 

FOH, dated May 14, 2008

● OSHA Form 300 Log of Work-related Injuries and Illnesses 

from 2005–2008 for the Los Angeles facility

● SOP for the chemical dip process

● APHIS Safety and Health Manual, current version dated 

2004

● Circular and memorandum from CDC to USDA listing 

snails of medical importance [Ciordano 1972; Sullivan 1990].

We consulted with a parasitologist from the CDC National 

Center for Zoonotic, Vector-Borne, and Enteric Diseases, who also 

serves as a subject matter expert for APHIS. He confirmed that 

he was not aware of any reports of adverse health effects among 

APHIS PPQ inspectors and that he has had previous discussions 

with APHIS personnel about aquatic snails found in shipments 

from Southeast Asia and Peru [Sullivan 2008]. He created a list 

of aquatic snails with potential for transmitting parasitic diseases 

that was shared with APHIS in May 1998. This list has not been 

updated since 1998.

None of the 20 pesticides we analyzed for were detected in PBZ 

and GA air samples or in surface wipe samples. The MDC for the 

20 pesticides whose concentrations were quantitatively determined 

in the air samples are presented in Appendix A. The analytical 

LODs for pesticides analyzed in the surface wipe samples are also 

listed in Appendix A. Captan 50 W, a fungicide, was qualitatively 

identified in one of the air samples at an estimated concentration 

of 1.5 μg/m3.
Health Hazard Evaluation Report 2008-0070-3112 Page 5

Results (continued) Although APHIS PPQ inspectors have reported no work-related 

illnesses (specifically no parasitic disease, insect bites, or pesticide 

intoxication), they have observed snails, insects, and visible residue 

on some plant shipments and were concerned about contaminated 

residual water arriving with aquatic plant shipments. No aquatic 

snails were found on aquatic plants during our evaluation. The 

OSHA Logs also listed no injuries or illnesses.

Document Review

The FOH report from the San Juan PPQ station included three 

wipe samples, two from orchid leaves and one from the inside of a 

cardboard box. The samples were analyzed for organophosphorous 

pesticides and for Captan. Captan, a fungicide, ranged from 

10–170 μg/sample and chlorpyrifos, an organophosphorus 

insecticide, ranged from not detected to 0.11 μg/sample. No other 

organophosphorous pesticides were detected. FOH recommended 

conducting personal air sampling for pesticides identified in its 

evaluation.

The written SOP for the chemical dip process required the brokers 

to use safety goggles, nitrile gloves, protective long sleeve clothing, 

and respirators when using specific pesticides. A “NIOSHapproved cartridge respirator” was to be used when using Sevin® 

or malathion, and a “respirator mask” was required when using 

“Bordeaux” fungicide. No additional details on the specific type of 

respirator or respirator cartridges were provided.

The APHIS Safety and Health Manual described testing programs 

for pesticides and communicable diseases of public health concern. 

The PPE section described jobs “typically requiring respiratory 

protection include laboratory work, welding, cutting or brazing, 

handling hazardous chemicals or substances, and during pesticide 

application or fumigation” [Petch 2008]. The written respiratory 

protection program section governs all APHIS facilities in the 

United States and discusses evaluating operations to determine the 

nature of the hazard and level of respiratory protection needed, 

selection of respirators, employee training, medical requirements, 

fit testing, and maintenance of respirators.

The two CDC documents together list approximately 100 aquatic 

snails that can act as hosts for a dozen parasites of public health 

importance. The documents state that aquatic plant shipments 
Page 6 Health Hazard Evaluation Report 2008-0070-3112

Results (continued) contaminated with snails of public health importance should be 

treated with a molluscicide, incinerated, or returned to the broker.

Other Observations and Findings 

The Los Angeles APHIS management informed us that PPQ 

inspectors were provided with lab coats to prevent transfer of 

contamination from agricultural products to their uniforms. 

However, we found no lab coats in the inspection area, and PPQ 

inspectors were not aware of their availability.

PPQ inspectors wore disposable latex or nitrile gloves that were 

typically discarded after each inspection. Dry products were laid on 

the inspection benches for examination; however, when inspecting 

aquatic plants, the inspectors covered benches with newspaper to 

absorb any condensate present in the shipment. These newspapers 

were disposed of after each inspection. PPQ inspectors informed 

us that they used bleach on alternate days to clean work surfaces 

before starting their work shift. PPQ inspectors used a long brush 

and a dust pan to clean surfaces between shipment inspections. 

We observed some PPQ inspectors checking for pesticides on the 

plants by smelling them.

Although we did not observe the chemical dip process during 

our site visit, PPQ inspectors explained the process to us. At the 

Los Angeles PPQ station, the process is conducted by the broker 

after normal business hours in a separate room fitted with a wall 

mounted exhaust fan. The pesticide is diluted to the required 

concentration in large wide-mouth tubs. Infected plant material is 

dipped completely in the solution and then air dried on shelves in 

the room. The broker is responsible for obtaining all the required 

PPE per the APHIS written SOP for this process. PPQ inspectors 

in the area during this process have the potential of being exposed 

to pesticides used for treating plant shipments.

Neither respiratory protection nor special clothing are required 

during routine plant inspections. However, activities such as 

shaking wet plants can pose a splash hazard against which 

employees need to be adequately protected. We noted that PPQ 

inspectors were provided one air-purifying elastomeric half-mask 

respirator equipped with a combination organic vapor and P100 

particulate filter (North by Honeywell, Cranston, Rhode Island) 
Health Hazard Evaluation Report 2008-0070-3112 Page 7

Results (continued) for common use. PPQ inspectors mentioned that they were fit 

tested for this respirator but were unclear about its intended use. 

In addition, APHIS provided no air monitoring results that would 

support the need for respiratory protection. PPQ inspectors used 

the respirator voluntarily; its use was rare because the broker, 

with guidance from PPQ inspectors, conducted the chemical dip 

process. In addition, PPQ inspectors had not received a copy of 

Appendix D of the OSHA respiratory protection standard 

(29 CFR 1910.134), which is required when employees voluntarily 

use respirators.

Pesticides typically have a high molecular weight and are 

nonvolatile compounds. The highest exposures to pesticides have 

been reported in workers handling and/or applying pesticides 

during farming activities [Curwin et al. 2005]. Pesticide exposures 

can occur through ingestion, skin contact, and inhalation. 

However, in occupational settings, worker exposure occurs 

primarily through skin contact and to a lesser extent by inhalation 

[Geno et al. 1996; Franklin and Worgan 2005]. The aquatic plant 

shipments we observed contained plants individually wrapped in 

plastic with some residual moisture usually present.

According to EPA, more than 1055 active ingredients are registered 

as pesticides, which are formulated into thousands of pesticide 

products [EPA 2007]. All these compounds cannot be sampled and 

analyzed using a single analytical method. We used EPA Method 

TO-10A with gas chromatography-mass spectroscopy analysis 

to confirm the identity of chemical compounds in the air and 

in surface wipe samples. We detected none of the 20 pesticides 

we specifically analyzed for in our air samples. However, using 

mass spectroscopy we identified the presence of Captan 50 W, a 

fungicide, in one air sample. The chemical dip process was not 

conducted during the time of our evaluation; therefore, we could 

not evaluate PPQ inspectors’ exposures during this task.

We found none of the 20 pesticides we analyzed for in the 18 

surface wipe samples. However, PPQ inspectors may be splashed 

with the residual water in aquatic plant shipments when they 

vigorously shake the plants. No pesticide surface contamination 

standards exist, but the presence of surface contamination can 

indicate the need for improved housekeeping and the potential for 

dermal exposure or ingestion from contaminated hands, clothing, 

or work surfaces.

Discussion
Page 8 Health Hazard Evaluation Report 2008-0070-3112

Discussion (continued) In their natural habitat, aquatic plants can harbor insects and 

snails that serve as vectors for parasitic diseases. For example, 

eosinophilic meningitis, a presentation of infection with the 

parasite Angiostrongylus cantonensis, can be contracted by skin 

contact with or ingestion of infected aquatic snails of the genus 

Pila sp. Although the risk of infection is greatest for people 

living and working in areas where these plants are grown, APHIS 

inspectors are at risk of accidental contact with these insects 

and snails. In addition, aquatic plants may be grown in water 

contaminated with human or animal feces, which may carry 

disease-causing bacteria. When inspecting shipments of aquatic 

plants, APHIS inspector’s skin and mucosa could be exposed to 

potentially contaminated water [Rosen 1998]. APHIS inspectors 

were aware of the hazards associated with exposure to snails and 

contaminated water in aquatic plant shipments. To reduce this 

possibility of exposure, they regularly wear disposable gloves. 

Although this exposure awareness exists, the inspectors do not use 

lab coats or eye or face protection when inspecting aquatic plants.

Although the APHIS written respiratory protection program has 

most elements of a comprehensive respiratory protection program, 

it lacks guidance for worksite-specific procedures. For example, it 

does not provide specific guidance on the type of respirator the 

broker should use during the chemical dip process. PPQ inspectors 

had access to one respirator and indicated that it was available for 

common use if needed, but did not know the intended use (i.e., 

under what conditions). This suggests a gap in employee training 

and a lack of site-specific implementation of the respiratory 

protection program.

The written SOP for the chemical dip process did not provide 

specific PPE guidance. Nitrile gloves are appropriate when using 

carbaryl (brand name Sevin®) but are not appropriate for use with 

malathion. Silver Shield® gloves are recommended when using 

malathion [Forsberg and Mansdorf 2007]. Tighter fitting gloves 

such as disposable nitrile gloves should be worn over the Silver 

Shield gloves to increase dexterity.
Health Hazard Evaluation Report 2008-0070-3112 Page 9

We conclude that no health hazard to pesticides existed for APHIS 

personnel conducting plant inspections. Our findings indicate that 

no respiratory protection is needed during routine inspection of 

imported plants. Contracting a parasitic or bacterial infection from 

inspecting imported aquatic plants is a potential risk. However, a 

clean work environment, regular PPE use, and low frequency of 

aquatic plant shipments make this an unlikely event. Disposable 

gloves, long sleeve garments such as lab coats, and face shields 

along with safety glasses will help prevent employee exposure to 

pesticides, parasites, bacteria, and disease-carrying insects that may 

be present in imported plant shipments.

Based on our findings, we recommend the actions listed below 

to create a more healthful workplace. We encourage APHIS to 

use the existing labor-management health and safety committee 

to discuss the recommendations in this report and develop an 

action plan. Those involved in the work can best set priorities 

and assess the feasibility of our recommendations for the specific 

situation at APHIS PPQ station in Los Angeles, California. 

Our recommendations are based on the hierarchy of controls 

approach (Appendix B: Occupational Exposure Limits and Health 

Effects). This approach groups actions by their likely effectiveness 

in reducing or removing hazards. In most cases, the preferred 

approach is to eliminate hazardous materials or processes and 

install engineering controls to reduce exposure or shield employees. 

Until such controls are in place, or if they are not effective or 

feasible, administrative measures and/or personal protective 

equipment may be needed.

Administrative Controls 

Administrative controls are management-dictated work practices 

and policies to reduce or prevent exposures to workplace hazards. 

The effectiveness of administrative changes in work practices 

for controlling workplace hazards is dependent on management 

commitment and employee acceptance. Regular monitoring and 

reinforcement are necessary to ensure that control policies and 

procedures are not circumvented in the name of convenience or 

production.

1. Revise the written respiratory protection program to identify 

the job tasks, type of respirator, and work locations where 

Conclusions

Recommendations
Page 10 Health Hazard Evaluation Report 2008-0070-3112

Recommendations

(continued) respirator use is required. Respiratory hazards should 

be evaluated for job tasks where respiratory protection 

is currently required to ensure that the respirators worn 

are necessary and appropriate. If respirators are deemed 

necessary, the respirator program must identify the type 

of respirator required for those tasks (e.g., chemical dip 

process). Job tasks where employees may voluntarily wear 

respirators should also be noted in the written program. 

Ensure that the requirements listed in the OSHA 

Respiratory Protection Standard (29 CFR 1910.134) are 

followed. The OSHA Small Entity Compliance Guide provides 

guidance for respiratory protection programs and is available 

at http://www.osha.gov/Publications/SECG_RPS/ secg_

rps.html.

2. Revise the SOP for the chemical dip process to specify the 

user and the type of respirator to be worn, if needed.

3. Instruct employees not to smell the plants in an attempt to 

detect the presence of pesticides during inspection.

4. Encourage employees to wash hands with soap and water 

before eating, drinking, smoking, and after removing gloves.

5. Communicate to employees in writing any changes that are 

made to SOPs and other written materials that guide them 

in their daily job duties.

6. Integrate the list of disease-carrying snails into the APHIS 

Safety and Health Manual. The list should be periodically 

reviewed and updated by CDC’s medical parasitologist.

Personal Protective Equipment 

PPE is the least effective means for controlling employee exposures. 

Proper use of PPE requires a comprehensive program, and calls 

for a high level of employee involvement and commitment to be 

effective. The use of PPE requires the choice of the appropriate 

equipment to reduce the hazard and the development of 

supporting programs such as training, change-out schedules, and 

medical assessment if needed. PPE should not be relied upon as 

the sole method for limiting employee exposures. Rather, PPE 

should be used until engineering and administrative controls can 

be demonstrated to be effective in limiting exposures to acceptable 

levels.
Health Hazard Evaluation Report 2008-0070-3112 Page 11

Recommendations

(continued) 1. Continue to wear appropriate disposable gloves, preferably 

nonlatex, when routinely inspecting imported plant 

shipments. Some employees exposed to latex products 

such as latex gloves can develop latex allergy. Additional 

information on latex allergy and related hazards is available 

at http://www.cdc.gov/niosh/topics/latex/.

2. If inspecting aquatic plants poses a potential splash hazard, 

wear clear face shields along with safety glasses and long 

sleeve garments such as lab coats.

3. Continue to use newspapers as absorbent pads or procure 

disposable absorbent pads for use when inspecting imported 

aquatic plants.

4. Wear tighter fitting disposable nitrile gloves over the Silver 

Shield gloves when using a mixture of sevin and malathion 

insecticides in the chemical dip process.
Page 12 Health Hazard Evaluation Report 2008-0070-3112

References

Ciordano JF [1972]. Circular No. 132 (Revised) Supplement 

2 of December 11, 1972, from J.F. Giordano, Quarantine 

Program, Epidemiology Program, to Officers in Charge, Type I 

and II Quarantine Stations, Centers for Disease Control, U.S. 

Department of Health, Education and Welfare.

Curwin BD, Hein MJ, Sanderson WT, Barr DB, Heederik D, 

Reynolds SJ, Ward EM, Alavanaja MC [2005]. Urinary and hand 

wipe pesticide levels among farmers and nonfarmers in Iowa. J 

Expo Anal Environ Epidemol 15(6):500–508.

EPA [2007]. Assessing health risks from pesticides. [http://www.

epa.gov/pesticides/factsheets/ riskassess.htm]. Date accessed: April 

2010.

Forsberg K, Mansdorf SZ [2007]. Quick selection guide to 

protective clothing. 5th ed. Hoboken, NJ: John Wiley and Sons, 

Inc.

Franklin CA, Worgan JP, eds. [2005]. Occupational and residential 

exposure assessment for pesticides. Sussex, England: John Wiley 

and Sons, Ltd., pp. 2–3.

Geno PW, Camann DE, Harding HJ, Villalobos K, Lewis RG 

[1996]. Handwipe sampling and analysis procedure for the 

measurement of dermal contact with pesticides. Arch Environ 

Contam Toxicol 30(1):132–138.

NIOSH [1997a]. Hazard evaluation and technical assistance 

report: United States Department of Agriculture, Plant Inspection 

and Quarantine Station, Miami, FL. By Kiefer M. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for 

Occupational Safety and Health. NIOSH HETA Report No. 

94-0353-2629.

NIOSH [1997b]. Hazard evaluation and technical assistance report: 

United States Department of Agriculture, Animal and Plant 

Health Inspection Service, Miami, FL. By Kiefer M. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for 

Occupational Safety and Health. NIOSH HETA Report No. 

96-0083-2628.
Health Hazard Evaluation Report 2008-0070-3112 Page 13

References (continued) Petch PA (peter.a.petch@aphis.usda.gov) [2008]. APHIS Safety 

and Health Manual. Private e-mail message Srinivas Durgam 

(sdurgam@cdc.gov), February 1.

Rosen J [1998]. Inspection services. In: Stellman JM, ed. 

Encyclopedia of occupational health and safety. 4th ed. Vol. III, 

Geneva: International Labor Office, pp.101.3–101.5.

Sullivan JJ [1990]. Memorandum of May 9, 1990, from J.J. 

Sullivan, Division of Parasitic Diseases, National Center for 

Infectious Diseases, to M. Kiley, Office of Health and Safety, 

Centers for Disease Control, U.S. Department of Health and 

Human Services.

Sullivan JJ [2008]. Telephone conversation on March 7, 2008, 

between J.J. Sullivan, National Center for Zoonotic, Vector-Borne, 

and Enteric Diseases, and S. Durgam, Division of Surveillance, 

Hazard Evaluations and Field Studies, National Institute for 

Occupational Safety and Health, Centers for Disease Control and 

Prevention, U.S. Department of Health and Human Services.
Page 14 Health Hazard Evaluation Report 2008-0070-3112

Pesticide Air Sampling 

Air samples were collected on sorbent tubes containing Tenax® (750 milligram) placed between two 

polyurethane foam plugs using SKC PCXR4 air sampling pumps (SKC Incorporated, Eighty Four, 

Pennsylvania) calibrated at a flow rate of 4 liters per minute. The inlet port of the sampling pump was 

connected to the sampling media with Tygon® tubing. All air sampling pumps were calibrated before 

and after use. For PBZ samples, the sampling media was attached to the employees’ lapels within their 

breathing zone, roughly defined as an area in front of the shoulders with a radius of 6 to 9 inches. All 

samples were extracted according to procedures described in EPA Method 3545 and analyzed by gas 

chromatography-mass spectroscopy according to EPA Method TO-10A [EPA 2009]. Chromatogram peaks 

for all the eluted chemicals were identified and their identities confirmed from the spectral library.

The LOD for Endosulfan sulfate was 3 μg/sample. The MDC was obtained by dividing the analytical LOD 

by the sample volume. Therefore, for a sample volume of 1.6 m3, the MDC was 1.88 μg/m3. The LOD for 

the remainder of the pesticides listed in Table B1 was 2 μg/sample. Therefore, the MDC for a sampling 

volume of 1.6 m3 would be 1.25 μg/m3.

Pesticide Surface Sampling 

Surface wipe samples were collected using a commercially available 10 x 10-cm Sof-Wick® dressing sponge 

(Johnson and Johnson, Arlington, Texas) moistened with 10 milliliters of 100% isopropyl alcohol [Curwin 

et al. 2005]. The collection procedure was as follows: (1) identify the surface to be sampled and mark a 

2 x 1-ft area; (2) don a pair of disposable nitrile gloves; (3) place wipe flat on surface and wipe using 

horizontal S-strokes, side-to-side so the entire surface is covered; (4) fold the exposed side of the wipe in 

and wipe the area with vertical S-strokes; (5) fold the wipe once more and wipe the area with horizontal 

S-strokes; and (6) fold the pad, exposed side in, and place in a sterile container. A new pair of disposable 

gloves was used for each surface wipe sample. All samples were analyzed by gas chromatography-mass 

spectroscopy according to EPA Method TO-10A, modified for the wipe media [EPA 2009]. Chromatogram 

peaks for all the eluted chemicals were identified and their identities confirmed from the spectral library. 

The analytical LOD for pesticides analyzed in surface wipe samples ranged from 0.4–0.7 μg/sample.

References

Curwin BD, Hein MJ, Sanderson WT, Barr DB, Heederik D, Reynolds SJ, Ward EM, Alavanaja MC 

[2005]. Urinary and hand wipe pesticide levels among farmers and nonfarmers in Iowa. J Expo Anal 

Environ Epidemiol 15(6):500–508.

EPA [2009]. EPA standardized analytical methods. Chemical methods query. [http://www.epa.gov/sam/

searchchem.htm]. Date accessed: March 2010.

Appendix A: Methods
Health Hazard Evaluation Report 2008-0070-3112 Page 15

In evaluating the hazards posed by workplace exposures, NIOSH investigators use both mandatory (legally 

enforceable) and recommended OELs for chemical, physical, and biological agents as a guide for making 

recommendations. OELs have been developed by Federal agencies and safety and health organizations to 

prevent the occurrence of adverse health effects from workplace exposures. Generally, OELs suggest levels 

of exposure that most employees may be exposed up to 10 hours per day, 40 hours per week for a working 

lifetime without experiencing adverse health effects. However, not all employees will be protected from 

adverse health effects even if their exposures are maintained below these levels. A small percentage may 

experience adverse health effects because of individual susceptibility, a preexisting medical condition, 

and/or a hypersensitivity (allergy). In addition, some hazardous substances may act in combination with 

other workplace exposures, the general environment, or with medications or personal habits of the 

employee to produce health effects even if the occupational exposures are controlled at the level set by 

the exposure limit. Also, some substances can be absorbed by direct contact with the skin and mucous 

membranes in addition to being inhaled, which contributes to the individual’s overall exposure.

Most OELs are expressed as a TWA exposure. A TWA refers to the average exposure during a normal

8- to 10-hour workday. Some chemical substances and physical agents have recommended STEL or ceiling 

values where health effects are caused by exposures over a short period. Unless otherwise noted, the STEL 

is a 15-minute TWA exposure that should not be exceeded at any time during a workday, and the ceiling 

limit is an exposure that should not be exceeded at any time.

In the United States, OELs have been established by Federal agencies, professional organizations, state 

and local governments, and other entities. Some OELs are legally enforceable limits, while others are 

recommendations. The U.S. Department of Labor OSHA PELs (29 CFR 1910 [general industry]; 

29 CFR 1926 [construction industry]; and 29 CFR 1917 [maritime industry]) are legal limits enforceable in 

workplaces covered under the Occupational Safety and Health Act. NIOSH RELs are recommendations 

based on a critical review of the scientific and technical information available on a given hazard and the 

adequacy of methods to identify and control the hazard. NIOSH RELs can be found in the NIOSH Pocket 

Guide to Chemical Hazards [NIOSH 2005]. NIOSH also recommends different types of risk management 

practices (e.g., engineering controls, safe work practices, employee education/training, personal protective 

equipment, and exposure and medical monitoring) to minimize the risk of exposure and adverse health 

effects from these hazards. Other OELs that are commonly used and cited in the United States include 

the TLVs recommended by ACGIH, a professional organization, and the WEELs recommended by the 

American Industrial Hygiene Association, another professional organization. The TLVs and WEELs are 

developed by committee members of these associations from a review of the published, peer-reviewed 

literature. They are not consensus standards. ACGIH TLVs are considered voluntary exposure guidelines 

for use by industrial hygienists and others trained in this discipline “to assist in the control of health 

hazards” [ACGIH 2009]. WEELs have been established for some chemicals “when no other legal or 

authoritative limits exist” [AIHA 2009].

Outside the United States, OELs have been established by various agencies and organizations and include 

both legal and recommended limits. Since 2006, the Berufsgenossenschaftliches Institut für Arbeitsschutz 

(German Institute for Occupational Safety and Health) has maintained a database of international 

Appendix B: Occupational Exposure Limits and Health Effects
Page 16 Health Hazard Evaluation Report 2008-0070-3112

Appendix B: Occupational Exposure Limits and Health Effects (continued)

OELs from European Union member states, Canada (Québec), Japan, Switzerland, and the United 

States available at http://www.dguv.de/bgia/en/gestis/limit_ values/index.jsp. The database contains 

international limits for over 1250 hazardous substances and is updated annually.

Employers should understand that not all hazardous chemicals have specific OSHA PELs, and for some 

agents the legally enforceable and recommended limits may not reflect current health-based information. 

However, an employer is still required by OSHA to protect its employees from hazards even in the absence 

of a specific OSHA PEL. OSHA requires an employer to furnish employees a place of employment free 

from recognized hazards that cause or are likely to cause death or serious physical harm [Occupational 

Safety and Health Act of 1970 (Public Law 91–596, sec. 5(a)(1))]. Thus, NIOSH investigators encourage 

employers to make use of other OELs when making risk assessment and risk management decisions to 

best protect the health of their employees. NIOSH investigators also encourage the use of the traditional 

hierarchy of controls approach to eliminate or minimize identified workplace hazards. This includes, in 

order of preference, the use of: (1) substitution or elimination of the hazardous agent, (2) engineering 

controls (e.g., local exhaust ventilation, process enclosure, dilution ventilation), (3) administrative controls 

(e.g., limiting time of exposure, employee training, work practice changes, medical surveillance), and (4) 

personal protective equipment (e.g., respiratory protection, gloves, eye protection, hearing protection). 

Control banding, a qualitative risk assessment and risk management tool, is a complementary approach 

to protecting employee health that focuses resources on exposure controls by describing how a risk 

needs to be managed. Information on control banding is available at http://www.cdc.gov/niosh/topics/

ctrlbanding/. This approach can be applied in situations where OELs have not been established or can be 

used to supplement the OELs, when available.

Pesticides 

A pesticide is any substance or mixture intended to prevent, destroy, repel, or mitigate insects (insecticide, 

miticide, acaricide); rodents (rodenticide); nematodes (nematocide); fungi (fungicide); or weeds (herbicide) 

designated as a “pest.” Each type of pesticide has numerous modes of action, chemical classes, target 

organs, formulations, and physicochemical properties. Pesticide toxicity is equally diverse, and even within 

a similar chemical class, individual compounds ranging from extremely toxic to practically nontoxic can 

be found. As such, generalizations about the toxicity of pesticides cannot be made without considerable 

qualification and explanation. In the United States, regulatory responsibility to protect public health and 

the environment from the risks posed by pesticides lies with the EPA Office of Pesticide Programs. In 

the United States alone, approximately five billion pounds of pesticide products are used each year [EPA 

2001]. Table B1 contains the list of 20 pesticides we analyzed for in air and on surfaces and their relevant 

OELs.
Health Hazard Evaluation Report 2008-0070-3112 Page 17

Appendix B: Occupational Exposure Limits and Health Effects (continued)

References 

ACGIH [2009]. 2009 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

agents and biological exposure indices. Cincinnati, OH: American Conference of Governmental 

Industrial Hygienists.

AIHA [2009]. AIHA 2009 Emergency response planning guidelines (ERPG) & workplace environmental 

exposure levels (WEEL) handbook. Fairfax, VA: American Industrial Hygiene Association.

CFR. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office, Office of the 

Federal Register.

Table B1. Pesticides and associated OELs

Pesticide

 NIOSH REL OSHA PEL ACGIH TLV NIOSH 

 μg/m3 Carcinogenicity

4,4 ́-DDD* 500 1000 1000

4,4 ́-DDE* 500 1000 1000

4,4 ́-DDT 500 1000 1000 Ca†

Aldrin 250 250 250 Ca

BHC-alpha 500 500 500

BHC-beta 500 500 500

BHC-delta 500 500 500

BHC-gamma 500 500 500

Chlordane-alpha 500 500 500 Ca

Chlordane-gamma 500 500 500 Ca

Dieldrin 250 250 250 Ca

Endosulfan I 100 None 100

Endosulfan II 100 None 100

Endosulfan sulfate None None None

Endrin 100 100 100

Endrin aldehyde None None None

Endrin ketone None None None

Heptachlor 500 500 50 Ca

Heptachlor epoxide None None 50

Methoxychlor LFC‡ 15000 10000 Ca

* Isomers of 4,4’-DDT

† Considered a potential occupational carcinogen by NIOSH

‡ Lowest feasible concentration
Page 18 Health Hazard Evaluation Report 2008-0070-3112

Appendix B: Occupational Exposure Limits and Health Effects (continued)

EPA [2001]. Pesticides industry sales and usage. 2000 and 2001 market estimates. [http://www.epa.gov/

oppbead1/pestsales/01pestsales/market_estimates2001.pdf]. Date accessed: March 2010.

NIOSH [2005]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 2005-149. [http://www.cdc.gov/niosh/npg/]. Date 

accessed: March 2010.
Health Hazard Evaluation Report 2008-0070-3112 Page 19

Acknowledgments and

Availability of Report

The Hazard Evaluations and Technical Assistance Branch 

(HETAB) of the National Institute for Occupational Safety and 

Health (NIOSH) conducts field investigations of possible health 

hazards in the workplace. These investigations are conducted 

under the authority of Section 20(a)(6) of the Occupational Safety 

and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes 

the Secretary of Health and Human Services, following a written 

request from any employer or authorized representative of 

employees, to determine whether any substance normally found 

in the place of employment has potentially toxic effects in such 

concentrations as used or found. HETAB also provides, upon 

request, technical and consultative assistance to federal, state, and 

local agencies; labor; industry; and other groups or individuals to 

control occupational health hazards and to prevent related trauma 

and disease.

The findings and conclusions in this report are those of the 

authors and do not necessarily represent the views of NIOSH. 

Mention of any company or product does not constitute 

endorsement by NIOSH. In addition, citations to websites 

external to NIOSH do not constitute NIOSH endorsement of 

the sponsoring organizations or their programs or products. 

Furthermore, NIOSH is not responsible for the content of these 

websites. All Web addresses referenced in this document were 

accessible as of the publication date.

This report was prepared by Srinivas Durgam and Carlos 

Aristeguieta of HETAB, Division of Surveillance, Hazard 

Evaluations and Field Studies. Analytical support was provided by 

Bureau Veritas North America. Health communication assistance 

was provided by Stefanie Evans. Editorial assistance was provided 

by Ellen Galloway. Desktop publishing was performed by Robin 

Smith.

Copies of this report have been sent to employee and management 

representatives at USDA APHIS, the state health department, 

and the Occupational Safety and Health Administration 

Regional Office. This report is not copyrighted and may be freely 

reproduced. The report may be viewed and printed at http://

www.cdc.gov/niosh/hhe/. Copies may be purchased from the 

National Technical Information Service at 5825 Port Royal Road, 

Springfield, Virginia 22161.
Below is a recommended citation for this report:

NIOSH [2010]. Health hazard evaluation report: evaluation of exposures to 

pesticides and parasitic vectors during inspection of imported aquatic plants, Los 

Angeles, CA. By Durgam S, Aristeguieta C. Cincinnati, OH: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and Health, NIOSH HETA No. 2008-0070-3112.

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