OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM 2009.07
Subject: Requirements for coating lead weights; handling lead weights, storing lead weights, testing for lead contamination, and testing employee lead-blood levels
This memorandum (1) reports on evaluations of lead sounding-weight coatings and suggests some alternatives in selecting lead weight coatings; (2) describes hygiene for handling lead weights, (3) provides guidance on storing lead weights, (4) describes procedures for testing for lead contamination, and (5) describes requirements for offering testing for employee blood-lead levels. This Office of Surface Water (OSW) memorandum has been coordinated with the U.S. Geological Survey Safety and Health Management Branch (SHMB) and supersedes OSW Technical Memorandum 2005.02.
Testing of Columbus-type lead sounding weights and of surfaces in contact with or near them has indicated that the weights may be a source of lead contamination. Hazards associated with this contamination were described in a USGS Safety Memorandum (URL: http://internal.usgs.gov/ops/safetynet/lead10.doc) issued on January 17, 2004, by USGS SHMB. In response to the SHMB safety memorandum, OSW tasked the Hydrologic Instrumentation Facility (HIF) with investigating lead weight coatings that could be used to abate the contamination hazards arising from continued use of the Columbus weights. In addition, SHMB prepared technical guidance describing recommended procedures for cleaning contaminated areas and for disposing of the resulting refuse. OSW Technical Memorandum 2005.02 transmitted the SHMB guidance and required USGS Water Science Centers (WSCs) to have Columbus-type lead sounding weights encased with powder coatings to abate lead-contamination hazards, test sounding-weight storage areas for lead contamination, clean these areas of lead contaminates, and offer blood testing for lead to employees.
Coating of Lead Weights
Soon after issuing OSW Technical Memorandum 2005.02, feedback from WSCs indicated that the powder coatings were not adhering to the weights as well as had been expected. A follow-up email from the Chief of OSW, distributed on February 15, 2005, advised WSCs to delay coating efforts while OSW and the HIF reviewed and tested additional products. The results of those tests are summarized in attachment 1. In general, coatings are still considered a viable approach to abating lead contamination that might result from use or storage of lead sounding weights, but the performance and availability of specific coatings vary. They require careful handing, storage, and transport to prevent scratching and chipping, and are not well suited to some measurement conditions such as high-velocity streams or heavy course-sediment loads. As an alternative to coating lead weights, WSCs are encouraged to institute hygiene procedures to limit employee exposure to lead from the weights and to minimize the spread of lead debris in the work environment.
Hygiene for Handling Lead Weights
The basic premise of the hygiene program is that accumulated exposure to hazardous levels of lead can be prevented by frequent and proper cleaning of the weights, storage surfaces, hands, and clothing that may have come into contact with the weights and that periodic testing of these surfaces can be used to detect hazardous conditions needing further mitigation.
Prior to first use of a leaded weight during a field trip, the weight and surrounding storages surfaces should be wiped clean. Put on gloves (preferably nitrile rubber gloves) and wipe the surface of the weight and storage rack with a damp paper towel to remove any loose lead oxide. Place the towel and glove in a double plastic, sealable bag for disposal. After the cleaning, the weight may be handled with leather or canvass work gloves, but the gloves should be washed or replaced frequently, at least every 3 or 4 field trips.
After handling a lead weight, employees must wash their hands thoroughly before eating, drinking, or smoking even if gloves were worn to handle the weights. Some studies indicate mild soap and water are not as effective in removing lead from the skin, as other commercially available hand cleansers, such as those containing chelating agents for the removal of lead and toxic metal residues (URL: http://www.hygenall.com/). Regardless of the hand cleaning product used, the most effective way to prevent skin contamination is to always wear gloves when handling lead and thoroughly wash hands immediately after.
Storing Lead Weights
Store uncoated lead sounding weights, or weights with deteriorating coatings, in a manner that minimizes contamination of surrounding surfaces and equipment with lead dust. For example, in warehouse facilities, store weights on plastic sheeting or rubber mats on the warehouse floor in a designated area of the facility away from traffic corridors and apart from more frequently used equipment. Replace the underlayment frequently to prevent accumulation of lead dust, generally about once a year.
If an uncoated weight or a weight with deteriorating coating is stored in a vehicle, such as a van, ensure that lead oxide dust does not contaminate the vehicle, especially the passenger compartment. Where practical, store weights in external vehicle compartments or weight racks. If the weights must be stored in a van, minimize opportunities for metal-to-metal abrasion by using rubber padding or plastic sheets and cover the weights with plastic bags or sheeting to minimize the generation and mobility of lead oxide dust.
Keep clothing (including personal protective clothing) in a separate area of the vehicle or in an enclosed container so that it is not on the floor or in contact with the weights or the lead dust that might otherwise accumulate on them.
Testing for Lead Contamination
Periodic testing and cleaning of surfaces where lead sounding weights are stored is crucial to effectively control lead contamination. Vehicle and storage surfaces should be tested for lead contamination at least once every year. Test surfaces such as vehicle cargo and passenger compartments, lockers, and warehouse shelves and floors where lead weights are stored at least once a year.
Clean surfaces where tests results indicate lead contamination. Clean surfaces using a wet sponge mop or cloth. DO NOT SWEEP OR BRUSH lead dust. Large quantities of debris and dust can be removed using a High Efficiency Particulate Air (HEPA)-filtered vacuum. (Note: Change out of vacuum filters may require additional precautions and disposal procedures. Contact your collateral duty safety office for further guidance.)
Once a contaminated surface has been cleaned, a second test should be conducted to verify that the surface is no longer contaminated.
The “USGS Clean-up Plan for Surface Contamination from Lead Weights” (attachment 2) provides procedures for testing and clean-up and identifies sources for testing kits and laboratory services.
Testing Employee Blood-Lead Levels
Concerned employees are entitled to have their blood tested for lead at cost center expense. Blood testing can be achieved through existing arrangements with contract occupational health units or local doctors and health clinics. The venous blood sample that is collected should be shipped to a laboratory participating in the Center for Disease Control (CDC) National Center for Environmental Health (NCEH) Blood Lead Level Reference System (BLLRS). A list of OSHA approved laboratories is posted on the OSHA home page (URL: http://www.osha.gov/SLTC/bloodlead/state_list.html). In addition, cost centers should include testing for lead in blood as a routine part of their medical monitoring program.
Please contact your Regional Safety Officer or the USGS Industrial Hygienist (Anthony Zepeda; 703-648-7551; email@example.com) for advice or if you have questions about lead contamination, testing, or clean up.
Concern about contamination from lead weights is a relatively recent phenomenon sparked by positive results of testing of some WSC weight-storage areas. While we do not believe that lead contamination has affected the health of any Water Resources Discipline employee, the use of coatings or improved storage, handling, and hygiene practices will mitigate any residual concern.
Stephen F. Blanchard //signed//
Chief, Office of Surface Water