# Presentation: 663878

## Lead Exposure Among Females of Childbearing Age — United States, 2004What Does ABLES Tell Us?

**Sara Luckhaupt, MD, MPH**
**Surveillance Branch**
**CDC, NIOSH, DSHEFS**

**Notes:**
Good morning.

## Lead Exposure

**Blood lead levels (BLLs) declining in US**
**Remains a substantial public health problem among certain groups at high risk **
**Workers in certain industries**
**CDC recommends interventions for children with BLL **_**>**_**10 ********g/dL **
**Recommendations for adults less consistent **

**Notes:**
Although Blood lead levels (abbreviated BLLs) among the US population have declined in recent decades,
Lead remains a substantial public health problem among certain high risk groups, including workers in certain industries
Although CDC recommends interventions for children with BLLs >=10 g/dL,
Recommendations regarding safe BLLs for adults are less consistent 

## Prenatal Lead Exposure

**Childhood neurobehavioral development affected by lead exposure**
**Lead crosses the placenta **
**Prenatal BLL **_**>**_**5 ********g/dL inversely associated with child’s IQ through age 10**
**Exposure should be prevented among all females of child-bearing age**

**Notes:**
Prenatal lead exposure is a concern because it affects childhood neurobehavioral development 
Lead crosses the placenta to the developing fetus and 
According to recent studies, prenatal blood lead levels (BLLs) >=5 ug/dL are inversely associated with a child’s IQ through at least age 10
Since many pregnancies in the US are unplanned, exposure should be prevented in all females of child-bearing age

## Adult BLL Recommendations

**<5 ********g/dL: limit recommended for pregnant women by the Association of Occupational and Environmental Clinics**
**25 ********g/dL: limit set by *****Healthy People 2010***** **
**≤****40 ********g/dL: OSHA limit for returning to work after being medically removed   **

**Notes:**
Here are some examples of adult BLL recommendations:

5 g/dL is the limit recently recommended for pregnant women by the Association of Occupational and Environmental Clinics 
25 g/dL is the limit set by Healthy People 2010 in its public health objective for adults; the goal is to eliminate all BLLs above this level 
40 g/dL is the limit at which OSHA will permit a worker to return to work after being medically removed due to lead exposure.  

## Study Objectives

**Use ABLES data to estimate the prevalence of females of child-bearing age in the US whose BLLs exceed recommendations ranging from 5 to 40 ********g/dL**
**Identify risk factors for elevated BLLs**
**Compare ABLES estimate to population-based NHANES sample**

**Notes:**
The objectives of this study were to Use ABLES data to estimate the prevalence of females of childbearing age in the US whose BLLs exceed recommendations ranging from 5 to 40 g/dL,
Compare an ABLES-based estimate of the number of females of childbearing age with BLLs >=10 to that predicted by the population-based National Health and Nutrition Examination Survey (or NHANES) sample,
And Identify risk factors for elevated BLLs among females of childbearing age

## Adult Blood Lead Epidemiology and Surveillance (ABLES)

**NIOSH ****— ****State partnership **
**Laboratory-based BLL reporting legally mandated in states**
**Reasons for BLL testing **
**OSHA mandated medical surveillance based on workplace air lead level**
**Clinical judgment of risk for lead exposure **

**Notes:**
The Adult Blood Lead Epidemiology and Surveillance program, known by the acronym ABLES, is a NIOSH--State partnership to prevent elevated blood lead levels in adults
Laboratory-based BLL reporting is legally mandated in most participating states.
ABLES is a passive surveillance system.
BLL testing, and thus inclusion in the surveillance system, is based on compliance with OSHA mandated medical surveillance based on elevated air lead levels in the workplace or clinical judgment of risk for lead exposure.

## Adult Blood Lead Epidemiology and Surveillance (ABLES)

**ABLES Data Includes**
**BLL**
**Sex, age, race**
**Standard codes for occupation and industry**
**Nonoccupational sources of lead exposure**
**Code for work-relatedness of lead exposure**

**Notes:**
Each ABLES record Includes
BLL
Demographics including Sex, Age, and Race
Standard codes for occupation & industry
non-occupational sources of lead exposure
And a code for work-relatedness of lead exposure

## States Participating in ABLES, 2004

**States Participating in ABLES, 2004**

**States reporting BLLs **_**>**_**25 ********g/dL**

**States reporting all BLLs**

**States not participating**

**Notes:**
37 states, participated in ABLES in 2004
All participating states are required to report all BLLs >25 g/dL 
10 states (shown in solid yellow) chose to report all BLLs of all levels to ABLES in 2004

## Case Definitions

**Occupational cases **
**Females age 16****–****44**
**BLL **_**>**_**5********g/dL **
**Valid industry code *****or***** work-related code**
**Nonoccupational cases**
**Females age 16****–****44**
**BLL **_**>**_** 5********g/dL **
**No valid industry code or work-related code**

**Notes:**
These are the case definitions used for this analysis of ABLES data:
Occupational cases: 
Females aged 16-44
BLL > 5g/dL 
Records contain a valid industry code or work-related code

Non-occupational cases:
Females aged 16-44
BLL > 5g/dL 
Records do not contain valid industry code or work-related code

## Rate Calculations

**Occupational cases**
**Denominator: female workers aged 16****–****44 in reporting states **
**All cases**
**Denominator: female residents aged 16****–****44 in reporting states**
**Rates above 5 and 10 ********g/dL calculated by using 10 states that reported all BLLs in 2004**
**Rates above 25 and 40 ug/dL calculated by using all 37 ABLES states**

**Notes:**
Rates of Occupational cases were calculated using as the
    Denominator: # of female workers aged 16-44 in reporting states 
According to Bureau of Labor Statistics 2004 Current Population Survey 

Rates of All cases were calculated using as the
Denominator: # of female residents aged 16-44 in reporting states 
According to Census estimates for 2004

Rates of BLLs above the cutpoints of 5 and 10 ug/dL were calculated by using 10 states in the numerator and the denominator (the states that reported all BLLs to ABLES in 2004); rates above 25 and 40 ug/dL were calculated by using all 37 ABLES states in the numerator and denominator.

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 10 States that Reported all BLLs to ABLES—2004

| Exposure status | BLL >40 |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | No. | Rate* |  |  |  |  |  |  |
| 
All exposures | 
8 | 
0.06 |  |  |  |  |  |  |
| 
Occupational exposures
 | 
2 | 
0.02 |  |  |  |  |  |  |

***Rate per 100,000 female residents aged 16-44**

**Notes:**
These next few slides show the number and rate of females reported to ABLES with BLLs above cutpoints of decreasing magnitude.  You will see that as the cutpoint for calling a BLL elevated decreases, the number and rate of females with elevated BLLs increase.  These numbers and rates are based on the 10 states that reported BLLs of all levels to ABLES in 2004.  Rates are per 100,000 female residents aged 16-44.

8 females of child-bearing age from these 10 states had BLLs >=40 reported to ABLES in 2004, for a rate of 0.06 per 100,000.
2 of these cases had evidence of occupational exposure.

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 10 States that Reported all BLLs to ABLES—2004

| Exposure status | BLL >40 |  | BLL >25 |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | No. | Rate* | No. | Rate* |  |  |  |  |
| 
All exposures | 
8 | 
0.06 | 
86 | 
0.7 |  |  |  |  |
| 
Occupational exposures
 | 
2 | 
0.02 | 
55 | 
0.6 |  |  |  |  |

***Rate per 100,000 female residents aged 16-44**

**Notes:**
86 females of childbearing age from these 10 states had BLLs >=25, including the 8 females with BLLs >=40.
A majority of the cases >=25 had evidence of occupational exposure.

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 10 States that Reported all BLLs to ABLES—2004

| Exposure status | BLL >40 |  | BLL >25 |  | BLL >10 |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | No. | Rate* | No. | Rate* | No. | Rate* |  |  |
| 
All exposures | 
8 | 
0.06 | 
86 | 
0.7 | 
476 | 
3.8 |  |  |
| 
Occupational exposures
 | 
2 | 
0.02 | 
55 | 
0.6 | 
254
 | 
2.9 |  |  |

***Rate per 100,000 female residents aged 16-44**

**Notes:**
If the cutpoint for elevated BLLs is lowered to 10 ug/dL, 476 cases meet the definition for BLL of concern, for a rate of 3.8 per 100,000 females.
A majority of cases at this level have evidence of occupational exposure.

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 10 States that Reported all BLLs to ABLES—2004

| Exposure status | BLL >40 |  | BLL >25 |  | BLL >10 |  | BLL >5 |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | No. | Rate* | No. | Rate* | No. | Rate* | No. | Rate* |
| 
All exposures | 
8 | 
0.06 | 
86 | 
0.7 | 
476 | 
3.8 | 
1,370 | 
10.9 |
| 
Occupational exposures
 | 
2 | 
0.02 | 
55 | 
0.6 | 
254
 | 
2.9 | 
442 | 
5.0
 |

***Rate per 100,000 female residents aged 16-44**

**Notes:**
If the cutpoint for elevated BLLs is lowered to 5, as has been suggested for pregnant women by the Association of Occupational and Environmental Clinics, 1,370 females of childbearing age would be considered to have elevated BLLs in the 10 ABLES states with complete recording, for a rate of 10.9 per 100,000 females residents.
Less than half of cases at or above 5 ug/dL had evidence of occupational exposure.

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 37 States that Participated in ABLES—2004

| Exposure status | BLL >40 |  | BLL >25 |  |
| --- | --- | --- | --- | --- |
|  | No. | Rate* | No. | Rate* |
| 
All exposures | 
42 | 
0.08 | 
342 | 
0.7 |
| 
Occupational exposures
   All manufacturing
   Manufacturing CIC 3490 †
   Metal ore mining
   Construction
   Other industry
 | 
14
11
6
1
0
2 | 
0.04
0.4
8.4
—
—
0.0006 | 
224
199
178
13
7
2 | 
0.6
7.1
244
—
1.2
0.006 |

***Rate per 100,000 female workers aged 16-44**
**†****Includes lead storage battery manufacturing**

**Notes:**
For cases with evidence of occupational exposure, we calculated numbers and rates of female workers with BLLs >=40 and >=25 in all 37 states participating in ABLES.
We calculated summary rates for all workers and industry-specific rates for workers in industries with a high potential for lead exposure.

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 37 States that Participated in ABLES—2004

| Exposure status | BLL >40 |  | BLL >25 |  |
| --- | --- | --- | --- | --- |
|  | No. | Rate* | No. | Rate* |
| 
All exposures | 
42 | 
0.08 | 
342 | 
0.7 |
| 
Occupational exposures
   All manufacturing
   Manufacturing CIC 3490 †
   Metal ore mining
   Construction
   Other industry
 | 
14
11
6
1
0
2 | 
0.04
0.4
8.4
—
—
0.0006 | 
224
199
178
13
7
2 | 
0.6
7.1
244
—
1.2
0.006 |

***Rate per 100,000 female workers aged 16-44**
**†****CIC=****Census Industry Code; 3490 includes lead storage battery manufacturing**

**Notes:**
The highest rate was 244 BLLs >=25 ug/dL per 100,000 females employed in the manufacturing industry that includes lead storage battery manufacturing, compared to 7.1 per 100,000 females employed in the whole manufacturing sector, 1.2 per 100,000 females employed in construction, and 0.6 per 100,000 female workers overall.

## Sources of Non-occupational Exposure for Women of Child-bearing Age with BLL >25 g/dL — ABLES, 2004

**Notes:**
This graph shows Sources of Non-occupational Exposure for Women of Child-bearing Age with BLL >25 g/dL in the 37 ABLES states in 2004.  70% of cases without evidence of occupational exposure had unknown sources of exposure.  Among those with known sources of nonoccupational exposure, common sources included home painting and remodeling (shown in orange).  

## ABLES vs. NHANES

|  | ABLES | NHANES |
| --- | --- | --- |
| 
Sampling strategy | 
Labs report all BLLs performed during clinical practice | 
Complex, multistage probability sample of US civilian population |
| 
Sample timing | 
Highest BLL reported during calendar year | 
Random |
| 
Number of females (16-44) tested in 2003-2004 | 
17,990 (10 states) | 
1,649 |
| 
Representativeness in 2003-2004 | 
10 states reported all BLLs: CA, HI, IA, MN, MO, MN, NM, RI, WI, WY | 
Designed to be nationally-representative |

## Number and Rate of Females of Childbearing Age with BLLs >10 g/dL

|  | ABLES, 2004 |  |
| --- | --- | --- |
|  | No. | Rate* |
| All exposures | 
476 | 
3.8 |
|  |  |  |

***Rate per 100,000 female residents aged 16-44**

**Notes:**
Now I will discuss how the rate of BLLs >=10 ug/dL among females of childbearing age indicated by ABLES data compares to the rate predicted by NHANES data for females in a similar age group from 1999-2002.
The NHANES estimate is based on blood tests from a random sample of females in the US.
On the other hand, the ABLES estimate assumes that all females exposed to lead have been identified through workplace screening or by their private health care providers and appropriately tested, and that all lab tests have been reported to the ABLES program through the state health department. 

## Number and Rate of Females of Childbearing Age with BLLs >10 g/dL

|  | ABLES, 2004
 |  | NHANES, 2003-2004
 |  |
| --- | --- | --- | --- | --- |
|  | No. | Rate* | No. | Rate† |
| All exposures | 
476 | 
3.8 | 
 2 | 
81.9 |
|  |  |  |  |  |

***Rate per 100,000 female residents aged 16-44**
**†****Rate per 100,000 females aged 16-44**

**Notes:**
The right column, in yellow, shows NHANES results.
The estimated rate based on ABLES is almost 100-fold lower than the rate predicted by NHANES, suggesting that ABLES, and current clinical practice, are missing a majority of females of child-bearing age with BLLs >=10 ug/dL.

## Predicted Total Number of US Females  of Childbearing Age with BLLs >10 g/dL

**Based on 2004 ABLES data**
**2,282 (95% CI 763****–3,800)**
**Based on 2003****–****2004 NHANES data**
**49,352 (95% CI 0****–117,752)**
**1⁄3**** ****to 1⁄2 of US pregnancies unplanned**

**Notes:**
Multiplying the rates estimated with ABLES and NHANES data by the number of females aged 16-44 in the US, yields estimates of the number of females of childbearing age with BLLs >=10.  
Using ABLES data this number is 2,282 with a 95% upper confidence limit of 3,800.
Using NHANES data this number is 49,352 but the confidence interval is very wide with a lower 95% confidence limit of 0.
These numbers are concerning because 1/3 to 1⁄2 of US pregnancies are unplanned.

## Conclusions

**According to ABLES, many females of child-bearing age in the US have elevated BLLs**
**Discrepency between ABLES data and NHANES prediction suggests many exposed women are not tested**
**Rates of nonoccupational exposure similar to occupational exposure**
**Magnitude of the problem varies greatly according to BLL recommendation**
**Current occupational standards not protective**

**Notes:**
In conclusion,
According to ABLES, many females of child-bearing age in the US have elevated BLLs
The large Discrepency between ABLES data and the NHANES prediction suggests many exposed women are not tested
Rates of nonoccupational exposure are similar to occupational exposure; and many nonoccupational exposure sources are unknown
The Magnitude of the problem varies greatly according to the BLL recommendation used as a cutpoint
Current occupational standards are not protective

## Limitations

**Population estimates from ABLES data underestimate true prevalence of lead exposure****	**
**Many women at risk do not have their BLLs measured **
**Some labs might not report results to States**
**Underreporting likely varies by industry**
**Data on occupational sources of exposure might be incomplete, causing misclassification**
**Industry-specific denominators based on limited sample sizes**
**Comparison to NHANES limited by differing methodology**

**Notes:**
This study was subject to several limitations:
First, ABLES likely underestimates the true prevalence of lead exposure because many women at risk do not have their BLLs measured and some labs might not report all results to State Health Departments
Second, Underreporting likely varies by industry; for example, the battery industry may appear high due to consistent reporting, while reporting within the construction industry may be less consistent, making its rate appear lower than it actually is
Third, Data on occupational sources of exposure may be incomplete, causing misclassification
Industry-specific denominators are based on limited sample sizes
Finally, there are several limitations associated with our comparison between ABLES and NHANES data

## Recommendations

**Educational campaigns to increase awareness of occupational and nonoccupational risks for lead exposure among HCWs and the public**
**Better guidance for HCWs regarding when to test adults**
**More protective occupational standards and clinical recommendations **

**Notes:**
We recommend 
Educational campaigns to increase awareness of occupational and nonoccupational risks for lead exposure among HCWs and the public
Better guidance for HCWs regarding when to test adults for lead exposure
More protective occupational standards and clinical recommendations 

## Acknowledgments

**NIOSH**
**Geoffrey Calvert**
**Marie Haring-Sweeney**
**Robert Roscoe**
**Janet Graydon**
**Marty Petersen**
**ABLES State Coordinators**

***The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.***

**Notes:**
I wish to acknowledge my supervisors, Geoff Calvert and Marie Haring-Sweeney,
Bob Roscoe, the ABLES project officer
Janet Graydon, the ABLES data manager

And I also want to acknowledge the ABLES state coordinators

## 

EXTRA SLIDES

**EXTRA SLIDES**

## Rate of Females Aged 16-44 Years with Elevated BLLs Among 37 States that Participated in ABLES, 2003–2005

**No significant linear trend**

## Occupational Lead Standards

**NIOSH *****Recommended***** Exposure Limit (REL): 50 ********g/m****3**** in air, averaged over an 8-hour period (1978?)**
**OSHA *****Permissible***** Exposure Limit (PEL): 50 ********g/m****3**** in air, averaged over an 8-hour period (1978)**
**OSHA Action Level: 30 ********g/m****3**** in air, averaged over an 8-hour period**
**Medical surveillance required for employees exposed at or above action level for >30 days/yr**
**Employee removed if BLL **_**>**_**60 ********g/dL or average **_**>**_**50 ********g/dL**
**Employee may return to work when BLL **_**<**_**40 ********g/dL (x2)**

## Slide 29

## Sex-Specific Occupational Exposure Limits for Lead

| Country | Airborne Limit (mg/m3) | BLL for Men (g/dL) | BLL for Women (g/dL)
 |
| --- | --- | --- | --- |
| Australia | 0.2 | 50 | 20 |
| Finland | N/A | 40 | 40* |
| Germany | 0.1 | 70 | 30 |
| Israel | 0.1 | 60 | 30 |
| Netherlands | 0.1 | 60 | 45 |
| South Africa | 0.15 | 80 | 40 |
| Sweden | 0.1 | 50 | 30 |
| UK | 0.15 | 70 | 40 |
| USA | 0.05 | 50 | 50* |

**Source: www.okinternational.org/StandardTable.pdf**

***No difference in limits for women vs. men**

## Results

**BLLs for 20,079 women of child-bearing age (WCBA) reported to ABLES in 2004**
**1,773 (8.8%) had multiple tests**
**In 10 states that reported  BLLs of all levels**
**1,370 WCBA had BLLs **_**>**_**5 ********g/dL**
**476 WCBA had BLLs **_**>**_**10 ********g/dL**
**In 37 states that reported all BLLs **_**>**_**25 ********g/dL**
**342 WCBA had BLLs **_**>**_**25 ********g/dL**
**42 WCBA had BLLs **_**>**_**40 ********g/dL**

**Notes:**
BLLs for 20,079 women of child-bearing age (WCBA) were reported to ABLES in 2004
1,773 women (or 8.8%) had multiple tests
In 10 states that reported  BLLs of all levels
1,370 WCBA had BLLs >5 g/dL
476 WCBA had BLLs >10 g/dL
In 37 states that reported all BLLs >25 g/dL
342 WCBA had BLLs >25 g/dL
42 WCBA had BLLs >40 g/dL

## Number and Rate of Females Aged 16-44 Years with Elevated BLLs Among 10 States that Reported all BLLs to ABLES—2004

| Exposure status | BLL > 5 |  | BLL >10 |  | BLL >25 |  | BLL >40 |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | No. | Rate | No. | Rate | No. | Rate | No. | Rate |
| 
All exposures | 
1,370 | 
10.9 | 
476 | 
3.8 | 
86 | 
0.7 | 
8 | 
0.06 |
| 
Occupational exposures
 | 
442 | 
5.0
 | 
254
 | 
2.9 | 
55 | 
0.6 | 
2 | 
0.02 |