# Presentation: 006022

## Michael.Kosnett@uchsc.edu

**Michael.Kosnett@uchsc.edu**

## OSHA Lead Standards: Medical removal not mandatory until blood lead concentrations ≥ 50 μg/dL 

**Health effects of lead at low dose warrant a reappraisal of the levels of lead exposure that may be safely tolerated in the workplace.**
** *****Chronic****** effects of ******cumulative****** dose ***
-  ***Acute effects of recent dose***
***hypertension***
***decrements in renal function******	***
***cognitive dysfunction***
***adverse reproductive outcome***

## Meta-analyses: 

- Nawrot et al, 2002

- Schwartz, 1995

**Meta-analyses: **
******PbB  5 ******** 10 μg/dL**
**= ******** 1.0 or 1.25 mmHg in systolic blood pressure**

## The Relationship of Bone and Blood Lead to Hypertension. The Normative Aging Study Hu H et al, JAMA 1996; 275:1171-1176

**Case control study: 146 hypertensive men; 444 controls selected from large, ongoing prospective study of aging. Mean age = 66.6 ±7.2 y**
**Exposure reflects that of general population.   Mean PbB = 6.3 ug/dL**

**Final logistic model (backward elimination) yielded 3 significant risk factors for hypertension:**
**	****	****Body mass index**
**	****	****Family history of hypertension**
**	****	****Tibia bone lead concentration**

***From the lowest quintile of bone lead to the highest quintile,***
***the odds of being hypertensive increased by 50 % ***
***O.R. = 1.5 (95% C.I. 1.1 - 1.8)***

## Impairment of renal function with increasing blood               lead concentration in the general population 

**Impairment of renal function with increasing blood               lead concentration in the general population **

**Staessen JA et al. NEJM 327:151-6; 1992**

**• ****Random population sample of 965 men and 1016 women (age 20 to 88)**
**• ****Blood lead range 1.7 - 72.5 ug/dL; geometric mean (GM) ≈ 10 ug/dL**
**• ****Significant correlation between age-adjusted creatinine clearance and blood lead **
**• ****Relationship persisted after excluding subjects with occupational Pb exposure, or those with highest tercile of PbB ( GM = 18.4 ug/dL)**

## Bone lead concentration predicts decrements in cognitive function in older adults

**1. Baltimore Memory Study (Shih et al, 2006**)

**N = 991 randomly selected, sociodemographically diverse community dwelling adults, aged 50 to 70 yrs**
**	****Mean PbB = 3.5 ± 2.2 μg/dL****	****	****	****	****	****Tibia lead:  ********visuoconstruction on neuropsych testing****	*********** 13 ppm equivalent impact of 4.8 years of age***

## Spontaneous Abortion [Borja-Aburto et al, 1999]

**Spontaneous Abortion**** ****[Borja-Aburto et al, 1999]**

**• ****562 of 668 women followed through week 20; (16% loss to follow-up)**
**• ****Average blood lead at enrollment:  11 ug/dL**
**• ****Cases (n=35) PbB = 12 ug/dL****	****	****Controls  (n=60) PbB = 10ug/dL**

_**PbB level (ug/dL)**_**	****	**_**Odds Ratio**_
**< 5****	****	****	****	****  1.0 [referent]**
**5-9****	****	****	****	****  2.3**
**10-14****	****	****	****	****  5.4**
**≥ ****15****	****	****	****	****12.2**

**test for trend *****p***** = 0.021;  ****	****	****	****	****	*****for ************PbB of 5 μg/dL, O.R. = 1.8  (C.I. 1.1, 3.1)***

## Mexico City Prospective Lead Study 		(Schnaas et al 2006)

**3rd Trimester PbB = 7.8 μg/dL**
**Every doubling of PbB associated with IQ ********2.7 pts     at  6 - 10 yrs of age**

**N = 150**

## Slide 9

| BLL (μg/dL) | Management |
| --- | --- |
| < 5 | None indicated |
| 5 - 9 | Discuss health risks	
Reduce Pb exposure for women who are or may become pregnant |
| 10 - 19 | Decrease lead exposure. 
Increase biological monitoring.	 Consider removal from exposure to avoid long term risks if exposure control over an extended period does not decrease BLL < 10, or if medical condition present that increases risk with continued exposure     |
| 20 -29 | Remove from exposure if repeat BLL measured in 4 weeks remains ≥ 20 |

## Slide 10

| BLL (μg/dL) | Management |
| --- | --- |
| 30 - 39 | Remove from lead exposure |
| 40 - 79 | Remove from lead exposure	
Refer for prompt medical evaluation
Consider chelation for BLL >50 with significant symptoms or signs |
| ≥ 80 | Remove from lead exposure	
Refer for immediate/urgent medical evaluation			
Probable chelation therapy	     |

## Slide 11

| Category | Recommended medical surveillance |
| --- | --- |
| All lead-exposed workers | Baseline/preplacement H&P, baseline BLL, serum creatinine |
| BLL < 10 | BLL q month for first 3 mo. or if ∆ to higher exp., then BLL q 6 mo.				     
If BLL  ≥ 5, evaluate exposure and protective measures.  Increase monitoring if indicated |
| BLL 10 - 19 | As above for BLL < 10, plus:			
BLL q 3 months
Evaluate exposure, controls, work practices
Consider removal
Revert to BLL q 6 mo after 3 BLLs < 10 |
| BLL ≥ 20 | Remove from exposure if repeat BLL measured in 4 weeks remains ≥ 20, or if first BLL ≥ 30
Monthly BLL
Consider return to lead work after 2 BLLs <15 a month apart, then monitor as above |

## Surveillance recommendations apply to all potential lead exposed workers, even in absence of documented elevations in air lead levels.

**Routine measurement of zinc protoporphyrin not indicated**

**With potential exception of annual BP measurement and risk factor questionnaire, medical evaluations unnecessary for workers maintaining BLL < 20 μg/dL.**

**Annual worker education about lead hazards is recommended.**

## Chelation for lead intoxication in adults

**BLLs ≥ 100 μg/dL almost always warrant chelation.**
**BLL 80 - 99 μg/dL, with or without symptoms, can be considered for chelation, as may some symptomatic individuals with blood lead concentrations of 50 - 79**
**Chelation not recommended for asymptomatic individuals with low blood lead concentrations**

## Slide 14

## Slide 15