Lead Testing

Though the consequences of lead exposure in the occupational setting and in pediatric preventive health have been extensively reported, the issue of agricultural exposure to lead has likely been underappreciated. Lead exposure on farms has been recognized for decades, but few scientific studies have focused on this health risk factor (see Chapter 23).

Occupational exposures have been attributed to work in smelters and with paint, storage batteries, pigments, solder, ammunition, and gasoline additives. Greater than 100 occupational activities and job titles have been associated with risk of lead exposure.

Agricultural activities can include many of the same lead exposure scenarios. Farm equipment maintenance may involve exposure because of lead-based paint on older equipment. Many farmers perform cutting, welding, soldering, and brazing without the benefit of personal protective equipment or even minimal environmental controls. In some farm settings, water systems are soldered with lead-based solder, which may leach into water supplies. Older buildings may contain lead-based paint. Melting of lead to produce weights, sinkers, and ammunition can pose a threat of lead exposure. Despite the potential risks, family farms and most agricultural activities are not subject to monitoring. Table 9.2 provides a summary of United States regulations and standards for lead.

Farm environments can expose certain at-risk populations, including pregnant women and children, to higher-than-acceptable lead concentrations. A report by the Institute of Medicine described a "glaring and significant gap

Table 9.2. Summary of standards and regulations for lead.

Agency

Media

Level

Comments

Centers for Disease

Blood

10 |g/dL

Advisory; level of concern for

Control and

children

Prevention

Occupational Safety

Blood

40 |g/dL

Regulation; cause for written

and Health

notification and medical exam

Administration

50 |g/dL

Regulation; cause for medical removal from exposure

Air (workplace)

50 |g/m3 30 |g/m3

Regulation; permissible exposure limit (8-hr average) (general industry) Regulation; action level

National Institute

Air (workplace)

50 | g/m3

Advisory; recommended exposure

for Occupational

limit (nonenforceable)

Safety and Health

100 mg/m3

Advisory; immediately dangerous to life and health

American

Air (workplace)

150 |g/m3

TLV/TWA guideline for lead

Conference of

arsenate

Governmental

50 | g lead/m3

TLV/TWA guideline for other

Industrial

forms of lead

Hygienists

Blood

30 |g/dL

Advisory; biological exposure index

U.S. Environmental

Air (ambient)

1.5 | g/m3

Regulation; National Ambient

Protection

Air Quality Standard; 3-month

Agency

average

Soil (residential)

400 mg/kg

Soil screening guidance

Water (drinking)

15 | g/L 0 |g/L

Action level for public supplies Nonenforceable goal; maximum contaminant level goal

Food and Drug

Food

Various

Action levels for various foods;

Administration

example: lead-soldered food cans now banned

Consumer Product

Paint

600 ppm

Regulation; by dry weight

Safety Commission

(0.06%)

TLV/TWA, threshold limit value/time-weighted average; ppm: parts per million.

Source: Data from Center for Disease Control and Prevention, Agency for Toxic Substances and

Disease Registry (13).

TLV/TWA, threshold limit value/time-weighted average; ppm: parts per million.

Source: Data from Center for Disease Control and Prevention, Agency for Toxic Substances and

Disease Registry (13).

in the scientific literature" for research on health hazards to the children of migrant workers (14,15).

The clinical risks associated with lead have been abundantly documented. Low-level exposures in pediatric populations have been associated with abnormalities of neural development, cognitive development, and behavior. Chronic low-level exposure in adults has recently been associated with all-cause mortality (16,17).

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