Cadmium, diesel, lead, manganese, mercury,
methylene chloride, and nickel showed
roughly linear dose–response relationships
between concentration and OR of ASD
(Figure 1). Of these, the test of linear trend
in models with each observation assigned the
median of its quintile was statistically significant
for all except cadmium (p = 0.06). The
pooled metals metric was significant as well
(Table 2). In models restricted to boys, linear
trends were steeper with smaller p-values.
Adjusted for false discovery rate, no linear
trend tests were significant at p < 0.05 for
both sexes together. For boys, linear trends
of all metals except for cadmium were statistically
significantly associated with ASD
after adjustment for false discovery rate, as
were diesel and methylene chloride (Table 2).
We did not find meaningful differences in
the relationship between the overall metals
metric and ASD in models accounting
for birth state, family income, spouse/
partner’s education, smoking during pregnancy,
HAP model year, or urbanicity [see
Supplemental Material, Table S3 (http://
dx.doi.org/10.1289/ehp.1206187)].